Ecole Doctorale

Gaïa These

Asma Djeddi

Professeur Anne-Sylvie Andre-Mayer

Professeur Sébastien Pilet

Johann Tuduri

Anne-Sylvie Andre-Meyer

Emilie Bruand

Johan Tuduri D'

Christophe Nevado

Doriane Delmas

Céline Martin

Léa Causse

Fabrice Barou

Bernard Boyer

Romain Lafay

Loïc Blanchard

Merci À Clément

Maël Agathe Nestor

Pétrogenèse des carbonatites et magmas alcalins protérozoïques d'Ihouhaouene (terrane de l'In Ouzzal, Hoggar occidental, Algérie) Devant le jury composé de

Keywords: Carbonatite, Syénites, Terres rares, Immiscibilité, Hybridation, Ihouhaouene, Archéen Carbonatite, Syenites, Rare earth element, Immiscibility, Hybridization, Ihouhaouene, Archaean

Ce travail de thèse a pu voir le jour grâce à la participation des autorités, des guides de terrain et des chauffeurs durant ma mission de terrain dans le Hoggar. Je tiens à exprimer ma gratitude à Massinissa, Bouaalam et Basset pour l'aide qu'ils m'ont offerte lors de ces 15 jours de travail dans des conditions extrêmes dans le désert du Hoggar.

Je tiens en particulier à exprimer ma gratitude à mes directeurs de thèse :

Ouzegane, merci de m'avoir proposé ce sujet passionnant et de m'avoir donner la chance de réaliser cette cotutelle de thèse. Merci pour tes encouragements et pour toutes les discussions lucratives à l'USTHB, à Montpellier ou par téléphone et de m'avoir fait confiance durant toutes ces années. Fleurice Parat, je tiens particulièrement à te remercier pour toutes ces années de Carbonatites ! Merci de m'avoir initiée aux Processus magmatiques et d'avoir partagé avec moi la chasse aux trésors dans les britholites et les monazites. Oui, il ne me reste plus que! La phrase qui nous a fait tant rire. Merci d'avoir cru en moi et de m'avoir accompagnée jusqu'au bout de cette thèse. Merci à Jean Louis-Bodinier de m'avoir donnée la chance de bénéficier et participer au Projet MEDYNA qui a financé une bonne partie de ma thèse et toutes les analyses réalisées dans le cadre de ma cotutelle. Merci pour toutes les discussions instructives et merci de m'avoir intégrée dans le monde de la modélisation géochimique. Un grand merci à Jean-Marie Dautria (Dodo) pour tous les débats scientifiques et pourquoi pas parfois politiques ! Merci de m'avoir aidée dans tous les moments de stupeur des britholites et d'apatites et en général des carbonatites.

Jusqu'à la fin des années cinquante, les carbonatites ont été cartographiées comme des calcaires (revue dans Louardi, 1994). En 1910, Daly, proposa le premier modèle d'assimilation de calcaire par les magmas granitiques. Puis en 1962, Pecora explique la genèse de ces roches alcalines par le transfert d'éléments volatils ou par précipitation à partir de solutions hydrothermales. [START_REF] Borodin | The role of metasomatic processes in the formation of alkaline rocks[END_REF] ont attribué quand à eux une origine métasomatique aux complexes ultrabasiques alcalins. L'origine magmatique des roches carbonatées a été longtemps rejetée pour des raisons physiques dû au point de fusion élevé de la calcite (1310ºC) incompatible avec les températures de mise en place des carbonatites obtenues à partir des équilibres minéralogiques [START_REF] Bowen | The Evolution of the Igneous Rocks[END_REF].

L'origine magmatique est définitivement acceptée pour les carbonatites après plusieurs travaux expérimentaux menés durant les 3 dernières décennies et suite aux études du seul volcan carbonatitique actif d'Oldoinyo Lengai en Tanzanie célèbre pour ses extrusions de natrocarbonatites [START_REF] Bell | Carbonatite Volcanism: Oldoinyo Lengai and the Petrogenesis of Natrocarbonatites[END_REF]. Cependant, les températures de mise en place des carbonatites font toujours l'objet de plusieurs études et controverses. [START_REF] Gittins | Problems inherent in the application of calcite-dolomite geothermometry to carbonatites Contrib[END_REF] propose une température de 885ºC à partir des carbonates pour les carbonatites de Goldary (Ontario). [START_REF] Romanchev | Liquation in the production and geochemistry of rocks in carbonatite complexes[END_REF] proposent 14 des intervalles de températures de 550 à 850ºC et de 760 à 1180ºC à partir de l'étude des inclusions fluides dans diverses carbonatites (e.g. Kodvor, Péninsule de Kola, Russie).

Les derniers travaux expérimentaux proposent trois hypothèses selon lesquelles les magmas carbonatés sont: (1) des magmas mantelliques primaires provenant de la fusion partielle d'une péridotite carbonatée [START_REF] Dalton | The compositions of primary carbonate melts and their evolution through wallrock reaction in the mantle[END_REF][START_REF] Gudfinnsson | Continuous gradations among primary carbonatitic, kimberlitic, melilititic, basaltic, picritic, and komatiitic melts in equilibrium with garnet lherzolite at 3-8 GPa[END_REF]Dasgupta et Hirschmann, 2006) (Figure 2); (2) Un liquide résiduel d'une melilitite riche en CO 2 par cristallisation fractionnée [START_REF] Gittins | Differentiation of natrocarbonatite magma at Oldoinyo Lengai volcano, Tanzania[END_REF];

(3) Un liquide immiscible d'un liquide silicaté saturé en CO 2 [START_REF] Freestone | The role of liquid immiscibility in the genesis of carbonatites -An experimental study[END_REF][START_REF] Baker | Liquid immiscibility in a nephelinite-carbonate system at 25 kbar and implications for carbonatite origin[END_REF]Brooker et Kajarsgaard, 2011). [START_REF] Gudfinnsson | Continuous gradations among primary carbonatitic, kimberlitic, melilititic, basaltic, picritic, and komatiitic melts in equilibrium with garnet lherzolite at 3-8 GPa[END_REF].

(1) Les magmas carbonatitiques ont été reproduit expérimentalement à partir de faible taux de fusion d'un manteau péridotitique à olivine + opx + cpx + grenat riche en CO 2 à forte pression (P > 3GPa, Figure 2). Ces magmas sont principalement des magnesiocarbonatites [START_REF] Dalton | The compositions of primary carbonate melts and their evolution through wallrock reaction in the mantle[END_REF] ; (2) Les études pétrologiques et géochimiques démontrent que les carbonatites peuvent être également issues de la cristallisation fractionnée d'une melilitite riche en CO 2 [START_REF] Dawson | Peralkaline nephelinite-natrocarbonatite relationships at Oldoinyo Lengai, Tanzania[END_REF][START_REF] Gittins | Differentiation of natrocarbonatite magma at Oldoinyo Lengai volcano, Tanzania[END_REF][START_REF] Baudouin | Nephelinite lavas at early stage of rift initiation (Hanang volcano, North Tanzanian Divergence)[END_REF][START_REF] Weidendorfer | Fractional crystallization of Si-undersaturated alkaline magmas leading to unmixing of carbonatites on Brava Island (Cape Verde) and a general model of carbonatite genesis in alkaline magma suites[END_REF]. Les roches alcalines silicatés associées aux carbonatites représentent des suites plutoniques melteigite -ijolite -urite et néphélinesyenite et volcaniques nephelinite-phonolite dont les magmas parents sont des magmas sous-saturés mélilititiques (Figure 2). Ces séries alcalines sont composées essentiellement de mélilite, olivine, phlogopite, clinopyroxene, perovskite et néphéline. Si les derniers liquides lors de la différentiation de ces suites sont riches en carbonate, ils peuvent se différencier en carbonatite résiduelle et finalement un résidu carbothermal [START_REF] Mitchell | Carbonatites and Carbonatites and Carbonatites[END_REF] (Figure 4). [START_REF] Mitchell | Carbonatites and Carbonatites and Carbonatites[END_REF]. La plupart des carbonatites sont des roches plutoniques et leur mise en place implique souvent des processus tardi-magmatiques subsolidus [START_REF] Chen | Geochemistry of Monazite within Carbonatite Related REE Deposits[END_REF]. Les processus supergènes, à basses températures et en présences de fluides peuvent engendrer une remobilisation et un fractionnement des éléments incompatibles au sein des minéraux, qu'il est important de prendre en compte pour retracer l'évolution des magmas.

Introduction ! 15
Les terres rares en particuliers sont remobilisés et peuvent former des minéraux sub-solidus riches en terres rares (e.g. monazite, bastnaésite) à partir des minéraux magmatiques [START_REF] Harlov | Apatite and fluids: a fingerprint for metasomatic processes Elements[END_REF][START_REF] Chen | Geochemistry of Monazite within Carbonatite Related REE Deposits[END_REF]. Ces minéraux sont essentiels car concentrent les terres rares et autres métaux (Nb, Ta) qui

Introduction ! Introduction ! 20
• Problématique

Les carbonatites sont des roches magmatiques relativement rares dont les processus à l'origine sont encore mal contraints. Différentes études s'intéressent à comprendre les diverses occurrences de roches alcalines et carbonatitiques dans le monde ainsi que l'évolution du manteau sub-continental source à travers les temps géologiques. L'étude de ces roches est cruciale car elle permettent de caractériser le manteau lithosphérique et/ou asthénosphérique riche en carbone dont elles sont issues et apporter de nouvelles contraintes sur le cycle du carbone et l'échange de carbone entre les grands réservoirs terrestres à grandes échelles depuis l'Archéen jusqu'à l'actuel. Au delà de leur intérêt scientifique, les carbonatites ont une importance économique non-négligeable de par leur richesse en terres rares.

L'étude des carbonatites et des magmas alcalins d'Ihouhaouene présentée dans ma thèse adresse plusieurs questions :

-Quelle est la composition du manteau source des liquides carbonatés et magmas alcalins riches en CO 2 ?

-Les calciocarbonatites dérivent-elles directement du manteau ? Ou dérivent-elles de Les études précédentes ont démontrés une origine mantellique de ces carbonatites [START_REF] Ouzegane | Les granulites Al-Mg et les carbonatites dans la série de l'In Ouzzal[END_REF][START_REF] Bernard-Griffiths | Origin and evolution of 2 Ga old carbonatite complex (Ihouhaouene, Ahaggar, Algeria): Nd and Sr isotopic evidence[END_REF]) alors que les syenites d'Ihouhaouene ont été considérées comme le résultat de fénitisation par métasomatisme de magmas alcalins [START_REF] Fourcade | Metasomatic effects related to channelled fluid streaming through deep crust: Fenites and associated carbonatites (In Ouzzal Proterozoic granulites, Hoggar, Algeria)[END_REF] Il présente un bloc cénozoïque de 550 000 km 2 composé de roches précambriennes entourées de sédiments paléozoïques déposés après la fin de l'orogenèse panafricaine [START_REF] Liégeois | A New Synthetic Geological Map of the Tuareg Shield: An Overview of Its Global Structure and Geological Evolution[END_REF]. Il expose le résultat d'une exhumation généralisée du bouclier à l'Eocène [START_REF] Rougier | Eocene exhumation of the Tuareg Shield (Sahara, Africa)[END_REF][START_REF] English | Intraplate uplift: new constraints on the Hoggar dome from the Illizi basin (Algeria)[END_REF][START_REF] Liégeois | A New Synthetic Geological Map of the Tuareg Shield: An Overview of Its Global Structure and Geological Evolution[END_REF], suivie par différents épisodes volcaniques intraplaques allant de 35

Ma au quaternaire [START_REF] Liégeois | The Hoggar swell and volcanism: reactivation of the Precambrian Tuareg shield during Alpine convergence and west African Cenozoic volcanism[END_REF].

Le bouclier Touareg fait partie de la ceinture transsaharienne où la tectonique des plaques était encore active au précambrien [START_REF] Black | Pan-African displaced terranes in the Tuareg shield (central Sahara)[END_REF]. [START_REF] Caby | Pan-African ocean in the hoggar-iforas segment, central sahara[END_REF] Chapitre I : Contexte géologique ! ! 27 [START_REF] Black | Pan-African displaced terranes in the Tuareg shield (central Sahara)[END_REF] et [START_REF] Liégeois | Early and late Pan-African orogenies in the Aïr assembly of terranes (Tuareg Shield, Niger)[END_REF] ont subdivisé le bouclier Touareg en 23 terranes (Figure . I.2) séparés par de grandes shear-zones qui se sont joints au panafricain. [START_REF] Liégeois | A New Synthetic Geological Map of the Tuareg Shield: An Overview of Its Global Structure and Geological Evolution[END_REF] ont ajouté 2 nouveaux terranes au bouclier, le terrane de Aouilène et le terrane d'Afara. Chacun des terranes se caractérise par une lithologie et une histoire tectono-métamorphique et magmatique différente.

Ces terranes sont des domaines juvéniles panafricains [START_REF] Caby | Cadre géologique et géochronologie U/Pb sur zircon des batholites précoces dans le segment pan-Africain du Hoggar central (Algérie)[END_REF], 1989[START_REF] Bendaoud | Pétrologie et Géochimie des séries basiques et ultrabasiques Précambriennes de l'In Ouzzal et du Hoggar Central et leur relation avec l'Encaissant[END_REF]) associés à d'autres domaines archéens à éburnéens remobilisés durant le panafricain avec des évidences d'anciennes lithologies préservées sur de grandes étendues comme dans le terrane de l'In

Ouzzal [START_REF] Ouzegane | Les granulites Al-Mg et les carbonatites dans la série de l'In Ouzzal[END_REF][START_REF] Ludwig | Isoplot 3.00[END_REF][START_REF] Benbatta | Ternary feldspar thermometry of Paleoproterozoic granulites from In-Ouzzal terrane (Western Hoggar, southern Algeria)[END_REF].

Bertrand et [START_REF] Bertrand | The late Pan-African intracontinental linear fold belt of the eastern Hoggar (Central Sahara, Algeria): geology, structural development, U/Pb geochronology, tectonic implications for the Hoggar shield[END_REF] ont subdivisé le bouclier en trois grands compartiments: le Hoggar occidental, central et oriental suivant les deux grands accidents N-S 4º50' et 8º30'.

Le Hoggar occidental (Figure . I.2) est caractérisé par la présence de deux zones, le rameau occidental et le rameau oriental, séparées par l'unité granulitique de l'In Ouzzal composée de roches archéennes remobilisées au Paléoprotérozoïque (2000Ma, Ouzegane, 1987 ;[START_REF] Haddoum | Structural evolution of the precambrian In ouzzal massif, central sahara, Algeria[END_REF][START_REF] Peucat | Major and trace element geochemistry and isotope Sr, Nd, Pb, O systematics of an Archaean basement involved in a 2.0 Ga VHT 1000ºC metamorphic event: In Ouzzal massif, Hoggar, Algeria[END_REF][START_REF] Ouzegane | A review of Archaean and Paleoproterozoic evolution of the In Ouzzal granulitic terrane (Western Hoggar, Algeria)[END_REF]. Chapitre I : Contexte géologique ! ! 28

I.1.b. Le terrane de l'In Ouzzal

Le terrane de l'In Ouzzal (Figure . I.2) est un bloc rigide de 450 km de long et 80 km de large dans sa partie septentrionale, orienté N-S, situé au centre du Hoggar occidental entre deux grands bassins volcano-sédimentaires d'âge protérozoïque moyen à protérozoïque terminal constituant la chaine pharusienne [START_REF] Ouzegane | A review of Archaean and Paleoproterozoic evolution of the In Ouzzal granulitic terrane (Western Hoggar, Algeria)[END_REF][START_REF] Bendaoud | Pétrologie et Géochimie des séries basiques et ultrabasiques Précambriennes de l'In Ouzzal et du Hoggar Central et leur relation avec l'Encaissant[END_REF][START_REF] Haddoum | Extrusion du bloc In Ouzzal vers le Nord (Hoggar Occidental, Algérie): Conséquence d'un poinçonnement panafricain Extrusion de l[END_REF][START_REF] Liégeois | A New Synthetic Geological Map of the Tuareg Shield: An Overview of Its Global Structure and Geological Evolution[END_REF].

Il est bordé par deux grandes zones de cisaillement sub-verticales s'enracinant profondément sous la base de croûte traversant une lithosphère très épaisse sous l'In Ouzzal [START_REF] Liégeois | The Hoggar swell and volcanism: reactivation of the Precambrian Tuareg shield during Alpine convergence and west African Cenozoic volcanism[END_REF][START_REF] Bouzid | Modélisation magnétotellurique de la structure géologique profonde de l'unité granulitique de l'In Ouzzal (Hoggar occidental)[END_REF]. [START_REF] Caby | A review of the In Ouzzal granulitic terrane, Tuareg shield, Algeria: its significance within the Pan-African Trans-Saharan Belt[END_REF] et [START_REF] Djemai | Les pyrigarnites et les granulites alumineuses d'Amesmessa, Môle[END_REF] ont montré que les mouvements opposés des deux décrochements déplacent le terrane vers le Nord au cours de la compression panafricaine.

L'histoire de l'In Ouzzal s'étale entre 3200 et 2000 Ma et se caractérise par divers activités orogéniques entre l'Archéen, le Protérozoïque et le Panafricain. Deux unités composent le terrane de l'In Ouzzal ; (i) l'unité inférieure en dômes essentiellement à TTG (tonalite, trondjhémites, granodiorites) formant une série de gneiss charnokitiques et d'enderbites, granulitiques orthodérivés et (ii) l'Unité supracrustale granulitique occupant des bassins, composée de granulites aluminomagnésiennes, granulites alumino-ferrifères, marbres, quartzites et des leptynites [START_REF] Ouzegane | Les granulites Al-Mg et les carbonatites dans la série de l'In Ouzzal[END_REF]Ouzegane et Kienast, 1996 ;[START_REF] Haddoum | Structural evolution of the precambrian In ouzzal massif, central sahara, Algeria[END_REF][START_REF] Ouzegane | A review of Archaean and Paleoproterozoic evolution of the In Ouzzal granulitic terrane (Western Hoggar, Algeria)[END_REF]. Toutes ces roches ont donné des âges archéens et ont été remobilisés au Paléoprotérozoïque à 2000 Ma (Ferrara et Gravelle, 1996 ;[START_REF] Haddoum | Structural evolution of the precambrian In ouzzal massif, central sahara, Algeria[END_REF][START_REF] Peucat | Behaviour of Sr, Nd, Pb isotopic systems during a high temperature granulite metamorphism[END_REF][START_REF] Peucat | Major and trace element geochemistry and isotope Sr, Nd, Pb, O systematics of an Archaean basement involved in a 2.0 Ga VHT 1000ºC metamorphic event: In Ouzzal massif, Hoggar, Algeria[END_REF].

L'histoire archéenne de l'In Ouzzal remonte à plus de 3200 Ma [START_REF] Allègre | U-Th-Pb systematics of hydroxyapatite intergrowths[END_REF][START_REF] Lancelot | Uranium and lead isotopic dating with grain-by grain zircon analysis: a study of a complex geological history with a single rock[END_REF][START_REF] Othman | Nd-Sr isotopic composition of granulites and constraints on the evolution of the lower continental crust[END_REF]Ferrara et Gravelle, 1996 ;[START_REF] Haddoum | Structural evolution of the precambrian In ouzzal massif, central sahara, Algeria[END_REF][START_REF] Peucat | Behaviour of Sr, Nd, Pb isotopic systems during a high temperature granulite metamorphism[END_REF][START_REF] Peucat | Major and trace element geochemistry and isotope Sr, Nd, Pb, O systematics of an Archaean basement involved in a 2.0 Ga VHT 1000ºC metamorphic event: In Ouzzal massif, Hoggar, Algeria[END_REF][START_REF] Ouzegane | A review of Archaean and Paleoproterozoic evolution of the In Ouzzal granulitic terrane (Western Hoggar, Algeria)[END_REF] et se caractérise par trois stades majeurs [START_REF] Ouzegane | A review of Archaean and Paleoproterozoic evolution of the In Ouzzal granulitic terrane (Western Hoggar, Algeria)[END_REF]Drareni et al. 2007, Figure. I.3). Un premier stade se définit par la mise en place de croûte continentale composée de roches d'affinité andésitique et de TTG entre 3200 et 3300

Ma, formée par accrétion d'arcs [START_REF] Ouzegane | A review of Archaean and Paleoproterozoic evolution of the In Ouzzal granulitic terrane (Western Hoggar, Algeria)[END_REF][START_REF] Drareni | L'archéen du Hoggar : Géochronologie et evolution géodynamique[END_REF]. Le deuxième stade se caractérise par une autre série de TTG (ceinture de roches vertes) qui s'est mise en place vers 2700 Ma suivie par l'intrusion de granites de type A vers 2600 Ma et le dépôt des protolithes des granulites Al-Mg des formations ferrifères et carbonatées associées à des tholéiites magnésiennes et des komatiites dans des bassins d'arrières arcs (Figure. I.3). La période archéenne à 2500 Ma se termine par un raccourcissement homogène et le développement de structures en dôme et bassin caractérisées par la mise en place de plutons granitiques calco-alcalins issus de la fusion partielle de la croûte inférieure [START_REF] Ouzegane | A review of Archaean and Paleoproterozoic evolution of the In Ouzzal granulitic terrane (Western Hoggar, Algeria)[END_REF][START_REF] Drareni | L'archéen du Hoggar : Géochronologie et evolution géodynamique[END_REF]. Chapitre I : Contexte géologique ! ! 30

L'histoire paléoprotérozoïque de l'In Ouzzal se caractérise par la succession de plusieurs évènements métamorphiques granulitiques de très haute température durant l'orogenèse éburnéenne [START_REF] Ouzegane | Les granulites Al-Mg et les carbonatites dans la série de l'In Ouzzal[END_REF][START_REF] Ouzegane | A review of Archaean and Paleoproterozoic evolution of the In Ouzzal granulitic terrane (Western Hoggar, Algeria)[END_REF][START_REF] Bendaoud | Pétrologie et Géochimie des séries basiques et ultrabasiques Précambriennes de l'In Ouzzal et du Hoggar Central et leur relation avec l'Encaissant[END_REF][START_REF] Adjerid | First report of ultrahigh-temperature sapphirine + spinel + quartz and orthopyroxene + spinel + quartz parageneses discovered in Al-Mg granulites from the Khanfous area (In Ouzzal metacraton, Hoggar, Algeria). The Boundaries of the West African Craton[END_REF][START_REF] Adjerid | Multistage progressive evolution of rare osumilite-bearing assemblages preserved in ultrahigh-temperature granulites from In Ouzzal (Hoggar, Algeria)[END_REF][START_REF] Benbatta | Ternary feldspar thermometry of Paleoproterozoic granulites from In-Ouzzal terrane (Western Hoggar, southern Algeria)[END_REF] dont la phase majeure a lieu à 2000 Ma (BenOthman et al. 1984).

L'évolution P-T du métamorphisme granulitique de l'In Ouzzal est enregistrée à travers différentes paragenèses : dans les granulites Al-Mg [START_REF] Ouzegane | Les granulites Al-Mg et les carbonatites dans la série de l'In Ouzzal[END_REF][START_REF] Kienast | Polymetamorphic A1, Mg-rich granulites with orthopyroxenesillimanite and sapphirine parageneses in Archaean rocks from Hoggar, Algeria[END_REF]Bertrand et al. 1992 ;[START_REF] Ait Djafer | Relation cristallisation fusion et cheminement pression température dans les migmatites de l'In Ouzzal NW Hoggar[END_REF][START_REF] Boumaza | Pétrologie d'un nodule migmatitique _a saphirine d'In Hihaou In Ouzzal, Hoggar occidental: diffusion chimique et comparaison avec les granulites Al-Mg de l'encaissant[END_REF][START_REF] Mouri | Petrology of phlogopite-sapphirine--bearing Al-Mg granulites from Ihouhaouene Mole In Ouzzal-Hoggar Algeria: an example of phlogopite stable at high temperature[END_REF]Ouzegane & Boumaza, 1996 ;Adjerid, 2002 ;[START_REF] Bendaoud | Pétrologie et Géochimie des séries basiques et ultrabasiques Précambriennes de l'In Ouzzal et du Hoggar Central et leur relation avec l'Encaissant[END_REF][START_REF] Benbatta | Ternary feldspar thermometry of Paleoproterozoic granulites from In-Ouzzal terrane (Western Hoggar, southern Algeria)[END_REF]) avec les températures les plus élevées, les granulites Al-Fe [START_REF] Ait Djafer | Relation cristallisation fusion et cheminement pression température dans les migmatites de l'In Ouzzal NW Hoggar[END_REF][START_REF] Djemai | Les pyrigarnites et les granulites alumineuses d'Amesmessa, Môle[END_REF][START_REF] Ouzegane | Nature et _evolution des séries métamorphiques de très haute température de l'Unité Granulitique de l'In Ouzzal Ouest Hoggar[END_REF], les quartzites à corindon-magnétite [START_REF] Guiraud | Corundum-quartz bearing assemblage in the Ihouhaouene area In Ouzzal, Algeria[END_REF], les granulites à silicates-calciques [START_REF] Benyahia | Les granulites à silicates calciques du môle In Ouzzal NW Hoggar: Minéralogie géochimie et relation de phases[END_REF] et les pyroxénites à grenat [START_REF] Ouzegane | Les granulites Al-Mg et les carbonatites dans la série de l'In Ouzzal[END_REF][START_REF] Kienast | Polymetamorphic A1, Mg-rich granulites with orthopyroxenesillimanite and sapphirine parageneses in Archaean rocks from Hoggar, Algeria[END_REF][START_REF] Djemai | Les pyrigarnites et les granulites alumineuses d'Amesmessa, Môle[END_REF][START_REF] Bendaoud | Pétrologie et Géochimie des séries basiques et ultrabasiques Précambriennes de l'In Ouzzal et du Hoggar Central et leur relation avec l'Encaissant[END_REF].

Deux stades métamorphiques majeurs sont connus dans l'In Ouzzal (Figure . I.4): (i) un stade prograde caractérisé par de hautes pressions et températures, de 10 à 11 Kbar et de 800 à 1050ºC, respectivement ; (ii) un stade rétrograde marqué par une décompression de 9 à 5 Kbar avec un maintien des températures autour de 900-1000ºC [START_REF] Ouzegane | Les granulites Al-Mg et les carbonatites dans la série de l'In Ouzzal[END_REF]Bertrand et al. 1992 ;[START_REF] Ouzegane | A review of Archaean and Paleoproterozoic evolution of the In Ouzzal granulitic terrane (Western Hoggar, Algeria)[END_REF]. Cet évènement tectono-métamorphique se manifeste par un cisaillement ductile plat, une foliation contemporaine du métamorphisme granulitique prograde et d'une fusion partielle limitée [START_REF] Peucat | Major and trace element geochemistry and isotope Sr, Nd, Pb, O systematics of an Archaean basement involved in a 2.0 Ga VHT 1000ºC metamorphic event: In Ouzzal massif, Hoggar, Algeria[END_REF][START_REF] Haddoum | Extrusion du bloc In Ouzzal vers le Nord (Hoggar Occidental, Algérie): Conséquence d'un poinçonnement panafricain Extrusion de l[END_REF]. L'histoire éburnéenne (stade rétrograde) se termine par un relâchement des contraintes et la mise en place du complexe alcalin des carbonatites et syénites associées [START_REF] Ouzegane | A review of Archaean and Paleoproterozoic evolution of the In Ouzzal granulitic terrane (Western Hoggar, Algeria)[END_REF].

Stade précoce : poursuite de la tectonique en dômes et bassins archéens avec un raccourcissement et un épaississement crustal. L'histoire panafricaine de l'In Ouzzal se manifeste par d'importante schistosité et rétromorphose des granulites dans le facies amphibolite localisée dans les grandes shear-zones délimitant le terrane [START_REF] Djemai | Les séries archéennes d'Amesmessa (ouest Hoggar) remobilisées au Protérozoïque: cartographie, évolution tectonique et cheminement P-T[END_REF]. Un magmatisme acide localisé au Nord avec les plutons granitiques alcalins, des champs filoniens de dolérites et gabbro-dolérites au Sud, orientés NNW-SSE témoignant d'une distension pré-panafricaine, aussi observée dans le Craton Ouest africain [START_REF] Haddoum | Extrusion du bloc In Ouzzal vers le Nord (Hoggar Occidental, Algérie): Conséquence d'un poinçonnement panafricain Extrusion de l[END_REF].

Le terrane de l'In Ouzzal est limité par deux grands-décrochements, l'Ouest-ouzzalien est senestre [START_REF] Caby | La chaine Pharusienne dans le NW de l'Ahaggar Central Sahara, Algérie: sa place Références bibliographiques ! 180 dans l'orogenèse du Précambrien supérieur en Afrique[END_REF] et l'Est-ouzzalien est dextre [START_REF] Caby | La chaine Pharusienne dans le NW de l'Ahaggar Central Sahara, Algérie: sa place Références bibliographiques ! 180 dans l'orogenèse du Précambrien supérieur en Afrique[END_REF][START_REF] Caby | A review of the In Ouzzal granulitic terrane, Tuareg shield, Algeria: its significance within the Pan-African Trans-Saharan Belt[END_REF][START_REF] Attoum | Etude géologique et structurale des mylonites Panafricaines et des minéralisations aurifères associées dans le secteur de Tirek Hoggar, Algérie. Thèse 3_eme cycle Montpellier[END_REF][START_REF] Attoum | Contribution à l'étude des zones de cisaillement panafricaines: tectonique, microtectonique et cinématique des mylonites de Tirek (Hoggar, Algérie)[END_REF][START_REF] Haddoum | Etude structurale des terrains archéens du môle In Ouzzal Hoggar occidental, Algérie[END_REF][START_REF] Haddoum | Structural evolution of the precambrian In ouzzal massif, central sahara, Algeria[END_REF][START_REF] Ferkous | Gold mineralization in the West Hoggar shear zone, Algeria[END_REF][START_REF] Semiani | Métallogénie de la zone de cisaillement aurifère est-ouzzalienne: structure, pétrologie et géochimie des gisements d'or de Tirek-Amessmessa (Hoggar occidental, Algérie)[END_REF][START_REF] Djemai | Les pyrigarnites et les granulites alumineuses d'Amesmessa, Môle[END_REF][START_REF] Djemai | Les séries archéennes d'Amesmessa (ouest Hoggar) remobilisées au Protérozoïque: cartographie, évolution tectonique et cheminement P-T[END_REF]) faisant expulsé l'In Ouzzal vers le Nord [START_REF] Haddoum | Extrusion du bloc In Ouzzal vers le Nord (Hoggar Occidental, Algérie): Conséquence d'un poinçonnement panafricain Extrusion de l[END_REF]. [START_REF] Caby | Neoproterozoic subduction and differential exhumation of western Hoggar (south-west Hoggar, Algeria): new structural, petrological and geochronological evidence[END_REF] long de grandes zones de cisaillement [START_REF] Ouzegane | New carbonatite complexes in the Archaean In'Ouzzal nucleus (Ahaggar, Algeria): Mineralogical and Geochemical data[END_REF], Lapin et Plashko 1988).

I.2.a. Les carbonatites

Toutes les carbonatites d'Ihouhaouene sont des calciocarbonatites [START_REF] Streckeisen | Classification and nomenclature of plutonic rocks recommendations of the IUGS subcommission on the systematics of Igneous Rocks[END_REF] Chapitre I : Contexte géologique ! ! 44

I.2.c. Les échantillons des études antérieures

Plusieurs échantillons récoltés par K. 3 ; en annexe A).

Analyse des éléments en trace (ICP-MS)

Les éléments en trace ont été analysés par spectrométrie de masse couplée à un plasma inductif à Géosciences Montpellier (plate-forme AETE OSU-OREME). Une attaque à l'acide sur 100 mg de poudre d'échantillon, pesé à l'aide d'une balance de précision (± 1mg), dans des Savilex en téflon est réalisée avec 1 ml de HClO 4 et 2,5 ml de HF sur une plaque chauffante à 100 ° C pendant 24 heures. L'acide fluorhydrique brise les liaisons chimiques des silicates dans la roche et met les ions libérés en solution, tandis que l'acide perchlorique agit comme un oxydant comme le nitrique et l'objectif de cet acide est d'assurer une évacuation aussi complète que possible de l'excès de HF.

Ensuite, les échantillons sont évaporés à sec à 150ºC et 50W. Une seconde attaque à l'acide est appliquée avec 0,5 ml de HClO 4 et 1 ml de HF pendant 24 heures suivie par une évaporation, puis les

Analyse des éléments majeurs

Les éléments majeurs sur roche totale ont été analysés par ICP-OES (iCap 6500

ThermoFisher) au service SARM du CRPG (Nancy, France). La procédure suivie est conforme au protocole de Carignan [START_REF] Carignan | Routine Analyses of Trace Elements in Geological Samples using Flow Injection and Low Pressure On-Line Liquid Chromatography Coupled to ICP-MS: A Study of Geochemical Reference Materials BR, DRN, UB-N, AN-G and GH[END_REF]. La poudre de roche entière est fondue avec du LiBO 2 , puis le verre de fusion est dissous dans un mélange de HNO 3 , H 2 O et Glycérol. L'écart-type relatif pour les principaux éléments est inférieur à 5%.

Analyse des éléments volatils

Les éléments volatils ont été analysés au SARM à l'aide d'un analyseur d'éléments pour le contenu en soufre et en carbone de la roche totale. Les teneurs en F et Cl ont été déterminées par spectrophotométrie de ferrithiocyanate de précipitation humide avec le spectrophotomètre Varian Cary 50 [START_REF] Vernet | Dosage du fluor et du chlore dans les matériaux géologiques y compris les échantillons hyperalumineux[END_REF].

I.3.b Analyse in-situ des minéraux

Analyse à la microsonde électronique (EPMA) [START_REF] Ludwig | Isoplot 3.00[END_REF]. The close spatial association of carbonatite and alkaline silicate rocks formed the key question of several experimental studies to explain their complex relationships, the processes at their co-genetic origin or not and the kind of parental melt they derived from. Almost all carbonatites are associated with alkali silicate rocks that are usually of nephelinitic or melilititic affinity or their plutonic equivalents [START_REF] Bell | Carbonatites -Into the twenty-first century[END_REF]. The study of natural carbonatite-alkaline rocks and experimental studies suggest that carbonatites may result from two processes involving (1) direct partial melting of carbonate-rich mantle [START_REF] Stoppa | Geochemistry of carbonatite-silicate pairs in nature: A case history from Central Italy[END_REF][START_REF] Gudfinnsson | Continuous gradations among primary carbonatitic, kimberlitic, melilititic, basaltic, picritic, and komatiitic melts in equilibrium with garnet lherzolite at 3-8 GPa[END_REF]Dasgupta & Hirschmann 2006); (2) magmatic differentiation and immiscibility of carbonated silicate melts [START_REF] Freestone | The role of liquid immiscibility in the genesis of carbonatites -An experimental study[END_REF][START_REF] Baker | Liquid immiscibility in a nephelinite-carbonate system at 25 kbar and implications for carbonatite origin[END_REF][START_REF] Dawson | Peralkaline nephelinite-natrocarbonatite relationships at Oldoinyo Lengai, Tanzania[END_REF][START_REF] Gittins | Differentiation of natrocarbonatite magma at Oldoinyo Lengai volcano, Tanzania[END_REF]Dasgupta et al. 2006;Brooker & Kajarsgaard 2011). But this kind of carbonatites can only be magnesiocarbonatites, isolated in the mantle and risen rapidly to the surface [START_REF] Dalton | Carbonatitic melts along the solidus of model lherzolite in the system CaO-MgO-Al 2 O 3 -SiO 2 -CO 2 from 3 to 7 GPa[END_REF][START_REF] Wyllie | Model system controls on conditions for formation of magnesiocarbonatite and calciocarbonatite magmas from the mantle[END_REF]. Based on experimentally equilibrated silicate and carbonate melt, calciocarbonatites may be generated through reaction of carbonate melts rich in volatiles with depleted lherzolite or harzburgite at low pressures [START_REF] Dalton | The compositions of primary carbonate melts and their evolution through wallrock reaction in the mantle[END_REF].

Analyse des microstructures cristallines à l'EBSD

The Ihouhaouene (∼ 2 Ga; [START_REF] Bernard-Griffiths | Origin and evolution of 2 Ga old carbonatite complex (Ihouhaouene, Ahaggar, Algeria): Nd and Sr isotopic evidence[END_REF]) carbonatite massifs (In Ouzzal terrane, south of Algeria) are plutonic rocks and are systematically associated with SiO 2 -saturated syenitic rocks. The syenite complexes associated to carbonatites were emplaced concordantly with respect to the foliation of granulites, [START_REF] Ouzegane | Les granulites Al-Mg et les carbonatites dans la série de l'In Ouzzal[END_REF][START_REF] Bernard-Griffiths | Origin and evolution of 2 Ga old carbonatite complex (Ihouhaouene, Ahaggar, Algeria): Nd and Sr isotopic evidence[END_REF][START_REF] Fourcade | Metasomatic effects related to channelled fluid streaming through deep crust: Fenites and associated carbonatites (In Ouzzal Proterozoic granulites, Hoggar, Algeria)[END_REF], Ouzegane et al. 1988) and represent a unique opportunity to understand carbonatites and alkaline magmas genesis during the Paleoproterozoic.

In this paper, we study the major, trace and volatile elements of bulk-rock and in situ mineral of carbonatites and syenites to understand the genetic relationship between carbonatite and alkaline magmas in order to determine the origin of carbonate-rich silicate magmas and magmatic evolution in Archean crust during Proterozoic time. A numerical model is proposed in order to simulate the processes at the origin of composition evolution observed in Ihouhaouene and similar carbonatite complexes.

II.2. GEOLOGICAL SETTING AND FIELD RELATIONSHIPS

The Ihouhaouene area is located in the northern part of In Ouzzal terrane (Western Hoggar, South of Algeria) (23º36'14"N, 3º10'32"E) and contains carbonatite bodies associated with syenites that are among the oldest in the world (~ 2 Ga, [START_REF] Bernard-Griffiths | Origin and evolution of 2 Ga old carbonatite complex (Ihouhaouene, Ahaggar, Algeria): Nd and Sr isotopic evidence[END_REF]. The In Ouzzal terrane is an Archaean crust remobilized during the Paleoproterozoic ultra-high-temperature metamorphism (2 Ga, T = 800-1050°C at 10-11 kbar, Ouzegane et al. 2003a). Two Archaean units occur: a lower crustal unit mainly composed of orthogneiss with igneous activity at 3.2 Ga [START_REF] Peucat | Major and trace element geochemistry and isotope Sr, Nd, Pb, O systematics of an Archaean basement involved in a 2.0 Ga VHT 1000ºC metamorphic event: In Ouzzal massif, Hoggar, Algeria[END_REF]) and a supracrustal unit that depositional age falls within the range 2.7 -2.6 Ga [START_REF] Peucat | Major and trace element geochemistry and isotope Sr, Nd, Pb, O systematics of an Archaean basement involved in a 2.0 Ga VHT 1000ºC metamorphic event: In Ouzzal massif, Hoggar, Algeria[END_REF] with

Chapitre II : Processus magmatiques ! ""! quartzites, banded iron formations, marbles, Al-Mg and Al-Fe granulites associated with mafic and ultramafic rocks (Ouzegane et al. 2003a;[START_REF] Guiraud | Corundum-quartz bearing assemblage in the Ihouhaouene area In Ouzzal, Algeria[END_REF][START_REF] Peucat | Major and trace element geochemistry and isotope Sr, Nd, Pb, O systematics of an Archaean basement involved in a 2.0 Ga VHT 1000ºC metamorphic event: In Ouzzal massif, Hoggar, Algeria[END_REF][START_REF] Adjerid | Multistage progressive evolution of rare osumilite-bearing assemblages preserved in ultrahigh-temperature granulites from In Ouzzal (Hoggar, Algeria)[END_REF].

The carbonatites and syenites occur as linear deposits along shear zones in three sectors [START_REF] Ouzegane | New carbonatite complexes in the Archaean In'Ouzzal nucleus (Ahaggar, Algeria): Mineralogical and Geochemical data[END_REF]Lapin & Plashko 1988 Red syenites are more abundant in Oued Ihouhaouene and north wadi Tirahart complexes. In Tirahart wadi North complex outcrops a feldspathic breccia, which present fragments of white syenite with wollastonite, garnet and large crystals of pyroxene cemented by feldspars. The contact between red and white syenites is brecciated. Only in Oued Ihouhaouene, we observed sharp contacts, with large white syenite bodies crosscutting red syenites (previously mapped as granites by [START_REF] Fourcade | Metasomatic effects related to channelled fluid streaming through deep crust: Fenites and associated carbonatites (In Ouzzal Proterozoic granulites, Hoggar, Algeria)[END_REF].

The contact between syenites and granulitic basement is not obvious because of sand in this area, et al. 1987;Drüppel et al. 2005). In Ihouhaouene area, syenites have the same mineralogy from the contact with carbonatite veins to the granulite host-rock. No fenitization aureole has been observed.

Chapitre II : Processus magmatiques ! "'! Chapitre II : Processus magmatiques ! "(!

II.3. PETROGRAPHY

II.3.a. Carbonatites

All carbonatites from Ihouhaouene contain apatite and clinopyroxene set in a matrix with up to 50 vol.% of primary calcite and can be defined as calciocarbonatite [START_REF] Streckeisen | Classification and nomenclature of plutonic rocks recommendations of the IUGS subcommission on the systematics of Igneous Rocks[END_REF]. Chapitre II : Processus magmatiques ! ")!

II.4. METHODOLOGY

Fifty-four intrusive silicate and carbonatite rocks representing the diversity of rock types in the Ihouhaouene area were selected for petrological and geochemical study. All granulitic basement rocks from the three sectors of carbonatites and syenites are presented in table 1 of supplementary data B.

Samples were chosen according to the localities and the different types of carbonatites (brecciated, pegmatitic or calcite veins) and the two types of red and white syenites. Brecciated carbonatites were well separated and cleaned of syenite fragments before milling. A significant amount (∼ 3 kg) of pegmatitic carbonatites was milled to have a representative bulk-rock composition.

II.4.a. Whole-rock major, trace and volatile element analysis

All samples were cut, crushed and milled in agate into fine powders (≥5 μm) without using

Chapitre II : Processus magmatiques

! &*!
water. Major elements were analysed by ICP-OES (iCap ThermoFisher) at the SARM service of the CRPG (Nancy, France). The procedure followed is according to the Carignan protocol [START_REF] Carignan | Routine Analyses of Trace Elements in Geological Samples using Flow Injection and Low Pressure On-Line Liquid Chromatography Coupled to ICP-MS: A Study of Geochemical Reference Materials BR, DRN, UB-N, AN-G and GH[END_REF]. The whole rock powder is fused with LiBO 2 then the fusion glass is dissolved in a HNO 3 , H 2 O and Glycerol mixture. The relative standard deviation for the major elements is less than 5%. Volatile elements were determined at the SARM by element analyser for sulphur and carbon whole rock contents. F and Cl contents were determined by wet precipitation ferrithiocyanate spectrophotometry using Varian Cary 50 spectrophotometer.

Trace elements were analysed by ICP-Mass Spectrometry at Geosciences Montpellier (AETE platform OSU-OREME). An acid attack on 0.1 g of sample powder weighed in Teflon Savilex is carried out with 1 ml of HClO 4 and 2.5 ml of HF on a hot plate at 100ºC for 24 hours. Hydrofluoric acid breaks the silicate link of rocks and puts the released ions in solution, while nitric acid acts as a powerful oxidant. Then the samples were evaporated to dryness at 150ºC and 50W. A second attack is applied with 0.5 ml of HClO 4 and 1 ml of HF for 24 hours followed by evaporation, and the samples are then taken up in three steps, separated by evaporation, in 0.5 ml, 0.25 ml and then 0. Chondrite values from [START_REF] Sun | Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes[END_REF].

Chapitre II : Processus magmatiques ! ""! Primitive mantle values from [START_REF] Sun | Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes[END_REF].

II.5.b. Syenites

Red syenites have high silica and high alkali contents ranging from 57.49 to 71.67 wt.% and Chapitre II : Processus magmatiques Chapitre II : Processus magmatiques ! %)! [START_REF] Sun | Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes[END_REF].

! "&!

II.6.c. Apatite

Apatites in carbonatites and syenites are fluor-apatites (2.7-6.31 wt.% F). Despite their relative large size (up to 5 mm), apatites do not have significant zonation from core to rim although they have different compositions in silica and phosphorus as well as in calcium and rare earth elements depending of the host rock (Figure II.12).

In Si-poor with positive anomaly in Th (Th= 892.61 ppm) also fractionation in Nb-Ta and Zr-Hf.

Garnet

Garnet has intermediate composition between grossular (63 to 72 %) and andradite (25 to 33 %) (Supplementary data B1) with low TiO 2 content (0.01 to 0.78 wt.%) and high FeO content (15.37-26.14 wt.%). Titanian andradite-rich garnet with Fe 3+ > Ti is referred to melanite [START_REF] Deer | Rock-forming minerals[END_REF].

Chapitre II : Processus magmatiques ! %&!

Oxide and sphene

Oxide in carbonatites and syenites is magnetite Chakhmouradian et al. 2008, Figure II.4). For all carbonatite/syenite complexes, a genetic relation between alkaline rocks and carbonatites has been presumed although in most cases, the occurrence of hydrothermal/metamorphic imprint does not allow to access to original magmatic processes (e.g. Wyllie and Jones, 1985;Ramasamy 1986;Smith et al. 2000;[START_REF] Chakhmouradian | Postorogenic carbonatites at Eden Lake, Trans-Hudson Orogen (northern Manitoba, Canada): Geological setting, mineralogy and geochemistry[END_REF][START_REF] Saha | Occurrence of melanite garnet in syenite and ijolitemelteigite rocks of Samchampi -Samteran alkaline complex, Mikir Hills , Northeastern India[END_REF].

In Ihouhaouene complex, the coexistence of unaltered syenites and carbonatites with a wide range of silica content (3 -35 wt.% SiO 2 ) makes it a key area to decipher the relationships between these two rock types and contributes to our knowledge on the origin of carbonatites. A petrogenetic model to link the carbonatites and syenites must integrate salient features of the Ihouhaouene complex, such as the structural relationships between rock facies and the major-and trace-element systematics of whole rocks and minerals. These notably include:

(1) Close spatial relationships between carbonatites and syenites in the field, as well as similar, pegmatitic/brecciated textures in the two rock types (Figure II.2), suggesting that they were emplaced during a single igneous event.

(2) Almost continuous range of whole-rock major-element compositions, from silica-poor carbonatites to silica-rich (red) syenites (Figures II. 4,5) suggesting genetic relationships between all rock facies.

(3) Striking similitudes of pyroxene and apatite compositions in carbonatites and syenites, particularly in the silica-rich carbonatites and white syenites (hedenbergite and wollastonite, melting degree of a carbonated mantle source or via segregation of immiscible carbonate melt from a silicate parental melt are expected to be strongly LREE enriched [START_REF] Hamilton | The behaviour of trace elements in the evolution of carbonatites[END_REF][START_REF] Jones | Experimental investigations of the partitioning of Nb, Mo, Ba, Ce, Pb, Ra, Th, Pa, and U between immiscible carbonate and silicate liquids[END_REF][START_REF] Martin | Element Partitioning between Immiscible Carbonatite and Silicate Melts for Dry and H2O-bearing Systems at 1-3 GPa[END_REF]. Together with the low Nb/Ta values observed in several minerals from Si-poor carbonatites including sample IC1-4B (down to 1.9, Figures II. 11 and 12), the low LREE signature rules out its origin either as a pristine carbonate melt from the mantle, or as a carbonate fraction segregated from a primary silicate melt. Rather, the Si-poor carbonatites of the Ihouhaouene complex were segregated from geochemically evolved silicate melts. In this scheme, the low LREE/HREE and Nb/Ta ratios of sample IC1-4B is chiefly the reflection of its parental melt composition, inherited from former differentiation stages involving several steps of carbonated melt immiscibility.

Due to their complex compositions resulting from the assemblage of disequilibrium minerals of different origins, the analyzed whole-rocks do not provide full information on the extent and nature of the differentiation processes in the Ihouhaouene complex. Moreover, the whole-rock compositions do not represent melt compositions and therefore cannot be straightforwardly used for modelling the differentiation.

In order to evaluate the whole extent of geochemical differentiation in the complex and assess the ability of igneous differentiation mechanisms (segregation of cumulus minerals and immiscible melts)

to account for the differentiation, we used two complementary approaches:

(1) Calculation of equilibrium melts from clinopyroxene and apatite composition, using experimental mineral/melt partition coefficients;

(2) Modelling the differentiation of a silico-carbonated melt with a stepwise approach combining distillation equations for the immiscibility and -alternately -fractional crystallization. The red syenites are distinguished from the other rock types by similar REE contents in apatite and clinopyroxene equilibrium melts (Figure II.13). Moreover, these compositions are roughly comparable to those of nephelinitic and melilitic primary melts [START_REF] Baudouin | Nephelinite lavas at early stage of rift initiation (Hanang volcano, North Tanzanian Divergence)[END_REF], suggesting that the red syenites have crystallized from less evolved melts, compared with the other facies. The

Chapitre II : Processus magmatiques

! &+!
similarities of apatite and clinopyroxene equilibrium melts in term of REE content may also suggest that the red syenites were formed from homogeneous melt batches.

In detail however, the equilibrium melts calculated from apatite and clinopyroxene differ by from each other by:

-higher Ce/Lu ratios in the majority of the clinopyroxene equilibrium melts (higher in fact These differences are not consistent with the duality of parental melts (carbonate and silicate liquids) suggested for the other facies. However, although their compositional differences were less pronounced, heterogeneous parental melts were nevertheless involved in the formation of the red syenites. This indicates that the formation of this rock type also involved immiscibility/fractional crystallization processes. The comparatively less contrasted parental melt compositions may reflect the formation of the red syenites in an earlier differentiation stage of the Ihouhaouene complex, compared with the other rock types.

Chapitre II : Processus magmatiques (experiments performed with green apatite from Ihouahouene) and carbonatite and clinopyroxene from [START_REF] Klemme | Experimentally determined trace and minor element partitioning between climopyroxene and carbonatite melt under upper mantle conditions[END_REF][START_REF] Blundy | Experimental comparison of trace element partitioning between clinopyroxene and melt in carbonate and silicate systems, and implications for mantle metasomatism[END_REF][START_REF] Blundy | Experimental comparison of trace element partitioning between clinopyroxene and melt in carbonate and silicate systems, and implications for mantle metasomatism[END_REF]. For syenites, we selected partition coefficients between silica-rich melt and apatite from [START_REF] Mahood | Trace-element partitioning in pantellerites and trachytes[END_REF] and [START_REF] Prowatke | Trace element partitioning between apatite and silicate melts[END_REF] and partition coefficients between silica-rich melt and clinopyroxene from Larsen

! &#!
Chapitre II : Processus magmatiques 1979) and [START_REF] Mahood | Trace-element partitioning in pantellerites and trachytes[END_REF]

! &$! (

II.7.b. Modelling

To simulate the superimposed effects of crystal fractionation and segregation of immiscible melts on trace-element differentiation, we used a stepwise approach combining two Rayleigh distillation equations, alternately: the fractional crystallization equation for the mineral (clinopyroxene and apatite) segregation and an equation formally similar to the fractional melting equation [START_REF] Shaw | Trace element fractionation during anatexis[END_REF] for the segregation of immiscible melt fractions (supplementary data B2, supplementary data illustration). In the latter, element partition coefficients between carbonate and silicate melts stand for the bulk solid/liquid partition coefficients of the modal fractional melting model. This approach is used to assess the ability of the inferred crystal fractionation-melt segregation model to account for Critical parameters of the model include:

-Initial melt compositions. To reproduce the whole complexity of the Ce/Lu vs. Nb/Ta systematics, we used two distinct compositions for parental melts: a primary, melilitic composition [START_REF] Baudouin | Nephelinite lavas at early stage of rift initiation (Hanang volcano, North Tanzanian Divergence)[END_REF] for the less differentiated rock types (the red syenites, notably) and an evolved, syenite-carbonatite melange for the most evolved facies (the Si-poor carbonatites).

-Partition coefficients between carbonate and silicate melts. The experimentally determined values available in the literature were determined for "pure" carbonate/silicate immiscibility [START_REF] Hamilton | The behaviour of trace elements in the evolution of carbonatites[END_REF][START_REF] Jones | Experimental investigations of the partitioning of Nb, Mo, Ba, Ce, Pb, Ra, Th, Pa, and U between immiscible carbonate and silicate liquids[END_REF][START_REF] Veksler I V, Petibon | Trace element partitioning in immiscible silicate-carbonate liquid systems: An initial experimental study using a centrifuge autoclave[END_REF][START_REF] Martin | Element Partitioning between Immiscible Carbonatite and Silicate Melts for Dry and H2O-bearing Systems at 1-3 GPa[END_REF] and do not allow us to account for trace element concentrations and ratios of Ihouhaouene magma compositions (supplementary data B2). Therefore we used liquid/liquid partition coefficients deduced from the equilibrium melt compositions calculated in our study. Partition coefficients are considered constant within a given step of melt segregation but they are allowed to vary to account for changes in parental melt compositions [START_REF] Martin | Element Partitioning between Immiscible Carbonatite and Silicate Melts for Dry and H2O-bearing Systems at 1-3 GPa[END_REF].

Chapitre II : Processus magmatiques

! &"!
-The residual melt proportion ("f") and the immiscible melt fraction ("F") represent melt fractions after each increment of 50% Cpx fractional crystallization (early mineral) and immiscible melt segregation, respectively. We used a trial-and-error approach to provide a best fit of our data. Given the uncertainties on several parameters and the relative inadequacy of the model to reproduce the whole complexity of the differentiation processes in the Ihouhaouene complex, constraining the actual f and F values was clearly beyond the scope of our approach. The aim of our numerical experiments was merely to assess the ability of the crystal fractionation-melt segregation model to account for the Ce/Lu and Nb/Ta variations within a reasonable range of f and F values (Table II.6).

! ! Chapitre II : Processus magmatiques ! &&!

II.8. SUMMARY AND CONCLUDING REMARKS

At first sight, the extreme diversity of trace-element compositions recorded by the Ihouhaouene equilibrium melts might suggest that the complex was formed from a range of primary mantle melts generated by variable degrees of melting of a carbonated, heterogeneous mantle source. This would also account for the almost continuous range of major-element compositions, from Si-poor carbonatites to .

This simple scheme is however at odds with the occurrence of LREE-depleted minerals (e.g., Previous studies of volcanic alkaline/carbonatite systems clearly demonstrated the role of fractional crystallization to reach carbonate saturation and immiscibility. To our knowledge, although complex cyclic processes including several stages of fractional crystallization and immiscibility are mentioned as the fractional crystallization models proposed by [START_REF] Holm | Sampling the Cape Verde mantle plume: evolution of melt composition on Santo Antão, Cape Verde Islands[END_REF][START_REF] Weidendorfer | Fractional crystallization of Si-undersaturated alkaline magmas leading to unmixing of carbonatites on Brava Island (Cape Verde) and a general model of carbonatite genesis in alkaline magma suites[END_REF], no models considered a multi-stage process involving alternating steps of fractional crystallization and melt exsolution.

Additional complexity in the petrogenesis of the Ihouhaouene complex arises from the fact that all rock facies show hybrid compositions resulting from the assemblage of minerals crystallized from distinct melt types. Equilibrium melts show only moderate differences of compositions in the red syenites, which also represent the less differentiated silicate melt. In contrast, the more differentiated silicate melt for the white syenites and the carbonatites show contrasted equilibrium melt compositions where the apatite is equilibrated with carbonate liquids while the clinopyroxene is equilibrated with silicate melts.

Altogether, these observations suggest an evolutionary scheme for the Ihouhaouene alkaline complex whereby all rock facies are intimately related. Progressive cooling of a silico-carbonated

III.1. Introduction

Apatite is a liquidus phase in carbonatite magmas (Elby 1975;[START_REF] Bas | Variation in apatite composition in ijolitic and carbonatitic igneous rocks[END_REF]Erikson et al. 1985) and is also known to crystallize throughout alkaline and carbonatite magma fractional crystallization (e.g. [START_REF] Hogarth | Rare-earth element minerals in four carbonatites near Gatineau, Quebec[END_REF]Gittins 1989;Djeddi et al. 2019). Its abundance and common occurrence in alkaline and carbonatite rocks favour fluorapatites as a petrogenetic and geochemical tracer among comagmatic suite of igneous rocks (e.g. alkaline and carbonatite complex of Kola Peninsula in Russia, [START_REF] Brassinnes | Magmatic evolution of the differentiated ultramafic, alkaline and carbonatite intrusion of Vuoriyarvi (Kola Peninsula, Russia). A LAICP-MS study of apatite[END_REF]. The importance of apatite as a tracer of magma evolution in carbonatite and alkaline complexes was first recognized by Le [START_REF] Bas | Variation in apatite composition in ijolitic and carbonatitic igneous rocks[END_REF] and further explored by Hogarth (1989), Hornig & Kjarsgaard (1988) and Bühn et al. ( 2001) that examined the apatite composition in carbonatite and associated rocks from a number of localities and supplied first reliable trace-element data for this mineral [START_REF] Chakhmouradian | Lithos Apatite in carbonatitic rocks : Compositional variation, zoning, element partitioning and petrogenetic significance[END_REF].

The crystal structure of apatite Ca 5 (PO 4 ) 3 (F,Cl,OH) allows a wide range of structural distortions [START_REF] Humphries | Rare Earth Elements: the Global Supply Chain[END_REF]. They represent the igneous source for REE and further evolution through sub-solidus remobilisation and formation of REE ore deposits (Wei [START_REF] Chen | Geochemistry of Monazite within Carbonatite Related REE Deposits[END_REF]. Furthermore, apatite is highly susceptible to various fluid induced (metasomatic) chemical and textural changes over a wide range of pressure and temperature making it an ideal mineral for fingerprinting metasomatic processes [START_REF] Harlov | Apatite : A Fingerprint for Metasomatic Processes[END_REF].

Most of petrological and geochemical studies have been performed on evolved carbonatite and alkaline complexes that have undergone complex hydrothermal and metamorphic events (Mountain Pass, Mariano & Mariano Jr, 2012; Bayan Obo, Möller 1989), whereas few study have considered early stage of REE remobilization [START_REF] Andrade | Hydrothermal rare earth elements mineralization in the Barra do Itapirapuã carbonatite, southern Brazil: behaviour of selected trace elements and stable isotopes[END_REF]. In Ihouhaouene carbonatites, the occurrence of igneous apatite free of sub-solidus inclusions and apatite with britholite and monazite inclusions is exceptional because they record early stage of REE remobilization and enrichment leading to the crystallization of REE-phosphates that are often associated to REE oxides in more evolved magmatic complexes [START_REF] Chakhmouradian | Lithos Apatite in carbonatitic rocks : Compositional variation, zoning, element partitioning and petrogenetic significance[END_REF]. They are precursor for the crystallization of rare-earth oxides.

This paper is devoted to a petro-geochemical characterization of the apatite-inclusions in Ihouhaouene carbonatites to highlight apatite and REE-phosphate equilibrium and determine the sub-solidus environment and fluid composition in carbonatite and alkaline rocks at early stage of REE remobilization.

III.2. Ihouhaouene carbonatite/syenite complex -Geological background

The Ihouhaouene alkaline complex consists of syenites and carbonatites intruded in the Archaean granulites of the In Ouzzal block in Algeria [START_REF] Lelubre | Recherches sur la géologie de l'Ahaggar central et occidental (Sahara central)[END_REF][START_REF] Kienast | Polymetamorphic A1, Mg-rich granulites with orthopyroxenesillimanite and sapphirine parageneses in Archaean rocks from Hoggar, Algeria[END_REF][START_REF] Ouzegane | Les granulites Al-Mg et les carbonatites dans la série de l'In Ouzzal[END_REF][START_REF] Ouzegane | New carbonatite complexes in the Archaean In'Ouzzal nucleus (Ahaggar, Algeria): Mineralogical and Geochemical data[END_REF]Djeddi et al. 2019)

III.3. Apatite as tracer of magmatic and sub-solidus evolution

Magmatic apatite crystallized from silicate melts, concentrated hydrothermal brines, lowtemperature aqueous solutions and possibly from the vapour phase [START_REF] Mcconnell | The substitution of SiO 4and SO 4groups for po4-groups in the apatite structure[END_REF]. Apatite is REE-rich mineral and it is one of the most important minerals affecting rare earth element trends in igneous rocks and volatile evolution in magmas [START_REF] Nash | Mineralogy and petrology of the Iron Hill carbonatite complex[END_REF]Picolli & Candella, 2002;[START_REF] Rakovan | Growth and Surface Properties of Apatite ; In: Phosphates (reviews in mineralogy and geochemistry)[END_REF].

Trace elements partition in favour of silicate melts relative to apatite and in apatite relative to carbonate melts and in both systems, REE are preferentially incorporated in apatite [START_REF] Prowatke | Trace element partitioning between apatite and silicate melts[END_REF]Webster & Piccoli, 2015). In the apatite/carbonatite system, REE are compatible in apatite depending on apatite silica content [START_REF] Hammouda | Apatite solubility in carbonatitic liquids and trace element partitioning between apatite and carbonatite at high pressure[END_REF]. All these element incorporations yield a large variety of apatite compositions.

Apatite crystallizes over a wide temperature range (>200ºC; Webster & Piccoli, 2015) and the REE substitution increases with decreasing temperature and increasing SiO 2 content of the melt [START_REF] Watson | Apatite liquid partition coefficients for the rare earth elements and strontium[END_REF]. REE 3+ substituted Ca 2+ in apatite structure by the main four substitution reactions with charge-compensating mechanisms [START_REF] Pan | Compositions of the Apatite-Group Minerals : Substitution Mechanisms and Controlling Factors[END_REF][START_REF] Hughes | Structurally robust, chemically diverse: apatite and apatite supergroup minerals[END_REF][START_REF] Harlov | Apatite : A Fingerprint for Metasomatic Processes[END_REF]:

Chapitre III: Processus sub-solidus

98

(1) REE 3+ + M + = 2 Ca 2+ (M= Ca, Sr, Pb, Na, Th..)

(2) REE 3+ + X 2-= Ca 2+ + F - (X= F, OH, Cl……….)

(3) 2 REE 3+ + ---= 2 Ca 2+ (---, Ca-vacancy site) and ( 4) Boggild, 1905), in Oka magnetite veins, Quebec (Guirault, 1953;Hughson et al., 1964), in alkaline syenites and granites of Soviet Union and China (Valsov, 1966), in the highly differentiated sodic syenites of Montana, USA, where britholite is observed instead of apatite [START_REF] Nash | Mineralogy and petrology of the Iron Hill carbonatite complex[END_REF] as well as alkaline rocks of the Pilansberg Complex, South Africa (Von Backstrom, 1976). In the In Ouzzal terrane, britholite is found in carbonatites as inclusions in apatite. This is original considering that in all the other occurrences; it does not coexist with apatite (Nash, 1984).

REE 3+ + Si 4+ = Ca 2+ + P 5+
Britholite is mainly described in nepheline syenites and contact metasomatic deposits. It The amounts of REE in apatite are also linked to wether apatite has undergone metasomatism.

REE can be removed from apatite by fluid-transfer to form other REE-bearing minerals such as monazite [START_REF] Harlov | Apatite and fluids: a fingerprint for metasomatic processes Elements[END_REF]. Monazite has the nominal composition (LREE)PO 4 with LREEs (La+Ce+Nd) generally comprise approximately 75% of the total cation proportions [START_REF] Spear | Apatite, monazite and xenotime in metamorphic rocks[END_REF]. Monazite is commonly found as inclusions in apatite and attests of a fluid-rock interaction.

The association of monazite and apatite is common in carbonatites (e.g., Mountain Pass, Moriano & Moriano Jr 2012; Bayan Obo Smith et al. 2000) where monazite occurs as small crystals on the edge of crystal replacing apatite or included within apatite crystals formed in a hydrothermal scenario from REEs rich fluids reacted with apatite [START_REF] Chen | Geochemistry of Monazite within Carbonatite Related REE Deposits[END_REF]. These fluids can be the result of internal mineral reaction or from outside the rock system [START_REF] Harlov | Apatite : A Fingerprint for Metasomatic Processes[END_REF].

The hypothesis that fluids can induce monazite inclusions to form in apatite in nature under a wide range of P-T conditions is supported experimentally (Harlov et al. 2002b(Harlov et al. , 2005;;Harlov & Forster, 2003;[START_REF] Harlov | Apatite : A Fingerprint for Metasomatic Processes[END_REF]. The crystallization of monazite inclusions or rim grains is the result of coupled dissolution-reprecipitation process during the metasomatic alteration of apatite (Putnis, 2009;[START_REF] Harlov | Apatite : A Fingerprint for Metasomatic Processes[END_REF]. The crystallographic continuity in the monazite host apatite, reveal that the regions affected by coupled dissolution and precipitation are characterized by a three dimensional micro-and nanoporosity in reacted regions allowing fluids to infiltrate the apatite structure (Harlov et al. 2005;Putnis, 2009;[START_REF] Harlov | Apatite : A Fingerprint for Metasomatic Processes[END_REF].

According to the monazite and apatite unit-cell parameters, there is a poor correspondence between the lattices of monazite and apatite in the plane of interface (Pan et al. 1993). The only similarity in the crystal structures of monazite and apatite in the orientation of the intergrowth is in the layering of the phosphate groups normal to the b-axis of monazite and c-axis of apatite (Pan et al. 1993). This may explain that monazite inclusions have precipitated by oriented reaction and suggest an epitaxial relationship with host-apatite (Pan et al. 1993;[START_REF] Pan | Compositions of the Apatite-Group Minerals : Substitution Mechanisms and Controlling Factors[END_REF][START_REF] Harlov | Apatite and fluids: a fingerprint for metasomatic processes Elements[END_REF].

III.4. Analytical methods

III.4.a. In situ mineral analysis for major, trace and volatile elements

The concentrations of major, trace and volatile element in minerals were measured by electron microprobe (Cameca SX100 at the Microsonde sud, University of Montpellier, France). Operating conditions are: acceleration voltage of 20 kV, beam current of 10 nA and a beam focalized (1 µm).

Background counting time of 09min for all elements was applied: 30 s for each REE Th and K except Ce, Y and Th that were analysed for 60s as for major elements, F and S and 20s for Cl. The internal standards chosen for each element were: Al 2 O 3 for Al, TiO 2 for Ti, wollastonite for Ca and Si, albite for Na, orthose for K, forsterite for Mg, hematite for Fe, apatite for P, native metal for Ni, Mn, Cu, celestine for Sr, ThO 2 for Th, enriched glasses for REE: REE2 for Nd, Sm, Yb, Lu; REE3 for La, Ce, Pr, Y; REE4 for Dy, baryte for S and Ba, fluorite for F and chloroapatite for Cl. Distribution of five major elements (Ca, P, Si, Ce, La) within apatite crystal and monazite inclusions was characterized by collecting WDS X-ray element maps with a step size of 16 µ.

In-situ trace element analyses were conducted by LA-ICP-MS at Geosciences Montpellier (AETE platform, OSU-OREME), using GeoLas Q + Excimer CompEx102 with a spot diameter of 26 µm laser beam for apatite and britholite, a repetition rate of 7 Hz, a laser power of 5 J/cm 2 and a mixture of helium and argon as carrier gas. The concentrations were calibrated with NIST 612 and the SiO 2 -CaO concentrations determined previously with electron microprobe for each mineral. BIR-1 standard is used as external standard. Data were processed with Glitter software [START_REF] Griffin | GLITTER: data reduction software for laser ablation ICP-MS. Laser ablation-ICP-MS in the earth sciences[END_REF].

III.4.b. Bulk mineral analysis for major, trace and volatile elements

Bulk-apatite trace element analyses were realised by ICP-Mass Spectrometry at Geosciences

III.4.c. Microstructure orientation

The crystallographic preferred orientations CPOs of apatite, britholite and monazite were characterized by the indexing of electron backscattered diffraction (EBSD) patterns using a SEM high resolution CamScan Crystal Probe X500FE type (FEG) equipped with a NordlysNano EBSD HKL detector for crystallographic analysis and an X-ray spectrophotometer EDS X-Max N detector for qualitative chemical analysis at Geosciences Montpellier (CNRS-University of Montpellier, France).

An accelerating voltage of 15-20 kV, a beam current of 5 nA, a step size of 2, 7 and 10 µm, a hit rate of 92% and a working distance of 20-25 mm were used for automatic measurements. The angular deviation for measurements of 20º between the electron beam and the sample surface is used to reach maximum diffraction intensity. The data have then been noise-reduced using a "wild spikes" correction to fill non-indexed pixels based on neighbouring pixels using the CHANNEL5s software

III.5. Results

Apatite

III.5.a. Si-rich apatite and britholite exsolution

Si-rich apatites are present as phenocryst (3 mm-10 cm) in Si-rich carbonatites. They may be free of inclusions (Figures III.2

Britholite-bearing apatites

Crystallographic orientation

EBSD analyses were performed to determine the crystal orientation relationships between apatite and britholite. We selected perpendicular section to the c-axis and performed apatite map

III.5.b. Si-poor apatite and monazite-quartz-calcite mineral assemblage

Si-poor apatites are present in Si-poor with contours levels in normalized multiples of uniform distribution where relative high concentrations of axis orientation are reported in dark red. e apatite-rim zone. f monazite-rim grains. g apatite-core zone. h monazite inclusions in apatite-core zone.

III.6. Discussion

Apatites from Ihouhaouene carbonatites are remarkable by their pegmatitic size-grain, their composition and crystallization in a complex magmatic context of immiscibility and hybridization.

The Ihouhaouene complex was formed from primary mantle melts generated by variable degrees of melting of carbonated heterogeneous mantle source and records high trace-element diversity.

III.6.a. Britholite exsolution in Si-rich apatite

Although apatites may record varying degrees of fluid-rock interaction starting from shortly after crystallization and continuing down to ambient P-T conditions [START_REF] Harlov | Apatite : A Fingerprint for Metasomatic Processes[END_REF], the presence of inclusion-free apatites in Si-rich carbonatite allows estimation of apatite composition that underwent with little low temperature and fluid re-equilibration. Inclusion-free REE-Si-rich apatites are interpreted as magmatic on account of the absence of typical dissolution-reprecipitation features and their homogeneous composition therefore their high SiO 2 content indicate that they crystallized from a melt with high silica activity at magmatic conditions.

Apatite REE-evolution

The evolution of apatite composition during britholite exsolution can be estimated assuming that inclusion-free Si-rich apatite represents the composition of apatite before exsolution and comparing in situ apatite composition both inclusion-free and britholite-bearing Si-rich apatites have high concentrations of LREEs, silica and sulphur.

2REE 3+ + --= 3Ca 2+ (1) S 6+ + Si 4+ = 2P 5+ (2)
and (2).

REE 3+ + Si 4+ = Ca 2+ + P 5+ (3)

Britholite exsolution

According to the REE and major element content of apatite and britholite, both minerals form The variation of composition between apatites is less than 1 apfu for all cationic-sites and The exchange reaction considering the variation britholite-bearing apatite composition shows REE-enrichment and slight deficient amount of Si for substitution and local replacement and intercrystallization of britholite (Figure III.15). Apatite-britholite reaction implies that REE content of the primary apatite (inclusion-free) is not sufficient to allow for the precipitation of the observed amounts of britholite at the expense of apatite caused by REE-bearing fluid. Also, britholite and apatite compositions don't display an intermediate composition as observed for the thorian mineral in Oka (Illimaussaq, Canada). As a consequence, the sub-solidus reaction involved for britholite exsolution can be considered as a solvus and requires the contribution of Si-REE-rich fluid. This is supported by the crystallization of britholite in the same orientation that host-apatite suggesting that britholiteexsolutions are topotactic and precipitate by an oriented fluid reaction (Pan, 1993).

The transportation of these elements into fluids, particularly REE, has been proposed as complexes. Ligands may be CO 3 2- (Balshov et al., 1975), PO 4 3-, F -, Cl - (Mineyev, 1963;Kapustin, 1966;Flynn & Burnham, 1978, Harlov et al., 2002a;Harlov & Forster, 2003). For Si-rich apatite, the high Cl, Th and U in britholite compare to the host apatite corroborate the presence of saline fluid during cooling and re-equilibration at subsolidus conditions.

III.6.b. Apatite and monazite-quartz-calcite inclusions

The REE-Si-poor-apatites are magmatic and crystallized from the segregated CO 2 -rich melt from an evolved SiO 2 -CO 2 -rich melt (Djeddi et al. 2019). The low silica and REE content of Si-poor apatites are interpreted as magmatic because of the absence of typical dissolution-reprecipitation features and indicate that they crystallized from a melt with low silica activity at magmatic conditions.

Apatite-REE evolution

The However, according to cationic mass balance between apatite, monazite, quartz and calcite in Si-poor apatite from Ihouahouene, the reaction needs to be adjusted. Following the low proportions

(1.48% monazite, 2.47 % calcite, 1.4% quartz, Figure III.10 see results section) of this mineral assemblage in apatite, S and REE contents in monazite can derived from the primary apatite considering the high sulphur contents in Si-poor inclusion-free apatites and the close REE-bulk compositions of Si-poor apatites.

The stoichiometric composition of all apatite analyses (inclusion-free or monazite-bearing)

presents a close composition for the P-and Ca-sites. The variation of average composition between apatites is less than 1 apfu for all cationic-sites, thus monazite-quartz-calcite inclusions precipitate During the exchange reaction Si and REE are preferentially removed out of the apatite and system [START_REF] Harlov | Apatite and fluids: a fingerprint for metasomatic processes Elements[END_REF]. The mass transfer of REE, Si and S between apatites assisted by fluid transfer can be sufficient in concentrations for nucleation and inter-crystallization of monazite, quartz and calcite. This is further supported by the crystallization of subhedral monazite elongated (b-axis) parallel to the orientation of host-apatite (c-axis) suggesting an epitaxial relationship and precipitate by an oriented fluid reaction (Pan, 1993;[START_REF] Harlov | Apatite and fluids: a fingerprint for metasomatic processes Elements[END_REF]. Likewise, the reacted apatites display the same crystallographic orientation over all the crystal suggesting fluid-assisted re-equilibration after a weak dissolution-precipitation at subsolidus conditions. The volatile components in inclusion-free apatites and inclusion-bearing apatites can be a tracer of temperature at magmatic and sub-magmatic conditions. Britholite and monazite can both crystallize at high temperature conditions. Cl and Th in fluid inducing britholite exsolution indicate an elevated temperature at sub-solidus conditions (Piccoli & Candela, 1994[START_REF] Rakovan | Growth and Surface Properties of Apatite ; In: Phosphates (reviews in mineralogy and geochemistry)[END_REF]. The high S-contents in magmatic inclusion-free Si-poor apatite and the rich-S monazite inclusion can be explained by the late stage oxidation of the residual carbonatitic melt and by degassing at magma late-stage and submagmatic fluid-rock re-equilibration (Burgisser & Scaillet, 2007). That attests of distinct apatite compositions at magmatic conditions (Si-rich and Si-poor) and different sub-magmatic conditions controlling fluid-rock interaction.

III.6.c. Fluid-rock interaction and REE enrichment reaction

Rocks

III.6.d. Britholite and monazite: sub-magmatic minerals before REE-oxides crystallization?

The distribution of REE in minerals is a useful geochemical and petrogenetic tracer of igneous crystallization and sub-solidus re-equilibration. The Ihouhaouene alkaline site represents an important step between magmatic and metamorphic processes. The presence of REE-bearing mineral such as britholite and monazite attests of little fluids-rock interaction and re-equilibration during metamorphic episode, whereas most of carbonatite underwent complex and multistage history of REE-deposition and enrichment (e.g. ore-deposits at Bayan Obo and Mountain Pass, Smith et al. 2000;[START_REF] Castor | The Mountain Pass rare-earth carbonatite and associated ultrapotassic rocks[END_REF].

In most ore-deposit carbonatite, further sub-solidus reaction and hydrothermal remobilization Previous studies have noted variations in the distribution of the REE in LREE-enriched monazite and bastnasite, and attempted to relate this to the formation environment of late-magmatic and/or hydrothermal origin (Fleischer, 1965;Fleischer, 1978;Fleischer & Altschuler, 1969;Smith et al. 2000). Such deposits have also received much attention because of their potential act as indicators of hydrothermal fluid source, chemistry and processes (Smith et al. 2017 and references in).

Monazite is a common REE-phosphate associated to apatite as are the result of coupled dissolution-reprecipitation processes during the metasomatic alteration of apatite and can form over a wide P-T range, starting at near-surface pressures and 100 °C (Harlov, 2005;Putnis 2009;Harlov, 2015 and references in). In Ihouhaouene apatites monazite can growth at sub-magmatic high P-T conditions and at low P-T conditions during carbonatite exhumation and fluid-apatite re-equilibration.

The REE contents of magmatic Si-poor apatites are high enough to account for the formation of the observed amounts of monazite inclusions.

Only Carbonatites are low degree carbonate-rich melts that derived from the mantle. The formation ages of carbonatites span a time period of 3 Ga with an increasing abundance towards more recent times [START_REF] Tichomirowa | Different zircon recrystallization types in carbonatites caused by magma mixing : Evidence from U -Pb dating , trace element and isotope composition (Hf and O) of zircons from two Precambrian carbonatites from Fennoscandia[END_REF][START_REF] Rukhlov | Geochronology of carbonatites from the Canadian and Baltic Shields, and the Canadian Cordillera : clues to mantle evolution[END_REF]. The oldest known carbonatite were formed in the Archaean period in the Tupertalik, western Greenland [START_REF] Bizzarro | Hf isotope evidence for a hidden mantle reservoir[END_REF] whereas the youngest carbonatite is the presently active volcano Oldoinyo Lengai in the East-African Rift system (Dawson, 1962;[START_REF] Bell | Carbonatite Volcanism: Oldoinyo Lengai and the Petrogenesis of Natrocarbonatites[END_REF][START_REF] Baudouin | Nephelinite lavas at early stage of rift initiation (Hanang volcano, North Tanzanian Divergence)[END_REF].

Most of the known carbonatite occurrences are situated in anorogenic settings related to intracontinental rifting [START_REF] Xu | ScienceDirect Origin of carbonatites in the South Qinling orogen : Implications for crustal recycling and timing of collision between the South and North China Blocks[END_REF]. Collision-related or post-collisional carbonatites as

Ihouhaouene carbonatites (In Ouzzal terrane, Western Hoggar, Algeria) are much rarer [START_REF] Tilton | Pb-Sr-Nd isotope data from 30 and 300 Ma collision zone carbonatites in northwest Pakistan[END_REF][START_REF] Hou | The Himalayan collision zone carbonatites in western Sichuan, SW China: petrogenesis, mantle source and tectonic implication[END_REF][START_REF] Chakhmouradian | Postorogenic carbonatites at Eden Lake, Trans-Hudson Orogen (northern Manitoba, Canada): Geological setting, mineralogy and geochemistry[END_REF]).

The study of isotope systems of such rocks as Ihouhaouene carbonatites supply useful information on the composition of the mantle and his evolution during time, owing to their isotopic characteristics generally inherited from the mantle source on account of the initially high concentrations of Sr and rare-earth elements (REE) in carbonatitic magmas [START_REF] Nelson | Geochemical and isotopic systematic in carbonatites and implications for the evolution of ocean-island sources[END_REF][START_REF] Xu | ScienceDirect Origin of carbonatites in the South Qinling orogen : Implications for crustal recycling and timing of collision between the South and North China Blocks[END_REF] and their rapid ascent to the surface [START_REF] Treiman | Carbonatites magma: properties and processes[END_REF]. Carbonatite melts could cause significant changes to the sub-continental mantle by the carbonatite metasomatism [START_REF] Dupuy | Zr/Hf fractionation in intraplate basaltic rocks: carbonatite metasomatism in the mantle source[END_REF]). Nevertheless, carbonatite rocks are themselves susceptible to secondary alteration processes that can disturb their primary isotope composition [START_REF] Deines | Stable isotope variations in carbonatites[END_REF]Demeny et al. 2004a;[START_REF] Tichomirowa | Different zircon recrystallization types in carbonatites caused by magma mixing : Evidence from U -Pb dating , trace element and isotope composition (Hf and O) of zircons from two Precambrian carbonatites from Fennoscandia[END_REF][START_REF] Xu | ScienceDirect Origin of carbonatites in the South Qinling orogen : Implications for crustal recycling and timing of collision between the South and North China Blocks[END_REF]. They are often affected by alteration processes such as interaction with water fluids (weathering), degassing of CO 2 (Rayleigh fractionation processes) and further sub-solidus re-equilibration processes [START_REF] Deines | Stable isotope variations in carbonatites[END_REF]Demeny et al. 2004a;Tichomirowa et al. 2006;[START_REF] Tichomirowa | Different zircon recrystallization types in carbonatites caused by magma mixing : Evidence from U -Pb dating , trace element and isotope composition (Hf and O) of zircons from two Precambrian carbonatites from Fennoscandia[END_REF][START_REF] Xu | ScienceDirect Origin of carbonatites in the South Qinling orogen : Implications for crustal recycling and timing of collision between the South and North China Blocks[END_REF].

Carbonatites contain several minerals enriched in U and (or) Th such as baddeleyite, monazite, zircon, apatite, zirconolite, perovskite, and pyrochlore that make therefore a precise age determination of these rocks using the U-Pb method [START_REF] Amelin | Precise geochronology of phoscorites and carbonatites : The critical role of U-series disequilibrium in age interpretations[END_REF]. However, enrichment in U, Th and their decay products causes deviation from the secular radioactive equilibrium in growing minerals that results over time in the excess or deficiency of radiogenic Pb isotopes [START_REF] Amelin | Precise geochronology of phoscorites and carbonatites : The critical role of U-series disequilibrium in age interpretations[END_REF].

Ihouhaouene carbonatites are associated to alkaline syenites and only carbonatites were previously dated on zircon and apatite grains by ID-TIMS that record an eburnean age of 2 Ga [START_REF] Bernard-Griffiths | Origin and evolution of 2 Ga old carbonatite complex (Ihouhaouene, Ahaggar, Algeria): Nd and Sr isotopic evidence[END_REF][START_REF] Allègre | U-Th-Pb systematics of hydroxyapatite intergrowths[END_REF]. The age of syenites is unknown; therefore, our primary objective is to explain both the geochemical and structural relations of the Ihouhaouene alkaline rocks and confirm their Eburnean age (2Ga) by L(-ICPMS on in situ minerals.

At present, we studied apatite and zircon formed as a primary minerals from Precambrian carbonatite complex from Ihouhaouene, In Ouzzal (2 Ga). These carbonatites were partially studied

Chapitre IV : U-Pb datations ! ")*!

for their mineral isotope composition (O, C, Rb-Sr, Sm-Nd) and their age (U-Pb on zircon). Their cogenetic origin is always disputed in the literature.

Zircon was chosen for U-Pb investigations because of its physical and chemical resistance to alteration processes (Cherniak & Watson, 2001) and inclusion-free apatites representative of magmatic apatite is the most U-bearing mineral available to date carbonatites when zircon is not present. The aim of U-Pb dating of apatites and zircons from Ihouhaouene carbonatites and syenites is to develop alternative models of carbonatite petrogenesis and magmatic to post magmatic processes in syn-metamorphic orogenic settings that will explain both the structural relations with the associated syenites and granulitic host-rocks and unusual isotopic signatures of the Ihouhaouene rocks. In a broader context, interpretation of the geodynamic evolution of the Ihouhaouene area resulted from isotopic data is important to clarify the tectonic history of In Ouzzal terrane.

IV.2. Geological setting

!

Ihouhaouene Carbonatites and syenites intrude the In Ouzzal granulite host rocks. The In Ouzzal terrane (Western Hoggar) is an example of Archaean crust [START_REF] Ferrara | Radiometric ages from Western Ahaggar (Sahara) suggesting an eastern limit for the West African Craton[END_REF][START_REF] Lancelot | Uranium and lead isotopic dating with grain-by grain zircon analysis: a study of a complex geological history with a single rock[END_REF][START_REF] Othman | Nd-Sr isotopic composition of granulites and constraints on the evolution of the lower continental crust[END_REF]Rousseau et al. 1995) remobilized during a very-hightemperature metamorphism related to the paleoproterozoic orogeny (2 Ga) [START_REF] Ferrara | Radiometric ages from Western Ahaggar (Sahara) suggesting an eastern limit for the West African Craton[END_REF][START_REF] Allègre | U-Th-Pb systematics of hydroxyapatite intergrowths[END_REF] and characterized by prograde evolution at high pressures (800-1050ºC at 10-11 kbar) followed by an isothermal decompression (9-5 kbar) [START_REF] Ouzegane | A review of Archaean and Paleoproterozoic evolution of the In Ouzzal granulitic terrane (Western Hoggar, Algeria)[END_REF]) (Table IV-

IV.3. Instrumentaion and analytical methods

For zircons, we analysed the carbonatitic and syenitic thin sections by scanning electronic microscopy combined with cathodoluminescence (SEM-CL) to identify all zircons with up to 20 µm size on thin section samples. Optical microscopy combined to cathodoluminescence (OM-CL) was applied on apatite in carbonatite and syenite thin sections to understand the CL colours changes caused by alteration processes. Then, in-situ isotope U-Pb analyses from zircons and apatites were performed to characterize both primary and secondary signatures of carbonatite and syenite.

IV.3.a. EPMA in situ zircon analysis for major elements

The major element concentrations in zircons from carbonatite IC2-9A and syenite IC2-6A

were measured by electron microprobe (Cameca SX100 at the Microsonde sud, University of Montpellier, France). Operating conditions used are: acceleration voltage of 20 kV, beam current of 100 nA and a beam focalized (1 µm). Background counting time of 10min for all elements: 30 s for each major element and Y, Yb, Hf and 40 s were applied. The internal standards chosen for each

Chapitre IV : U-Pb datations ! ")#! element were: andradite for Ca, Fe and Si, TiO 2 for Ti, ZrSiO 4 for Zr, Cl-apatite for P, ThO 2 for Th, Yb 3 Fe 5 O 12 for Yb, HfO 2 for Hf, UO 2 for U, enriched glass REE3 for Ce and YIG for Y. Distribution of five major elements (Hf, Si, Th, U, Ce) within zircon crystals was characterized by collecting WDS Xray element maps with a step size of 0.4 to 3 µ according to the crystal dimensions.

IV.3.b. Apatite U-Pb dating

U-Pb apatite geochronology was performed by laser ablation (LA-ICP-MS) on thick sections at Rennes Geosciences using a ESI NWR193UC Excimer laser inductively coupled to an Agilent 7700x Quadripole plasma mass spectrometer ICP-MS. The detailed analytical procedures are described in the table IV.2. Optical Microscopy Cathodoluminescence (OM-CL) images using a

Reliotron CL system equipped with a digital colour camera available at Rennes Geosciences were performed on the analysed apatites in order to verify the homogeneity of the crystals and avoid any inclusion contamination. The analyses consisted of 20s background measurement followed by 60s integration time, then 15 seconds wash-out delay time to clean out the previous sample. Chapitre IV : U-Pb datations ! "))! Chapitre IV : U-Pb datations ! ")+!

IV.3.c. Zircon U-Pb dating

Material preparation protocol

Mineral separation procedures were applied to concentrate the zircon crystals using the facilities available at Granada Institute (IACT). All devices are thoroughly cleaned before and after each use to avoid contamination from a previously treated sample. The carbonatite and syenite samples are reduced using a jaw crusher to obtain a powder of a particle size of 250 µm. The powder is sieved for 50 minutes to keep only the material of diameter between 100 and 250 microns. A first stage of concentration of the heavy minerals is carried out using a Wilfley shaking table. The heavier fraction, after being dried, is separated according to the magnetic susceptibility of heavy minerals using a Frantz isodynamic separator. The second step is performed using heavy liquids of bromoform (density of 2.89) and methylene iodide (density of 3.3). Zircons characterized by diamagnetic properties and superior density than 3.3 are examined and carefully handpicked under a binocular microscope on the basis of their quality (absence of micro-fractures, evidence of deterioration and inclusions) and then classified according to their morphology, the development of the crystalline faces and their colour. The selected zircon grains are then embedded in epoxy mounts, grounded and polished on a lap wheel with 6 and 1 mm diamond suspensions successively.

Analytical procedure

Uranium-Pb dating of zircons in carbonatite (IC2-9A) and syenite (IC2-6A) thin sections was performed at the Instituto Andaluz de Ciencias de la Tierra (IACT) (Granada, Spain) using the Laser Ablation ICP-MS. The analyses were acquired using an Excimer laser of 193 nm wavelength coupled to an Agilent 8800 Triple Quadripole ICP-MS multi-collector mass spectrometer. The detailed analytical procedures are described in the table IV.3.

A diameter laser ablation of 15 μm, 10 Hz frequencies and a laser power of 8J/cm 2 were used.

The analyte thus produced is transported in a 100% helium gas mixture to the plasma source for ionization. Each analysis consists of an ablation pulse of 30 seconds integration time. The ages are then derived from the [START_REF] York | Least-squares fitting of a straight line with correlated errors[END_REF] linear regression calculations performed using the ISOPLOT version 3 software [START_REF] Ludwig | Isoplot 3.00[END_REF].

Chapitre IV : U-Pb datations ! "),! Chapitre IV : U-Pb datations ! ")$!

IV.4. Results

IV.4.a. Apatite in situ U-Pb dating

The free-inclusion apatite samples from Ihouhaouene carbonatite (INH 170) and syenite (IC3- Chapitre IV : U-Pb datations ! ")%! [START_REF] Stacey | Approximation of terrestrial lead isotopic evolution by a two-stage model[END_REF]. Ellipses and errors are reported at 2 σ.

Chapitre IV : U-Pb datations ! "+#!

IV.4.b. Zircon mineral chemistry

Carbonatite zircon grains (Table IV.5) have homogenous composition with 27.9-31.7 wt.% In syenite, zircon grains (Table IV.5) have higher HfO 2 of 0.9 to 1. Chapitre IV : U-Pb datations ! "#$! Chapitre IV : U-Pb datations ! "#%!

IV.4.c. Zircon in situ U-Pb dating

From the IC2-6A syenite zircons (Figure 3 in supplementary material D), fifty-four U-Pb isotopes analyses on twelve zircon grains were carried out (Table IV.6). These analyses are characterized by variable U and Th contents ranging from 96 to 8000 ppm, and from 7.4 to 3980 ppm respectively and associated to low to moderate Th/U ratio bracketed between 0.01 and 0.55 (Table IV.6, Figure IV.8a). In the Concordia diagram, the ellipses are in concordant to discordant positions (83 to 120 % of concordance ; Table IV Chapitre IV : U-Pb datations Ellipses and errors are reported at 2 σ.

! "#&!
From the IC2-9A carbonatite zircons (Figures 1 and 2 in supplementary material D), eighteen U-Pb isotopes analyses on five zircon grains were performed (Table IV Chapitre IV : U-Pb datations ! "#$! Chapitre IV : U-Pb datations ! "%"! Chapitre IV : U-Pb datations ! "#$!

IV.5. Discussion

IV.5.a. U-Pb Apatite dating: Pb diffusion or dissolution-recrystallization

Apatites in carbonatite have violet-bluish CL that is similar to magmatic apatites from alkaline rock complexes [START_REF] Kempe | Cathodoluminescence (CL) behaviour and crystal chemistry of apatite from rare-metal deposits[END_REF]Tichomirowa et al. 2003;[START_REF] Chakhmouradian | Postorogenic carbonatites at Eden Lake, Trans-Hudson Orogen (northern Manitoba, Canada): Geological setting, mineralogy and geochemistry[END_REF].

Instead apatites from syenite sample have yellow CL that is typical of apatites in silicate melts (Tichomirowa et al. 2003;Demeny et al. 2004b;[START_REF] Karchevsky | Phoscorites and Carbonatites from Mantle to Mine: The Key Example of the Kola Alkaline Province[END_REF][START_REF] Chakhmouradian | Postorogenic carbonatites at Eden Lake, Trans-Hudson Orogen (northern Manitoba, Canada): Geological setting, mineralogy and geochemistry[END_REF]. While the main indicator for yellow CL colour is Mn 2+ , that of bluish CL is the Eu 2+ (Tichomirowa et al. 2003).

The 207Pb/206Pb corrected ages obtained on five apatite crystals vary between 1588 ± 124 and 2025± 142 Ma. There does not seem to be any relationship between these different ages and the position of analysis in the crystal (rim, center). The weighted average 207Pb/206Pb corrected ages for center and rim grains yields similar ages within the errors of 1867 ± 88 Ma (MSWD = 2.4, N= 8; (Ouzegane et al. 2003 and references in). This age of 1834 Ma obtained on the apatites is younger than the ages of 2090 Ma and 1994 ± 22-17 Ma obtained by U/Pb on hydroxyapatite and zircon [START_REF] Allègre | U-Th-Pb systematics of hydroxyapatite intergrowths[END_REF][START_REF] Bernard-Griffiths | Origin and evolution of 2 Ga old carbonatite complex (Ihouhaouene, Ahaggar, Algeria): Nd and Sr isotopic evidence[END_REF]) that were interpreted by these authors as the ages of setting up of the syenitecarbonatite complex.

Pb diffusion between the center and rim of carbonatitic apatite grains should be synchronous with the crystallization process. The closure temperatures for Pb in an apatite of 1cm effective diffusion radius for a cooling rate of 10ºC/Ma are 750ºC (Cherniak & Watson 2001), which imply a higher Pb closure temperature in apatite for higher effective diffusion radius. In the In Ouzzal terrane, temperature remains high for a long period, therefore the Ihouhaouene apatites probably have a slow cooling rate and slow mineral diffusion rate.

Apatites in syenite have low and heterogeneous Th concentrations (Table IV.4) compare to the carbonatitic-apatites. They are heterogeneous with obvious crystal growth and Mn-F-fluid interaction, characterized by a smaller grain size compare to apatite in carbonatites.

Chapitre IV : U-Pb datations

! "#%!
Ages recorded in apatite grains of syenite IC3-10 are much younger (~ 651 Ma) than the ages of carbonatitic apatites and correspond to the Pan-African event which is well-know in the Hoggar (800-550 Ma). Therefore, syenites record the thermic event during the emplacement of alkaline granite-plutons (T>450ºC; [START_REF] Haddoum | Extrusion du bloc In Ouzzal vers le Nord (Hoggar Occidental, Algérie): Conséquence d'un poinçonnement panafricain Extrusion de l[END_REF] in the Ihouhaouene area given that no Pan-African metamorphism had affected the In Ouzzal terrane rocks because of his refractory behaviour after the granulitic metamorphism [START_REF] Ouzegane | A review of Archaean and Paleoproterozoic evolution of the In Ouzzal granulitic terrane (Western Hoggar, Algeria)[END_REF][START_REF] Haddoum | Extrusion du bloc In Ouzzal vers le Nord (Hoggar Occidental, Algérie): Conséquence d'un poinçonnement panafricain Extrusion de l[END_REF]. A similar Pan-African age has been found by Carpena et a l(1988) by fission-track (~ 600 Ma) and suggested an exhumation age of carbonatites at Pan-African.

IV.5.b. U-Pb Zircon dating and growth in carbonatites and syenites

Zoning in Hf and Y have been observed in EMP maps but Pb couldn't be observed in CL zircon images because of its low abundance and the fact that its electronic structure militates against its being a CL activator in zircon (Cherniak & Watson, 2001). The EPMA data presented here, indicate that carbonatitic and syenitic zircons underwent recrystallization caused by infiltration of Sirich carbonatitic late-stage melts.

Significant differences in geochemical composition of immiscible carbonate-melts and evolution in hybrid system led to different types of zircon recrystallization and isotope compositions of zircon grains in syenites. Hf in zircons is higher in syenite than carbonatite ( IV.6) and that are similar to concentrations in Kimberlitic zircons and significantly lower than other igneous zircons [START_REF] Hoskin | The composition of zircon and igneous and metamorphic petrogenesis[END_REF]Grims et al. 2007;[START_REF] Tichomirowa | Different zircon recrystallization types in carbonatites caused by magma mixing : Evidence from U -Pb dating , trace element and isotope composition (Hf and O) of zircons from two Precambrian carbonatites from Fennoscandia[END_REF]. The incorporation of Th in zircon is primarily controlled by the availability of Th and U in the system and partitioning with other phases [START_REF] Rubatto | Zircon: The Metamorphic Mineral[END_REF]. The presence of Th-rich minerals as REE-rich apatite, britholite and monazite in carbonatites is the reason for low Th/U in coexisting zircons.

All dated carbonatitic zircons have Th/U ratio >0.1 (Figure IV.12a) and are intermediary to magmatic zircon types [START_REF] Williams | An extended episode of early Mesoproterozoic fluid flow in the Reynolds Range, central Australia[END_REF][START_REF] Schaltegger | Growth, annealing and recrystallization of zircon and preservation of monazite in high-grade metamorphism: conventional and in-situ U-Pb isotope, cathodoluminescence and microchemical evidence[END_REF][START_REF] Rubatto | Zircon trace element geochemistry : partitioning with garnet and the link between U -Pb ages and metamorphism[END_REF]. Two zircon compositions have Th/U ratio 0.1<Th/U<0.3 as intermediate between metamorphic and magmatic values [START_REF] Rubatto | Zircon trace element geochemistry : partitioning with garnet and the link between U -Pb ages and metamorphism[END_REF][START_REF] Hoskin | The composition of zircon and igneous and metamorphic petrogenesis[END_REF][START_REF] Teipel | U-Pb SHRIMP and Nd isotopic data from the western Bohemian Massif (Bayerischer Wald, Germany): Implications for Upper Vendian and Lower Ordovician magmatism[END_REF]) and corresponding Concordia ages are of 1816 ± 91 Ma and 1840.9 ± 56 Ma (Table IV.6) and correspond to the metamorphic ages recorded in the In Ouzzal terrane [START_REF] Ouzegane | A review of Archaean and Paleoproterozoic evolution of the In Ouzzal granulitic terrane (Western Hoggar, Algeria)[END_REF]. The other (N=16) carbonatitic zircons have Th/U > 0.3 and correspond to magmatic zircons types [START_REF] Rubatto | Zircon trace element geochemistry : partitioning with garnet and the link between U -Pb ages and metamorphism[END_REF][START_REF] Schaltegger | Growth, annealing and recrystallization of zircon and preservation of monazite in high-grade metamorphism: conventional and in-situ U-Pb isotope, cathodoluminescence and microchemical evidence[END_REF][START_REF] Williams | An extended episode of early Mesoproterozoic fluid flow in the Reynolds Range, central Australia[END_REF]. While syenitic zircons have a wide range of Concordia ages with: 18 zircons have Th/U < 0.1 that can be considered as metamorphic zircons [START_REF] Williams | An extended episode of early Mesoproterozoic fluid flow in the Reynolds Range, central Australia[END_REF][START_REF] Schaltegger | Growth, annealing and recrystallization of zircon and preservation of monazite in high-grade metamorphism: conventional and in-situ U-Pb isotope, cathodoluminescence and microchemical evidence[END_REF][START_REF] Rubatto | Zircon trace element geochemistry : partitioning with garnet and the link between U -Pb ages and metamorphism[END_REF] Zircons from Ihouhaouene carbonatites have low Th/U ratio values 0.1<Th/U<1.16 compare to the atypical Th/U zircon ratio from carbonatites (e.g. Zircons from carbonatites from the Kola Peninsula, Russia have Th/U ratios varying up to 9000; [START_REF] Amelin | Precise geochronology of phoscorites and carbonatites : The critical role of U-series disequilibrium in age interpretations[END_REF]. Th/U ratios don't allow us to attribute them a magmatic origin because of the high Th and U contents in carbonatites. In the case they have a magmatic source they may suggest an intermediate to felsic melt source [START_REF] Hoskin | The composition of zircon and igneous and metamorphic petrogenesis[END_REF]Liu et al. 2008;[START_REF] Linnemann | Lithos Sands of West Gondwana : An archive of secular magmatism and plate interactions -A case study from the Cambro-Ordovician section of the Tassili Ouan Ahaggar (Algerian Sahara) using U -Pb -LA-ICP-MS detrital zircon ages[END_REF]. Magmatic Proterozoic zircons from Hoggar have Th/U ratios higher than 1.5 and derived from mafic magmas [START_REF] Linnemann | Lithos Sands of West Gondwana : An archive of secular magmatism and plate interactions -A case study from the Cambro-Ordovician section of the Tassili Ouan Ahaggar (Algerian Sahara) using U -Pb -LA-ICP-MS detrital zircon ages[END_REF].

Therefore Ihouhaouene carbonatites couldn't arise directly from mantle and the carbonatitic zircon compositions confirm their origin by immiscibility from an evolved CO 2 -Si-rich magma. Zircons from Ihouhaouene syenites have intermediate Th/U ratio values 0.1<Th/U<0.55 (felsic melt source) and different U-Pb Concordia ages. This ion probe analyses disturbance in zircons crystals on thin sections didn't appear in CL images and that could be attributed to mixing as consequence of combining isotope information from distinct fractionation and immiscibility-hybridization episodes during the magmatic event and/or to the inherited zircons of granulitic metamorphism in the In Ouzzal.

That is accurate in the case we consider the analysed zircons in carbonatites as magmatic grains. Although, the crystallization of apatite, monazite, allanite and britholite in carbonatites in magmatic to sub-magmatic environments may influence the Th budget of the rock and the Th/U of equilibrated zircon in magmatic and sub-solidus conditions then the data presented here can not form a discriminant results for the Ihouhaouene carbonatitic magmatic or metamorphic history. The in situ LA-ICP-MS method on thin section facilitates dating high zircon number during an analytical session and allows to determine the position of zircons related to the associated minerals but not the structure and texture of zircon grain as core or rim crystal-region in 3D. Thus, zircons in syenites require more textural study on separated zircon grains to more understand the U/Pb isotopic compositions and relationship to the carbonatitic zircons and the In Ouzzal granulitic host rock. Chapitre IV : U-Pb datations This thesis carries out some key results to these major questions about the petrogenesis of carbonatites through the detailed petro-geochemical study of the Proterozoic carbonatites and associated syenites of Ihouhaouene area in South Algeria.

! "#)! Discussion ! Discussion ! "#$!

Discussion

! "#"!

Are carbonatites derived from primary carbonated mantle melt or by fractional-crystallizationimmiscibility processes? And what is their relation with the associated silicate rocks?

The intra-cratonic Ihouhaouene carbonatites and syenites are silica-saturated, syn-orogenic and form linear intrusive rock outcrops in large shear-zones. They are characterized by the absence of felspathoids and differ from the most typical petrographic environment of intrusive carbonatites in intra-cratonic settings that includes a broad spectrum of silica-undersaturated peralkaline rocks, including melilitolites, foidolites and foid syenites [START_REF] Chakhmouradian | Postorogenic carbonatites at Eden Lake, Trans-Hudson Orogen (northern Manitoba, Canada): Geological setting, mineralogy and geochemistry[END_REF]. These types of rocks are not recognized in Ihouhaouene area.

Only few localities reported carbonatites and silica-saturated syenites similar to Ihouhaouene igneous complex, whereas the cogenetic relationship between alkaline rocks and carbonatites have not been studied; Eden Lake in Canada [START_REF] Chakhmouradian | Postorogenic carbonatites at Eden Lake, Trans-Hudson Orogen (northern Manitoba, Canada): Geological setting, mineralogy and geochemistry[END_REF], Murun, Khalyuta, Oshurkovo and numerous other localities in eastern Siberia (Konev et al. 1996;Yarmolyuk et al. 1997;Nikiforov et al. 2003), Mushugai-Khuduk, Bayan Hushuu, Tsogt-ovoo and Ulugei in Mongolia (Samoylov & Kovalenko, 1983), Dalucao and Maoniuping in China (Xu et al. 2003;[START_REF] Hou | The Himalayan collision zone carbonatites in western Sichuan, SW China: petrogenesis, mantle source and tectonic implication[END_REF]), Sevathur and Samalpatti in India (Viladkar & Subramanian, 1995;Schleicher et al. 1998), Dunkel'dyk in Tajikistan (Faiziev et al. 1998), Loch Urigill in Scotland (Young et al. 1994), Halpanen and Naantali in Finland (Puustinen & Karhu, 1999;Woodard and Hölttä, 2005), and El Picacho in Mexico (Ramírez Fernández et al. 2000).

The petro-mineralogical and geochemical study of Ihouhaouene igneous complex permits to determine a cogenetic relationship between carbonatites and syenites. Through the structural relationships, the bulk-rock compositions and mineral chemistry of apatite and clinopyroxene in both carbonatites and syenites we highlight important features and similarities of these two rock types:

(1) Ihouhaouene carbonatites and syenites are intimately related. They have close spatial distribution on the field and share the same magmatic mineral assemblages of apatite and clinopyroxene in all rock facies. Whole-rock major-and trace-element compositions of carbonatites and syenites characterize four rock facies as function of silica contents and present a continuous range from continuous range of CO 2 and silica whole-rock compositions from silica-poor carbonatites to silica-rich (red) syenites suggesting a cogenetic evolution from the same parental melt between all rock facies.

(

In this scheme, the carbonatite and syenite rock facies reflect the parental melt compositions inherited from complex differentiation stages of carbonated-silicate melt as a result of several steps of fractional crystallization and carbonated melt immiscibility unsettled by hybridization process

that we illustrate by the proposed geodynamic model (Figure 8).

Discussion

! "#&!

Discussion

! "#'!

What is the composition of the mantle and the carbonated-silicate primary melt they derived from?

And which parameters control such Nb/Ta variation in immiscible carbonated melts?

To explain the complex evolution of silicate melts in the Ihouhaouene area and reproduce the melt source compositions, I performed a numerical model (Chapter II) using a stepwise approach integrating two Rayleigh distillation equations, alternately. I used the fractional crystallization equation for the mineral (clinopyroxene and apatite) segregation and an equation formally similar to the fractional melting equation [START_REF] Shaw | Trace element fractionation during anatexis[END_REF] for the segregation of immiscible melt fractions.

Ihouhaouene carbonatites with high Nb/Ta are Si-rich and don't have pure carbonatite composition in a silica-undersaturated rock system as in experimental studies. Therefore the choice of partitioning coefficients between carbonate and silicate melts is imperative for the calculation of petrogenetic model. Partition coefficients are considered constant within a given step of melt segregation but they strongly depend of parental melt compositions [START_REF] Martin | Element Partitioning between Immiscible Carbonatite and Silicate Melts for Dry and H2O-bearing Systems at 1-3 GPa[END_REF]. To account for the parental melt evolution, I used liquid/liquid partition coefficients deduced from the equilibrium melt compositions calculated in my study (Chapter II).

My results for Ce/Lu vs Nb/Ta behaviour from successive numerical experiment A and B, using a primary melilitite composition [START_REF] Baudouin | Nephelinite lavas at early stage of rift initiation (Hanang volcano, North Tanzanian Divergence)[END_REF] as initial parental melt and liquid/liquid partition coefficients inferred from average equilibrium between apatites in Si-rich carbonatites and clinopyroxene in red syenites for model A and from equilibrium between apatites and clinopyroxenes in White syenites for model B suggest that:

-The high Nb/Ta and LREE/HREE apatite equilibrium melts from Si-rich carbonatites represent a poorly evolved magma from low immiscible melt fractions (F).

-The low Nb/Ta and LREE/HREE apatite and clinopyroxene equilibrium melts from red syenites represent segregated silicate melt fraction from a poorly to mildly evolved parental magma.

-Hybridization and mingling of both carbonated immiscible fractions and segregated silico-carbonated melt fractions induce evolved-mixt parental melt with hybrid mineral compositions for evolved immiscibilities.

-The low Nb/Ta and LREE/HREE clinopyroxene equilibrium melts from white syenites represent a segregated carbonated melt from the evolved-mixt magma.

-The low Nb/Ta and High LREE/HREE apatite equilibrium melts from Si-poor carbonatite represent a strongly evolved magma from high immiscible melt fraction (F).

Discussion

! "#(!

The petrogenetic numerical model of carbonatites and syenites highlight three key parameters among other than hybridization that explain the atypical Nb/Ta compositions and the high REE concentrations observed in Ihouhaouene:

-Initial melt compositions control the coefficient partitioning behaviour of Nb, Ta and rare earth elements between the segregated carbonate and silicate melts during immiscibility process.

-The immiscibility rate "F" strongly controls the REE distribution and Nb/Ta ratio systematics between segregated carbonated and residual silicate-melt fractions.

-The fractional crystallization rate ("f") after each immiscibility step controls the REE concentration in the residual silicate-melt fractions and thus the parental melt increments.

The reproduced compositions of Ihouhaouene carbonatites and syenites through the petrogenetic modelling of the complex processes (fractional-crystallization immiscibility and hybridization)

suggest that the alkaline complex derived from a carbonated-silicate melt of a melilititic composition. Dalton and Presnal (1998b) demonstrated experimentally the continuum between carbonatite and silicate melts and denoted the carbonatite-kimberlite transition at the 6 GPa isobar. Moore and Wood (1998) report the carbonatite to melilitite melts transition at the 3 GPa isobar (Hamouda & Keshav, 2015). The silicate melts composition as kimberlitic or melilititic composition can result from melting of the same source and it is a matter of degree of melting (of no more than 1%) and variation of temperature and pressure [START_REF] Gudfinnsson | Continuous gradations among primary carbonatitic, kimberlitic, melilititic, basaltic, picritic, and komatiitic melts in equilibrium with garnet lherzolite at 3-8 GPa[END_REF]Keshav & Gudfinnsson, 2013;Novella et al. 2014;Keshav & Hamouda, 2015) and liquid immiscibility at low pressure (~2-2.6 GPa) could be behind silicate and carbonatitic liquids observed in nature.

The high silica contents in Ihouhaouene alkaline complex can be the result of early crustal contamination during magmatic evolution affecting the melilitite magmatic precursor of carbonatites.

This contamination event is observed in the uncommon isotopic signatures of εND (T) and εSr (T) [START_REF] Ouzegane | New carbonatite complexes in the Archaean In'Ouzzal nucleus (Ahaggar, Algeria): Mineralogical and Geochemical data[END_REF][START_REF] Bernard-Griffiths | Origin and evolution of 2 Ga old carbonatite complex (Ihouhaouene, Ahaggar, Algeria): Nd and Sr isotopic evidence[END_REF]) suggesting an enriched source.

Otherwise calciocarbonatites can be generated through reaction of carbonated melts containing H 2 O or other volatiles with depleted harzburgitic or lherzolitic assemblages at low pressures (15 Kbar, 1150ºC) [START_REF] Dalton | The compositions of primary carbonate melts and their evolution through wallrock reaction in the mantle[END_REF]. However, carbonated harzburgitic assemblages would produce more magnesian melts while residual wehrlites are in equilibrium with calcic melts [START_REF] Dalton | The compositions of primary carbonate melts and their evolution through wallrock reaction in the mantle[END_REF].

Discussion

! "##! Furthermore, the petrogenetic modelling of Ihouhaouene calcic carbonatite and syenite involve immiscibility and fractional crystallization processes at the origin of the carbonated and alkaline segregated melts. Immiscibility of calcio-carbonatites has been observed in experiments of carbonated eclogites melting and on carbonate stability during subduction and show that, in the case carbonates are carried by silica-saturated (tholeiitic) crust, they will not survive transport to depths greater than 300 km (Hammouda & Keshav, 2015). However, In the case of continents, the low Tº gradients tend to stabilize solid carbonates at depths. And then, carbonatitic magmas observed in continental areas, if primary, must be caused by thermal perturbation of regions by carbonated melt metasomatism (mantle plumes?).

The subchondritic to superchondritic Nb/Ta ratio of the modelled equilibrium melts from melilititic (30 wt.% CO 2 ) and evolved silico-carbonated hybrid parental melts and calculated partitioning coefficients from Ihouhaouene apatites and clinopyroxenes involve partial melting (<1%) of melilitite from carbonated REE-rich mantle and separation of immiscible carbonate melts with low

segregation rates less than 1 % (0.01 and 0.08 %) from differentiated silicate melts. The

Ihouhaouene carbonatites present evidence for carbon in the Archaean mantle and the question of carbon mass-balance at this period of the Earth's history remains critical.

Are REE in carbonatite from primary melt or the result of late-enrichment processes?

Ihouhaouene carbonatites have high concentrations in rare earth elements (up to 7000*Chondrite) that are essentially controlled by apatite megacrysts and represent one of the most global rare earth resources carbonatite related deposit. The Si-rich and Si-poor carbonatites in Ihouhaouene are characterized by the presence of Si-rich and Si-poor apatites, respectively. Both rock facies have inclusion-free apatites and inclusion-bearing apatites. REE-rich inclusions in Ihouhaouene apatites are britholite exsolutions and monazite-quartz-calcite assemblage that are two of the most important REE minerals.

The petro-geochemical and micro-structural study of apatites and REE-rich britholite exsolutions and monazite inclusions from Ihouhaouene carbonatites allow us to highlight chief features of REEenrichment processes and determine the fluid compositions at sub-magmatic stage:

(1) Inclusion-free apatites from Ihouhaouene carbonatites are remarkable by their pegmatitic sizegrain and present tracer of primary carbonate-silicate melt composition from which they crystallized, whereas inclusion-bearing apatite record sub-solidus reactions involving possible fluid-rock interactions.

Discussion

! "#)!

(2) REE-Th-rich britholite and monazite-quartz-calcite inclusions in apatites from Ihouhaouene carbonatite complex present chemical and textural variations through all rock facies and attest of different REE-rich fluid-rock re-equilibrations.

(3) Both inclusion-free apatite and inclusion-bearing apatite (britholite or monazite) have similar geochemical Nb/Ta signature suggesting that Nb and Ta do not fractionate during fluid-apatite re-equilibrations and all apatites have magmatic signature.

Therefore, Ihouhaouene apatites record variable degree of fluid-rock interactions. The presence of inclusion-free apatites in Si-rich and Si-poor carbonatites and different apatite mineral-inclusions imply that carbonatites underwent fluid re-equilibration starting from shortly after crystallization and continuing down to ambient P-T conditions.

What is the composition of fluids responsible for REE-britholite exsolution in Si-rich apatites and

REE-monazite quartz and calcite inclusions in Si-poor apatites?

The fluid composition in equilibrium with britholite-and monazite-bearing apatites can be addressed, considering the REE-bulk-apatite compositions with and without inclusions in both Si-rich and Si-poor rock facies and compared with the correspondent in-situ compositions:

(1) The REE bulk-apatite composition of free-inclusion apatites from both Si-rich and Si-poor carbonatites have close compositions to their correspondent in-situ apatite composition and have high REE concentrations.

(2) The bulk britholite-bearing Si-rich apatite have slightly higher LREE concentrations than bulk free-inclusion Si-rich apatite owing to the britholite REE rate from fluid import.

(3) Both inclusion-free Si-rich apatites and britholite-bearing apatites have high in-situ REE and SiO 2 (~ 5 wt.%) contents indicating that they crystallized from a melt with high silica activity at magmatic conditions.

(4) The high Cl, Th and U in britholite exsolutions compared to the Si-rich host and inclusion free-apatite corroborate the presence of saline fluid during cooling and re-equilibration at subsolidus conditions.

(5) The bulk monazite-bearing Si-poor apatite have slightly lower LREE composition than bulk free-inclusion Si-rich apatite owing to the apatite-fluid re-equilibration.

Discussion

! "#*! (6) The presence of quartz and calcite inclusions with monazite in Si-poor apatite strongly suggests sub-solidus reaction and the presence of Si-CO 2 -bearing supergene fluids.

(7) The high content of sulphur (~ 1.7 wt.%) in monazite compare to the low content in hostedapatite and inclusion-free apatite indicate the presence of sulphur-bearing fluid during reequilibration at subsolidus conditions or mass transfer in expense of precursor apatites.

These close chemical features of apatites and britholite and monazite-quartz-calcite inclusions are supported by the microstructural texture results on that I carried out on inclusion-bearing apatites by EBSD measurements:

(1) Britholite crystallizes with a-, m-and c-axes in the same orientation that a-, m-and c-axes of host-apatite and britholite orientation rotates as observed for apatite in progressive replacement and crosscut the apatite sub-grains.

(2) Monazite has the b-axis orientation parallel the c axis (0001) orientation of host apatite and the same a-and c-axes orientations follow the a-and m-axes of apatite. Whereas quartz has the same axes orientations than apatite.

Accordingly, to explain the crystallization environment and the rock-fluid interaction and reequilibration at subsolidus conditions leading to the britholite and monazite-quartz-calcite inclusions in apatites from the Ihouhaouene carbonatites I assumed that inclusion-free apatites are representative of magmatic apatite before britholite exsolution and monazite inclusions. In this case, the exchange reaction for cationic mass balance for both britholite-apatite and monazite-apatite according to two re-

Ihouhaouene carbonatite and syenite complex in the regional tectono-metamorphic context

The detailed petro-geochemical results in the first part of my thesis on carbonatites and syenites from Ihouhaouene indicate a cogenetic relationship between these two types of rocks.

Based on the 2090 Ma and 1994 ± 22-17 Ma U-Pb ages obtained previously from apatite and zircon in carbonatite by [START_REF] Allègre | U-Th-Pb systematics of hydroxyapatite intergrowths[END_REF] and [START_REF] Bernard-Griffiths | Origin and evolution of 2 Ga old carbonatite complex (Ihouhaouene, Ahaggar, Algeria): Nd and Sr isotopic evidence[END_REF], respectively, the alkaline complex of Ihouhaouene was emplaced at the period of transition between the Archaean primitive earth environment and the regional ultra-high-temperature metamorphic event at Eburnean in the In Ouzzal terrane. However, the U-Pb determined age by [START_REF] Bernard-Griffiths | Origin and evolution of 2 Ga old carbonatite complex (Ihouhaouene, Ahaggar, Algeria): Nd and Sr isotopic evidence[END_REF] characterizes the age of carbonatites from a single zircon grain, the reason why more detailed geochronological study in my thesis has been performed to confirm and better constrained the relationship between carbonatites and syenites. The age of the Ihouhaouene complex allow us to replace the magmatic occurrence in the regional tectono-metamorphic context of the In Ouzzal terrane.

Discussion

! ")$!

LA-ICP-MS U-Pb dating on apatites and zircons from Ihouhaouene carbonatite and syenite thin section samples from this study allow to bring up the following ages and open even more questions on the complexity of the emplacement context of carbonatite and syenite rocks of Ihouhaouene:

(1) The apatites in carbonatite sample have homogeneous violet-bluish cathodoluminescence colour by Eu 2+ indicator and do not have any obvious zoning.

(2) The U-Pb ages from the center to the rim of carbonatitic apatite vary from 1744 ± 106 Ma to 2025 ± 142 Ma and 1588 ± 124 Ma to 1976 ± 154 Ma respectively, suggesting Pb diffusion in the apatite crystal but the weighted average 207 Pb/ 206 Pb corrected ages obtained to the center and rim grains yields similar ages within errors (1867 ± 88 Ma; 1794 ± 57 Ma, respectively) that correspond to the peak and cooling ages of eburnean ultra high temperature metamorphism in the In Ouzzal terrane.

(3) The apatites in syenite samples have heterogeneous yellow cathodoluminescence colour with obvious crystal recrystallized zones revealed by Mn 2+ indicator.

(4) The U-Pb Ages recorded in the core and rim of apatites from syenites are much younger ~ 651

Ma, than the carbonatitic ages and correspond to the Pan-African event in the Hoggar (800-550 Ma).

For a cooling rate of 10ºC/Ma, the Pb diffusion in apatite is not effective when the diffusion radius is higher than 1cm and thus the closure temperature is higher than 750ºC (Cherniak & Watson 2001).

The In Ouzzal temperatures at 2000 Ma has been estimated at 1100ºC and decreased to 750ºC at 1800

Ma [START_REF] Ouzegane | A review of Archaean and Paleoproterozoic evolution of the In Ouzzal granulitic terrane (Western Hoggar, Algeria)[END_REF]. This implies that high temperatures remain for a long period of time, and the Ihouhaouene carbonatitic apatites may have recorded In Ouzzal metamorphism over 200 Ma.

However the lack of zoning and mineral growth textures in carbonatitic apatite suggests slow cooling and mineral diffusion rates.

In addition, the ages recorded in syenite are Pan-African; a tectonic event characterized by the emplacement of granitic plutons in the In Ouzzal terrane where temperatures were up to 450ºC. These temperatures may result in Pb diffusion in apatite (with a small effective diffusion radius) and apatites are more susceptible to low temperature fluids because of their small apatite grains. A similar age has been found by [START_REF] Carpena | Apatites from In Ouzzal carbonatites (N.W. Hoggar): the final thermal history of an Archaean basement[END_REF] by fission-track (~ 600 Ma) and suggested an exhumation age of carbonatites and syenites at Pan-African.

The ages determined on apatite correspond to the Eburnean metamorphic age in the In Ouzzal terrane that don't correspond to the crystallization age obtained by Allègre et al. 1972 at 2090 Ma in carbonatite, that is 90 Ma older than the eburnean peak metamorphism (1100ºC) of In Ouzzal terrane (2000 Ma), suggesting that magmatic intrusion occurred close to or before the 2100-1800

Discussion ! ")"!

Ma UHT metamorphism in the In Ouzzal terrane and the crystallization of carbonatites cover all this period. The syenites, on the other hand, recorded an exhumation age at the Pan-African ~ 651

Ma.

What is the magmatic age of associated syenites?

(1) Zircons in carbonatite and syenite have obvious Hf and Y zoning in the EMP maps. This implies different fluid infiltration in late-stage melts leading to zircon crystal-growth with different isotopic compositions on account of the significant differences in geochemical composition of immiscible carbonate-melts and evolution in hybrid system.

(2) Zircons in syenite have higher Hf contents than zircons in carbonatite suggesting that Hf increases in zircon with magmatic differentiation and corroborate the fact that Hf has high partitioning in the segregated silicate melts from immiscibility process.

(3) Carbonatitic zircons have 0.1<Th/U< 1.16, whereas zircons in syenite have 0.01 <Th/U< 0.55. Craton that suggest the emplacement of Ihouhaouene carbonatites and syenites in a extensive tectonic and explain their emplacement in shear-zones and the linear magmatic textures of syenites.

The oldest ages recorded in apatites and zircons from carbonatite and syenite in Ihouhaouene reveal crystallization close to or before the UHT metamorphism in In Ouzzal terrane. This suggests crystallization of the alkaline complex may be around 2162 Ma (Concordia age of zircons from syenite) considering the Archaean zircon ages and the late Eburnean zircons as inherited ages.

However, the complex geodynamic history of Ihouahouene complex required additional dating (e.g.

monazite, allanite, and additional apatite and zircon) to reconstruct accurate magmatic and metamorphic geochronology events.

Discussion

! ")%!

Conclusion et perspectives

! Conclusion et perspectives ! ! "#$!
The bulk rock and mineral geochemistry of carbonatites and syenites allow us to determine four rocks facies: Si-rich and Si-poor carbonatites and Red and White syenites. The equilibrium melts compositions of these rock facies have subchondritic to superchondritic Nb/Ta geochemical signatures and reflect different parental melt compositions inherited from previous differentiation stages of carbonated-silicate melt as a result of several steps of carbonated melt immiscibility. These processes are mainly accompanied by hybridization that assemblage crystallized minerals from distinct melt compositions.

All the rock facies have high bulk REE and segregated from a primary CO 2 -rich silicate melt that evolved during immiscibility process and form evolved carbonated and silicate melts.

The geochemical model proposed in my thesis explain the subchondritic to superchondritic Nb/Ta ratio equilibrium melts and involve partial melting of carbonated REE-rich mantle and separation of immiscible carbonate melts with low segregation rates less than 1 % (0.01 and 0.08 %) from melilititic and evolved silico-carbonated hybrid parental melts. Hybridization in the atypical Ihouhaouene system induces important variations in coefficient partitioning behaviour of Nb, Ta and rare earth elements between the segregated carbonate and silicate melts during immiscibility process.

The Ihouhaouene immiscible carbonatites and syenites are well preserved and characterized by exceptional occurrence of REE-rich minerals, britholite, monazite, and allanite and thus represent a unique opportunity to trace tardy-magmatic processes and re-equilibration at sub-solidus conditions.

More specifically, the enrichment and distribution REE in apatite may represent an early stage before extreme REE-deposition and REE-oxides crystallization (e.g. Bastnasite) link to complex metamorphic events as observed for the two world's major ore-deposits Bayan Obo, Mountain Pass

Conclusion et perspectives ! !

"#%!

• Outlook

The complexity of multistage processes involved during the formation of igneous alkaline complex has led to several open questions that still need to be addressed:

- Oued Ihouhaouene pegmatite de syénite pegmatitique X X X X ?

Contact Sy-pegm

IC1-1B X X pegmatite IC1-2A carbonatite pegmatitique X X X X X X Annexe A ! "#'!
+ - + - + - - - + + + - + + Ech - - + - - - + + - - + - - - EPMA - cpx, amph ap, cpx, wol, gt ap,all, - - - - - - all, - - ap,all, isotope - C, O (in cal) - C, O (in cal) -C, O (in cal) C, O (in cal) C, O (in cal) - - C, O (in cal) C, O (in cal) - C, O (in cal) REE - - + ap rose - - - - + - + - - cpx,
+ + + + EPMA cpx, amph isotope C, O (in cal) C, O (in cal) C, O (in cal) C, O (in cal) C, O (in cal) REE traces calcite Annexe A ! "#(!
P2O5 - - - - - Cr2O3 - 0,01 - 0,03 - NiO - - - La2O3 - - - - - Ce2O3 - - - - - Pr2O3 - - - - - Nd2O3 - - - - - Sm2O3 - - - - - Gd2O3 - - - - - Dy2O3 - - - - - Y2O3 - - - - - ThO2 - - - - - SO2 - - - - - F - - - - - Cl - - - - -
P - - - - - Cr - - - 0,002 - La - - - - - Ce - - - - - Pr - - - - - Nd - - - - - Pm - - - - - Sm - - - - - Eu - - - - - Gd - - - - - Tb - - - - - Dy - - - - - Y - - - - - Th - - - - - S - - - - - F - - - - - Cl - - - - - Total
- - - - - Ce2O3 - - - - - Pr2O3 - - - - - Nd2O3 - - - - - Sm2O3 - - - - - Gd2O3 - - - - - Dy2O3 - - - - - Y2O3 - - - - - ThO2 - - - - - SO2 - - - - - F - - - - - Cl - - - - -
- P - - - - - Cr - - 0,0002 - - La - - - - - Ce - - - - - Pr - - - - - Nd - - - - - Pm - - - - - Sm - - - - - Eu - - - - - Gd - - - - - Tb - - - - - Dy - - - - - Y - - - - - Th - - - - - S - - - - - F - - - - - Cl - - - - - Total 8,

Supplementary data B2:

The model illustrates the immiscibility-fractional crystallization processes from a silicatecarbonate-rich parental melt. For this numerical modelling we used:

-A stepwise approach combining two Rayleigh distillation equations, alternately: the fractional crystallization equation for the mineral (clinopyroxene) segregation and an equation formally similar to the fractional melting equation (Shaw, 1979) for the segregation of immiscible melt fractions (supplementary data B2).

-Liquid/liquid partition coefficients deduced from the equilibrium melt compositions calculated in our study. Partition coefficients are considered constant within a given step of melt segregation but they are allowed to vary to account for changes in parental melt compositions.

-The residual melt proportion ("f") and the immiscible melt fraction ("F") after each increment of fractional crystallization and immiscible melt segregation, respectively. The aim of our numerical experiments was merely to assess the ability of the crystal fractionation-melt segregation model to account for the Ce/Lu and Nb/Ta variations within a reasonable range of f and F values.

! Model A

-The parental melt composition is a melilitite [START_REF] Baudouin | Nephelinite lavas at early stage of rift initiation (Hanang volcano, North Tanzanian Divergence)[END_REF].! -The extracted melt rate "F" is of 0.01! -The liquid/liquid partition coefficient is calculated from: clinopyroxene equilibrium liquid from red syenites / apatite equilibrium liquid from Si-rich carbonatites.! Annexe C

! 234 Le craton archéen de l'In Ouzzal représente une succession d'événements intrusifs et métamorphiques depuis l'Eburnéen qui en font un marqueur important des processus géodynamiques à travers les temps géologiques. La région d'Ihouhaouene située au N-W du terrane de l'In Ouzzal en Algérie est unique de par la présence d'intrusions protérozoïques de carbonatites associées à des roches alcalines saturées. Ces carbonatites intracontinentales comptent parmi les plus anciennes et inhabituelles de par leurs diversités et la présence de minéraux à terres rares. Les carbonatites sont pegmatitiques ou bréchiques avec des fragments de syénite. Elles sont des calciocarbonatites composées de calcite (>50 vol.%), apatite, clinopyroxène et wollastonite et sont associées à des syénites rouges ou blanches présentes sous forme massive. Les syénites sont composées d'alternance de niveaux clairs de feldspaths alcalins rouges ou de wollastonites associées aux feldspaths blancs et de niveaux sombres d'apatites et de clinopyroxènes.

Les carbonatites et syénites forment une suite cogénétique caractérisée par une augmentation en SiO2 et une diminution en CaO et CO2. Les carbonatites ont des compositions en silice comprises entre 5 et 35 pds.%, 28 et 53 pds.% CaO et 11 à 36 pds.% CO2. Les syénites montrent une forte teneur en K2O (12 pds.%) et des teneurs très faibles en Na2O (1 pds.%). Les carbonatites et syénites sont riches en éléments incompatibles avec des teneurs en REE supérieures à 7000 fois les chondrites et 1000 fois les chondrites dans les syénites, respectivement, et de fortes teneurs en U, Sr et Th. Les éléments en trace dans les minéraux magmatiques (apatite et pyroxène) mettent en évidence des processus complexes à l'origine de ces roches impliquant plusieurs étapes de cristallisation fractionnée et d'immiscibilité à partir d'un magma mélilititique riche en CO2. Les minéraux des carbonatites riches en silice et des syénites blanches ont des signatures géochimiques similaires et se caractérisent par des rapports élevés en Nb/Ta typiques de magmas riches en carbonate par immiscibilité. Les syénites rouges ont des caractéristiques de liquides silicatés évolués par différentiation. Les minéraux des carbonatites pauvres en silice ont des rapports Nb/Ta très variables, sub-chondritiques (<10), indiquant une cristallisation à partir de liquides très évolués et la présence de magmas carbonatitiques tardifs.

Les apatites, en particuliers, enregistrent divers épisodes magmatiques et également supergènes. Elles présentent dans certaines roches une redistribution et un enrichissement en terres rares variables qui se caractérisent par des exsolutions de britholite dans les carbonatites riches en silice et monazite dans les carbonatites pauvres en silice. Ces exsolutions traduisent des rééquilibrations locales sub-solidus avec des fluides tardi-magmatiques de composition riche en Cl-Th-REE pour l'exsolution de la britholite et S-Ca-P-CO2 pour les inclusions de monazite. The In Ouzzal Archaean craton represents a succession of intrusive and metamorphic events since Eburnean, and an important marker of geodynamic processes through geological time. The Ihouhaouene area located in the N-W of In Ouzzal terrane in Algeria is unique by the presence of Proterozoic carbonatite intrusions associated with silica-saturated alkaline rocks. These intracontinental carbonatites are among the oldest and exceptional because of their diversity and the presence of unusual rare earth minerals. Carbonatites are pegmatitic or brecciated with fragments of syenite. They are calciocarbonatites with calcite (> 50 vol.%), apatite, clinopyroxene and wollastonite and are associated with red or white syenites in massive outcrops. Syenites are composed of alternating light levels of red alkaline feldspar or wollastonite associated with white feldspar and dark levels of apatite and clinopyroxene.

Carbonatites and syenites form a cogenetic suite characterized by an increase in silica and decrease in calcium and CO2 content. The carbonatites have silica content ranging from 5 to 35 wt.%, 28 to 53 wt.% CaO, and 11 to 36 wt.% CO2. Syenites have high K2O (12 wt.%) and low Na2O content (1 wt.%). Carbonatites and syenites have high incompatible element concentrations with high REE content (7000*chondrites and 1000*chondrites, respectively) and high U, Pb, Sr and Th content. Trace elements (eg. Rare Earths, Nb-Ta, Zr-Hf) in magmatic minerals (apatite-pyroxene) of carbonatites and syenites reveal complex magmatic processes at the origin of these rocks involving several stages of fractional crystallization and immiscibility from a CO2-rich melilititic magma. Silica-rich carbonatites and white syenites are characterized by high Nb/Ta, Y/Zr and Rb/Sr ratios, typical of carbonate-rich magmas by immiscibility. The red syenites have characteristics of immiscible differentiated silicate melt. Silica-poor carbonatite minerals have variable subchondritic Nb/Ta (<10) indicating crystallization from highly evolved liquids and the presence of late carbonatitic magmas.

Apatites, in particular, record various magmatic and supergene processes. They present, in some rocks, redistribution and enrichment in rare earth elements, which are characterized by exsolutions of britholite in silica-rich carbonatites and monazite-quartz-calcite inclusions in silica-poor carbonatites. These minerals reflect local sub-solidus re-equilibration with late-magmatic fluids rich in Cl-Th-REE for the exsolution of britholite and S-Ca-P-CO2 for monazite inclusions.

The apatite and zircon present in these alkaline and carbonatite rocks, allow determination of the syn-metamorphic crystallization age of the Ihouahouene magmatic complex at 2100 Ma and confirm the pan-African age of its exhumation. The petrological, geochemical and geochronological study of Ihouhaouene carbonatites and syenites highlights the magmatic origin of these rocks and constrains the fluid-rock interactions at sub-solidus conditions leading to REE-enrichment. The carbonatites and syenites result from a low partial melting rate of a CO2-rich Precambrian mantle. Several fractional crystallization and immiscibility stages allowed the genesis of these hybrid magmas, trapped along large shear-zones during the Archean/Eburnean transition period in the In Ouzzal terrane, characterized by extensive deformation in ultra-high-temperature granulitic environment.

  environnement océanique est rare. On peut citer celles du Cap Vert et des îles Canaries caractérisées par une minéralogie indiquant une source riche en H 2 O[START_REF] Cornu | Evolution magmatique d'un volcan bouclier océanique avant et après une déstabilisation massive de ses flancs: Fogo, Cap Vert et Tenerife, Canaries[END_REF].

Figure 1 .

 1 Figure 1. Représentation schématique des différents sites géodynamiques des magmas carbonatitiques en relation avec les gisements majeurs de dépôts de REE (modifiée après Chakhmouradian et Wall 2012).

Figure 2 .

 2 Figure 2. Conditions de formation des carbonatites dans le manteau à partir de la fusion partielle d'une lherzolite riche en CO 2 (Gudfinnsson et Presnall 2005).

Figure 3 .

 3 Figure 3. Compositions et conditions de formation des carbonatites issue de la fusion partielle d'une péridotite ou d'une éclogite riche en CO 2 et diagramme ternaire représentant la composition des carbonatites expérimentales et des carbonatites naturelles d'après Hammouda et Keshav, 2015.

Figure 4 .

 4 Figure 4. Modèle de formation des carbonatites par cristallisation fractionnée d'une melilitite[START_REF] Mitchell | Carbonatites and Carbonatites and Carbonatites[END_REF].

Figure 6 .Figure 7 .

 67 Figure 6. Composition moyenne des magmas alcalins anorogéniques comparée aux données de basaltes océaniques (normalisées par rapport au manteau primitif de McDonough et Sun 1995) (Chakhmouradian et Zaitsev, 2012).

  processus d'immiscibilité et cristallisation fractionnée à partir d'un magma carbonatésilicaté ? -Quelles sont les relations co-génétiques entre les carbonatites et les roches alcalines silicatés associées ? Les carbonatites sont-elles seulement associées à des roches alcalines sous-saturées ? -Comment ces liquides carbonatés migrent et affectent la croûte continentale encaissante ? et quelle est la composition des fluides présents lors de l'evolution des magmas et lors des processus-subsolidus? -Quelle est la distribution et le fractionnement des terres rares entre les liquides carbonatés et les liquides silicatés et les minéraux magmatiques? Et quels sont les processus/environnements supergènes permettant l'enrichissement en terres rares des carbonatites ? Introduction ! 21 apatite et wollastonite. La présence exceptionnelle de minéraux riches en terres rares tel la britholite [(REE 3 Ca 2 (SiO 4 ) 3 (F,Cl,OH)] et la monazite [(Ce,La,Nd,Th)PO 4 ] confère aux carbonatites et aux syénites un intérêt particulier en faisant des traceurs importants des processus profonds et supergènes et des gisements potentiels pour les Terres Rares. La distribution et l'enrichissement de ces éléments durant les processus magmatiques et sub-solidus est essentielle pour déterminer les conditions de cristallisation et les compositions des fluides tardi-magmatiques (éléments volatils, REE) en lien avec la formation de ces minéraux de Terres Rares.

•!

  . Le complexe alcalin d'Ihouhaouene s'est mis en place durant une période de transition entre la terre primitive archéenne et le grand évènement métamorphique régional d'ultra haute température (UHT) à l'Eburnéen. Une seule étude par Bernard-Griffiths et al. (1988) a défini un âge protérozoïque pour les carbonatites d'Ihouhaouene (datation U/Pb sur un zircon). De par le contexte géodynamique complexe et les relations entre carbonatites, syenites et granulite (encaissant), une étude géochronologique plus détaillée est cependant indispensable afin de comprendre la chronologie des évènements magmatiques et métamorphiques. Objectifs et approche L'objectif de cette thèse est d'étudier la genèse des carbonatites et magmas alcalins d'Ihouhaouène présent dans le Nord-Ouest du Hoggar au Sud de l'Algérie. Ce travail se focalise sur une étude de terrain et sur la caractérisation des signatures pétrologiques et géochimiques des carbonatites et des syénites associées dans les trois secteurs d'Ihouhaouene. Ce travail permettra de Introduction ! 22 Une étude géochimique des roches et minéraux et une modélisation basées sur les données expérimentales des coefficients de partage entre les liquides carbonatés et silicatés et des calculs simples de fusion et de cristallisation fractionnée a été développée afin de caractériser les magmas en équilibre avec les minéraux magmatiques (apatite, pyroxène) dans les carbonatites et syénites et contraindre les processus magmatiques. Un modèle a été développé afin d'expliquer les compositions complexes des liquides primaires des carbonatites et des syénites d'Ihouhaouene. Dans un deuxième temps, l'étude in-situ des apatites et minéraux de terres rares dans les carbonatites et syénites et l'imagerie EBSD et EMP, ont permis de caractériser les environnements subsolidus et la composition des fluides liée à l'enrichissement en terres rares à un stade sub-magmatique précoce. Par ailleurs, des datations U-Pb in situ sur apatites et zircons dans les syénites et carbonatites ont été effectuée afin de déterminer l'âge magmatique du complexe alcalin d'Ihouhaouene et le lien avec l'évènement tectonométamorphique granulitique de l'In Ouzzal à l'Eburnéen. • Organisation du manuscrit Cette thèse comporte quatre chapitres dont trois articles scientifiques (II, III et IV) rédigés en anglais et intégrés dans le corps du texte en respectant le format du manuscrit dont le déroulé est le suivant. Le chapitre I présente le contexte géodynamique de la zone d'étude Ihouhaouene lié à la formation des granulites de l'unité de l'In Ouzzal au Hoggar occidental. Il présente aussi une étude pétrographique détaillée des carbonatites et des syénites de la région d'Ihouhaouene et les différentes méthodes utilisées pour les analyses en roches totales (éléments majeurs, volatils et en trace), in situ des minéraux et des datations. Le chapitre II correspond à l'étude pétrographique et minéralogique des phases liquidus et l'étude géochimique multi-échelle et multi-élément (majeur, volatils et en trace) des roches carbonatitiques et des roches alcalines dans le craton de l'In Ouzzal afin de caractériser la composition des liquides profonds et les processus complexes d'immiscibilité, de cristallisation fractionnée et d'hybridation à l'origine des roches. Ce chapitre correspond à un article scientifique soumis et accepté dans la revue Introduction ! Introduction Les carbonatites d'Ihouhaouene dans le terrane de l'In Ouzzal au Hoggar occidental Ce chapitre introduit le contexte géologique de la zone d'étude Ihouhaouene dans l'In Ouzzal avec : l'histoire géodynamique du bouclier Touareg et l'amalgamation des terranes au Panafricain ; L'evolution tectonométamorphique du terrane de l'In Ouzzal dans le Hoggar occidental de l'Archéen au Panafricain; Les relations de terrain entre les carbonatites et les syénites d'Ihouhaouene dans les trois secteurs de l'Oued Ihouahouene, Wadi Tirahart Sud et Wadi Tirahart Nord. Il présente aussi une étude pétrographique détaillée des carbonatites et des syénites associées et les différentes méthodes utilisées pour les analyses des éléments majeurs, volatils et en traces, en roches totales des minéraux et des datations in situ. constitue un site géologique important par la présence de diverses roches qui comptent parmi les plus anciennes au monde et qui permettent de retracer leur évolution tectonique et géochimique à l'échelle des continents au cours des temps. Le bouclier Touareg comprend trois massifs (Figure. I.1 et Figure. I.2): (1) le Hoggar qui forme la majeure partie du bouclier et se situe au sud de l'Algérie (2) l'Adrar des Iforas au Mali et (3) le massif de l'Aïr au Niger.

  ont montré que le bouclier a été comprimé entre deux grands continents convergents (Figure. I.1), le craton Ouest Africain à l'Ouest et le métacraton saharien à l'Est, durant l'orogenèse panafricaine due à la fermeture d'un large océan.

Figure. I. 1 .

 1 Figure. I.1. Carte de l'Afrique de l'Ouest avec les principales entités géodynamiques (Liégeois et al. 2019). La bande au centre correspond à la ceinture transsaharienne, avec le bouclier nigérien et le bouclier touareg et le socle situé au-dessous des bassins sédimentaires d'Iullemeden et du Sahara.

Figure. I. 2 .

 2 Figure. I.2. Carte géologique simplifiée du bouclier touareg avec les 23 terranes de Black et al. (1994) et Liégeois et al. (2003) avec attribution géodynamique modifiée de Liégeois et al. (2019).

  Figure. I.3. Modèle géodynamique montrant trois stades de formation de la croûte continentale et des séries supracrustales du terrane de l'In Ouzzal à l'Archéen entre 3200 et 2500 Ma (Drareni et al. 2007).

Stade 1 :

 1 Délamination du manteau lithosphérique et remonté de l'asthénosphère. Stade 2 : Décompression et rééquilibrage isostatique avec reprise du manteau lithosphérique dans les conditions postérieures post-collisionnelles et d'équilibre thermique.

Figure. I. 4 .

 4 Figure. I.4. Modèle géodynamique (Ouzegane et al. 2003) montrant l'évolution tectono-métamorphique (cheminements P -T) du terrane granulitique de l'In Ouzzal et la mise en place des carbonatites à la suite d'une délamination lithosphérique et la remonté asthénosphérique lors de l'événement Eburnéen.

  considèrent ces décrochements comme des zones de subduction convergentes actives entre 900 et 850 Ma, transformées en sutures entre 620 et 580 Ma en considérant Chapitre I : Contexte géologique ! ! 32 que l'In Ouzzal n'a pas été affecté par le métamorphisme et la déformation panafricains en préservant les paragenèses éburnéennes granulitiques (2000 Ma). Haddoum et al. (2013), considèrent quand à eux que l'In Ouzzal a été remobilisé durant le panafricain, particulièrement dans sa partie Sud où des formations volcano-sédimentaires pharusiennes (Protérozoïque supérieur-Protérozoïque terminal) affleurent en discordance sur les granulites paléoprotérozoïques. La zone d'étude Ihouhaouene se situe au Nord du terrane de l'In Ouzzal (23º36'14"N, 3º10'32"E) au Hoggar occidental (Sud de l'Algérie) (Figure. I.5). Elle est recoupée par de grandes zones de cisaillement méridiennes auxquelles sont associés des granites panafricains et des minéralisations aurifères. La région d'Ihouhaouene contient de nombreux corps de carbonatites associées à des syénites (Figure. I.5) d'âge éburnéen (~ 2000 Ma ; Bernard-Griffiths et al. 1988) qui comptent parmi les plus anciennes connues au monde. Les complexes de carbonatites d'Ihouhaouène sont syn-orogéniques et se distinguent, par la forme de leur gisement linéaire en relation avec leur mode de mise en place le

Figure. I. 5 .

 5 Figure. I.5. Carte géologique simplifiée de la région d'Ihouhaouene dans la partie Nord-Ouest du terrane de l'In Ouzzal et emplacement des carbonatites et syénites associées d'après Ouzegane et al. (1988).

  syénites affleurent dans trois secteurs dans la région d'Ihouhaouene, à l'Oued Ihouhaouene, à Wadi Tirahart Sud et à Wadi Tirahart Nord, décrits comme trois centres par Ouzegane (1987) (Figure. I.6).

Figure. I. 6 .

 6 Figure. I.6. Carte géologique des trois centres carbonatitiques linéaires (Ouzegane, 1987) dans la région d'Ihouhaouene montrant la distribution des carbonatites, des syénites rouges et blanches et leur concordance avec l'encaissant granulitique d'après Fourcade et al. (1996). Coordonnées GPS en annexe D. Dans le complexe de l'Oued Ihouhaouene (centre 1), les syénites affleurent sous forme de plusieurs chainons orientés EW à NW-SE (Figure. I.7a) recoupés par des veines ou filons plus où moins massifs de carbonatites bréchiques et pegmatitiques (Figure. I.7b, c, d). Dans cette zone les carbonatites sont essentiellement associées à des syénites rouges rubanées avec une alternance de niveaux clairs et sombres, cm à dcm composés de feldspath rouges et de pyroxène (Figure. I.7e).

Figure. I. 7

 7 Figure. I.7 Photographies d'affleurements des carbonatites et des syénites associées à l'Oued Ihouhaouene (centre1). a. le complexe de syénites et carbonatites en chaînons linéaires de l'Oued Ihouhaouene (N23°33'55'', E03°04'51'') orientés E-W. b. filon de carbonatite bréchique en contact avec des syénites rouges. c. filon de carbonatite pegmatitique en contact avec des syénites blanches. d. fragments de syénite dans une carbonatite béchique. e. syénite rouge rubanée avec une alternance de niveaux clairs et sombres de clinopyroxène et feldspath alcalin.

Figure. I. 8 .

 8 Figure. I.8. Photographies d'affleurements des carbonatites et des syénites associées au Sud Wadi Tirahart (centre 2). a. le complexe de syénites et carbonatites en chaînons linéaires (N23°39'29'', E03°18'02'') orientés NNE-SSW. b. syénite rouge rubanée avec une alternance de niveaux clairs de feldspath alcalin et sombres de clinopyroxène. c. filon de carbonatite bréchique en contact avec des syénites blanches. d. fragments de syénite dans une carbonatite bréchique. Niveau de wollastonite intercalé entre les pyroxènes et les feldspaths alcalins de la syénite blanche. e. veine de carbonatite pegmatitique dans les syénites rouges

  et contiennent des carbonates de calcium primaires qui sont dominants par rapport aux autre minéraux (supérieurs à 50 vol.%). Les deux autres minéraux omniprésents dans le complexe carbonatitique d'Ihouhaouene sont les apatites et les clinopyroxènes avec des tailles et des proportions différentes selon la texture bréchique ou pegmatitique de la roche. Les carbonatites bréchiques sont à grain moyen à grossier (Fig.I.10) avec une texture grenue porphyroïde à phénocristaux d'apatites automorphes vertes, vert-jaunâtre ou rose (3-5 mm, 1 à 22 vol.%), de clinopyroxènes verdâtres (3 mm, 1-20 vol.%), dans une matrice de calcite rose, grise ou blanche (3-8 mm, 50 à 70 vol.%). Les carbonatites bréchiques contiennent des fragments de syénites avec des contacts concentrés en clinopyroxène (Figure I.10.a) ou s'infiltrent dans les syénites où les feldspaths et clinopyroxènes syénitiques sont entourés d'allanites (Figure I.10.b).

Figure I. 10 .

 10 Figure I.10. Photos d'échantillons et d'assemblages minéralogiques de carbonatites bréchiques montrant a. le contact riche en clinopyroxènes entre carbonatite bréchique et syénite. b. l'infiltration de la carbonatite dans la syénite.

Figure I. 11 .

 11 Figure I.11. Photos d'échantillons et d'assemblages minéralogiques des carbonatites pegmatitiques. a. la carbonatite à apatite verte sans inclusions. b. la carbonatite à apatite vert-jaunâtre riche en britholite. c. la carbonatite à apatite rose sans inclusions. Les apatites sont très fracturées perpendiculairement à l'axe d'allongement (001) (Figure I.11 et Figure I.12.a). Elles sont présentes sans inclusions ou avec de nombreuses inclusions de quartz, calcite, fluorite, allanite, monazite et britholite.

Figure I. 12 .

 12 Figure I.12. Microphotographies des carbonatites pegmatitiques et bréchiques d'Ihouhaouene. a. apatite verte sans inclusions et calcite. b. apatite vert-jaunâtre riche en exsolutions de britholite. c. l'allanite dans les fissures d'apatites à britholite. d. Apatite riche en inclusions de monazite et quartz. e. clinopyroxène sub-automorphe entouré d'allanite. f. wollastonite automorphe déstabilisé en quartz calcite.

Figure I. 13 .

 13 Figure I.13. Photos d'échantillons et d'assemblages minéralogiques des syénites. a. la syénite rouge riche en allanite et à gros cristaux automorphes de feldspath potassique. b. la syénite blanche à apatite vert-jaunâtre riche en britholite montrant de gros cristaux de wollastonite associées aux clinopyroxènes.

Figure I. 14 .

 14 Figure I.14. Microphotographies des syénites d'Ihouhaouene. a. assemblage minéralogique d'une syénite blanche avec le grenat et le quartz autours des clinopyroxènes. b. assemblage minéralogique d'une syénite rouge avec une alternance des cristaux automorphes de clinopyroxène et de feldspath potassique.

  en trois fois, séparés par des évaporations, en 0,5 ml, 0,25 ml, puis 0,25 ml de HClO 4 . L'échantillon est évaporé en un résidu solide. Une première dilution est réalisée avec ce résidu en ajoutant de l'acide nitrique et de l'eau MilliQ jusqu'à obtenir une solution de 20,6 g. Avant l'analyse par spectromètre de masse, la solution d'échantillon est diluée avec 9,45 ml d'H 2 O, 0,25 ml d'HNO 3 et 0,1 d'InBi selon un facteur de 10 000 choisi pour les carbonatites et les syénites associées pour éviter la saturation en éléments en trace lors de l'analyse. Pour chaque série d'analyses (20 échantillons), 4 blancs (seuls des acides ont été introduits dans le savilex) et quatre standards: BHVO-1, BEN, UBN et COQ-1 ont été analysés pour détecter les traces de contamination au cours de la série d'attaques et/ou d'analyses et la dérive interne de la machine. Le spectromètre de masse utilisé pour quantifier les concentrations des éléments en traces dans la roche totale est l'Agilent 7700x, dont la sensibilité est de l'ordre de 200 x 106 cps / ppm sur 115In (Indium). Les étalons internes A2 et A4 sont étalonnés pour les concentrations de Zr-Nb et de Hf-Ta et des courbes d'étalonnage sur Rb, Sr, Y, Zr et Ce sont effectuées pour vérifier l'étalonnage interne.

  ; Figure II.1): (i) Oued Ihouhaouene characterized by several small hills oriented EW and NW-SE; (ii) the South Tirahart wadi complex with approximately 4 km long and 1 km wide outcrops, and (iii) Tirahart wadi north, a hill spreading over 2.5 km long and 250 m wide. Carbonatites outcrop as veins or massive formations in syenites. The contact is sharp and syenites have mylonitized edges (< 20 cm).

Figure

  Figure II.1.a Geological map of the Ihouhaouene area in N.W part of the In Ouzzal terrane and localization of carbonatites and associated syenites (Ouzegane et al. 1988). b The Tuareg Shield map with the 23 terranes (Black et al. 1994) modified by Liégeois et al. (2003) and position of the Ihouhaouene area in Western Hoggar.

  but the outcropping granulites (far from ~ 20 m) in Oued Ihouhaouene and north wadi Tirahart present no evidence of fenitization. The granulitic crust has undergone high temperature metamorphism during paleoproterozoic and preserved refractory chemical compositions (Ouzegane et al. 2003), hardly consistent with metasomatism and fenitization induced by a second local fluid (e.g. in situ alkali-metasomatism of country rock around intrusions of carbonatites and/or alkaline rocks, Kresten

Figure II. 2 .

 2 Figure II.2. Field photographs of the alkaline syenites and carbonatites in the three sectors of Ihouhaouene area. a North wadi Tirahart brecciated carbonatite vein with clinopyroxene (cpx) and syenite fragments intruding a red syenite. b South wadi Tirahart pegmatitic carbonatite with apatite (ap) crystals in white syenite. c Oued Ihouhaouene syenite fragment surrounded by clinopyroxene aureole in brecciated carbonatite. d South wadi Tirahart carbonatite pocket rich in wollastonite (wo) and k-feldspar (kfs) in white syenite. e North wadi Tirahart layered red syenite with light k-feldspar levels and dark clinopyroxene levels. f South wadi Tirahart pegmatitic carbonatite vein intruding a white syenite rich in wollastonite levels.

  Brecciated carbonatites are medium to coarse grained (3-8 mm, Figure II.3.a) with clinopyroxene (3 mm 1-20 vol.%), wollastonite (8 mm, < 10 vol.%), green or pink apatite (3-5 mm 1 to 22 vol.%) set in groundmass of pink, gray or white calcite (3-8 mm, 50 to 70 vol.%). Green apatites have quartz, calcite and fluorite as inclusions, whereas monazite, calcite, quartz and allanite occur as inclusions or around pink apatites. Accessory minerals are K-feldspars (4-8 mm, < 1 vol.%), magnetite (< 1 vol.%) as inclusions in clinopyroxenes, allanite (0.5-1 vol.%) around clinopyroxene, sphene (< 2 vol.%), quartz (< 1 vol.%) and coronitic garnet (< 3 vol.%). The pegmatitic carbonatites (Figure II.3.b) have large calcite grains (1-3 cm, up to 70 vol.%), clinopyroxene (1 to 5 vol.%) and green, pink or yellow apatite (up to 10 cm, 1 to 10 vol.%). Green and pink apatites are similar to apatites in brecciated carbonatite with the same inclusions. Yellow apatites differ from apatite in brecciated carbonatite with britholite exsolutions (up to 40 vol.%). Allanite, fluorite, quartz, wollastonite and alkali feldspar are present as accessory minerals (< 1 vol.%). II.3.b. Syenites Red syenites have medium to coarse-grained layered texture (5-10 mm, Figure II.3.c) with Kfeldspar (3-9 mm, 40 to 80 vol.%) with perthitic exsolution, clinopyroxene (3-8 mm, 20 to 40 vol.%), pink apatite (1-4 mm, 1 to 3 vol.%) and interstitial xenomorphe quartz grains (1 to 3 vol.%). Sphene is present as accessory mineral. Allanite and magnetite are present around and as inclusion in clinopyroxene, respectively. White syenites (Figure II.3.d) are layered with light bands of K-feldspar, wollastonite (5-10 mm, 5 to 20%) and yellow apatite with britholite and dark bands with clinopyroxene (3-8 mm, 40 vol.%) surrounded by garnet and magnetite. They show a coronitic texture composed of calcite associated with quartz and garnet around the wollastonite.

Figure II. 3 .

 3 Figure II.3. Microphotographs of (a-b) carbonatites and (c-d) syenites. a Si-poor brecciated carbonatite with apatite (ap), clinopyroxene (cpx) and calcite (cal). Clinopyroxene with allanite (aln) inclusions and apatite with calcite and allanite inclusions. b Pegmatitic Si-rich carbonatite with apatite and wollastonite (wo) surrounded by quartz (qtz) and calcite. c Red syenite with altered k-feldspar (kfs) with apatite and clinopyroxene. d White syenite with K-feldspar, clinopyroxene and wollastonite surrounded by garnet (Grt).

Figure II. 6 .

 6 Figure II.6. Normalized REE content of Ihouhaouene carbonatites and associated syenites.

Figure II. 7 .

 7 Figure II.7. Normalized trace element composition of Ihouhaouene carbonatites and syenites.

Figure II. 8 .

 8 Figure II.8. Clinopyroxene mineral chemistry of the Ihouhaouene carbonatites and syenites in molar units. a Al versus Mg# (p.f.u.); Mg# = Mg/Mg+Fetot. b Wo versus Fs diagram.

Figure II. 9 .

 9 Figure II.9. Normalized REE content of apatite and clinopyroxene from Ihouhaouene carbonatites and associated silicate rocks. Chondrite values from Sun and McDonough (1989).

  LREE content in carbonatites (La N /Yb N = 8.65-9.82) and flat regular patterns in syenites (10-50*Chondrite, La N /Yb N = 0.37-0.53) and small negative Eu anomaly (Figure II.11.a). Wollastonite in white syenites has a higher negative anomaly in Nb-Ta than in carbonatites (Nb/Ta= 1.53 and 18.94 respectively, Supplementary data B1).

Figure II. 11 .

 11 Figure II.11. Normalized REE content of wollastonite and calcite from Ihouhaouene carbonatites and associated silicate rocks. Chondrite values from Sun and McDonough (1989).

Figures

  FiguresII. 8, 9). These two facies differ from each other chiefly by the presence of carbonate

  The compositions of equilibrium melt calculated from clinopyroxene and apatite are illustrated on Figure13for chondrite-normalized REE and on Figure14for selected trace-element ratios (Ce/Lu, Nb/Ta, Rb/Sr, and Y/Zr). The calculated melts show considerable variation ranges, encompassingroughly -4 orders of magnitude for LREE (Figure II.13), 3 for Ce/Lu and Nb/Ta, 5 for Y/Zr, and 7 for Rb/Sr (Figure II.14). However, some systematics are observed according to the rock facies.

Figure II. 13 .

 13 Figure II.13. Normalized REE content of recalculated apatite and clinopyroxene equilibrium liquids from Ihouhaouene carbonatites and associated syenites compared to nephelinite, melilitite REE compositions. Chondrite values from Sun and McDonough (1989). Hanang nephelinite and Labait melilitite from Baudouin et al. 2016.

  than in most clinopyroxene equilibrium melts and more comparable to the values observed in apatite equilibrium melts -Figure II.14.b), -somewhat higher Nb/Ta values in the apatite equilibrium melts, compared with their clinopyroxene counterparts (Figure II.14.b), -above all by a significant difference in term of Rb/Sr and Y/Zr, with the apatite equilibrium melts distinguished from the clinopyroxene equilibrium melts by higher Rb/Sr and lower Y/Zr values (Figure II.14.c).

Figure II. 14 .

 14 Figure II.14. Recalculated apatite (ap) and clinopyroxene (cpx) equilibrium liquids a Ce/Lu versus Nb/Ta of Ihouhaouene carbonatites b Ce/Lu versus Nb/Ta of associated syenites. c Rb/Sr versus Y/Zr of carbonatites and syenites. FC: Fractional crystallization. For Si-poor and Si-rich carbonatite, we chose partition coefficient between carbonatite and apatite from Hammouda et al. 2010

  Ce/Lu vs. Nb/Ta systematics in the calculated equilibrium melts, notably the paradoxically low Nb/Ta values inferred for carbonatitic melts in the Si-poor carbonatites (Figure II.14.a).

  Results of the numerical experiment are displayed on Figure 15d. Model A uses a primary melilitite composition as initial parental melt and liquid/liquid partition coefficients inferred from equilibrium between: -a silico-carbonated melt component represented by the average of clinopyroxene equilibrium melts in the Ihouhaouene red syenites (Figure II.14.b), considered to represent a poorly evolved magma. -a carbonate melt component represented by the average of apatite equilibrium melts in the Ihouhaouene Si-rich carbonatites (Figure II.14.a), considered to be segregated from a poorly to mildly evolved parental magma. The carbonate melt fractions generated by Model A are distinguished by elevated values of both Ce/Lu and Nb/Ta ratios, comparable to the values yielded by the apatite equilibrium melts in the Sirich carbonatites and the white syenites (Figure II.14.a, b). Both equilibrium melts were considered to represent carbonate melts. The residual liquid after segregation of carbonate melt shows only a subtle decrease of Ce/Lu at constant Nb/Ta, a feature which might explain the dispersion of Ce/Lu values in the clinopyroxene equilibrium melts of the red syenites (Figure II.14.b). For Model B we used a parental melt with a hybrid composition with evolved carbonate and silicate melts (Model A, Nb/Ta= 51) (Figure II.14.d) and liquid/liquid partition coefficients inferred from equilibrium between: -a silico-carbonated melt component represented by the average of clinopyroxene equilibrium melts in the Ihouhaouene white syenites (Figure II.14.b), considered to represent an evolved magma. -a carbonate melt component represented by the average of apatite equilibrium melts in the Ihouhaouene white syenites (Figure II.14.b), considered to be segregated from an evolved magma. The liquid/liquid partition coefficients calculated for Nb/Ta from evolved carbonate-silicate melts are higher than those calculated from poorly evolved melt (Model A) and segregated carbonated melts after immiscibility can only have lower Nb/Ta ratio compared to the parental melt. The carbonate melt fractions generated by Model B have high Ce/Lu and low Nb/Ta ratios similar to the apatite equilibrium melts in the Si-poor carbonatites (Figure II.14.a). The high Ce/Lu ratios modelled for silicate melts do not reproduce the low Ce/Lu ratio of clinopyroxene equilibrium liquids in Si-poor carbonatite. Further hybridizations are required to account for the low REE concentrations.

  clinopyroxene on Figure II.9 and wollastonite on Figure II.11) in the Si-poor carbonatites, whereas the melting model would predict the opposite -i.e. selective LREE enrichment in carbonate-rich melts produced by the lowest melting degrees. Moreover, variable-melting degrees would hardly account for the considerable range of Nb/Ta variations in equilibrium melt (Figure II.14), a feature, which cannot be explained by fractional crystallization alone, either. Conversely, the segregation of carbonated immiscible melt from a silico-carbonated parental magma may account for substantial Nb-Ta fractionation (e.g. Martin et al. 2013). However, carbonatites generated by liquid-liquid separation from a primary mantle melt are expected to show elevated Nb/Ta values. This is the case for the equilibrium melts calculated from apatite in the Si-rich carbonatites, but not for the apatite equilibrium melts in the Si-poor carbonatites (Figure II.14.a). The latter are mostly characterized by low, subchondritic Nb/Ta ratios. As illustrated by our modeling (Figure II.14.d), this signature may reflect the segregation of carbonated melts from an evolved parental melt residual after previous stages of immiscible melt separation.

  in the segregation of both cumulus minerals (clinopyroxene, wollastonite, apatite…) and immiscible carbonate melt fractions, as well as in the concomitant chemical evolution of the silicate parental melt. However, this process was partly counterbalanced by intermingling of partially crystallized melt fractions of contrasted compositions. This resulted in the formation of hybrid crystal aggregates composed of disequilibrium "cumulus" phases on one hand, and mobile carbonate melt fractions on the other hand. In this scheme, the differentiation of Si-rich carbonatites from syenites (at least the white ones) is mostly due to the late segregation and spatial redistribution of the interstitial carbonate fraction. Local segregation of carbonate melts also generated the Si-poor carbonatites. Les conditions sub-solidus d'enrichissement en REE : inclusions de britholite et monazite dans les apatites des carbonatites et syénites d'Ihouhaouene Ce chapitre se focalise sur l'étude des apatites et des inclusions minérales riches en terres rares (britholite-monazite) afin de caractériser la composition magmatique en terres rares des minéraux et déterminer la composition des fluides tardi-magmatiques lors des processus de diffusion sub-solidus. 1,2* , F. Parat 1 , K. Ouzegane 2 , J. -L. Bodinier 1,3 , J. -M. Dautria 1 Géosciences Montpellier, UMR 5243, CC60, Université de Montpellier, Place Eugène Bataillon, 34095 Montpellier cedex 5, France FSTGAT-USTHB, BP32, El Alia, 16111 Bab Ezzouar, Algeria Geology & Sustainable Mining, UM6P, Hay Moulay Rachid, Ben Guerir, Morocco *E-mail : asma.djeddi@gm.univ-montp2.fr Chapitre III: Processus sub-solidus 93 Abstract Apatite is a solvus mineral in carbonatites and syenites located in the Archaean In Ouzzal craton (Ihouhaouene, NW Hoggar). Ihouhaouene carbonatitic and alkaline complex includes diverse REE mineral assemblages in apatite (britholite, monazite) formed during different stages and/or environments and reveals an outstanding case because of their potential as geochemical tracers and increasing interest in the mineralogy and geochemistry of rare-earth element ore deposits. Apatites in Ihouhaouene complex are Si-rich and Si-poor, present without inclusions and metasomatic features or they are inclusion-bearing apatites with REE-rich britholite exsolutions or monazite inclusions associated to quartz and calcite, respectively that reflect variable fluid compositions or sub-solidus environments. Inclusion-free and inclusion-bearing apatites in Ihouhaouene carbonatites present key minerals to understand the evolution of carbonatite-related REE mineralization from magmatic to latemagmatic stages and their secondary post-magmatic overprint. Si-rich apatites (~5 wt.%SiO 2 ) contain high REE contents 6.5 to 7.4 wt.% ΣREE ox in inclusion-free apatites and 3.95 to 19.18 wt.% ΣREE ox in britholite-bearing apatites. Whereas, Si-poor apatites (<2.4 wt.% SiO 2 ) have <5.3 wt.% ΣREE ox in inclusion-free apatites and monazite bearing apatites. Britholite (REE: 38 to 67 wt.%) occurs always as exsolutions in apatite and monazite (REE: 66 to 69 wt.%) occurs as inclusions and rim grains in apatite, often associated to quartz and calcite.Geochemical analyses and microstructure orientation of both apatites suggest that britholite exsolutions are topotactic and precipitate as solvus phases and requires the contribution of Cl-Th-Si-REE-rich fluid by an oriented fluid reaction following the substitution mechanism of Si 4+ + S 6+ + 2REE 3+ = 2P 5+ + 3Ca 2+ and F -= Cl -. However, monazite, quartz and calcite inclusions in Si-poor apatites suggest an epitaxial relationship and they are formed during S-Si-REE mass transfer by Ca-P-CO 2 -rich fluid-assisted and apatite re-equilibration at sub-magmatic conditions. Silica and Sulphur content of precursor apatites and/or P-T sub-magmatic conditions mainly control REE distribution and remobilization in apatites and REE-rich mineral inclusions. Ihouhaouene apatites attest of little fluids-rock interaction and re-equilibration during metamorphic episode and underwent sub-magmatic to supergene history of REE-deposition and enrichment.

  and chemical substitutions at magmatic conditions including water, halogens, S, C and significant amounts of trace elements comprising Sr, Th, U and rare earth elements (REE)[START_REF] Pan | Compositions of the Apatite-Group Minerals : Substitution Mechanisms and Controlling Factors[END_REF] Webster & Piccoli 2015;[START_REF] Chakhmouradian | Lithos Apatite in carbonatitic rocks : Compositional variation, zoning, element partitioning and petrogenetic significance[END_REF]. Apatite is among the most important minerals in controlling rare-earth element (REE) variations in igneous rocks[START_REF] Watson | Apatite liquid partition coefficients for the rare earth elements and strontium[END_REF][START_REF] Watson | The behavior of apatite during crustal anatexis: Equilibrium and kinetic considerations Geochim[END_REF][START_REF] Hoskin | Rare earth element chemistry of zircon and its use as a provenance indicator[END_REF]. At subsolidus-conditions, magmatic REE-rich apatites reequilibrate in the presence of fluid (McCubbin & Jones 2015; Harlov 2018) and are often found associated to monazite and bastnasite

  (Figure III.1). The close spatial relationships between carbonatite and syenite of Ihouhaouene complex (2 Ga; In Ouzzal terrane, Hoggar, South of Algeria) and the similar pegmatitic/brecciated textures and mineral assemblages of diopside/hedenbergite cpx, apatite, wollastonite +/-calcite and alkali-feldspar in the two rock types suggest that they were emplaced during a single igneous event (Djeddi et al. 2019). Progressive cooling of a silicocarbonated mantle melts result in the crystallisation and segregation of cumulus minerals and immiscible carbonate melt fractions that formed Si-rich carbonatite and syenite, whereas local segregation of carbonate melts from evolved silica-rich carbonated melt generated Si-poor carbonatite (Djeddi et al. 2019).

Figure III. 1 a

 1 Figure III.1 a Geological map of the Ihouhaouene area in N.W part of the In Ouzzal terrane and localization of carbonatites and associated syenites (Ouzegane et al. 1988). b Location of the studied zone in Western Hoggar.

  generally forms during hydrothermal processes related to the replacement of apatite or monazite(Budzyń et al. 2011; Uher et al. 2015; Zirner et al. 2015; Giebel et al. 2017). Britholite is assumed to be a late stage to post-magmatic origin for most occurrences (subsolidus alteration of primary minerals)(Wall et al. 1993; Uher et al. 2015). The relationship between intergrown REE-rich fluorapatite and fluorbritholite indicate a continuous to sudden crystallization in this mineral sequence during fluid evolution(Zozulya et al. 2017).

  Montpellier (AETE platform OSU-OREME). Several acid attacks on powder samples are carried out with HClO 4 and HF on a hot plate at 100ºC (Detailed protocol inDjeddi et al. 2019). 4 blanks (only acids were introduced into savilex) and four standards: BHVO-1, BEN, UBN and COQ-1 have been analysed to monitor internal drift. Before mass spectrometer analysis, the sample solution is diluted with 9.45 ml of H 2 O, 0.25 ml of HNO 3 , and 0.1 of InBi according to a factor of 10000. The mass spectrometer used to quantify trace element concentrations in bulk-mineral is the Agilent 7700x, whose sensitivity is of the order of 200 x 106 cps/ppm on 115 In (Indium). Internal standards A2 and A4 are calibrated for Zr-Nb and Hf-Ta concentrations and calibration curves on Rb, Sr, Y, Zr and Ce are performed to verify the internal calibration.

(

  Oxford Instruments HKL). The microstructural maps and the pole figures were made to highlight the crystallographic orientation of the minerals. The orientation maps represent the crystallographic orientation of each pixel by a colour function of the inverse pole figure (IPF), along one of the three main axes (X, Y, Z).

  in carbonatite and syenite are large prismatic magmatic crystals enclosed by calcitic matrix or K-feldspar and clinopyroxene, respectively. According to the host-rock of apatite, apatites display a compositional range of composition from Si-rich apatite in Si-rich carbonatite and white syenite to Si-poor apatite in Si-poor carbonatite and Red syenite (0.48 to 6 wt.% SiO 2 ) (Figure II.12 in Djeddi et al. 2019; Chapter II). The diversity of apatite composition is then related to the crystallization at different stage of fractional crystallization and immiscibility during alkaline magma differentiation (Djeddi et al. 2019).

  .a) or may contain up to 40 vol.% of britholite (Figures III.2.b). Both textures have never been found together in one single sample whereas, they occurs in samples with similar primary mineral assemblages. Britholites are present in the core and the rim of apatite crystals as yellow grain exsolutions (1 to 200 µm, Figures III.2.b). They occur as large irregular-or amoeboidal-shaped grains (10-200 µm) (Figures III.2.b) and fine elongated hexagonal lamellae (<2-10 µm) in apatite (Figures III.2.b).

Figure III. 2

 2 Figure III.2 Microphotographs of apatites and apatite-inclusions. a Si-rich apatite free-inclusion (Ap). b Britholite (Bri) exsolutions in apatite. c Si-poor apatite free-inclusion. d Monazite (Mnz) inclusions and rim grains in apatite.

Figure III. 3

 3 Figure III.3 Chemical substitutions in apatite-britholite exsolutions and apatite-monazite inclusions from the Ihouhaouene carbonatites and syenites. a Si versus P (a.p.f.u). b REE+Sr+Th (a.p.f.u) versus Ca. c Cl versus F (a.p.f.u). d F versus S.

Figure III. 4

 4 Figure III.4 Normalized REE content of free-inclusion apatites, apatite-britholite and apatitemonazite from Ihouhaouene carbonatites. Chondrite values from Sun and McDonough (1989).

Figure III. 5 .

 5 Figure III.5. Normalized trace element content of apatite free-inclusions, britholite-exsolutions and monazite from Ihouhaouene carbonatites. Primitive mantle values from Sun and McDonough (1989).

  orientation of entire apatite crystal (7 mm, Figure III.6.a) and closer map at apatite rim (Figure III.6.b).

Figure III. 6

 6 Figure III.6 EBSD-phases maps of apatite-britholite exsolutions from carbonatite INH604a. a All apatite crystal. b Apatite-britholite exsolutions zone from the apatite crystal.

Figure III. 7

 7 Figure III.7 EBSD-orientation maps of apatite-britholite exsolutions from carbonatite INH604a along the IPFX-axis of sample reference system a All apatite crystal orientation. b Apatite-britholite exsolutions orientation of a zone from the apatite crystal. c Britholite exsolutions orientation. (IPF: Inverse Pole Figure).

Figure

  Figure III.8. Apatite-britholite crystallographic preferred orientation in pole figures. Pole figures are generated as equal-area of upper hemisphere stereographic projection of the orientation of three crystallographic axes of all crystals for each phase individually. Crystallographic orientations are plotted along IPF-X axis of sample reference system. a scatter plot of crystallographic axes of all apatite crystal from carbonatite INH604a. b scatter plot of crystallographic axes of apatite from the focused-zone. c scatter plot of crystallographic axes of britholite exsolutions from the focused-zone. Contoured plots (d, e, f) with contours levels in normalized multiples of uniform distribution where relative high concentrations of axis orientation are reported in dark red. d all apatite crystal. e apatitebritholite exsolutions. f britholite exsolutions.

Figure

  Figure III.9) and display high enrichment in LREE relative to HREE (La N /Yb N = 27-56) with low fractionation of LREE compare to MREE (La N /Sm N = 0.8-1.6) (Figure III.4). Related to primitive mantle, apatites have negative anomalies in Zr-Hf and Nb-Ta (Zr/Hf=7-190; Nb/Ta= 6-61) (Figure III.5) and low contents in Th and U (Th=21-673 ppm; U= 2-17 ppm). Bulk REE pattern of monazitebearing Si-poor apatite displays high fractionation of LREE compare to HREE (La N /Yb N = 104) (Figure III.4) and present Nb-Ta and Zr-Hf fractionation (Nb/Ta = 4, Zr/Hf = 162) (Figure III.5).

  Monazites REE patterns have very high LREE fractionation compare to HREE (La N /Yb N = 20030-84060) (Figure III.4; Table III.5 in supplementary data C). They have high content in U (U= 0.8-53.4 ppm) and negative anomalies in Nb-Ta and Zr-Hf (Nb/Ta = 5-108; Zr/Hf = 19-77) (Figure III.5).

Figure III. 9 a

 9 Figure III.9 a Ce, Ca, P and Si compositions in monazite bearing apatite. b EMP phase-map of apatite-monazite crystal from INH693 carbonatite c EMP cerium-map of apatite crystal from INH693 carbonatite.

Figure

  Figure III.10 EBSD-phases maps of apatite, monazite-quartz and calcite inclusions from carbonatite INH693. a all apatite crystal. b monazite rim grains zone in the apatite-rim crystal. c monazite inclusions in the apatite-core crystal.

Figure

  Figure III.11 EBSD-orientation maps of apatite, monazite and calcite inclusions from carbonatite INH693 along the IPFX-axis of sample reference system a all apatite crystal orientation. b monazite rim grains orientation in the apatite-rim crystal. c monazite inclusions orientation in the apatite-core crystal .(IPF: Inverse Pole Figure).

Figure III. 12

 12 Figure III.12 Apatite-monazite-quartz and calcite crystallographic preferred orientation in pole figures. Pole figures are generated as equal-area of upper hemisphere stereographic projection of the orientation of three crystallographic axes of all crystals for each phase individually. Crystallographic orientations are plotted along IPF-X axis of sample reference system. a scatter plot of crystallographic axes of all apatite crystal from carbonatite INH693. b scatter plot of crystallographic axes of monazite in all apatite crystal. c scatter plot of crystallographic axes of quartz in all apatite crystal. d scatter plot of crystallographic axes of calcite in all apatite crystal. Contoured plots (e, f, g, h) with contours levels in normalized multiples of uniform distribution where relative high concentrations of axis orientation are reported in dark red. e all apatite crystal. f monazite inclusions. g quartz inclusions. h calcite inclusions.

Figure III. 13

 13 Figure III.13 Apatite-monazite crystallographic preferred orientation in pole figures. Pole figures are generated as equal-area of upper hemisphere stereographic projection of the orientation of three crystallographic axes of all crystals for each phase individually. Crystallographic orientations are plotted along IPF-X axis of sample reference system. a scatter plot of crystallographic axes of apatiterim zone from carbonatite INH693. b scatter plot of crystallographic axes of monazite rim grains in apatite-rim crystal. c scatter plot of crystallographic axes of apatite in apatite-core crystal. d scatter plot of crystallographic axes of monazite inclusions in apatite-core zone. Contoured plots (e, f, g, h)

  redistribution and/or enrichment in primary magmatic apatites.One important observation comparing magmatic inclusion-free apatite and inclusion-bearing apatite (britholite or monazite) is that both apatite types have similar geochemical signature suggesting that all apatites are primary magmatic phases. Si-rich apatites with and without britholite exsolutions have high Nb/Ta (Figure III.14.a) and record the hybrid characteristic of crystals during immiscibility and fractional crystallization. Likewise Si-poor apatites with or without monazite, quartz and calcite inclusions have variable Nb/Ta ratio (low and high ratio, Figure III.14.a), suggesting that they crystallized all from an evolved segregated melt.

Figure III. 14 .

 14 Figure III.14. Trace element compositions of free-inclusion apatites, apatite-britholite and apatitemonazite inclusions from Ihouhaouene carbonatites a. REE bulk-rock b. Ce/Lu versus Nb/Ta c. Rb/Sr versus Y/Zr.

  The ideal slope for REE-Si-S incorporation in apatites during the later substitution mechanisms is of (-1) (figures III.15.a). Inclusion-free and britholite-bearing Si-rich apatites are approximately consistent with equation (1) with a slope range between -0.5 and -1.5(Figure III.15.a).They are completely coherent with equation (2) with a slope of -0.9 to -1 (figureIII.15.b). The imperfect fit between measured inclusion-free and britholite-bearing apatite compositions and the ideal slope (-1) for the equation (1) may be assigned to the cation site vacancies and the high REE contents. This charge imbalance is compensated by substitution mechanism of equation (3)(Figure III.15.c). This suggests that Si 4+ is the main responsible for charge balancing during LREEs structural incorporation in apatites. Inclusion-free apatites have higher Si-content and lower REE-content than britholite-bearing apatites and that suggest higher silica contents than REE contents in the magmatic conditions. Moreover, britholite-bearing apatites have variable to high REE contents 0.3 to 0.8 (apfu) interpreted as REE-enrichment from fluid-rock interaction.

Figure III. 15 .

 15 Figure III.15. REE evolution in Si-poor and Si-rich apatites from Ihouhaouene carbonatites. a. ∑REE versus Ca (apfu) substitution following equation (1). b. Si+S versus P (apfu) substitution following equation (2). c. Si+S+REE versus Ca+P (apfu) following equation (3) and sum of equations (1) and

a

  solid solution between fluorapatite and britholite(Hughson et al. 1964;[START_REF] Oberti | On the symmetry and crystal chemistry of britholite: New structural and microanalytical data[END_REF][START_REF] Pan | Compositions of the Apatite-Group Minerals : Substitution Mechanisms and Controlling Factors[END_REF] Ardhaoui et al. 2006) (Figures III.3, 4; section III.5). Exsolution reaction can result from decreasing temperature (solvus) (Torró et al. 2012) or changing conditions during cooling (e.g. fluid interaction, Uher et al. 2015; Zozulya et al. 2017). For Si-rich apatite, crystallization in Si-rich carbonatite and syenite result from complex fractional crystallization and immiscibility processes that lead to hybridization. The very close composition of in situ apatite and bulk Si-rich apatite without and with inclusions (LREE/HREE fractionation (Ce/Lu= 2517 and 6057 respectively, Figure III.14.a) and the high Nb/Ta and Y/Zr ratios (Nb/Ta= 120 and 69 and Y/Zr= 15 and 10 respectively, Figure III.14.a, b) strongly suggest similar crystallization environment and apatite-britholite exsolution can be determined assuming that inclusion-free apatites are representative of magmatic apatite before britholite exsolution.

  Figure III.14.a, b) infer similar crystallization environment and apatite-monazite-quartz-calcite inclusions can be determined assuming that inclusion-free apatites are representative of magmatic apatite before monazite-quartz-calcite crystallization.

  Rocks undergo re-equilibration with fluids in various environments rising mineral replacement reactions. Replacement reactions commonly take the form of fluid-aided, coupled dissolution-precipitation and frequently result in pseudomorph formation (Wladyslaw et al., 2016). The difference in Ihouhaouene apatite REE-composition consists in the fact that they crystallized from Si-rich and Si-poor magmas and the composition of magmatic apatite plays also a key role during subsolidus reaction and re-equilibration and the crystallization of REE-minerals. The REE distribution and bulk-REE patterns recorded by Ihouhaouene Si-rich and Si-poor magmatic apatites are completely coherent with experimental studies of Watson & Green (1981) and Hammouda et al. (2010) that explain the increase of REE apatite-melt partitioning with increasing silica activity. The close spatial association of apatite-britholite and apatite-monazite in Ihouhaouene carbonatite indicates similar cooling environment (T, P) and a strong control of initial apatite Chapitre III: Processus sub-solidus 123 composition on REE-equilibration (Si-rich and Si-poor apatite). The presence of hydrothermal fluid and percolation can considered as local fluid-rock interaction, more or less enriched in Si-and CO 2 related to the silica and carbonate affinity of the Ihouahouene magmatic complex: -Si-REE-rich apatites crystallized under high magmatic silica activity and further cooling with Cl-Th-REE-rich fluid induced exsolution of britholite and REE-enrichment in apatite, and -Monazite-quartz-calcite inclusions are formed during S-Si-REE mass transfer by Ca-P-CO 2rich fluid-assisted and apatite re-equilibration at sub-magmatic conditions.

  of trace elements lead to trace element remobilization and crystallization of REE-oxides (Wei et al. 2017). The most important REE-mineral is bastnasite, a REE-carbonate mineral (REECO 3 F), which attests of the presence of LREE-CO 2 -F-rich fluids (Wei et al. 2017). The Mountain Pass, California (Mariano & Mariano Jr, 2012) and Bayan Obo, China (Smith et al. 2000) ore deposits have bastnäsite associated with monazite. These deposits are the two largest sources of cerium, yttrium and other light-rare-earth elements (Smithet al. 2000;[START_REF] Castor | The Mountain Pass rare-earth carbonatite and associated ultrapotassic rocks[END_REF] 2008; Yang et al. 2011;[START_REF]Rare earth mining and exploration in North America: Elements[END_REF] Wei et al. 2017).

  few occurrences of britholite have been reported in the literature.Uher et al. (2015) andGiebel et al. (2017) reported britholite occurrences in the Palabora carbonatite complex in South Africa as linked to late-magmatic crystallization or sub-solidus alteration of primary minerals (forsterite) by late magmatic to hydrothermal fluids. Britholite is mostly described from nepheline syenites and contact metasomatic deposits and generally forms during hydrothermal processes related to the replacement of apatite or monazite(Budzyń et al. 2011; Uher et al. 2015; Zirner et al. 2015; Gibel et al. 2017). Likewise, britholite has been described as a low-temperature phase (e.g. The Virulando carbonatite, Angola) and formed during late-stage supergene alteration processes(Torró et al. 2012). Generally, britholite is assumed to have a late stage to post-magmatic origin for most occurrences(Wall et al. 993; Uher et al. 2015; Gibel et al. 2017). In Ihouhaouene carbonatites, britholite exsolutions occur by apatite replacement and the mass-balance considerations imply that the REE content of both precursor apatite and britholite-bearing apatite are high and depend of the silica activity in magmas and at late-crystallization stages. Thus we suggest that the britholite exsolution following several apatite substitutions was caused by late carbonatitic REE-bearing fluid at low P-T sub-magmatic conditions. Chapitre IV : U-Pb datations ! "#$! Evidences de magmatisme et de métamorphisme contemporains dans les carbonatites et syénites d'Ihouhaouene au Nord-Ouest du terrane de l'In Ouzzal à l'Eburnéen : datations U-Pb in situ effectuées sur apatite et zircon Ce chapitre inclut une étude géochronologique préliminaire des complexes alcalins d'Ihouhaouene à partir des dations U-Pb in situ sur apatite et zircon dans les carbonatites et les syenites afin de déterminer l'âge de cristallisation de ces roches et comprendre leur mise en place durant l'évènement tectonométamorphique régional de l'In Ouzzal à l'éburnéen.! Introduction

  1).The Ihouhaouene carbonatites and associated syenites have a close field relationship and present a cogenetic relationship from their petrological and geochemical features(Djeddi et al. 2019).A geochemical model of their petrogenesis by immiscibility and fractional crystallization and hybridization is developed in the Chapter II(Djeddi et al. 2019).Previously published isotopic studies of Ihouhaouene carbonatites, identified a high Sr and low Nd initial ratios ( 87 Sr/ 86 Sr ≈ 0.709 and εNd (T) ≈ -6.4 to -8.6 with T DM = 3.3 -2.7 Ga) characterized an enriched Archaean source[START_REF] Bernard-Griffiths | Origin and evolution of 2 Ga old carbonatite complex (Ihouhaouene, Ahaggar, Algeria): Nd and Sr isotopic evidence[END_REF][START_REF] Fourcade | Metasomatic effects related to channelled fluid streaming through deep crust: Fenites and associated carbonatites (In Ouzzal Proterozoic granulites, Hoggar, Algeria)[END_REF]; The O and C stable isotope data (δ 13 C = -3.5 to -9.7 ‰; δ 18 O = +7.6 to +15.5 ‰) suggest these features reflect contamination of the hypothetical mantle derived magmatic carbonatites by the Archaean crust[START_REF] Ouzegane | New carbonatite complexes in the Archaean In'Ouzzal nucleus (Ahaggar, Algeria): Mineralogical and Geochemical data[END_REF]).Few works have been realized on the geochronology of Ihouhaouene carbonatitic complex.The U-Pb hydroxyapatites (2090 Ma;[START_REF] Allègre | U-Th-Pb systematics of hydroxyapatite intergrowths[END_REF] zircons (1994± 22-17 Ma;[START_REF] Bernard-Griffiths | Origin and evolution of 2 Ga old carbonatite complex (Ihouhaouene, Ahaggar, Algeria): Nd and Sr isotopic evidence[END_REF]) ages (ID TIMS) obtained from carbonatites show that the emplacement of syenitecarbonatite complex is syn-Eburnean and is synchronous of granulitic metamorphic event (2000 -1800 Ma;[START_REF] Ouzegane | A review of Archaean and Paleoproterozoic evolution of the In Ouzzal granulitic terrane (Western Hoggar, Algeria)[END_REF] and references in) (TableIV-1). Ihouhaouene carbonatites were interpreted as syn-granulitic rised up by the upwelling of the asthenospheric mantle during the eburnean (2000-1800 Ma) metamorphism of the In Ouzzal terrane[START_REF] Ouzegane | A review of Archaean and Paleoproterozoic evolution of the In Ouzzal granulitic terrane (Western Hoggar, Algeria)[END_REF]. The apatite Chapitre IV : U-Pb datations ! ")"! fission-track study of Carpena et al. 1988 on apatites from Ihouhaouene carbonatites exposed the low temperature thermal history of the Archaean unit of In Ouzzal and reveals that apatites have recorded the Pan-African orogeny event (500-630 Ma; 100-120ºC) (Table IV-1).

  calcite δ 18 O = -7.6 to 10.3‰; δ 13 C = -6 to -9.7‰ Bernards-Griffiths et al. 1988 Sr-Nd whole rock εNd(T)= -6.4 to -8.6; Isr(T) = 0.7097 Fourcade et al. 1996 Sr-Nd Whole rock, C-calcite, O-Cpx εNd(T)= -8.5 ; Isr(T) = 0.7095; δ 18 O = 6.9 to 8‰; δ 13 C = -3.5 to -9.7‰

  A 40 μm ablation beam diameter with 7 Hz repetition rates were used. Instrument and mass calibrations were carried out before each analysis session on the NIST SRM 612 reference glass, inspecting the 238U signal and minimizing the ThO + /Th + ratio (<0.5%). During the ablation analysis, the signals of the masses 43Ca, 204 (Pb + Hg), 206Pb, 207Pb, 208Pb and 238U are acquired. Signal 235U is calculated from 238U based on the ratio 238U/235U=137.88. The apatite standards used as internal references for apatite analyses are Madagascar (ID-TIMS age of 473.5 ± 0.7 Ma, Cochrane et al. 2014), Durango (31.44 ± 0.18 Ma, McDowell et al. 2005) and McClure (523.51 ± 2.09 Ma, Schoene and Bowring 2006). The data were corrected for U-Pb fractionation and for mass bias by repeated measurements of the Madagascar apatite standard. Durango and McClure apatite standard measurements were treated as external references and used to control the reproducibility and accuracy of corrections. They provided 207Pb corrected ages of 32.27 ± 0.70 Ma (MSWD = 0.44, probability = 0.98) and 527.2 ± 5.6 Ma(MSWD = 0.21, probability = 0.99) during the analyses, respectively. Data processing was performed using Igor Pro Iolite software[START_REF] Paton | Improved laser ablation U-Pb zircon geochronology through robust downhole fractionation correction[END_REF] with the data reduction scheme VizualAge_UcomPbine set[START_REF] Chew | U-Pb LA-ICPMS dating using accessory mineral standards with variable common Pb[END_REF]. This data treatment consists of a correction of the common Pb using the 207Pb method for the initial Pb isotope composition specified in the reference values of the Madagascar standard. Thus the fractionation curve 207Pb / 235U is adjusted with a correction of the common Pb based on 207Pb using an initial 207Pb/206Pb value of 0.8681[START_REF] Cochrane | High temperature (>350 °C) thermochronology and mechanisms of Pb loss in apatite[END_REF].

  The different isotopic masses(204Pb, 206Pb, 207Pb, 208Pb, 232Th, 235U and 238U) are simultaneously measured in static mode with a scan time between 150 ms for 204Pb, 206, 207, 208 and U238, 100 ms for 235U and 232Th and 60 ms for 202Hg using Faraday type detectors. The corrections for isotopic and elementary fractionations as well as for Isoprobe deviation are made from two standards: Zircon 91500 (1065.4 ± 0.3 Ma, Wiedenbeck et al. 1995) used as an internal standard and Plesovice (337 ± 0.7 Ma, Slama et al, 2008) used as an external standard. The data is processed on Igor Pro Iolite 2.5 software + VisualAge data Reduction scheme (School of Earth Sciences, University of Melbourne).

  10) are dominated by REE-activated luminescence emission. The CL behaviour of investigated apatites (Figure IV.1) is in accordance with the trace element characteristics of the samples (High LREE, Chapter III). INH 170 apatite displays the same CL behaviour in all the crystal from the rim to the core. This apatite is coloured in bluish-violet CL (Figure IV.1.a). Apatite from syenite IC3-10 sample displays different CL colours with high yellow and violet luminescent regions (Figure IV.1. b). CL image of syenites apatite reveals irregular internal structures. High bluish CL inclusions of fluorite are present in K-feldspars in syenite and around apatite crystals in carbonatite.

Figure IV. 1 .

 1 Figure IV. 1. Cathodoluminescence microscopy (CL) images of apatite from a. INH170 carbonatite sample showing one-generation apatite with bluish-violet CL colour. b. IC3-10 syenite sample showing different apatite yellow and violet CL colours. AP: apatite, Cal: calcite, Fl: fluorite, Kfs: feldspar.

  From the carbonatite sample (INH170), twenty-three U-Pb isotopes analyses on five apatite megacrysts (5mm to 1 cm) were carried out. In the Tera Wasserburg diagram, all ellipses are in discordant positions with a relatively high proportion of commun Pb ( 207 Pb/ 206 Pb = 0.198 -0.508) (TableIV.4). Apatites in carbonatite (INH170) have homogenous composition with no recrystallization evidences (Figure IV.1.a). The 207 Pb/ 206 Pb corrected ages from center and rim apatite grains ranging between 1744 ± 106 Ma to 2025 ± 142 Ma and 1588 ± 124 Ma to 1976 ± 154 Ma respectively, yield similar ages within the errors (Table IV.4). Furthermore, the weighted average 207 Pb/ 206 Pb corrected ages obtained from the center and rim grains yields a age of 1867 ± 88 Ma (MSWD = 2.4, N= 8; Figure IV.2.b) and 1794 ± 57 Ma (MSWD = 2.2, N= 15; Figure IV.2.a) respectively.

Figure IV. 2 .

 2 Figure IV.2. The weighted average 207 Pb/ 206 Pb-corrected age diagram of apatites from INH170.carbonatite. a. Center apatite grains. b. Rim apatite grains. Errors are reported at 2 σ.

Figure IV. 3 .

 3 Figure IV.3. The U-Pb Tera-Wasserburg Concordia diagram based on the unforced Intercept age of apatite from the carbonatite INH170. Ellipses and errors are reported at 2 σ.

Figure IV. 4 .

 4 Figure IV.4. The U-Pb Tera-Wasserburg discordia diagram of apatite from carbonatite INH170. a. The discordia is calculated with the initial common Pb value forced to 207 Pb/ 206 Pb of 0.98 calculated following the Pb evolution model of Stacey and Kramers (1975). b. Corresponding weighted average 207 Pb/ 206 Pb-corrected age diagram. Ellipses and errors are reported at 2 σ.

Figure IV. 5 .

 5 Figure IV.5. The U-Pb Tera-Wasserburg discordia diagram of apatite from syenite IC3-10 based on calculated age with the initial common Pb value forced to 207 Pb/ 206 Pb of 0.87 following the Pb evolution model of Stacey

  SiO 2 , 66.3-67.7 wt.% ZrO 2 (Figure IV.6a). They display a wide range in HfO 2 contents from 0.35 to 0.61 wt.% and TiO 2 < 0.01 wt.% (Figure IV.6b).

  4 wt.% (Figure IV.6) with 28.8-31.4 wt.% SiO 2 , 61.9-67.2 wt.% ZrO 2 and TiO 2 < 0.02 wt.% (Figure IV.6a and b).

Figure IV. 6 .

 6 Figure IV. 6. Zircon mineral chemistry from IC2-6A syenite and IC2-9A Si-rich carbonatite samples in molar units. a. Zr versus Hf (a.p.f.u). b. Ti versus Hf (a.p.f.u).

Figure IV. 7 .

 7 Figure IV. 7. Quantitative EMP mapping for Si, Y and Hf (wt.%) in zircons from samples (a-b) IC2-6A red syenite and (c-d) IC2-9A Si-rich carbonatite.

Figure

  Figure IV. 8. a. U versus Th (ppm) for carbonatite and syenite Zircon samples. Th/U versus Th (ppm) showing the magmatic or metamorphic zircon type following Rubatto et al. 2001 and Teipel et al. 2004 for b. syenite zircons and c. carbonatite zircons.

Figure

  Figure IV. 9. a. U-Pb Concordia diagram based on 207 Pb/ 235 U and 206 Pb/ 238 U isotopic ratios measured on zircons from syenite sample IC2-6A by LA-ICP-MS. b. Weighted mean age diagram using 206 Pb/ 238 U calculated ages.

Figure

  Figure IV. 10. a. U-Pb Concordia diagram based on 207 Pb/ 235 U and 206 Pb/ 238 U isotopic ratios measured on zircons from carbonatite sample IC2-9A by LA-ICP-MS. b. Weighted mean age diagram using 206 Pb/ 238 U calculated ages. Ellipses and errors are reported at 2 σ.

Figure

  Figure IV.2.b) and 1794 ± 57 Ma (MSWD = 2.2, N= 15; Figure IV.2.a) respectively, which implies that all these 5 grains record the cooling temperatures at the Eburnean event.

  Figure IV. 11. Zircon Hf mineral chemistry variation from IC2-6A syenite and IC2-9A Si-rich carbonatite samples in molar units. a. Bulk-rock Zr/Hf versus Hf (a.p.f.u). b. Bulk-rock SiO 2 versus Hf (a.p.f.u). Zircon crystals from Ihouhaouene carbonatites have low U and Th concentrations (U = 30.2-130 ppm and Th = 4.6-210 ppm) compare to zircons from associated syenites (U =96-17500 ppm and Th = 7.4-3980 ppm) (TableIV.6) and that are similar to concentrations in Kimberlitic zircons and

  , 28 syenitic zircons have 0.1<Th/U<0.3 (Figure IV.12b) (Intermediate values between magmatic and metamorphic zircons) and 8 zircons have 0.3<Th/U<0.55 (as magmatic zircons). All of syenitic zircons provide similar large U-Pb ages for all zircon types (Figure IV.12b). However, the Th/U> 0.1 ratios of zircons from carbonatites and syenites Chapitre IV : U-Pb datations ! "##! suggest that they crystallized from intermediate to felsic melt source (Linnemann et al. 2011) (Figure IV.12). Hoskin & Schaltegger 2003 recognized igneous zircons with Th/U ratios ≥0.5 and metamorphic zircons with Th/U ratios <0.01. Furthermore, Yakymchuk et al. (2018) considered that igneous zircons rarely have Th/U<0.1 and metamorphic zircons in ultra-high temperature granulitic conditions can have values ranging from Th/U< 0.01 to > 10 and that in the presence of Th-rich minerals as monazite and allanite. That suggests that all Th/U ratios from carbonatitic and syenitic zircons cannot be discriminant for a magmatic or metamorphic zircon origin because of the high amounts of Th-rich minerals in the Ihouhaouene alkaline rocks.

Figure IV. 12 .

 12 Figure IV. 12. Th/U versus U-Pb ages of Zircons showing the magmatic or metamorphic zircon type following Rubatto et al. 2001 and Teipel et al. 2004 and the felsic, intermediate or mafic source type for magmatic zircons (Th/U>0.3) following Linnemann et al. 2011 for a. syenites and b. carbonatites.

  This work was financially supported by the FP7-PEOPLE-IRSES projectMEDYNA (2014MEDYNA ( -2017) ) "Maghreb -EU research staff exchange on geodynamics, geohazards, and applied geology in Northwest Africa". The help of Françoise Roger gratefully acknowledged. We thank Romain Lafay and Loic Blanchard for their appreciated analytical work and we thank C. Nevado and D. Delmas for their technical assistance.

Figure 8 .

 8 Figure 8. Conceptual representation of the geodynamic emplacement of Ihouhaouene carbonatite and syenite association in the In Ouzzal terrane at the Eburnean tectono-metamorphic period.

  equilibration and diffusion reactions indicate that incorporation of REE into apatite structure and britholite exsolution are induced by substitution of P, Ca by Si and Cl-Th-REE-rich fluids during subsolidus conditions. Likewise monazite-quartz and calcite inclusions are formed during S-Ca-P-CO 2 -rich fluid-apatite re-equilibration and mineral diffusion.Therefore, Ihouhaouene apatites record variable degree of fluid-rock interactions. The presence of inclusion-free apatites in Si-rich and Si-poor carbonatites and different topotactic apatite mineral-carbonatites underwent different fluid re-equilibration and oriented fluid reaction starting from shortly after crystallization and continuing down to ambient P-T conditions.Furthermore, the REE-enrichment processes in Ihouhaouene complex reveal an early submagmatic stage, that can represent an early stage of the two world's major ore-deposits at BayanObo and Mountain Pass, where a multistage history of REE-deposition and enrichment are observed (Figure9).

Figure 9 .

 9 Figure 9. Worldwide map distribution of REE ore deposits (Modified after Mariano, Cox, Hedrick).

( 4 )

 4 The zircon calculated Concordia ages in carbonatites are between 1840 ± 56 Ma and 2131 ± 88 Ma, whereas syenite contains multiple age population of zircons (2738. ± 73 Ma to 1657 ± 87 Ma) where the ages obtained in carbonatite are recorded in syenite zircons. The period 2100 -1800 Ma in the In Ouzzal terrane corresponds to the UHT metamorphic events whereas the period between 2700 and 2500 Ma correspond to the Archaean ages of the cratonic in Ouzzal unit. The geodynamic signification of the transition period between 2500 and 2100 Ma in the In Ouzzal correspond to the Archaean-Eburnean transition characterized by a multitude of extension episodes and active shear-zones as observed in the Guinean Archaean domain of the West African

and

  Mount Weld. The incorporation of REE into apatite structure in Ihouhaouene carbonatites and syenites is assisted by the high silica composition of the alkaline magmas and substitution of P, Ca by Si, REE and from REE-rich fluids during subsolidus conditions. The intrusion of CO 2 -rich alkaline magmas beneath the continental craton Hoggar occurred at the beginning of the eburnean (2Ga) tectono-metamorphic event in the In Ouzzal terrane. The alkalinity and volatile rich-character of primary magmas clearly highlights the presence of CO 2 -rich lithospheric or asthenospheric mantle beneath the In Ouzzal craton that may be similar to the CO 2 -rich mantle beneath all the gathered cratons at the Paleoproterozoic period such: the Siberian craton (Russia), West African craton (Algeria, Morocco and Mauritania), the Kaapvaal craton (South Africa) and the Amazonian craton (Brazil) characterized by several carbonatitic-alkaline complex occurrences. Exhumation of Ihouhaouene continental crust occurred at 651 Ma synchronous to the Pan-African tectono-thermic event and the amalgamation of the several terranes in the Hoggar by the suturation of the oceanic areas between them.

Figure 1

 1 Figure 1 : a dyke de Dolérite recoupant une syénite rouge. b affleurement de breche feldspatique dans le Nord Wadi Tirahart. c Pegmatite de quartz-calcite dans l'Oued Ihouhaouene. d Un niveau de wollastonite dans la syenite blanche du Sud Wadi Tirahart.

-!

  The parental melt composition is a mixt liquid of a segregated melts from the second immiscibility of the model A. The mingling is calculated from the carbonate liquid and 20% of silicate liquid. Solely this modelling explains the compositions of the white syenites. ! -The extracted melt rate "F" is 0.08 (rate that allows decreasing Nb/Ta in segregated liquids) for the first immiscibility and 0.01 for the following immiscibilities. ! -The liquid/liquid partition coefficient is calculated from: clinopyroxene equilibrium liquid from white syenites / apatite equilibrium liquid from white syenites.! Schematic

Figure 1 268 Figure 2

 12682 Figure 1 Image MEB-CL de la lame de carbonatite IC2-9Ap et position des zircons analysés

L

  'apatite et le zircon présents dans ces roches alcalines et carbonatites, ont permis de déterminer l'âge de mise en place du complexe magmatique de Ihouahouene à 2100 Ma synmétamorphique et de confirmer l'âge panafricain de son exhumation. L'étude pétrologique, géochimique et géochronologique des carbonatites et syénites d'Ihouhaouene a permis de mettre en évidence l'origine magmatique de ces roches et de définir les interactions fluides-roches supergènes à l'origine des enrichissements en REE. Les carbonatites et syénites d'Ihouahouene proviennent d'un faible taux de fusion partielle d'un manteau Précambrien riche en CO2. Plusieurs étapes de cristallisation fractionnée et d'immiscibilité ont permis la genèse de ces roches hybrides, piégées le long de grandes zones de cisaillement durant la période de transition Archéen /Eburnéen dans un régime extensif à l'In Ouzzal caractérisé par un environnement granulitique d'ultra-haute-température. Mots-clés : Carbonatite ; Syénites ; Terres rares ; Immiscibilité ; Hybridation ; Ihouhaouene ; Archéen * Géosciences Montpellier, Université Montpellier, Place E.

  77 lames d'échantillons de carbonatites et de syénites d'Ihouhaouene ont été étudiées pour la caractérisation pétrographique du complexe. L'assemblage minéralogique de chaque échantillon est détaillé dans la Table 1 en annexe A.

		Chapitre I : Contexte géologique
	!
	I.2 Etude Pétrographique:
	!	38

  Ouzegane durant les missions de terrain antérieures (1987) ont été triés et classés selon les trois secteurs de carbonatites dans la région d'Ihouhaouene (Table 2 ; en annexe A).

	Les échantillons présentent les mêmes caractéristiques pétrographiques que les carbonatites et
	syénites échantillonnées durant ma mission de terrain et ont été utilisés dans l'étude géochimique de
	ma thèse. Quelques échantillons à minéraux d'altération locale tardive, telle la biotite et l'amphibole
	décrits dans la thèse de Ouzegane, (1987) ont été écartés dans cette étude petrogénique du complexe
	alcalin d'Ihouhaouene.
	Les carbonatites de types I dans les travaux de Ouzegane (1987), Bernard-Griffiths et al.

(1988)

et

[START_REF] Fourcade | Metasomatic effects related to channelled fluid streaming through deep crust: Fenites and associated carbonatites (In Ouzzal Proterozoic granulites, Hoggar, Algeria)[END_REF]

représentent les carbonatites bréchiques dans cette étude et les carbonatites II et III sont les carbonatites pegmatitiques.

I.3. Méthodes analytiques

I.3.a. Analyse des roches totales

Une soixantaine de roches intrusives de syénite et de carbonatite représentant la diversité et l'hétérogénéité des roches de la région d'Ihouhaouene ont été sélectionnées pour les études pétrologiques et géochimiques détaillées. Les échantillons ont été choisis en fonction des localités et des deux types de syénites rouges et blanches et des différents types de carbonatites : en veines bréchiques, pegmatitiques ou en veines de calcite. Les carbonatites bréchiques ont été concassées progressivement et nettoyées afin d'enlever des fragments de syénite avant le broyage fin. Une quantité significative de carbonatites pegmatitiques par rapport à la grande taille des minéraux (∼ 3 kg) a été broyée et cartée pour avoir une composition représentative pour chaque échantillon (Table

  pour Mg, hématite pour Fe, apatite pour P, métal natif pour Ni, Mn, Cu, célestine pour Sr, ThO 2 pour Th, verres enrichis pour les REE : REE2 pour Nd, Sm, Yb, Lu; REE3 pour La, Ce, Pr, Y; REE4 pour Dy, baryte pour S et Ba, fluorite pour F et chloroapatite pour Cl. L'erreur sur les mesures est inférieure à 0,5 pds.% (TableI.1).

	La distribution de cinq éléments majeurs (Ca, P, Si, Ce, La) au sein des cristaux d'apatite et
	des inclusions de monazite a été caractérisée par la collecte de cartes d'éléments aux rayons X par
	dispersion de longueur d'onde (WDS) avec une taille de pas de 16 µ sur un cristal de 1cm couplées à
	des analyses quantitatives ponctuelles (20 points).
	Les concentrations en éléments majeurs, mineurs et volatils dans les minéraux ont été
	analysées sur lames minces polies par microsonde électronique CAMECA SX100 de Géosciences
	Montpellier (service Microsonde Sud). La tension d'accélération et le courant du faisceau ont été
	réglés sur 20 keV et 10 nA, respectivement. Le faisceau est focalisé (1 µm) à l'exception des
	carbonates analysés avec un faisceau défocalisé. Le temps d'analyse a été fixé à 20 s pour chaque

élément majeur, 40 s pour les éléments mineurs tels les Terres Rares, Ni, Cr, Mn, Th, Sr, et Ba et 40 s pour le F, Cl et S. Les analyses ont été calibrées sur des standards internes choisis pour chaque élément: Al 2 O 3 pour Al, TiO 2 pour Ti, wollastonite pour Ca et Si, albite pour Na, orthose pour K, Chapitre I : Contexte géologique ! ! 46 forstérite

Table I . 1 :

 I1 Ecart type et limites de détection (pds %) des éléments majeurs dans l'apatite et la britholite.Les analyses des éléments en trace dans les minéraux ont été déterminées par LA-ICP-MS de Géosciences Montpellier (plate-forme AETE, OSU-OREME), à l'aide de GeoLas Q + Excimer CompEx102 couplé avec un spectromètre de masse à source plasma (ThermoFinnigan Element XR).Un diamètre de faisceau laser de 26 µm a été utilisé pour l'apatite et la britholite, 51 µm pour les minéraux silicatés et de 77 µm pour la calcite et la wollastonite avec une fréquence de 7 Hz, une puissance laser de 5 J/cm 2 et un mélange d'hélium et d'argon en tant que gaz vecteur. Chaque analyse consiste en une impulsion de pré-ablation de 10 secondes, 2 minutes de mesure de fond avant ablation et de 60 secondes de temps d'intégration après le déclenchement du laser. Les analyses sont calibrées à partir de deux standards le NIST 612 comme standard interne et le BIR comme standard externe. Les concentrations de SiO 2 -CaO pds% déterminées précédemment à la microsonde électronique pour Pb, 208 Pb et 238 U sont acquis. Le signal 235 U est calculé à partir de 238 U sur la base du rapport Les données ont été corrigées pour le fractionnement U-Pb et pour l'influence de masse par les mesures répétées du standard d'apatite de Madagascar. Les mesures des standards d'apatite, de Durango et de McClure ont été traitées comme des standards externes et utilisées pour contrôler la reproductibilité et la précision des corrections. Au cours des analyses, ils ont fourni des âges corrigés Chew et al. 2014). Cette correction de données consiste à une correction du Pb commun à l'aide de la méthode 207 Pb pour la composition initiale en isotope du Pb spécifiée dans les valeurs de référence du standard Madagascar. Ainsi la courbe de fractionnement 207 Pb/ 235 U est ajustée avec une correction du Pb commun basée sur 207 Pb en utilisant une valeur initiale de 207 Pb/ 206 Pb de 0,8681 (Cochrane et al. 2014).

				Chapitre I : Contexte géologique Chapitre I : Contexte géologique
	! !
	Analyses des éléments en trace par ablation laser (LA-ICPMS)
	au 207 Pb de 32,27 ± 0,70 Ma (MSWD = 0,44; probabilité = 0,98) et 527,2 ± 5,6 Ma (MSWD = 0,21;
	probabilité = 0,99), respectivement. Le traitement des données a été réalisé à l'aide du logiciel Igor Pro
	fonctionnant avec Iolite + VizualAge_UcomPbine (
		Std déviation	limite de détection
		Ap	Bri	Bri
		(n=55)		(n=40)
	SiO 2	0,01	0,03	0,01
	FeO	0,01	0,02	0,01
	MgO	0,001	0,004	0,01
	MnO	0,01	0,003	0,002
	CaO	0,03	0,05	0,01
	Na 2 O	0,01	0,01	0,02
	K 2 O	0,003	0,000	0,01
	P 2 O 5	0,05	0,03	0,01
	La 2 O 3	0,01	0,03	0,04
	Ce 2 O 3	0,02	0,07	0,04
	Pr 2 O 3	0,002	0,005	0,05
	Nd 2 O 3	0,01	0,02	0,04
	Sm 2 O 3	0,002	0,01	0,03
	Gd 2 O 3	0,01	0,005	0,07
	Dy 2 O 3	0,02	0,01	0,07
	Y 2 O 3	0,001	0,01	0,02
	Lu 2 O 3	0,02	0,02	0,03
	ThO 2	0,01	0,01	0,03
	SO 2	0,01	0,003	0,01
	Cl	0,001	0,003	0,01
	F	0,03	0,04	0,17
	Hz ont été utilisés.
		Les standards d'apatite utilisés comme matériau de référence interne pour les analyses d'apatite
	sont l'apatite de Madagascar (âge ID-TIMS de 473,5 ± 0,7 Ma; Cochrane et al. 2014), l'apatite de
	Durango (31,44 ± 0,18 Ma; McDowell et al. 2005) et l'apatite de McClure (523,51 ± 2,09 Ma;
	Schoene et Bowring 2006).
	! !			47 48

chaque minéral sont utilisées pour calculer les concentrations des éléments en trace. Puis le traitement des données est réalisé sous le logiciel GLITTER

[START_REF] Van Achterbergh | Laser Ablation-ICPMS in the Earth Sciences[END_REF][START_REF] Griffin | GLITTER: data reduction software for laser ablation ICP-MS. Laser ablation-ICP-MS in the earth sciences[END_REF]

.

Géochronologie U-Pb

La géochronologie U-Pb sur apatite a été réalisée par ablation laser (LA-ICP-MS) sur lames épaisses à Géosciences Rennes à l'aide d'un laser à Excimer ESI NWR193UC couplé à un spectromètre de masse à source plasma quadripôle Agilent 7700x ICP-MS équipé d'un double système de pompage pour améliorer la sensibilité (Paquette et al. 2014). Des images par cathodoluminescence (CL), utilisant un système Reliotron CL équipé d'une caméra couleur numérique disponible à Géosciences Rennes, ont été réalisées sur les apatites analysées afin de vérifier l'homogénéité des cristaux et éviter toute contamination par la présence d'inclusions. La calibration du spectromètre et des masses analysées a été effectuée avant chaque session d'analyse sur le verre de référence NIST SRM 612, en vérifiant le signal 238 U et en minimisant le rapport ThO + /Th + (<0,5%). Au cours d'une analyse, les signaux des masses 43 Ca, 204 (Pb + Hg), 206 Pb, 207 238 U/ 235 U=137,88. Les analyses consistaient en une mesure de fond de 20 s suivie de 60 s temps d'intégration, puis de 10 s entre deux analyses pour éliminer d'éventuelles contaminations par l'échantillon précédent. Un diamètre de faisceau d'ablation de 40 µm avec des taux de répétition de 7 Les analyses U-Pb des zircons des échantillons de carbonatite (IC2-9A) et de syénite (IC2-6A) ont été réalisées par la méthode LA-ICP-MS au laboratoire « Instituto Andaluz de Ciencias de la Tierra » (IACT) (Grenade, Espagne). L'analyse est effectuée à l'aide d'un laser de type Excimer d'une longueur d'onde 193 nm couplé à un spectromètre de masse à multicollecteurs Agilent 8800 Triple Quadripole ICP-MS. L'ablation du cristal est réalisée à l'aide du faisceau laser de 15 μm avec une fréquence de 10 Hz et une puissance laser de 8 J/cm 2 . Le matériel ablaté est transporté dans un mélange gazeux à 100% d'hélium vers la source de plasma pour être ionisé. Chaque analyse consiste en une impulsion d'ablation de 30 secondes de temps d'intégration. Les différentes masses isotopiques ( 204 Pb, 206 Pb, 207 Pb, 208 Pb, 232 Th, 235 U et 238 U) sont mesurées simultanément en mode statique avec un temps de balayage entre les masse de 150 ms pour 204 Pb, 206 Pb, 207 Pb, 208 Pb et 238 U, 100 ms pour 235 U et 232 Th et 60 ms pour 202 Hg en utilisant des détecteurs de type Faraday. Les corrections pour les fractionnements isotopiques et élémentaires ainsi que pour la dérive de l'Isoprobe sont effectuées à partir de deux standards : Le zircon 91500 (1065,4 ± 0.3 Ma, Wiedenbeck et al. 1995) utilisé comme standard interne et le Plesovice (337 ± 0.7 Ma, Slama et al, 2008) utilisé comme standard externe. Les données sont traitées sur le logiciel Igor! Pro Iolite 2.5 + VisualAge Data Reduction (School of Earth Sciences, University of Melbourne). Les âges sont ensuite établis à partir des calculs de régression linéaire selon la méthode de York (1969) et effectués en utilisant le logiciel ISOPLOT version 3

II.4.b. In situ mineral analysis for major, trace and volatile elements

  The silica and calcium contents in carbonatite range from 3 to 35 wt.% and 32.42 to 53.02 wt.%, respectively (TableII.1). According to the classification from[START_REF] Woolley | Carbonatites: nomenclature, average chemical compositions, and element distribution[END_REF], we distinguish two groups of carbonatites as a function of silica content: Si-poor carbonatites with SiO 2 < 20 wt.% and Si-rich carbonatites or silicocarbonatites with SiO 2 > 20 wt.%.Si-poor carbonatites have high CaO and CO 2 content (42.18 to 53.02 wt.% and 24.83 to 36.15 wt.%, respectively) decreasing with increasing SiO 2 content, variable FeO (0.37 to 4.10 wt.%), MgO (0.11 to 3.21 wt.%, Mg#= 0.54-0.84), Al 2 O 3 (0.11 to 2.82 wt.%) and P 2 O 5 (0.79 to 5.86 wt.%) and very low Na 2 O and K 2 O contents (Na 2 O+K 2 O = 0.15 to 1.39 wt.%) (Figures II. 4 and 5). Volatile contents range from 53 to 130 ppm Cl, 0.05 to 0.44 wt.% F and 0.01 to 0.11 wt.% S.

		Chapitre II : Processus magmatiques Chapitre II : Processus magmatiques	Chapitre II : Processus magmatiques Chapitre II : Processus magmatiques
	beam was used for apatite and britholite, 51 µm for silicate minerals and 77 µm for calcite and
	wollastonite with a repetition rate of 7 Hz, a laser power of 5 J/cm 2 and a mixture of helium and argon
	as carrier gas. Each analysis consisted of a pre-ablation pulse of 10 s, 2 min measurement of the
	background and 60 s integration while the laser fires. The concentrations were calibrated with NIST
	612 and the SiO 2 -CaO concentrations determined previously with electron microprobe for each
	mineral. BIR-1 standard is used as external standard. Data were processed with Glitter software
	(Griffin et al. 2008).
	II.5.	WHOLE ROCK COMPOSITION
	II.5.a. Carbonatites
	All carbonatites are calciocarbonatites with CaO / (CaO + MgO + FeOt + MnO)> 0.8 (Gittins
	25 ml of HClO 4 . The sample is evaporated to a solid residue. A first dilution is accomplished with this residue by adding nitric acid and MilliQ water until having a solution of 20.6 g. Before mass spectrometer analysis, the sample solution is diluted with 9.45 ml of H 2 O, 0.25 ml of HNO 3 , and 0.1 of InBi according to a factor of 10000, which has been chosen for the associated carbonatites and syenites. For each series of analysis (20 samples), 4 blanks (only acids were introduced into savilex) and four standards: BHVO-1, BEN, UBN and COQ-1 have been analysed to monitor internal drift. The mass spectrometer used to quantify trace element concentrations in whole-rock is the Agilent 7700x, whose sensitivity is of the order of 200 x 106 cps/ppm on 115 In (Indium). Internal standards A2 and A4 are calibrated for Zr-Nb and Hf-Ta concentrations and calibration curves on Rb, Sr, Y, Zr and Ce are performed to verify the internal calibration. Major and volatile element concentrations in minerals were analysed using electron microprobe (Cameca SX100 at Geosciences Montpellier, France). Acceleration voltage and beam current were set to 20 kV and 10 nA and a beam focalized (1 µm) except for carbonates that were analysed with a defocused beam. The background counting time was fixed at 20 s for major element and 40 s for F, Cl and S. The analyses were calibrated on internal standards chosen for each element: Al 2 O 3 for Al, TiO 2 for Ti, wollastonite for Ca and Si, albite for Na, orthose for K, forsterite for Mg, hematite for Fe, apatite for P, native metal for Ni, Mn, Cu, celestine for Sr, ThO 2 for Th, enriched & Harmer 1997). Figure II.4. Ihouhaouene carbonatites and associated syenites in total alkali-silica (TAS) diagram ! "#! ! "$!
	glasses for REE, baryte for S and Ba, fluorite for F and chloroapatite for Cl.
	Trace element analyses of mineral were determined by LA-ICP-MS at Geosciences Montpellier
	(AETE platform, OSU-OREME), using GeoLas Q + Excimer CompEx102. A diameter of 26 µm laser
	! !	&+! "#!

(after Le

[START_REF] Maitre | A Classification of Igneous Rocks and Glossary of Terms: Recommendations of the International Union of Geological Sciences Subcommission on the Systematics of Igneous Rocks[END_REF]

. Cap verde carbonatites

(Weinderdorfer et al. 2016)

, Eden Lake carbonatites and syenites

[START_REF] Chakhmouradian | Postorogenic carbonatites at Eden Lake, Trans-Hudson Orogen (northern Manitoba, Canada): Geological setting, mineralogy and geochemistry[END_REF]

, Burntwood Lake syenites

[START_REF] Martins | The Burntwood Lake alkali-feldspar syenite revisited, west-central Manitoba (part of NTS 63N8)[END_REF]

).

Figure II.5. Bulk

  rock major oxide compositions of the Ihouhaouene carbonatites and syenites. Chondrite with a slight negative anomaly in Eu and La N /Yb N ratio from 88 to 145. LILE and HFSE concentrations in Si-rich carbonatites are higher than in Si-poor carbonatites (e.g 1 ppm Cs, 29 ppm Rb, 2504 ppm Ba) with positive anomalies in U and Th and Nb-Ta and Zr-Hf fractionation (Zr/Hf = 22.28-59.20, Nb/Ta = 3.39-11.14).

		Chapitre II : Processus magmatiques
	Carbonatites have high trace element concentrations (Table II.1, Figures II. 6 and 7). Si-poor
	carbonatites have straight REE patterns with negative anomaly in Eu (Eu/Eu* = 0.69 to 0.81) and high
	fractionation in light rare earth elements (LREE) compared to heavy rare earth elements (HREE) (e.g
	1845 ppm La, La N /Yb N = 75-211). Relative to the primitive mantle (PM), Si-poor carbonatites have
	low LILE concentrations (e.g 0.018 ppm Cs 1.73 ppm Rb, 71.48 ppm Ba) with a positive anomaly in
	Th. They have fractionation in Nb compare to Ta (Nb/Ta = 1.59-17.34) with high fractionation and
	negative anomaly in Zr-Hf (Zr/Hf = 20.51-55.76).
	Si-rich carbonatite REE patterns are similar to those of Si-poor carbonatites. They are
	enriched up to 7000*
	Si-rich carbonatites have lower CaO (28.69 to 42.88 wt.%) and CO 2 (11.34-24.56 wt.%) and
	higher Al 2 O 3 (2.01 to 8.14 wt.%) contents than Si-poor carbonatites that decrease linearly with
	increasing SiO 2 content. The concentrations are variable for P 2 O 5 (0.71 to 4.02 wt.%), MgO (0.58 to
	3.31 wt.%, Mg#= 0.55-0.76) and FeO (1.09 to 4.09 wt.%). The alkali contents increase from 1.28 to
	6.20 wt.% Na 2 O+K 2 O (Figures II. 4 and 5) and volatile contents range from 52 to 195 ppm Cl, 0.07 to
	0.62 wt.% F and 0.03 to 0.13 wt.% S (Table 1).
	!	"$!

  TableII.2). Diopside has very low LREE concentrations (La N <1.2*Chondrite, La N /Yb N = 0.12-0.72) with regular flat patterns in MREE (Sm N /Yb N = 1-3.6) (Figure II.9) and positive anomalies in Ba, U, Pb and Sr (Figure II.10, TableII.3).

		Chapitre II : Processus magmatiques
	(0.09 ppm Cs) and Rb (63 ppm Rb), high Ba contents (13197 ppm Ba) and negative anomalies in Sr,
	Zr-Hf and Nb-Ta (Zr/Hf = 16.18-54.83, Nb/Ta = 0.19-7.81) (Figure II.7).
	II.6.	MINERAL CHEMISTRY
	II.6.a. Clinopyroxene
	All clinopyroxenes in carbonatites have small compositional variations. They present
	diopsidic (En 28-33 Fs 17-23 Wo 48-50 ) and hedenbergitic compositions (En 18-22 Fs 30-32 Wo 46-48 ) (Figure II.8).
	In Si-poor carbonatites, clinopyroxenes are diopsides with relatively high Mg# (Mg# =
	Mg/[Mg + Fe 2+ ] = 0.67-0.74), low Cr 2 O 3 , Na 2 O, TiO 2 and Al 2 O 3 contents (TiO 2 = 0.01-0.31 wt.%,
	Al 2 O 3 = 0.65-3.6 wt.%) (
	5.60 to 12.40 wt.% Na 2 O+K 2 O, respectively (Figure II.4), and 2.50 to 12.83 wt.% CaO. MgO content
	ranges from 0.53 to 7.68 wt.% (Mg#= 0.54-0.87), and FeO content ranges from 1.76 to 4.22 wt.%
	(Figure II.5).
	White syenites have lower alkali contents (Na 2 O+K 2 O = 7.19 to 12.7 wt.%) (Figure II.4) than
	red syenites with 52.75 to 58.47 wt.% SiO 2 10.14 to 15.5 wt.% CaO, 0.18 to 2.99 wt.% MgO (Mg#=
	0.4-0.72), and 0.69 to 4.76 wt.% FeO (Figure II.5). We can note that one wollastonite-rich white
	syenite has very low alkali content (2.65 wt.% Na 2 O+K 2 O) and very high CaO (33.87 wt.%) (Table
	II.1, IC2-27, Figure II.2.f).
	Red syenites are enriched up to 1000*Chondrite with a negative Eu anomaly (Eu/Eu* = 0.47
	to 0.84) (Figure II.6). They have higher LILE concentrations than Si-poor carbonatites, with negative
	anomalies in Nb-Ta and Zr-Hf (Zr/Hf = 13.47-29.88, Nb/Ta = 0.16-11.54) (Figure II.7).
	REE white syenite patterns are similar to red syenite patterns with high fractionation of LREE
	compare to HREE (La= 441 ppm, La N /Yb N = 131.25) (Figure II.6). They have low concentrations in Cs
	!	"%!

Table II .2 Representative major element composition of clinopyroxene Rock type Si-poor carbonatite Si-rich carbonatite Red syenite White syenite Sample

 II

		IC1-4B	IC1-4B	IC1-4B	IC2-9A	INH170a	IC1-	INH159	IC3-4	IC1-24A	IC2-27B	3-24	IC3-18
		.18	.23	.30	.4	.6	2C.35	.7	.11	.2	.9	.2	.7
	Mineral	Di	Di	Di	Hd	Di	Di	Di	Di	Di	Hd	Hd	Hd
	Type	Core	Rim	Core	Core	Core	Core	Core	Core	Middle	Core		Core
	SiO2	50.46	51.1	48.91	50.19	52.24	50.94	53.41	53.31	49.8	50.274 49.49 48.13
	TiO2	0.1	0.02	0.3	0.05	0.1	0.1	0.04	0.06	0.26	0.06	0.04	0.15
	Al2O3	1.92	0.66	3.67	0.62	1.41	1.33	0.6	0.6	2.2	0.9	0.74	2.15
	Fe2O3	12.8	10.75	13.32	18.55	12.7	13.28	7.03	6.81	14.65	19.02	18.58 20.89
	MnO	0.4	0.35	0.52	1.02	0.75	0.74	0.78	0.63	0.71	1.0304	1	0.54
	MgO	10.44	11.58	9.81	6.84	9.59	10.01	13.64	14.49	9.29	6.34	5.86	5.14
	CaO	23.71	24.61	23.54	23.51	23.74	24.1	24.08	23.03	22.75	23.32	22.54 21.83
	Na2O	0.38	0.33	0.44	0.4	0.41	0.46	0.54	0.64	0.80	0.52	0.78	0.79
	K2O	-	-	-	0.01	-	-	0.01	0.01	-	-	0.01	0.01
	Cr2O3	-	0.02	-	-	0.02	-	-	0.03	-	-	-	-
	NiO	-	-	-	-	0.02	0.05	-	-	0.04	-	-	0.04
	Total	100.23	99.42	100.52	101.19 100.98 101.05	100.14 99.67	100.5	101.51 117.62 99.68
	Mg#	0.67	0.75	0.67	0.45	0.58	0.66	0.82	0.84	0.63	0.42	0.41	0.36

Numbers of ions on the basis of 6O

								Chapitre II : Processus magmatiques
	Si	1.91	1.94	1.85	1.94	1.98	1.92	1.98	1.98	1.89	1.94	1.96	1.9
	Ti	-	-	0.01	0.002	0.003	0.003	0.001	0.002	0.007	0.002	0.001 0.005
	Al	0.09	0.03	0.16	0.03	0.06	0.06	0.03	0.03	0.1	0.04	0.03	0.1
	Fe3+	0.11	0.12	0.15	0.12	0.01	0.13	0.05	0.06	0.16	0.11	0.1	0.15
	Fe2+	0.29	0.22	0.27	0.48	0.39	0.29	0.17	0.15	0.31	0.5	0.5	0.54
	Mn	0.01	0.01	0.02	0.03	0.02	0.02	0.02	0.02	0.02	0.03	0.03	0.02
	Ni	-	-	-	-	0.001	0.002	-	-	0.001	-	-	0.001
	Mg	0.59	0.65	0.55	0.39	0.54	0.56	0.75	0.8	0.53	0.36	0.35	0.3
	Ca	0.96	1	0.95	0.97	0.96	0.98	0.96	0.92	0.93	0.96	0.96	0.92
	Na	0.03	0.02	0.03	0.03	0.03	0.03	0.04	0.05	0.06	0.04	0.06	0.06
	K	-	-	-	-	-	-	-	-	-	-	-	-
	Cr	-	0.001	-	-	0.001	-	-	0.001	-	-	-	-
	Total	4	4	4	4	4	4	4	4	4	4	4	4
	Di: Diopside		Hd: Hedenbergite		Mg# = Mg/(Mg+Fetot)
	!						"'!

Table II .3 Trace element composition of clinopyroxene Rock type Si-poor carbonatite Si-rich carbonatite Red syenite White syenite

 II

	Sample	IC1-4B.19	IC1-4B.23	IC1-4B.20	IC2-9A.4	INH 170a.6	IC1-2C.47	INH 159.6	IC3-4.11	IC1-24A.2	IC1-13.3	IC2-27B.9	IC3-18.7
	Mineral	Di	Di	Di	Hd	Di	Di	Di	Di	Di	Di	Hd	Hd
	Type	Core	Rim	Core	Core	Core	Core	Core Core Middle Core	Core	Core
	Rb	0.01	6.18	0.01	0.08	0.21	0.01	0.01	0.03	1.71	2.49	0.004	0.1
	Ba	0.41	158	1.56	0.30	0.16	0.04	0.04	0.06	4.71	1.11	0.21	0.78
	Th	0.001 <0.001 0.01	0.003 0.001 0.004	0.06	0.07	0.03	0.17	0.03	0.03
	U	0.02	0.22	0.04	0.03	0.06	0.03	0.03	0.03	0.15	0.04	0.03	0.003
	Nb	0.06	0.38	0.35	0.04	0.005	0.09	0.01	0.23	0.11	0.04	0.001	0.01
	Ta	0.003	0.002	0.03	0.02	0.004 0.001	0.003 0.02	0.002	0.02	0.001 0.004
	La	0.47	0.36	0.22	1.86	2.74	1.49	3.14 75.12	3	15.46	1.63	9.29
	Ce	2.32	1.52	1.27	6.23	7.81	4.87	16.15 292	5.78	64.8	6.34	29.5
	Pb	14.41	66.1	11.85	5.07	28.78 26.88	2.38	7	5.23	1.67	3.48	3.93
	Pr	0.58	0.39	0.37	0.84	1.4	0.8	3.3	51.31	1.95	12.46	0.95	4.24
	Sr	347	571	723	509	368	382	83	523	99.62 57.66	290	187
	Nd	3.49	2.98	2.66	3.36	6.83	3.49	18.6	244	10.49 66.74	4.24	16.83
	Zr	23.12	7.92	6.88	18.54 50.61 50.78	21.01 35.02	13.5	38.37	84.12 64.46
	Hf	1.32	0.4	0.58	0.68	1.93	2.16	2.1	1.63	1.83	3.15	1.85	2.63
	Sm	1.5	1.85	1.43	0.59	1.66	0.72	5.37 56.46	3.51	17.78	0.81	2.99
	Eu	0.47	0.73	0.44	0.15	0.34	0.16	1.29 11.59	0.49	3.6	0.17	0.57
	Gd	1.47	3.81	1.79	0.34	0.91	0.47	3.82 39.53	3.59	13.23	0.47	1.94
	Tb	0.22	0.66	0.32	0.04	0.12	0.06	0.48	4.71	0.63	1.64	0.05	0.23
	Dy	1.13	4.3	1.82	0.18	0.68	0.31	2.27 20.77	3.84	7.87	0.25	1.13
	Y	4.82	22.02	9.11	1.15	3.34	1.46	9.37 78.62 20.19	33.1	1.75	5.59
	Ho	0.19	0.8	0.33	0.03	0.1	0.05	0.33	3.01	0.76	1.18	0.05	0.18
	Er	0.43	1.73	0.73	0.11	0.39	0.16	0.76	6.44	2.15	2.55	0.27	0.59
	Tm	0.07	0.24	0.12	0.05	0.09	0.05	0.14	0.78	0.36	0.35	0.11	0.13
	Yb	0.44	1.98	0.87	0.69	1.07	0.76	1.12	5.39	3.47	2.49	2	1.58
	Lu	0.09	0.25	0.13	0.20	0.29	0.24	0.26	0.77	0.95	0.42	0.51	0.45
	Sc	20.81	26.03	17.76	10.29 21.58 22.78	31.41 29.22	118	24.56	8.08	21.56
	V	33.94	50.43	20.54	25.6	41.87 50.13	10.4	16.9	45.63 18.47	38.05	124
	Zn	211	498	191	391	277	349	385	227	532	405	415	224
	Cu	0.57	2.18	0.73	0.18	0.43	0.22	0.56	0.68	0.68	0.74	0.14	0.26
	Ni	7.96	19.38	8.05	8.1	15.08 18.92	0.29	2.64	17.09	0.45	3.44	11.72
	Cr	9.91	16.85	10.58	6.4	28.92 28.57	7.21	5.83	12.19	4.89	5.7	7.33
	Di: Diopside		Hd: Hedenbergite

Figure II.10. Normalized trace element content of apatite and clinopyroxene from Ihouhaouene carbonatites

		Chapitre II : Processus magmatiques Chapitre II : Processus magmatiques
	Si-rich carbonatites have both diopside and hedenbergite pyroxenes. Mg# ranges from 0.54 to II.6.b. Wollastonite
	0.70 and 0.42 to 0.49 for diopside and hedenbergite, respectively. Diopside and hedenbergite have low
	TiO 2 contents (TiO 2 = 0.02-0.33 wt.%) and Al 2 O 3 contents range from 0.53 to 1.41 wt.% and 0.22 to Wollastonite is present in Si-rich carbonatites and white syenites and has a homogeneous
	1.03 wt.%, respectively. REE patterns have a sinusoidal to asymmetric U-shaped with slight high composition (En 0-0.05 Fs 1-2 Wo 97-99 , Supplementary data B1). It has U-shaped REE patterns with high
	concentrations in LREE than HREE (La N /Yb N = 1.17-4.6) (Figure II.9, Table II.3). Large variations in
	LILE concentrations are observed in Si-rich carbonatite pyroxenes with strong positive anomalies for
	Pb and Sr in addition to Zr-Hf and Nb-Ta fractionation (Zr/Hf= 20.71-33.93, Nb/Ta= 0.63-74.43)
	(Figure II.10).
	In red syenites, pyroxenes are diopsides (En 27-41 Fs 11-25 Wo 46-49 ). They have high Mg# ranging
	from 0.63 to 0.85 with Na 2 O = 0.4-0.79 wt.%, TiO 2 = 0.01-0.21 wt.%, Al 2 O 3 = 0.27-2.21 wt.% and
	Cr 2 O 3 <0.05 wt.% (Figure II.8, Table II.2). Chondrite-normalized patterns of diopside in red syenites
	display a convex LREE section (La N /Sm N = 0.12-1.2) and a negative Eu anomaly (Figure II.9, Table
	II.3). Relative to the primitive mantle, they have high fractionation in Nb-Ta (Nb/Ta= 1.51-95.75)
	with negative anomalies in Ba, Pb, Sr, Zr and enrichment in Th (Figure II.10).
	White syenites are characterized by Fe-rich pyroxenes with hedenbergitic composition (En 15-
	19 Fs 32-38 Wo 47-49 ) (Figure II.8, Table II.2) and 0.39-0.98 wt.% Na 2 O, 0.76-2.58 wt.% Al 2 O 3 , < 0.16 wt.%
	TiO 2, and < 0.03 wt.% Cr 2 O 3 . The REE patterns of hedenbergite in white syenites have the same
	sinusoidal to asymmetric U-shaped pattern than Si-rich carbonatites with high LREE and HREE
	concentrations compared to MREE (La N /Yb N = 0.55-2.94, La N /Sm N = 0.7-2.2) (Figure II.9). They have
	more pronounced Nb-Ta fractionation (Nb/Ta= 0.4-4.34) and less positive Pb and Sr anomalies than
	pyroxenes in red syenites (Figure II.10).
	! !	%*! %+!

and associated silicate rocks. Primitive mantle values from

[START_REF] Sun | Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes[END_REF]

.

Figure II.12. SiO 2 versus REE ox wt.% of apatite from the Ihouhaouene carbonatites and syenites.

		Chapitre II : Processus magmatiques Chapitre II : Processus magmatiques
	pronounced enrichment of Th and U (Th = 1200-4731 ppm, U = 147-818 ppm) (Figure II.10, Table
	II.5).
		Apatites in red syenites have low silica contents (SiO 2 = 0.36-1.59 wt.%) with 37.84 -40 wt.%
	carbonatites, apatite has low silica contents SiO 2 (0.48-1.45 wt.%) with P 2 O 5 P 2 O 5 and 54.08 wt.% CaO with total REE from 2.74 to 4.78 wt.%. They have fractionation in LREE
	contents from 37.57 to 40.25 wt.% and low REE (ΣREE = 0.8-2.5 wt.%) (Table II.4). Apatite has low compared MREE (La N /Sm N = 0.13-0.76, La N /Yb N = 1.49-10.15) with a convex shaped patterns and an
	LREE concentrations compared to HREE with convex shaped patterns (La N /Sm N = 0.34-1.65, important negative anomaly in Eu (Figure II.9). Negative anomaly is observed for Ba and Nb-Ta and
	La N /Yb N = 5.94 -35.46) (Figure II.9). They have negative Nb-Ta and Zr-Hf anomalies in (Nb/Ta = Zr-Hf fractionation (Nb/Ta = 3.44-90.96, Zr/Hf = 4.33-127.77) (Figure II.10).
	0.71-35.41, Zr/Hf = 43.9-204.7) and positive anomalies are observed for Th and U (Th = 49-348 ppm, White syenites have silica-rich apatites with 2.55-3.48 wt.% SiO 2 , 33.39-37.87 wt.% P 2 O 5, and
	U = 2.3-39.3 ppm) (Figure II.10, Table II.5). 51.8-54.78 wt.% CaO. REE patterns of apatite in white syenites display the same regular shape than
	In Si-rich carbonatites, apatite is silica-and REE-rich (SiO 2 = 4.6-6.05 wt.%, ΣREE = 4.32-Si-rich apatite patterns with high fractionation in LREE compared to HREE (La N /Yb N = 71.96-158.48)
	11.21 wt.%, respectively). P 2 O 5 content ranges from 28.67 to 37.42 wt.% and CaO from 47.77 to (Figure II.9). They have high contents in Th (Th= 372-4984 ppm) and negative Zr-Hf and Nb-Ta
	52.39 wt.% (Table II.4). Apatite REE patterns in Si-rich carbonatites are straight with a slight Eu anomalies (Nb/Ta = 54.09-98.46, Zr/Hf = 97.66-232.34) (Figure II.10).
	anomaly. They have high fractionation in LREE compare to HREE (La N /Yb N = 82.18-134.38) (Figure
	II.9) and negative Nb-Ta, Zr-Hf anomalies (Nb/Ta = 33.66-101.9, Zr/Hf = 102.35-241.32) and a
	! !	%#! %$!

Table II .4 Representative major element composition of apatite Rock type Si-poor carbonatite Si-rich carbonatite Red syenite White syenite Sample

 II

		IC1-4B.33	INH 642.7	INH 458.35	IC2-9A.51	INH 170a.5	IC1-2C.9	INH 159.1	IC1-13.2	IC1-24A.2	IC2-27B.9	3-24.1
	Mineral	Ap	Ap	Ap	Ap	Ap	Ap	Ap	Ap	Ap	Ap	Ap
	Type	Core	Rim	Core	Core	Core	Core	Core	Core	Middle	Core	Core
	SiO2	0.43	1.85	0.74	4.03	5.04	5.8	0.31	0.8	0.43	2.89	2.85
	Fe2O3	0.01	-	-	-	0.06	-	0.03	0.01	0.02	-	-
	MnO	-	-	-	-	-	-	0.02	0.06	0.03	-	-
	CaO	54.28	53.23	55.21	50.42	50.29	48.67	56.72	54.60	56.11	50.78	54.1
	Na2O	0.001	-	0.02	-	-	-	0.01	0.01	0.003	-	-
	K2O	-	-	-	-	-	-	-	-	-	-	-
	P2O5	39.9	37.38	40.18	33.05	31.1	28.96	45.11	41.64	43.32	38.53	36.54
	La2O3	0.04	0.95	0.19	1.45	1.42	2.33	0.04	0.14	0.04	0.85	0.81
	Ce2O3	0.23	2.31	0.69	3.53	3.26	4.39	0.16	0.53	0.24	2.24	2.35
	Pr2O3	0.06	0.21	0.1	0.36	0.33	0.44	0.05	0.11	0.07	0.23	0.26
	Nd2O3	0.29	1.03	0.46	1.73	1.34	1.96	0.25	0.65	0.3	1.21	1.23
	Sm2O3	0.09	0.15	0.09	0.48	0.21	0.52	0.1	0.2	0.08	0.34	0.35
	Gd2O3	0.06	0.1	0.1	0.14	0.14	0.15	0.07	0.1	0.05	0.12	0.14
	Dy2O3	0.001	0.01	0.01	0.06	0.04	0.09	0.04	0.06	-	0.05	0.01
	Lu2O3	0.02	-	-	0.02	-	-	-	0.01	-	-	-
	Y2O3	0.04	0.13	0.04	0.21	0.22	0.28	0.08	0.19	0.16	0.1	0.16
	SrO	-	-	0.31	-	-	-	-	-	-	-	-
	ThO2	0.01	0.06	0.01	0.24	0.24	0.21	0.01	0.02	0.002	0.08	0.14
	SO2	0.13	0.11	0.16	1.07	1.78	1.98	0.07	0.11	0.04	0.58	0.77
	F	4.73	5.16	5.59	4.11	4.48	3.85	4.49	3.73	4.36	4.08	4.03
	Cl	0.02	0.002	0.08	0.04	0.04	0.07	0.03	0.09	0.04	0.07	0.01
	Total	100.35	102.66	103.98	100.93	100	99.7122	107.59	103.07	105.28	102.16 103.76
	∑ REEox	0.83	4.88	1.68	7.96	6.96	10.17	0.80	2	0.93	5.15	5.32

Numbers of ions on the basis of 26O

Table II .5 Trace element composition of apatite Rock type Si-poor carbonatite Si-rich carbonatite Red syenite White syenite

 II

							Chapitre II : Processus magmatiques
		II.6.d. Carbonates
	Sample	IC1-4B.37 Carbonate in the carbonatites of Ihouhaouene is calcite (CaO = 56-59 wt.%, MgO<0.16 wt.%, INH 458.35 IC2-9A.46 INH 170a.5 IC1-2C.1 INH 159.2 IC3-4.1 IC1-24A.2 IC2-27B.1 IC3-18.1
	Mineral FeO<0.15, supplementary data B1 ). REE patterns of calcite in Si-poor carbonatites have low LREE Ap Ap Ap Ap Ap Ap Ap Ap Ap Ap
	Type Rb concentrations (La N /Yb N =0.12-0.15), whereas calcites in Si-rich carbonatites have high LREE contents Core Core Core Core Core Core Core Core Core Core 0.41 0.38 0.24 0.3 0.23 0.04 0.31 0.35 0.09 0.21
	Ba Th compared to HREE (La N /Yb N =13.3-16.16) ( Figure II.11.b ). 0.36 6.98 3.51 2.56 1.45 351 350 2083 1201 1601	1.03 29.53	0.07 1.8	0.16 12.03	1.58 589	1.2 158
	U	39.31	39.32	344	150	198	19.13	21.27	3.06	69.79	9.47
	Nb	0.18 II.6.e. Alkali feldspar 0.19 2.52	3.92	2.54	0.12	0.3	0.24	1.09	0.12
	Ta	0.008	0.05	0.04	0.05	0.02	0.007	0.01	0.007	0.01	0.01
	La Ce	995 5239 In red and white syenites, the alkali feldspars are potassic with Or 57-96 contents and have 3103 16022 9841 12753 203 764 370 3731 1327 10081 38385 19008 26079 1048 3321 1901 10794 3419
	Pb perthitic exsolutions with Ab 66-94 . In Si-rich carbonatites, alkali feldspars have high orthoclase content 56.82 65.18 366 201 328 6.86 3.98 4.32 88.89 13.86
	Pr Sr of Or 95-98 (Supplementary data B1). 1050 1474 4205 6199 7063 5736	2158 4805	2837 5846	256 1668	581 2027	377 627	1386 4349	443 1007
	Nd	6356	6796	15684	8295	10930	1720	3341	2126	6079	1993
	Zr	4.3	6.86	205	162	33	0.09	2.07	0.35	43.31	4.29
	Hf	0.02	0.13	1.33	1.46	0.14	0.02	0.09	0.0092	0.23	0.04
	Sm	1602	1455	2260	1207	1572	559	789	534	1004	369
	Eu	343	299	451	206	275	85.71	138	52.81	195	48.12
	Gd	1268	1089	1435	925	1013	493	635	479	674	299
	Tb	144	112	134	86.44	100	52.05	74.12	55.49	64.03	31.04
	Dy	662	491	559	367	445	218	308	282	259	152
	Y	2985	2047	2476	1599	2019	861	1376	1798	1178	748
	Ho	96.89	68.21	77.74	53.63	63.68	30.48	43.98	51.42	35.56	26.1
	Er	203	136	155	115	135	60.35	89.39	119	67.72	62.8
	Tm	21.67	14.32	17.08	13.06	14.81	6.25	9.42	14.17	6.98	8.24
	Yb	112	69.31	91.33	70.68	78.41	32.18	50.84	80.2	35.03	52.09
	Lu	13.16	8.66	10.38	8.36	9.13	3.99	5.97	10.43	3.74	6.69
	Sc	0.22	0.65	1.15	1.11	0.13	0.1	0.19	0.1	0.27	0.12
	V	7.27	4.62	22.16	19.05	5.42	0.29	0.42	1.6	0.54	15.43
	Zn	0.24	2.43	9.05	1.13	0.17	0.31	0.31	0.19	2.57	2.9
	Cu	0.34	0.27	0.53	0.132	0.23	0.29	0.33	0.14	0.49	0.46
	Ni	1.23	16.99	0.61	0.27	0.68	1.17	2.23	0.77	0.38	1.03
	Cr	5.1	9.91	3.88	3.56	5.13	6.33	0.87	0.79	0.65	3.78
	Ap: Apatite
	!					%%!

II.6.f. Accessory minerals

	Britholite
	Britholite is a REE-rich mineral with general formula (Na,Ca, REE) 10 (Si,P) 6 O 24 (OH,F) 2 and Si
	> P (Oberti et al. 2001). In Ihouhaouene carbonatites, britholite occurs as fine lamellar exsolutions
	(<10 um) or as irregular-shaped grains (10-200 um) in apatite. The apatite-britholite exsolutions
	correspond to a substitution of Ca 2+ and P 5+ for REE 3+ and Si 4+ . All britholites contain 8-16 wt.% La 2 O 3
	21-43 wt.% Ce 2 O 3 and 7-12 wt.% Nd 2 O 3 . They contain up to 60 % ΣREE, dominated by LREE
	(La N /Yb N = 147-198) ( Supplementary data B1 ).
	Monazite
	Monazite is composed of more than 60% of REE, mainly rich in La and Ce (La= 16.53-23.34
	wt.%, Ce= 32.52-34.95 wt.%) (Supplementary data B1).
	Allanite
	Allanite is a rare-earth-bearing epidote mineral, characterized by SiO 2 (31.82-33.01 wt.%),
	CaO (12.73-14.93 wt.%), Al 2 O 3 (11.39-15.98 wt.%), FeO (10.4-16.94 wt.%) and ΣREE (18.76-22.44
	wt.%) (Supplementary data B1). Allanites are very rich in LREE than HREE (La N /Yb N = 2053-9323)

  wt.%) (Supplementary data B1). Sphene is present as an accessory mineral in carbonatites and syenites. It has27.64 to 29.83 wt.% SiO 2 , 31.06 to 35.03 wt.% TiO 2 25.13 to 17.36 wt.% CaO, and 1.37 to 3.25 wt.% FeO (Supplementary data B1).Among carbonatite/alkaline rock complexes worldwide, carbonatites are mostly associated to silica-undersaturated rocks (e.g. Cap verde in Brava Island,[START_REF] Weidendorfer | Fractional crystallization of Si-undersaturated alkaline magmas leading to unmixing of carbonatites on Brava Island (Cape Verde) and a general model of carbonatite genesis in alkaline magma suites[END_REF] and only few are associated to silica-saturated rocks (e.g. see review in[START_REF] Chakhmouradian | Postorogenic carbonatites at Eden Lake, Trans-Hudson Orogen (northern Manitoba, Canada): Geological setting, mineralogy and geochemistry[END_REF]. The calciocarbonatites associated solely with silica-saturated syenites (e.g. The Eden Lake in Canada,

	II.7.	DISCUSSION

[START_REF] Chakhmouradian | Postorogenic carbonatites at Eden Lake, Trans-Hudson Orogen (northern Manitoba, Canada): Geological setting, mineralogy and geochemistry[END_REF]

resemble their Ihouhaouene counterparts in term of mineral assemblage (diopside-hedenbergite, Si-rich apatite) and trace-element compositions (e.g. low Nb/Ta,

  . d Ce/Lu versus Nb/Ta of silicate and carbonate liquids from numerical modelling of immiscibility-fractional crystallization (FC) and mingling processes. The silicate/carbonate liquid partition coefficients used in the model are calculated from apatite and clinopyroxene equilibrium liquids from Ihouhaouene carbonatites and associated syenites (see text for further details and supplementary data B2). (A) Fractional immiscibility model of carbonate liquids from a melilitite (Baudouin et al. 2016). (B) Fractional immiscibility model of carbonate liquids from an evolved parental silicate liquid after mingling with carbonate liquid (supplementary data B2). Arrow represents compositional carbonate liquid evolution and dashed arrow represents compositional silicate liquid evolution after immiscibility (Table II.II. 6).

Table II .6. Input segregated and residual melt fractions and output melt compositions for the fractional crystallization-immiscibility model

 II

		residual melt fraction	segregated melt fraction	Csil	Ccarb	Csil Ccarb
		f	F	Ce/Lu	Nb/Ta
	Parental melt A				793	16.31
		0.55	0.01	709	4269	15.72 63.96
		0.5	0.011	637	3836	15.09 61.42
	Model A	0.45	0.012	578	3483	14.44 58.76
		0.4	0.013	533	3212	13.77 56.02
		0.35	0.014	503	4154	13.08 53.03
	Parental melt B			4176	51.09
		0.95	0.08	2931	6341	5.58 12.54
		0.96	0.01	2855	6176	4.27	9.61
	Model B	0.97	0.01	2767	5986	3.27	7.36
		0.98	0.01	2669	5774	2.5	5.63
		0.99	0.01	2562	5560	1.92	4.31
	Csil: Silicate melt composition; Ccarb: Carbonate melt composition

  Large euhedral magmatic apatites (2 to 5 cm) are present in both carbonatites and syenites. They are liquidus phases with cpx and calcite or alkali feldspar and crystallized at high temperature from REE-enriched carbonate-rich silicate melts(Djeddi et al. 2019). Apatites have either no inclusions, numerous inclusions of monazite, quartz and calcite or britholite inclusions. No systematic distribution has been observed according to the outcrop localities (Oued Ihouhaouene, South Wadi Tirahart or North Wadi Tirahart), or mineral assemblage and proportions in the host carbonatite and syenite rocks.The occurrence of various apatite textures is more likely the result of different sub-solidus environments. They are key minerals to determine the sub-solidus conditions that controlled REEenrichment in carbonatites and syenite by comparing the chemical composition (major, trace and volatile elements) and crystallographic relationship of apatite and secondary REE-rich minerals.

  Ba 2+ , Pb 2+ , Cd 2+ , Mg 2+ , Mn 2+ , Ni 2+ , Cu 2+ , Zn 2+ and monovalent cations as Na 1+ or trivalent cations, mostly REE 3+ and Y 3+ . The typically P 5+ Z site can be replaced by Si 4+ , C 4+ ,

	S 6+ , As 5+ , V 5+ and B 3+ (Pan & Fleet, 2002; Hughes & Rankovan, 2015; Riker et al. 2018). The halogen-
	monovalent anions-X site is occupied by F -, Cl -and OH -and sometimes by O 2	-, O 3	-, BO 2	-, NCO -,
	NO 3	-, NO 2	-and S 2

The apatite-group minerals have a general formula of [M 10 (ZO 4 ) 6 X 2 ]

[START_REF] Pan | Compositions of the Apatite-Group Minerals : Substitution Mechanisms and Controlling Factors[END_REF]

, allowing wide chemical substitutions. The M cation site is principally occupied by Ca 2+ and can also hold other common divalent cations Sr 2+ , -

(Mc Connell, 1973;[START_REF] Pan | Compositions of the Apatite-Group Minerals : Substitution Mechanisms and Controlling Factors[END_REF][START_REF] Koecke | An ab-initio study of the energetics and geometry of sulfide, sulfite and sulfate incorporation in apatite; the thermodinamic basis for using this system as an oxybarometer[END_REF] Konecke et al. 2017a

).

  Substitution of P 5+ in apatite by high amounts of Si 4+ yields other minerals belonging to different chemical classe namely silicates (e.g. britholite, Passero et al. 2010).Britholite is considered as a subgroup of the apatite group[START_REF] Pekov | Fluorcalciobritholite[END_REF] and present a solid solution of apatite indicative of extensive substitutions of PO4 3-by SiO4 4-and Ca 2+ by REE 3+

(Ransbo, 1989;[START_REF] Pan | Compositions of the Apatite-Group Minerals : Substitution Mechanisms and Controlling Factors[END_REF] Passero et al. 2010

). It's a rare mineral, known in only ten regions all over the world. It was described in nepheline-sodalite syenite of

Greenland (Winther et al., 1899;

  are Si-rich with the silica concentration increasing with decreasing P 2 O 5 contents (2.08 to 5.99 wt.%. SiO 2 , 39.23 to 29.8 wt.% P 2 O 5 , respectively) (Figure III.3.a, Table III.1 in supplementary data C). Apatites have 3.95 to 19.18 wt.% ΣREE ox and 42.12 to 53.75 wt.

% CaO (Figure III.3.b) with F contents ranging from 2.73 to 5.24 wt.% and Cl< 0.38 wt.% (Figure III.3.c).

free apatites are

  Si-poor with SiO 2 ranging from 0.6 to 2.4 wt.% and P 2 O 5 and CaO content ranging from 35.1 to 42.0 wt.% and 51.0 to 58.0 wt.%, respectively (Table1in supplementary data C). They have low to high REE contents from 1.7 to 5.3 wt.% ΣREE ox . Apatites are fluorapatites with 2.7 to 6.7 wt.% F contents and Cl is below detection limit.

	Mineral Chemistry
	Inclusion-The REE patterns of inclusion-free Si-poor apatite (bulk and in situ) display high enrichment
	in LREE relative to HREE (La N /Yb N = 137) (Figure III.4, Table 2 in supplementary data C) with slight
	Eu negative anomaly and have Nb-Ta and Zr-Hf fractionation in primitive mantle-normalized patterns
	(Nb/Ta = 9, Zr/Hf = 198) (Figure III.5).
	Monazite-bearing apatites in Si-poor carbonatites are Si-poor (0.4 to 1.9 wt.% SiO 2 ) with
	P 2 O 5 and CaO contents ranging from 35.5 to 40.9 wt.% and 51.8 to 56.4 wt.%, respectively (Table
	(<10um to 20-100 µm), often associated with quartz and calcite and rarely as individual inclusions
	(Figures III.2.d).

carbonatite as large prismatic crystals with pyramidal endings surrounded by calcitic matrix. Two apatite textures are present in Si-poor carbonatites.

Apatites are free of inclusions

(Figures III.2.c)

or contain up to 20 vol.% of numerous inclusions of monazite, quartz, and calcite

(Figures III.2.d)

. Both apatites textures have never been found together and are present in rocks with similar mineral assemblages as observed for Si-rich apatites. Inclusions are homogeneously distributed in the entire crystal. Monazite crystals have prismatic to irregular shape III.3 in supplementary data C). Apatites are fluorapatites with high S (0.03 to 0.4 wt.%), 2.8 to 5.9 wt.% F and low Cl concentrations (<0.05 wt.%). The apatites are REE-rich (1.5 to 4.8 wt.% ΣREE ox ) with slightly higher high Ce contents in the rim than the core (Table

III

.3 in supplementary data C,

  They have close REE bulk apatite patterns(Figure III.14c) with slightly lower LREE in bulk britholite-bearing apatite than in bulk free-inclusion Si-rich apatite probably because of low REE rate in the primary apatite before exsolution. Incorporation of REE into apatite structure can be facilitated by several substitutions (section III.3). Ihouhaouene apatites are SiO 2 and SO 2 rich, inclusion-free Sirich apatite has highest average SiO 2 content (5 wt.%) compare to britholite-bearing apatite (3.6 wt.%) and don't have Na 2 O component owing the fact that apatite/liquid partitioning of REE enhances with increasing SiO 2 content in the magma following the substitution of P, Ca by Si and REE. All apatite analyses (inclusion-free or britholite-bearing) present a stoichiometric composition for the P-sites (6 apfu) including Si-and S-cations and Ca-sites (10 apfu) including REE-cations, calculated for 24 oxygen, indicating that REE compositions are proper during EMP analysis and the substitution mechanism considered for Si-rich apatites is following the equations (figure III.15):

  then we calculate an average representative composition to write the exchange reaction considering cationic mass balance for britholite and apatite: Ca 9.4 , REE 0.4 )(Si 0.6 , S 0.2 , P 5.2 )O 24 (F 2 )] + [(Ca 5 , REE 4.2 )(Si 5 , P 1 )O 24 (F 2 )]

	Apatite	+	Fluid
	[(Ca 9.6 , REE 0.2 )(Si 0.8 , S 0.4 , P 4.8 )O 24 (F 2 )] + 4.8 Ca 2+ + 4.4 REE 3+ + 4.8 Si 4+ + 24O 2-rich fluid =>
	Apatite	+	Britholite
	[(

Table IV .1: Summary of previous geochronological and stable isotopes data about the In Ouzzal granulites and Ihouhaouene carbonatites and syenites (Griffiths et al. 1988; Ouzegane et al. 2003):

 IV

	Authors	Method	Age
	Granulite
	Ferrara & Gravelle (1966)	Rb-Sr Whole rock isochron Biotites	2995±50 Ma >1830-1910 Ma
	Allegre & Caby (1972)	Rb-Sr and K-Ar (minerals)	1860 Ma
	Rousseau et al. 1995	U-Pb zircons	3500-3100 Ma; 2000 Ma
	Lancelot et al. 1976	U-Pb zircons	3100-2900 Ma; 2050 Ma
	ben Othman et al. 1984	Sm-Nd model ages	3473-3123 Ma
	Carbonatite
	Allegre et al. 1972	U-Pb-Th on hydroxyapatite	2090 Ma
	Carpena et al. 1988	Apatite Fission-tracks	≈ 600 Ma
	Griffiths et al. 1988	U-Pb zircons	1994± 22-17 Ma

Table IV .2: Operating conditions for the LA-ICP-MS apatite analysis Laboratory & Sample Preparation

 IV

	Laboratory name	Géosciences Rennes, UMR CNRS 6118, Rennes, France
	Sample type/mineral	Apatite
	Sample preparation	Thin sections
	Imaging	Optical Microscopy Cathodoluminescence (OM-CL)
	Laser ablation system
	Make, Model & type	ESI NWR193UC, Excimer
	Ablation cell	ESI NWR TwoVol2
	Laser wavelength	193 nm
	Pulse width	< 5 ns
	Fluence	6 J/cm 2
	Repetition rate	5Hz
	Spot size	40 μm
	Sampling mode / pattern	Single spot
	Carrier gas	100% He, Ar make-up gas and N2 (3 ml/mn) combined using in-house
		smoothing device
	Background collection	20 seconds
	Ablation duration	60 seconds
	Wash-out delay	15 seconds
	Cell carrier gas flow (He) 0.75 l/min
	ICP-MS Instrument
	Make, Model & type	Agilent 7700x, Q-ICP-MS
	Sample introduction	Via conventional tubing
	RF power	1350W
	Sampler, skimmer cones	Ni
	Extraction lenses	X type
	Make-up gas flow (Ar)	0.85 l/min
	Detection system	Single collector secondary electron multiplier
	Data acquisition protocol Time-resolved analysis
	Scanning mode	Peak hopping, one point per peak
	Detector mode	Pulse counting, dead time correction applied, and analog mode when signal
		intensity > ~ 10 6 cps
	Masses measured	204 (Hg + Pb), 206 Pb, 207 Pb, 208 Pb, 232 Th, 238 U + 43 Ca (Ap)
	Integration time per peak 10-30 ms
	Sensitivity / Efficiency	23000 cps/ppm Pb (50µm, 10Hz)
	Data Processing
	Gas blank	20 seconds on-peak
	Calibration strategy	Madagascar apatite standard used as primary reference material, McClure
		and Durango standards used as secondary reference material (quality
		control)
	Common-Pb correction,	No common-Pb correction.
	composition and
	uncertainty
	Reference Material info	Madagascar (Cochrane et al. 2014)
		McClure (Schoene & Bowring 2006)
		Durango (McDowell et al. 2005)
	Data processing package	Iolite (Paton et al. 2010), VizualAge_UcomPbine (Chew et al. 2014)
	used	More information on the procedure in Pochon et al. 2016
	Quality control /	McClure: 526 ± 4 Ma (N=19, MSWD=0.2 ; probability=1.0)
	Validation	Durango: 32 ± 0.6 Ma (N=25, MSWD=0.8 ; probability=0.8)

Table IV .3 Operating conditions for the LA-ICP-MS zircon analysis Laboratory & Sample Preparation

 IV

	Laboratory name	Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR)
		Petrology, Geochemistry and Geochronology
	Sample type/mineral	Zircons
	Sample preparation	Thin section
		CL, EVO15 Zeiss SEM, 10 nA, 8.5mm working distance,
	Imaging	2.6 A Fil I
	Laser ablation system
	Make, Model & type	Photon Machines Analyte Excite 193
	Ablation cell & volume	Hellex, Double Volume Cell
	Laser wavelength (nm)	193 nm
	Pulse width (ns)	4 ns
	Fluence (J.cm-2)	8 J.cm-2
	Repetition rate (Hz)	10 Hz
	Ablation duration (secs)	30 secs
	Ablation pit depth / ablation rate	N/A
	Spot diameter (mm) nominal/actual	15 µ
	Sampling mode / pattern	Static spot ablation
	Carrier gas	100% He in the cell
	Cell carrier gas flow (l/min)	0.9 l/min
	ICP-MS Instrument
	Make, Model & type	Agilent 8800 QQQ ICP-MS
	Sample introduction
	RF power (W)	1500W
	Make-up gas flow (l/min)	0.5 l/min
	Detection system	Mixed Faraday-multiple ion counting array
	Masses measured	202-207, 235, 238
	Integration time per peak/dwell times (ms); quadripole
	settling time between mass jumps	150 ms for Pb204, 206, 207, 208 and U238
		100 ms for U235 and Th232
		60 ms for Hg202
	Total integration time per output datapoint (secs)	~2.3 secs
	Data Processing
	Gas blank	30 second on-peak zero subtracted
	Calibration strategy	91500 used as primary reference material, Plesovice used as secondaries/validation
	Reference Material info	91500 (Wiedenbeck et al. 1995) Plesovice (Slama et al, 2008)
	Data processing package used / Correction for LIEF	Igor Pro Iolite 2.5 software + VisualAge Data Reduction
	Common-Pb correction, composition and uncertainty	No common-Pb correction applied to the data.
	Uncertainty level & propagation	Ages are quoted at 2s absolute, propagation is by quadratic
		addition.
		Reproducibility and age uncertainty of reference material
		and common-
		Pb composition uncertainty, are propagated where
		appropriate.
	Quality control / Validation	Plesovice (337 ± 0.7 Ma)

Table IV .4 LA-ICP-MS U-Pb geochronological results for apatite from the Ihouhaouene carbonatite and syenite (The 207 Pb/ 206 Pb and 206 Pb/ 238 U ages present the corrected ages)

 IV

	Sample	Th (ppm)	U (ppm)	Pb (ppm)	207Pb/206Pb ±2σ 238U/206Pb ±2σ	207Pb/206Pb Age (Ma)	±2σ	206Pb/238U Age (Ma)	±2σ
	INH 170
	INH170_1-b 3027	440	712	0,2229	0,004	2,693	0,189	1808	126	1809	111
	INH170_2-c 2764	391	632	0,2113	0,001	2,481	0,172	1995	152	1994	118
	INH170_3	2622	362	653	0,2659	0,005	2,272	0,155	2025	142	2030	115
	INH170_4	2181	290	526	0,2527	0,002	2,372	0,169	1976	154	1977	122
	INH170_5	2585	371	568	0,2054	0,001	2,720	0,192	1833	132	1830	111
	INH170_6	2858	391	712	0,2736	0,002	2,482	0,172	1835	144	1832	109
	INH170_7	3295	494	716	0,1946	0,002	3,103	0,212	1637	120	1628.5
	INH170_8	3042	435	904	0,3613	0,003	2,313	0,160	1734	150	1717	104
	INH170_10	2920	430	667	0,2137	0,010	3,115	0,233	1588	124	1578	103
	INH170_11	2801	413	660	0,2343	0,004	2,762	0,183	1744	106	1735.6
	INH170_12	2876	376	899	0,4127	0,006	2,069	0,146	1782	118	1759	112
	INH170_13	2273	302	536	0,2435	0,002	2,543	0,168	1863	132	1865	108
	INH170_14	2364	312	608	0,2988	0,002	2,330	0,163	1888	156	1883	112
	INH170_15	2531	357	552	0,1980	0,001	2,782	0,186	1809	126	1807	108
	INH170_16	2015	271	492	0,2652	0,006	2,416	0,163	1897	114	1901	109
	INH170_17	2208	293	496	0,2144	0,002	2,677	0,186	1842	146	1836	113
	INH170_18	2182	303	510	0,2282	0,002	2,639	0,181	1836	136	1830	109
	INH170_19	2704	385	950	0,4407	0,003	1,969	0,132	1785	166	1757	101
	INH170_20	2825	389	1000,2	0,4468	0,003	1,952	0,130	1782	168	1754	102
	INH170_21	2617	358	882	0,4233	0,002	2,050	0,143	1764	160	1741	104
	INH170_22	1576	212	424	0,2984	0,002	2,337	0,164	1883	148	1875	111
	INH170_23	1619	219	669	0,5106	0,003	1,549	0,106	1980	190	1980	121
	INH170_24	2062	283	830	0,5082	0,003	1,637	0,113	1883	180	1861	108
	IC3-10
	IC3_10_1	0,8	2,70	3,48	0,7170	0,015	2,665	0,313	-	-	425.6
	IC3_10_2	2,17	4,75	5,59	0,6804	0,010	2,845	0,267	-	-	510.1
	IC3_10_3	0,87	2,02	3,32	0,7310	0,014	2,229	0,224	-	-	469.2
	IC3_10_4	1,83	2,66	4,10	0,6910	0,017	2,387	0,456	-	-	584	107
	IC3_10_5	7,47	3,48	6,38	0,7480	0,011	2,179	0,261	-	-	408.3
	IC3_10_6	0,68	2,35	3,28	0,7040	0,013	2,439	0,232	-	-	521.9
	IC3_10_7	1,06	3,24	4,35	0,7020	0,011	2,580	0,246	-	-	495.6
	IC3_10_8	3,46	4,33	5,96	0,7020	0,012	2,623	0,261	-	-	486.8
	IC3_10_9	6,63	4,16	4,81	0,6650	0,011	3,002	0,288	-	-	523.6
	IC3_10_10	2,54	3,09	3,97	0,6880	0,013	2,650	0,267	-	-	527.2
	IC3_10_11	6,35	5,25	5,71	0,6420	0,014	3,146	0,317	-	-	557.6
	IC3_10_12	2,51	3,61	3,65	0,6590	0,013	3,206	0,329	-	-	501.2
	IC3_10_13	1,25	3,04	4,32	0,7250	0,012	2,550	0,247	-	-	420.7
	IC3_10_14	1,16	2,76	4,37	0,7510	0,011	2,305	0,218	-	-	367.7
	IC3_10_15	2,48	2,94	4,45	0,7330	0,013	2,421	0,276	-	-	417.2
	IC3_10_16	2,29	2,00	5,81	0,8140	0,012	1,389	0,131	-	-	198.3
	IC3_10_17	5,01	3,15	6,17	0,7640	0,015	1,996	0,187	-	-	376.0
	IC3_10_18	33,9	5,18	8,28	0,6850	0,011	2,850	0,317	-	-	494.0
	IC3_10_19	1,63	2,88	4,73	0,7460	0,012	2,206	0,234	-	-	410.1
	IC3_10_20	6,02	4,39	5,41	0,6980	0,011	2,807	0,268	-	-	461.3
	IC3_10_21	3,93	5,27	5,19	0,6470	0,010	3,184	0,324	-	-	538.5
	IC3_10_22	9,22	7,78	5,83	0,5750	0,010	3,967	0,393	-	-	571.1
	IC3_10_23	6,09	6,09	6,62	0,6730	0,010	3,078	0,284	-	-	485.9

Table IV .5: Representative major element composition of zircon from the Ihouhaouene carbonatite and syenite Rock type Si-rich carbonatite Sample Type

 IV

														Chapitre IV : U-Pb datations
		Core	Rim	Core	Rim	Core	Middle	Core	Rim	Core	Middle	Rim	Core	Rim	Core	Rim
	SiO 2	27.89	30.65	31.48	31.54	31.20	31.40	31.40	31.45	31.37	31.31	31.66	25.46	31.58	31.72	31.56
	TiO 2	0.01	0.02	0.02	0.02	0.01	0.02	0.12	0.07	0.02	0.01	0.02	0.00	0.02	0.01	0.01
	ZrO 2	64.65	67.96	66.77	67.00	67.38	67.13	67.24	67.07	66.91	66.54	66.16	56.32	66.28	66.61	66.34
	FeO	0.02	0.07	0.01	0.01	bdl	bdl	0.04	0.03	0.02	0.03	0.04	0.01	0.05	0.01	0.08
	CaO	0.11	0.33	0.01	0.01	0.02	0.01	0.08	0.05	0.02	0.03	0.04	10.27	0.06	0.01	0.04
	PbO	bdl	bdl	bdl	bdl	bdl	0.01	0.03	bdl	bdl	bdl	bdl	0.01	bdl	bdl	bdl
	UO 2	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl
	ThO 2	0.03	bdl	0.12	bdl	0.24	bdl	bdl	0.13	0.24	0.14	0.04	0.18	bdl	bdl	bdl
	Y 2 O 3	bdl	bdl	0.02	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	0.02
	Yb 2 O 3	0.07	bdl	bdl	0.04	0.02	bdl	bdl	0.05	0.04	0.04	bdl	bdl	0.02	bdl	0.01
	HfO 2	0.46	0.57	0.46	0.59	0.55	0.56	0.56	0.60	0.49	0.69	0.57	0.52	0.58	0.49	0.47
	Total	93.24	99.60	98.88	99.21	99.42	99.12	99.48	99.45	99.10	98.80	98.52	92.79	98.58	98.87	98.53
	Numbers of ions on the basis of 16O
	Si	3.74	3.82	3.92	3.92	3.88	3.91	3.89	3.90	3.91	3.91	3.95	3.47	3.94	3.89	3.94
	Ti	0.001	0.002	0.002	0.002	0.001	0.002	0.011	0.007	0.002	0.001	0.002	-	0.001	0.001	0.001
	Zr	4.23	4.13	4.06	4.06	4.09	4.07	4.07	4.06	4.06	4.05	4.02	3.75	4.03	4.09	4.04
	Fe 2+	0.002	0.007	0.001	0.001	-	-	0.005	0.003	0.002	0.003	0.004	0.002	0.005	0.001	0.001
	Ca	0.016	0.044	0.001	0.001	0.003	0.001	0.010	0.006	0.002	0.004	0.005	1.502	0.009	0.004	0.001
	Pb	-	-	-	-	-	-	0.001	-	-	-	-	0.001	-	-	-
	U	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-
	Th	0.001	-	0.003	-	0.007	-	-	0.004	0.007	0.004	0.001	0.006	-	-	-
	Y	-	-	0.001	-	-	-	-	-	-	-	-	-	-	-	0.002
	Yb	0.003	-	-	0.001	0.001	-	-	0.002	0.001	0.002	-	-	0.001	-	-
	Hf	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02
	Total	8	8	8	8	8	8	8	8	8	8	8	9	8	8	8
	bdl : below detection limit
	!								"##!

Table 5 : continued

 5

	Rock type

  .6). The 206 Pb/ 238 U ages are comprised between 1324 ± 341 Ma and 2699 ±

	763 Ma (Table IV.6). The 54 concordant ellipses yield a concordia age of 2162.64 ± 0.8 Ma (MSWD
	= 21, Figure IV.9a). The weighted mean 206 Pb/ 238 U age obtained by excluding 18 discordant data
	affected by Pb loss, yields a similar age within error of 2163.58 ± 0.82 Ma (MSWD = 3.27, Figure IV
	.9b).

Table IV .6: LA-ICP-MS U-Pb geochronological results for zircon from the Ihouhaouene carbonatite and syenite

 IV

															Chapitre IV : U-Pb datations
	Sample	Th (ppm)	U (ppm)	Th/U 207Pb/206Pb ±2σ 207Pb/235U ±2σ 206Pb/238U ±2σ	207Pb/206Pb Age (Ma)	±2σ	207Pb/235U Age (Ma)	±2σ	206Pb/238U Age (Ma)	±2σ	Concordia Age (Ma)	±2σ
	IC2-9A
	5105-R-2	53.6	88	0.59	0.1390	0.02	6.470	0.98	0.347	0.03	2167	144	2041.8	66.6	1920.3	59.8	1970.5	47.3
	5105-R-3	36.9	94.8	0.39	0.1300	0.02	6.900	1.10	0.368	0.03	2177	128	2098.7	70.7	2020	77.8	2063.3	64.5
	5105-R-4	40.3	75.1	0.56	0.1100	0.02	4.940	0.97	0.336	0.03	1743	191	1809.1	82.9	1867.4	62.7	1845.6	49.9
	5105-R-5	23	55.8	0.39	0.1510	0.03	7.900	1.70	0.368	0.05	2409	194	2219.7	97.0	2020	115	2131.3	88.0
	5105-R-6	210	217	0.98	0.1250	0.02	5.590	0.70	0.356	0.02	1862	126	1914.6	53.9	1963.2	49.9	1940.2	35.7
	5105-C-1	90	129	0.71	0.1330	0.02	6.910	0.96	0.348	0.03	2276	129	2099.9	61.6	1925	69.3	2016.9	52.8
	5105-C-2	95	130	0.75	0.1300	0.02	6.000	1.00	0.346	0.04	2040	132	1975.8	72.5	1915.5	93.4	1958.6	70.6
	5105-C-4	43.5	71.6	0.59	0.1140	0.02	5.800	0.93	0.346	0.03	1979	161	1946.4	69.4	1915.5	64.7	1929.7	46.8
	5105-C-5	104	125	0.81	0.1130	0.02	5.470	0.88	0.345	0.02	1880	127	1895.9	69.1	1910.7	50.3	1907.5	48.4
	5105-C-6	45.7	80.8	0.56	0.1420	0.03	7.100	1.60	0.365	0.03	2241	193	2124	100	2005.8	75.6	2039.6	68.9
	5105-C-7	90	138	0.69	0.1260	0.02	6.600	1.20	0.365	0.02	2113	144	2059.3	80.2	2005.8	49.6	2011.3	49.4
	5105-C-9	55.9	99	0.57	0.1160	0.03	5.500	1.10	0.346	0.02	1884	182	1900.6	85.9	1915.5	55.1	1911.5	48.7
	5105-C-10	41.2	80	0.56	0.1100	0.02	5.500	1.10	0.348	0.03	1874	180	1900.6	85.9	1925	81.3	1913.5	65.5
	5089-R-6	4.6	30.2	0.13	0.1470	0.08	7.600	4.00	0.356	0.06	2400	326	2185	236	1963	138	1816.8	91.0
	3922-R-2	54.6	46.6	1.16	0.1490	0.07	6.600	3.30	0.327	0.07	2304	365	2059	220	1824	175	1848	184
	3922-C-1	12.7	33.6	0.38	0.1250	0.04	6.000	1.80	0.362	0.06	1959	304	1976	131	1992	135	1983.4	92.9
	5373-C-2	15.7	42.8	0.38	0.1090	0.04	5.500	1.30	0.350	0.09	1864	389	1901	102	1935	224	1909.2	70.8
	3930-C	10.1	48.3	0.21	0.1070	0.02	4.950	0.99	0.336	0.03	1746	203	1810.8	84.5	1867.4	77.2	1840.9	56.0
	IC2-6A
	2209-R-1	83	195	0.45	0.0880	0.02	4.20	1.10	0.2940	0.05	1690	406	1674	215	1661	269	1671	208
	2209-C-1	100	218	0.53	0.1000	0.02	5.00	1.40	0.3460	0.08	1711	399	1819	237	1915	374	1817	231
	2209-R-2	65	149	0.51	0.1080	0.02	5.00	1.00	0.3300	0.08	1798	384	1819	169	1838	378	1818	168
	2209-C-2	39	96	0.36	0.0910	0.03	3.50	1.30	0.2660	0.05	1537	523	1527	293	1520	270	1523	258
	1359-R-1	51	198	0.25	0.1340	0.02	6.90	1.20	0.3940	0.08	2057	199	2099	154	2141	356	2084	129
	1359-R-2	31.4	340	0.10	0.1160	0.01	6.50	1.40	0.3760	0.07	2034	204	2046	190	2058	314	2041	173
	1359-C-1	65	480	0.16	0.1037	0.01	6.50	1.60	0.3650	0.06	2087	272	2046	217	2006	264	2043	224
	1359-C-2	57	660	0.08	0.1630	0.04	7.70	1.00	0.4070	0.10	2192	367	2197	117	2201	444	2196	114
	1689-R	159	620	0.24	0.1254	0.01	7.34	0.30	0.3988	0.00	2144.2	71.4	2153.7	36.5	2163.61	0.41	2163.6	0.40
	1689-C	267	1960	0.15	0.0953	0.01	3.69	0.82	0.2720	0.07	1594	194	1569	178	1551	375	1581	109
	2060-C-1	23.1	101	0.24	0.1300	0.03	7.70	2.10	0.3900	0.10	2266	131	2197	245	2123	464	2259	121
	2060-C-2	25	111	0.20	0.1480	0.03	7.50	1.80	0.3880	0.07	2230	300	2173	215	2114	316	2174	220
	!										"%&!

Table IV .6: continued

 IV

	Sample	Th (ppm)	U (ppm)	Th/U 207Pb/206Pb ±2σ 207Pb/235U ±2σ 206Pb/238U ±2σ	207Pb/206Pb Age (Ma)	±2σ	207Pb/235U Age (Ma)	±2σ	206Pb/238U Age (Ma)	±2σ	Concordia Age (Ma)	±2σ
	IC2-6A
	2060-C-3 32.1	215	0.15	0.1160	0.02	5.00	1.10	0.3420	0.08	1732	285	1819	186	1896		1797	171
	2060-R-2 18.1	116	0.16	0.1870	0.04	11.70	2.60	0.5200	0.18	2489	396	2581	208	2699		2558	174
	2060-R-3 27.1	135	0.19	0.1210	0.02	5.80	1.30	0.3480	0.08	1969	212	1946	194	1925		1956	162
	1235-C-1	149	1210 0.13	0.1160	0.01	5.80	1.10	0.3500	0.07	1959	130	1946	164	1935		1954.1	99.6
	1235-C-2	134	1940 0.08	0.1220	0.01	6.70	2.80	0.3700	0.15	2116	144	2073	369	2029		2113	137
	1235-C-3	121	850	0.14	0.0932	0.01	4.13	0.46	0.2970	0.04	1640	162	1660.3	91.0	1676		1657.2	87.9
	1235-R-2	370	1140 0.31	0.1420	0.03	9.50	3.10	0.4530	0.05	2370	478	2388	300	2409		2405	208
	2056-C	290	2380 0.12	0.0948	0.01	4.40	1.10	0.3000	0.07	1738	209	1712	207	1691		1725	166
	2056-R-2	359	670	0.45	0.0930	0.02	3.28	0.97	0.2280	0.07	1703	405	1476	230	1324		1482	244
	6478-R-1	10	378	0.03	0.0985	0.01	4.60	1.30	0.3120	0.10	1748	203	1749	236	1751		1748	143
	6478-R-2 12.4	570	0.02	0.1030	0.02	4.62	0.87	0.3070	0.08	1785	338	1753	157	1726		1757	150
	6478-C-1 40.1	800	0.05	0.1050	0.01	4.20	1.30	0.2570	0.06	1934	237	1674	254	1474		1819	239
	6478-C-2 17.5	560	0.03	0.0870	0.02	4.20	1.40	0.2740	0.08	1819	297	1674	273	1561		1730	255
	1038-R-1	38	1930 0.02	0.1120	0.04	4.90	1.80	0.3300	0.16	1761	456	1802	310	1838		1788	231
	1038-C-1	350	6600 0.04	0.1020	0.03	4.37	0.46	0.3000	0.13	1726	605	1706.7	87.0	1691		1709.0	14.1
	1038-R-3 11.3	570	0.02	0.0958	0.01	4.80	1.20	0.2990	0.07	1902	255	1785	210	1686		1826	185
	1038-C-2	7.4	247	0.03	0.1050	0.02	4.20	1.00	0.3230	0.08	1514	207	1674	195	1804		1600	150
	1038-R-4	10	490	0.02	0.1290	0.03	6.90	2.00	0.3800	0.13	2121	355	2099	257	2076		2106	214
	1097-C-1 34.3	157	0.20	0.0920	0.03	3.50	1.10	0.2810	0.08	1433	292	1527	248	1596		1492	224
	1097-C-2	73	490	0.13	0.1620	0.02	9.80	3.40	0.4400	0.15	2472	214	2416	320	2351		2458	189
	1097-R-2 42.5	120	0.36	0.1060	0.04	5.70	1.90	0.4000	0.15	1685	440	1931	288	2169		1863	261
	1368-R-1 23.9	1170 0.02	0.1140	0.01	6.10	2.10	0.3200	0.11	2205	167	1990	300	1790		2167	132
	1368-C-1	151	2040 0.07	0.0978	0.01	4.50	1.40	0.3000	0.10	1779	114	1731	258	1691		1768.9	88.7
	1368-C-2	64	1140 0.05	0.1280	0.02	6.60	1.90	0.3700	0.13	2089	216	2059	254	2029		2076	131
	1365-C-1	780	6900 0.10	0.1330	0.01	8.50	1.80	0.4260	0.07	2284	119	2286	192	2288		2284	116
	1365-R-2	370	3700 0.09	0.1170	0.01	5.80	2.10	0.3500	0.14	1959	215	1946	314	1935		1955	162
	1365-C-2	398	680	0.55	0.1240	0.01	7.50	1.20	0.4030	0.04	2164	175	2173	143	2183		2172	142
	1365-C-3	56	690	0.10	0.1590	0.02	11.70	2.20	0.5000	0.13	2555	339	2581	176	2614		2576	163
	1367-R-1 34.9	251	0.13	0.1830	0.03	14.00	3.50	0.5400	0.22	2725	286	2750	237	2783		2738.7	73.1
	1367-C-1	63	1140 0.04	0.1060	0.02	5.70	1.10	0.3440	0.06	1959	165	1931	167	1906		1945	137
	1367-R-2	119	1150 0.10	0.1130	0.01	6.20	1.50	0.3700	0.10	1979	200	2004	212	2029		1991	144

Table IV .6: continued

 IV

	Sample	Th (ppm)	U (ppm)	Th/U 207Pb/206Pb ±2σ 207Pb/235U ±2σ 206Pb/238U ±2σ	207Pb/206Pb Age (Ma)	±2σ	207Pb/235U Age (Ma)	±2σ	206Pb/238U Age (Ma)	±2σ	Concordia Age (Ma)	±2σ
	IC2-6A
	1008-R-1 1040	4500 0.21	0.1650	0.01	9.30	1.30	0.3840	0.07	2612	178	2368	128		326	2454.6	96.9
	1008-C	3400 17500 0.18	0.1092	0.01	6.36	0.83	0.3960	0.06	1903	108	2027	115		263	1962.1	81.3
	1008-R-2 3980 15200 0.24	0.1082	0.00	6.81	0.23	0.4270	0.01	1890.3	42.4	2087.0	29.9	2292.2	63.2	2035.2	28.2
	2303-R-1	67	189	0.33	0.1330	0.04	5.30	2.50	0.3400	0.13	1849	490	1869	403		625	1863	385
	2303-C-1	52	227	0.22	0.1290	0.03	6.20	1.70	0.3580	0.08	2037	335	2004	240		399	2010	236
	2303-C-2	78	339	0.23	0.1400	0.02	8.30	2.60	0.4100	0.12	2309	338	2264	284		549	2280	258
	2303-R-2	77	206	0.35	0.1160	0.03	6.70	2.60	0.3900	0.10	2023	470	2073	343		464	2073	335
	2055-R	30	87.8	0.26	0.1810	0.09	7.60	3.50	0.3100	0.10	2633	587	2185	413		492	1897	616
	1354-C-1	62	221	0.23	0.1600	0.05	9.10	4.30	0.3800	0.13	2593	479	2348	432		607	2391	491
	1354-C-2	63	217	0.24	0.1100	0.03	7.30	2.40	0.4100	0.11	2086	279	2149	294		503	2113	256

  Carbonatite and CO 2 -rich alkaline magmas are ideal for monitoring the evolution of the subcontinental upper mantle because they rise up rapidly to the surface (low density and low viscosity) and thus the crustal contamination is reduced.The edge of carbonatites over oceanic basalts is that they can be used to track the temporal evolution of the mantle over a considerable part of the Earth's history. Carbonatites are present on the continents in significant volumes and occur since Archaean ages (e.g. 2.68 Ga Lac Shortt carbonatite,

	Quebec). Hence, carbonatites and alkaline magmas are window on deep processes and allow
	characterization of the nature of deep mantle they derived from and understanding global geochemical
	and geodynamic cycle. The questions related to carbonatite petrogenesis are:
	-	Whether carbonatite melts are primary melts derived from carbonatitic mantle source? Or
		whether they are derived from a carbonated-silicate parent melt by fractional-
		crystallization and immiscibility?
	-	What is the relationship between carbonatites and the associated alkaline rocks?
	-	What is the composition of the CO 2 -rich parental melt?

-

Are REE in carbonatites from magmatic processes? Or the result of late-enrichment processes?

  2) Mineral compositions of apatite from Si-rich carbonatites and White syenites have extreme enrichment of LREE and Pb, Th compared to coexisting clinopyroxenes and apatite McDonough 1989) suggesting that they crystallized from different carbonate-rich silicate melt and form hybrid mineral aggregates that did not re-equilibrate afterwards: a-The high LREE and chondritic to superchondritic Nb/Ta ratios in recalculated equilibrium melts from apatite and clinopyroxene in Red syenites are similar to melilititic and nephelinitic

	compositions and reflect differentiated silicate-melt compositions by fractional crystallization
	and immiscibility.
	b-The high LREE and elevated superchondritic Nb/Ta values in Si-rich carbonatites from
	Ihouhaouene complex are coherent with Nb/Ta ratios in experimental carbonatites as a result
	of immiscibility processes from carbonate-rich silicate melts (Koster van Groos & Wyllie
	1968; Wyllie & Huang 1975; Freestone & Hamilton 1980; Kjarsgaard & Peterson 1991;
	Dalton & Wood 1993; Kjarsgaard et al. 1995; Mitchell 2009; Novella & Keshav 2010;
	Brooker & Kjarsgaard 2011; Martin et al. 2013).

compositions from Si-poor carbonatites and red syenites. Recalculated liquids in equilibrium with apatite and clinopyroxene from apatite and clinopyroxene in carbonatites and syenites have different subchondritic to superchondritic Nb/Ta ratio (0.8-110; Nb/Ta chondrite =18; Sun & Discussion ! "#%! c-The high superchondritic Nb/Ta values in minerals in white syenites like in Si-rich carbonatites suggest that Nb-Ta compositions were largely disordered in whole rocks compositions by the hybridization process and indicate that apatites in white syenites crystallized from carbonatitic melts. d-The low LREE and low Nb/Ta values observed in Si-poor carbonatites exclude its origin either as a primary carbonate melt from the mantle or as a segregated carbonate fraction from a primary CO 2 -rich silicate melt and require segregation from geochemically evolved silicate melts.

  Table 1 composition des carbonatites et syénites d'Ihouhaouene

	Echantillon	Centre	Type pétrographique	Textures	Ap	Brith	Mnz	Cal	Alla	Minéraux Cpx Qtz	FK	Sph	Wo	Am	oxy	autre	Remarque
	IC1-1A

Table 2

 2 Les carbonatites d'Ihouhaouene utilisés des travaux antérieurs

	Centre 1 (Oued Ihouhaouene)

Table 2

 2

	(suite)
							Centre 3 (Tirahart Nord)
	N° d'Echantillon		3,13	3,15	3,19	3,22	3,25	3,32	3,34	3,6	642	686	687	866 867
		RT			+		+	+	+
		Réf	Frd	Frd, soraya	Frd, soraya		Frd, soraya	Frd	Frd, soraya		anal2016	soraya ? Sy
		Lame	+	+	+	+	+	+	+	+	+	+	+	+	+
		Ech									poudre
	C I (bréchiques)	EPMA		cpx, fk, all	amph, fk, cal, sph		cal		all, fk , amph		ap
		isotope C, O (in cal) C, O (in cal)	C, O (in cal), Rb/Sr, Sm/Nd		C, O (in cal)	C, O (in cal), Rb/Sr, Sm/Nd	C, O (in cal)
		REE			Rb, Sr, sm Nd			Rb, Sr, sm Nd
	N° d'Echantillon		3,9	3,12	3,14	3,20	3,23	3,28	3,30	3,31	3,33	690 (a,b,c)	693	694 864 911
		RT
													soraya,
											Frd, soraya,		master,
		Réf			Frd, master				soraya	soraya	master		anal2016 Jullien
	C II (pegmatitiques)	Lame	+	+	+	+	+	+	+	+	+	+	+	+	+	+
		Ech	poudre											+
													monz,
		EPMA									ap, monz,		monz,
					brith, ap				sph, amph	cal, ap	brith, ap		monz, ap
		isotope			C, O (in cal)			C, O (in cal)			C, O (in cal)
	N° d'Echantillon		3,1	3,3	3,26	3,4	3,8	639
		RT
				Frd, master,
		Réf	Frd	soraya	Frd
	C III (veines de calcite)	Lame	+	+	+	+	+	+
		Ech				+
		EPMA		brith, ap, monz, ap
		isotope C, O (in cal) C, O (in cal)	C, O (in cal)

Table 2

 2

	(suite)
			Centre 2 (Tirahart Sud)
	N° d'Echantillon		545	604	603
		RT	+
				ouz,
		Réf	griff	anal2016 ouz
		Lame +	+	+
	C I (bréchiques)	Ech	C II (pegmatitiques)
		EPMA		ap, brith, ap	brith
		isotope
		REE	+

Table 1

 1 Representative major element whole-rock compositions of granulitic basement and cumulats in syenites

	Rock type	S.P	S.P	D	G	L	S.P	L	L	SK	M	M	L	N	S.P	S.C	S.C	D
	Localization						OI								SWT
	Sample	IC1-1 IC1-3 IC1-7a IC1-9 IC1-10 IC1-13B IC1-14 IC1-17 IC1-20B IC1-20 Tih1-a	IC2-3 IC2-6B IC2-7 IC2-15 IC2-15S IC2-16
	SiO 2 (wt%) 64,68 64,87 53,69 53,75 87,08	63,36	75,66 75,65	47,04	13,23 24,55	75,10 48,94 63,09 61,63	65,68	46,90
	Al 2 O 3	18,97 19,08 16,73 23,95 9,49	17,48	13,13 12,92	13,02	2,64	1,75	13,57 10,15 19,77 12,95	12,67	13,56
	Fe 2 O 3	0,34 0,19 10,21 14,41 0,52	1,01	1,32	1,38	2,59	4,46	1,32	0,88 6,92	0,74	9,52	8,39	16,62
	MnO	b.d	b.d	0,17	0,14	b.d	0,04	0,03	0,03	0,42	0,59	0,74	0,02	0,32	b.d	0,16	0,11	0,25
	MgO	0,21 0,04	5,47	3,04	0,11	0,40	0,27	0,18	9,51	15,14	0,96	0,19	8,13	0,3	1,57	0,95	4,22
	CaO	0,68 0,35	8,71	0,45	0,09	2,01	1,29	0,93	21,94	32,35 46,51	0,91 20,62	1,45	4,07	3,40	8,52
	Na 2 O	3,51 2,41	2,99	0,43	0,26	2,15	3,05	2,67	1,26	b.d	0,14	2,34	1,44	3,37	2,78	2,80	3,28
	K2O	10,75 12,56 1,03	2,3	2,12	11,89	4,89	5,61	0,43	0,47	0,42	6,52	0,6	10,1	3,89	3,81	1,3
	TiO 2	b.d	b.d	0,81	0,86	0,18	0,88	0,22	0,2	0,09	0,09	0,07	0,08	0,39	0,06	1,49	1,19	3,06
	P 2 O 5	b.d	b.d	0,27	b.d	b.d	b.d	b.d	b.d	0,15	b.d	b.d	0,10	b.d	0,31	0,59	0,42	0,62
	LOI	0,34 0,27	0,33	0,52	1,13	0,83	0,80	0,85	2,43	30,67 24,15	0,73	1,52	0,98	0,94	0,66	1,74
	Total	99,48 99,76 100,38 99,86 100,98 100,06 100,67 100,42 98,89	99,64 100,60	100,4 99,02 100,17 99,57 100,06 100,06
	CO 2	0,0	0,11	0,09	0,02	0,05	0,23	0,20	0,17	1,88	25,49 21,13	0,04	0,90	0,17	0,07	0,03	0,08
	F	0,006 0,003 0,058 0,003 0,002	0,044	0,008 0,007	0,022	0,064 0,008	0,002 0,036 0,024 0,084	0,058	0,10
	S	<0,01 <0,01 0,05	0,01 <0,01	<0,01	<0,01	0,01	0,25	0,03 <0,01	0,01	0,19	<0,01	0,06	<0,01	0,04
	Cl (ppm)	66	49	76	93	51	115	130	38	940	510	78	44	460	240	275	440	1870
	Mg#	0,72 0,45	0,68	0,46	0,46	0,61	0,45	0,34	0,94	0,93	0,74	0,46	0,82	0,62	0,40	0,31	0,50
	(N+K)ox/Alox 0,8	0,78	0,24	0,11	0,25	0,8	0,6	0,64	0,13	-	0,32	0,65	0,20	0,68	0,52	0,52	0,34
	Mg# =

Mg/(Mg+Fetot) OI: Oued Ihouhauene; SWT: South Wadi Tirahart; NWT: North Wadi Tirahart S.P: syenitic pegmatite; S.C: Syenitic cumulats; D: dolerite; L: leptynite; G: granulite Al-Fe; M: marble; SK: skarn; Q: quartzite; G.Q: garnet quartzit; AN: anorthosite; N: norite;

							Annexe B
	Table 1 Continued
	Rock type	Q	M	P	G.Q	AN	L
	Localization	SWT		NWT
	Sample	IC2-30 IC2-22	IC3-A1 IC3-A2 IC3-D	IC3-E
	SiO 2 (wt%)	99,21	12,35	49,85	65,33	49,07	78,02
	Al 2 O 3	0,42	1,78	3,40	10,55	24,66	12,43
	Fe 2 O 3	0,11	3,92	12,15	7,10	3,17	0,46
	MnO	b.d	1,04	11,26	12,0	0,15	b.d
	MgO	b.d	19,49	9,29	1,49	2,82	0,23
	CaO	0,03	28,46	13,24	3,77	12,35	1,18
	Na 2 O	b.d	b.d	0,18	b.d	3,39	3,27
	K2O	0,08	b.d	b.d	b.d	1,54	3,71
	TiO 2	0,05	0,05	0,15	0,14	0,04	0,04
	P 2 O 5	b.d	b.d	b.d	0,13	0,36	b.d
	LOI	0,3	31,73	0,2	-0,03	2,84	0,67
	Total	100,21	98,82	99,72	100,47 100,38	100,01
	CO 2	<0,01	25,79	0,24	0,07	0,03	0,05
	F	<0,002	0,004	0,01	0,01	0,09	0,003
	S	<0,01	<0,01	<0,01	<0,01	<0,01	<0,01
	Cl (ppm)	42	370	150	110	235	195
	Mg#	-	0,95	0,75	0,45	0,78	0,66
				202!

Table 2 Representative trace element whole-rock compositions of granulitic basement and cumulats in syenites

 2

	Rock type	S.P	S.P	D	G	L	S.P	L	L	SK	M	M	L	N	S.P	S.C	S.C	D
	Localization						OI									SWT
	Sample	IC1-1 IC1-3 IC1-7a IC1-9 IC1-10 IC1-13B IC1-14 IC1-17 IC1-20B IC1-20 Tih1-a	IC2-3 IC2-6B IC2-7 IC2-15 IC2-15S IC2-16
	Cs (ppm)	2,6	1,85	0,29	0,26	0,25	1,18	0,10	0,04	0,38	1,62	0,13	0,29	0,9	0,47	0,22	0,29	0,62
	Rb	440	397	21,46	68,2	47,79	368	76,67	57,23	19,74	28,57 11,48	196	27,21	179	63,8	77,45	47,25
	Ba	7704 4844	591	914	473	4164	1792	2221	306	440	270	516	284	5354 3581	2066	1204
	Th	80,1	0,37	6,59	18,56	7,17	44,49	24,44	9,98	27,38	23,04	2,13	94,18 26,13 74,07 21,8	26,59	4,13
	U	3,87	0,12	1,52	9,55	0,52	10,78	0,67	0,41	3,35	3,26	0,32	11,61 6,92	2,88	2,08	4,92	5,85
	Nb	1,74	0,34	56,26 78,45	3,78	799	4,52	5,26	8,32	20,9	2,02	9,96 56,19 7,31	213	189	489
	Ta	0,14	0,01	3,67	4,01	0,32	69,03	0,16	0,26	38,64	16,96	0,23	0,59	3,84	0,61 13,84	11,06	31,91
	La	51,6 18,68	31,1	52,41 33,91	98,72	126	90,68	11,57	52,89 33,66	37,28 63,52 96,58 99,95	98,09	52,6
	Ce	82,25 23,74 62,89 87,29 43,25	277	178	145	19,99	84,85 54,87	59,84	157	143	183	188	105
	Pb	1,68 90,72	0,13	0,27	13,67	1,16	33,42	26,08	0,08	0,14	13,96	0,82	0,11	0,7	0,3	0,31	0,28
	Pr	7,35	2,1	7,2	9,02	5,58	39,3	15,51	14,17	2,24	8,04	5,38	5,64 19,71 13,85 21,66	21,21	12,41
	Sr	3173 3164	361	140	43,02	1523	296	260	1319	1017	131	160	911	2355	334	273	472
	Nd	22,12	6,4	28,41	33,1	19,58	166	45,24	45,01	8,15	26,59 17,55	17,55 78,31 48,24 86,67	83,52	50,04
	Zr	1,73	0,55	106	49	77,29	49,5	150	77,64	26,06	19,11	8,55	93,2	135	4,06 23,62	14,53	278
	Hf	0,08	0,01	3,06	1,49	3,11	2,16	5,49	3,17	0,78	0,72	0,39	3,72	4,97	0,19	1,09	0,6	7,62
	Sm	2,34	0,83	5,32	6,81	2,81	32,61	4,57	5,34	1,55	3,95	2,61	2,83 14,09 6,38 15,97	15,44	9,96
	Eu	1,34	1,13	1,46	1,69	0,81	7,46	1,36	1,68	0,43	1,02	0,47	0,93	2,99	4,54	3,78	3,57	2,92
	Gd	1,26	0,51	5,02	6,98	1,98	20,75	2,46	3,25	1,39	3	2	2,31	9,53	3,63 14,51	13,7	9,49
	Tb	0,11	0,05	0,76	1,12	0,20	2,34	0,28	0,37	0,21	0,38	0,26	0,37	1,1	0,36	2,11	1,97	1,39
	Dy	0,43	0,24	4,61	6,99	0,89	10,04	1,35	1,86	1,3	1,99	1,35	2,27	4,82	1,44 12,32	11,32	8,05
	Y	1,65	1,18	24,38 39,12	3,87	35,9	5,76	7,87	6,53	11,45	7,11	14,27 18,93 5,61 60,76	57,75	38,68
	Ho	0,06	0,04	0,95	1,45	0,15	1,40	0,24	0,34	0,24	0,37	0,25	0,48	0,73	0,20	2,43	2,21	1,54
	Er	0,14	0,08	2,64	4	0,34	2,87	0,65	0,9	0,68	0,98	0,63	1,41	1,69	0,44	6,61	5,9	4,1
	Tm	0,02	0,01	0,39	0,6	0,05	0,32	0,09	0,13	0,11	0,15	0,09	0,22	0,23	0,05	0,95	0,83	0,56
	Yb	0,09	0,05	2,48	3,77	0,31	1,56	0,61	0,86	0,76	0,97	0,55	1,45	1,43	0,26	5,9	5,13	3,54
	Lu	0,02	0,01	0,37	0,55	0,05	0,18	0,09	0,13	0,12	0,14	0,08	0,2	0,22	0,03	0,87	0,75	0,51
	Eu/Eu*	0,78	1,73	0,28	0,25	0,34	0,29	0,41	0,4	0,29	0,3	0,21	0,36	0,26	0,94	0,25	0,25	0,3
	Nb/Ta	12,69 51,02 15,35 19,55 11,71	11,57	27,78	20,56	0,22	1,23	8,71	16,74 14,64 12,02 15,4	17,12	15,31
	Zr/Hf	22,34 94,23 34,49 33,05 24,86	22,88	27,3	24,53	33,52	26,66 21,85	25,04 27,18 21,52 21,68	24,02	36,41
	Mg

Mg/(Mg+Fetot) OI: Oued Ihouhauene; SWT: South Wadi Tirahart; NWT: North Wadi Tirahart S.P: syenitic pegmatite; S.C: Syenitic cumulats; D: dolerite; L: leptynite; G: granulite Al-Fe; M: marble; SK: skarn; Q: quartzite; G.Q: garnet quartzit; AN: anorthosite; N: norite

	Table 2 Continued Rock type Q Localizati on Sample IC2-30 Cs (ppm) 0,01 Rb 2,17 Ba 25,07 Th 0,7 U 0,98 Nb 3,67 Ta 0,24 La 4,73 Ce 7,20 Pb 0,01 Pr 0,89 Sr 3,39 Nd 2,93 Zr 11,78 Hf 0,37 Sm 0,38 Eu 0,08 Gd 0,24 Tb 0,03 Dy 0,14 Y 0,65 Ho 0,02 Er 0,06 Tm 0,01 Yb 0,05 Lu 0,01 Eu/Eu* 0,25 Nb/Ta 15,06 Zr/Hf 31,42 Mg# = Annexe B M P G.Q AN L SWT NWT IC2-22 IC3-A1 IC3-A2 IC3-D IC3-E 0,01 0,05 0,03 0,29 0,06 0,05 0,49 0,28 46,08 43,67 11,84 2,94 28,89 328 1394 1,25 2,96 1,87 7,99 15,08 0,14 15,71 16,19 3,67 2,34 2,23 5,09 2,1 30,83 0,43 0,47 2,37 0,22 2,86 0,08 5,63 20,39 18,56 11,02 34 10,47 60,07 35,60 17,11 42,27 0,002 0,01 0,003 0,09 0,14 1,29 7,79 4,05 1,63 3,57 30,6 26,9 8,73 302 406 5,06 29,08 15,21 5,04 10,45 30,5 28,19 17,35 12,22 56,69 0,9 1,3 0,55 0,44 1,73 1,11 5,45 4,99 0,81 1,07 0,25 0,3 0,41 0,34 1,33 1,29 4,35 7,75 0,66 0,58 0,21 0,76 1,44 0,1 0,06 1,43 4,93 8,59 0,59 0,21 10,34 28,23 45,18 3,2 1,07 0,32 1,01 1,49 0,12 0,04 0,98 2,8 3,54 0,31 0,11 0,15 0,40 0,45 0,05 0,02 1 2,43 2,51 0,31 0,12 0,16 0,33 0,3 0,05 0,02 0,21 0,06 0,07 0,47 1,69 4,75 2,14 9,46 10,79 5,67 32,93 21,21 31,36 27,80 32,75
	205!

Table II .6

 II Representative major element composition of minerals (Supplementary data B1)

	Rock type	Carb	Sy	Sy	Carb	Carb
	Sample	IC1-4B.13	IC3-4.1	IC3-4.2	Inh545.26	IC2-9A.22
	Mineral	Kfs	Kfs	Ab	Gt	Gt
	Type	Core	Core	Core	rim	rim
	SiO2	62,86	63,43	68,01	38,04	35,81
	TiO2	0,02	0,03	-	0,16	0,69
	Al2O3	18,1	18,01	19,53	9,67	4,42
	Fe2O3	0,1	0,19	0,02	16,67	24,62
	MnO	-	0,001	0,01	0,51	0,37
	MgO	-	0,01	0,002	0,03	0,03
	CaO	0,002	0,04	0,05	34,89	33,34
	Na2O	0,24	0,2	11,67	-	0,03
	K2O	17,24	17,3	0,23	0,01	-

-feldspar, Ab: Albite, Gt: Garnet, Cal: Calcite, Wo:Wollastonite, Aln: Alanite, Sph: Sphene, Br: Britholite

	5,05 0,01 2,08 97,91 Kfs: KAnnexe B 5,04 5,01 8,38 8,59 An 0,21 0,25 Ab 1,70 98,47 Or 98,09 1,27 Alm 1,71 2,74 Pyr 0,08 0,07 Spess 0,83 0,55 Gross 72,18 63,05 Andr 25,2 33,59
	206!

Table II .6 Continued

 II

	Rock type	Sy	Sy	Carb	Sy	Carb
	Sample	IC2-27B.44	IC1-4B.27	INH 545.25	IC2-27B.25	IC2-9A.16
	Mineral	Gt	Cal	Cal	Wo	Wo
	Type	rim	Core	Core	Core	Core
	SiO2	36,26	0,01	0,11	50,62	50,83
	TiO2	0,53	0,01	0,03	0,01	0,02
	Al2O3	5,55	0,01	0,04	0,01	0,01
	Fe2O3	23,06	0,15	0,04	0,27	0,46
	MnO	0,49	0,19	0,02	0,66	0,57
	MgO	0,03	0,16	-	-	0,004
	CaO	33,75	57,59	55,65	47,8	47,62
	Na2O	0,01	0,01	0,02	0,02	0,002
	K2O	0,004	-	0,03	0,002	-
	P2O5	-	-	-	-	-
	Cr2O3	-	0,001	0,02	-	-
	NiO		0,02	-	0,02	0,01
	La2O3

feldspar, Ab: Albite, Gt: Garnet, Cal: Calcite, Wo:Wollastonite, Aln: Alanite, Sph: Sphene, Br: Britholite

	55 2,24 0,07 0,74 64,69 32,29 Kfs: K-Annexe B 1 1 2,01 2,01 An Ab Or Alm Pyr Spess Gross Andr
	207!

Table II .6 Continued

 II

										Annexe B Annexe B Annexe B Annexe B	Annexe B
	Rock type Supplementary Data B2 Table 1 Continued Table 1 Continued Table 1 Continued Table 2 Calculated partition coefficient in model B Carb Carb Sample INH 458.24 INH 642. 29 Table 1 Calculated partition coefficient in model A Sample Nb Sample Pr Sample Dy Yb IC2-9A.41 Carb Ba Sm Sample Rb Sr Lu	Sy INH 3.24.5 La Eu Hf Y		Sy IC1-24A.34 Ce Gd Ta Zr Nb	Pb	Ba	La	Ce	Pr
	Mineral Type SiO2 TiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O recalculated liquids in equilibrium with apatite from White syenite	Aln Core 32,92 -15,05 12,21 0,05 1,53 13,51 0,03 INH170 INH170 INH170 INH170 INH170 INH170 INH170 INH170 INH170 INH170 INH170 INH170 INH170 INH170 INH170 INH170 INH170 INH170 IC2-27B INH170 INH170 INH170 IC2-27B	Sph Core 29,82 34,23 3,08 1,40 0,06 0,05 27,18 0,01 47.20 1040 142.66 Sample INH170 INH170 INH170 INH170 INH170 INH170 45.80 46.00 43.30 42.00 39.20 42.50 952 951 920 1040 968 1048 130.77 125.89 125.47 126.25 116.22 127.01	Br Core 20,29 --0,03 --16,6 0,08 Rb 0.24 0.22 0.22 0.20 0.20 0.20 0.76 500 29.66 0.90 0.60 0.69 0.78 1.59 0.51 476 460 451 468 428 469 26.62 24.71 26.08 86.00 1011.42 165.90 3508.33 993.64 13.17 327.24 836.78 102.69 Br Mt Core Core 20,12 0,09 -0,11 -0,04 -93,99 -0,07 -0,01 19,1 0,01 0,06 -Sr Y Zr 8443 78.39 8786 79.00 8474 79.61 9393 80.21 9065 80.82 9278 7428 10740 81.15 358.67 3.61 1.08 0.42 407.16 81.42 6812 9753 6805 9878 6622 9522 7350 11042 6882 10165 7421 11107 76.41 339.68 73.44 316.05 71.99 316.85 77.76 323.04 71.69 303.13 77.66 323.87 3.22 1.16 0.47 406.58 3.02 1.11 0.49 313.59 3.19 1.02 0.40 360.92 26.22 3.20 0.82 0.44 291.48 23.88 2.84 0.87 0.34 314.20 26.07 3.14 0.73 0.38 280.86 114.00 984.00 100.25 3532.14 121.82 12.08 258.87 676.10 83.86
	K2O P2O5 recalculated Cr2O3 recalculated recalculated recalculated liquids in	0,01 0,01 INH170 INH170 INH170 IC2-27B 0,15 INH170 INH170 INH170 IC2-27B	--40.90 920 111.83 INH170 -INH170 26.70 1131 130.16		0,004 3,73 0.21 0.75 417 22.85 0.20 121.12 2.71 8768 6463 0,01 2,6 69.31 0.91 2.17 --0.17 8136 1.02 8068 500 82.27 27.44 3.34 0.54 0.02 118.68 0.46	0,004 82.03 9716 286.63 0.31 378.22 47.74 0.39 -0,024 82.64 11967 339.98 0.19 368.28 31.32 0.00	3.40 0.50	3.56 0.60	9.85 1.56	1.17 0.18
	NiO La2O3 Ce2O3 Pr2O3 Nd2O3 Sm2O3 Gd2O3 Dy2O3 Y2O3 liquids in liquids in liquids in equilibrium Recalculated INH170 INH170 0,02 5,37 11,06 0,87 3,43 0,25 0,10 -<0.001 INH170 INH170 128.61 0,01 --------45.10 1007 IC2-27B INH170 equilibrium INH170 47.60 equilibrium INH170 949 equilibrium INH170 130.22 with Cpx from IC2-27B liquids in equilibrium with apatite from Si-rich carbonatites INH170 INH170 INH170 IC1-2C with apatite from Si-rich carbonatites INH170 43.70 INH170 43.40 IC1-2C 33.00 IC1-2C 48.30 with apatite from Si-rich carbonatites INH170 950 INH170 1168 IC1-2C 1543 IC1-2C 1142 with apatite from Si-rich carbonatites INH170 127.54 INH170 159.05 White Syenite IC2-27B IC1-2C 151.26 average Carbonatite liquid IC1-2C 123.49 composition Syenite liquid ThO2 0,03 -SO2 --F 0,39 -Cl 0,005 -IC1-2C IC1-2C 25.41 IC1-2C 1273 IC1-2C 140.79 IC1-2C IC1-2C IC1-2C 22.41 IC1-2C 33.10 IC1-2C 866 IC1-2C 1362 IC1-2C 90.96 IC1-2C 144.66 Partition coefficient D = SL / CL	-10,47 23,76 2,02 9,49 2,93 0,72 0,13 0,99 0.20 0.94 476 25.98 0.28 1160.52 2.65 -9,16 23,14 2,11 9,99 3,18 0,74 0,19 0,99 10446 7007 77.18 3.12 1.15 0.20 8679 0.93 6604 469 74.72 25.96 3.17 1.22 27.06 1182.72 1.16 0.21 8481 0.18 8548 0.25 9713 0.14 11761 0.74 6717 1.11 8280 0.90 11374 0.92 8195 461 72.81 565 89.76 605 105.67 476 81.51 25.93 3.16 1.17 32.85 4.03 0.91 0.28 1390.16 58.35 1310.00 57.80 0,02 -------83.24 10305 328.06 0.39 463.09 357.96 0.02 83.85 9682 327.05 0.47 468.50 108.30 0.09 2038.33 4.72 8.88 5.52 84.45 85.06 85.67 74.76 9723 11947 17100 12308 318.87 386.25 356.88 289.16 0.41 335.73 0.40 36.71 156.72 414.56 47.12 13.84 1.49 8.67 0.81 329.28 32.69 3.83 0.71 0.13 100.00 997.71 133.07 3520.24 557.73 12.63 293.05 756.44 93.27 475.78 25.72 3.05 1.12 0.52 5.57 794.64 12.96 371.06 11.66 417.56 34.23 89.70 10.15 615.72 -2,67 2,42 -0,20 0,24 -1,63 1,76 0,34 0,23 -0.18 9565 76.58 0.90 8918 13946 557 95.47 332.14 26.49 3.11 0.08 0.16 512.70 -0.11 10817 75.36 0.06 11246 75.97 0.36 6253 9514 0.73 8926 14494 374 63.85 222.06 566 98.15 337.99 16.97 1.97 0.15 0.04 386.56 29.53 3.47 0.83 0.22 569.20 0.06 0.80 0.10 0.11 0.02 33.07 0.12 0.12 0.11
	Total		96,97 IC2-9A IC2-9A IC2-9A	95,84 27.49 2158 217.33 IC1-2C		94,82 0.15 15.54 959 36.57	97,07 11032 13387 182.87 4.43 0.52		101,32 77.18 24569 569.53 0.21 805.25
	Numbers of ions on the basis of Si IC2-9A IC2-9A 13O 3,02 IC2-9A Ti -IC2-9A IC2-9A IC2-9A	5O 4 19.93 1531 159.30 IC2-9A 3,45 IC2-9A 17.84 2998 283.87		24O 5,34 0.23 1.92 701 27.27 -0.16 3.33 1289 3.19 11724 5,33 9181 134.26 0.53 -11495 19001 240.45 46.16 5.48 0.66		4O 85.18 16902 414.58 0.34 428.86 0,003 0,003 77.42 33859 750.34 0.38 917.05
	Al Fe3+		1,63 0,37 IC2-9A IC2-9A IC2-9A	0,49 -25.22 1886 176.89 IC2-9A		--0.22 2.18 801 30.85	--11204 11491 156.58 1235 3.53 0.80 0.30 0,002 1,98 98.71 20527 470.50 571.13
	Fe2+ Mn Ni		0,57 0,004 INH159 INH159 INH159 -INH159 INH159 INH159	0,16 0,01 7.16 7.67 4.61 IC2-9A 0,001 INH159 11.16 5.72 4.29		0,01 -0.16 134.17 7.70 1.60 -46.94 116.67 7.46 1.18	--27.09 10823 1.81 0.24 6.20 -637 17.74 1.48 0.17 4.15	19	1 124.13 58.14 7.74 0.21 55.88 0,002 -108.51 43.52 7.56 0.68 99.31
	Mg Ca Na K P Cr La Ce Pr Nd Pm equilibrium with Recalculated liquids in Cpx from Red syenites recalculated liquids in equilibrium with Cpx from Red syenites recalculated liquids in equilibrium with Cpx from Red syenites INH159 INH159 0,21 1,33 ----0,18 0,37 0,03 0,11 -INH159 INH159 IC3-4 IC3-4 IC3-4 IC3-4 INH159 INH159 INH159 IC3-4 IC3-4 IC3-4 IC3-4 recalculated INH159 liquids in INH159 equilibrium IC3-4 with Cpx IC3-4 from Red IC3-4 syenites IC3-4 Sm 0,01 Eu -Gd -IC3-4 IC3-4 IC3-4 IC3-4 IC3-4 IC3-4	0,01 3,91 0,003 --------0.45 0.06 0.81 10.12 23.44 5.60 6.23 9.29 9.91 7.67 61.87 60.47 69.57 64.50 3.14 INH159 INH159 INH159 INH159 IC3-4 IC3-4 IC3-4 2.86 3.63 36.58 33.09 35.35 38.23 ---IC3-4 3.82 56.20 25.29 IC3-4 9.20 80.80 27.19	-4,68 0,04 0,001 0,83 -1,02 2,29 0,19 0,89 -54.24 3.14 3.18 2.31 16.29 38.29 2.34 12.25 1.00 8.54 32.79 224.58 -5.96 7.26 7.26 7.67 70.01 61.64 70.82 72.09 1.66 0.23 448 826 801 576 2080 1877 1715 36.49 -5,42 0,03 0,005 0,58 -0,89 2,24 0,2 0,94 -43.01 26.05 122.36 189.83 165.61 149.73 1.93 1.76 2.02 16.71 14.84 17.38 17.55 9.44 1.48 0.19 9.29 1.77 0.21 6.53 7.74 0.67 3.08 7.03 0.57 2.88 8.09 0.68 3.20 8.56 0.72 3.33 0,27 0,29 --0,06 0,06 1.94 2093 1.13 135.03 55.74 14.02 5.66 0.50 3.26 3.41 1931 2.58 253.78 64.90 16.51 6.49 0.55 4.13 212! 17 16 14 19	----------58.04 211.57 212.34 136.85 109.02 99.49 115.62 77.73 87.49 59.69 407.14 450.04 502.16 448.49 5.75 5.71 6.30 60.10 53.07 58.88 60.99 0.05 43.92 0.06 44.31 0.06 35.29 0.22 56.47 0.66 78.92 0.15 55.98 0.21 57.35 ---149.02 408.54 43.12 0.06 43.73 -117.96 637.66 50.81 0.57 68.63
	Tb Dy average average average Carbonatite liquid --Carbonatite liquid IC3-4 Carbonatite liquid 144.10 36.64 --1264		-0,01 1.74 1.73 566.80 28.02 3.35 1358 8586 -0,02 97.95 0.82		--116.09 13580 364.15 0.34 454.55
	Y Th S F Cl Total An composition average composition composition Syenite liquid Carbonatite liquid ------0,11 ---7,95 12.02 Syenite liquid 7.10 Syenite liquid 39.43 19.48 composition Syenite liquid Partition kd: Cpx equilibrium liquid in red syenit (SL) / apatite equilibrium liquid in 0,14 0,14 0,16 0,15 0,05 0,06 1,36 1,48 0,15 0,1 17,49 17,94 0.19 9826 53.97 106.07 39.32 9.64 4.66 0.43 5.05 0.27 289.15 -----3 83.26 32.73 15.80 1304 87 130.41 58.16 kd: Cpx equilibrium liquid in red syenit (SL) / apatite equilibrium liquid in coefficient D = SL / CL 84.75 0.13 0.13 1.57 Partition coefficient D = SL / CL 0.19 31.15 0.01 0.02 Partition coefficient D = SL / CL 0.03 0.07 0.10 0.09 Partition coefficient D = SL / CL 0.14 0.17 0.13 6.13 0.79 0.13
	Ab kd: Cpx equilibrium liquid in red syenit (SL) / apatite equilibrium liquid in carbonatite (CL) carbonatite (CL) kd: Cpx equilibrium liquid in red syenit (SL) / apatite equilibrium liquid in carbonatite (CL)
	Or carbonatite (CL) Standard deviation Standard deviation Standard deviation Alm Pyr Standard deviation CL CL 10.09 CL 510.94 CL 40.20	0.04 3.15 210.23 5.65 0.68 1262 2963.25 165.97 43.66 0.32 0.13 6019 10.47 110.58 162.09
	Spess Gross	Standard deviation SL Standard deviation Standard deviation Standard deviation SL 6.66 SL 30.68 SL 15.56	20.44 656.21 77.65 80.41 30.83 7.57 68.70 3.09 0.22 2.46 0.25 223.16 46.26 25.49	18.37
	Andr
	Kfs: K-feldspar, Ab: Albite, Gt: Garnet, Cal: Calcite, Wo:Wollastonite, Aln: Alanite, Sph: Sphene, Br: Britholite
				208! 209! 210! 211!

kd: Cpx equilibrium liquid in white syenit (SL) / apatite equilibrium liquid in white syenite (CL). bd below detection limit

											Annexe B
	Table 2 Continued
		Sample	Sm	Eu	Gd	Dy	Yb	Lu	Hf	Ta	Pb
	recalculated liquids in	IC2-27B	62.39	bd	48.46 10.79 3.50 0.95 16.50 3.70 105.82
	equilibrium with
	apatite from
	White syenite	IC2-27B	51.73	bd	39.01	7.76 1.85 0.53	-	0.77	53.42
	recalculated	IC2-27B	1.06 0.28 0.83	0.45 0.29 0.04 0.63 0.07	4.24
	liquids in	IC2-27B	0.13 0.03 0.09	0.06 0.22 0.03 0.41 0.00	3.38
	equilibrium with	IC2-27B	0.94 0.24 0.60	0.33 2.40 0.37 4.68 0.02	34.12
	Cpx from White	IC2-27B	0.46 0.11 0.24	0.16 0.56 0.14 1.96 0.03 131.27
	Syenite	IC2-27B	36.31 9.19 25.91 13.84 3.75 0.37 15.62 0.40	39.51
	average	Carbonatite liquid	57.06	-	43.73	9.27 2.67 0.74 16.50 2.23	79.62
	composition	Syenite liquid	7.78 1.97 5.53	2.97 1.45 0.19 4.66 0.11	42.50
	Partition coefficient	D = SL / CL	0.14	-	0.13	0.32 0.54 0.26 0.28 0.05	0.53
		Standard deviation CL 19.80	19.38	46.42	16.84 616.47	0.77	48.34 113.62 13.32
		Standard deviation SL 12.01 622.43 25.39 541.01 25.79 906.15 68.50 181.66 20.67
				213!

kd: Cpx equilibrium liquid in white syenit (SL) / apatite equilibrium liquid in white syenite (CL). bd below detection limit

							Annexe B
	Standard deviation CL 7.53	-	6.69	2.15 1.17 0.30	-	2.07	37.06
	Standard deviation SL 15.95 4.04 11.40	6.08 1.57 0.17 6.36 0.17	52.33
			214!

Table 3

 3 Output trace element composition of crystal crystallization and immiscibility model A

				Ce	Lu	Nb	Ta	Rb	Sr	Y	Zr	Ce/Lu	Nb/Ta	Rb/Sr	Y/Zr
		50% Cpx	X %	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	-	-	-	-
	Partition coefficient minerals	D	0.23	0.70	0.01	0.02	0.01	0.13	0.33	0.12	-	-	-	-
	Melilitite (Baudouin et al. 2016)	C0	111	0.14	78.3	4.8	64.7	853	13.1	168	793	16.31	0.08	0.08
			D sil/carb	0.02	0.13	0.19	0.79	84.75	0.13	0.13	1.57
	Cliq: Composition of initial liquid after each fractional crystallization and immiscibility
			f	Ce	Lu	Nb	Ta	Rb	Sr	Y	Zr	Ce/Lu	Nb/Ta	Rb/Sr	Y/Zr
	FC1	Cliq	0.55	176	0	141	9	117	1439	20	285	1051	16.3	0.08	0.07
	FC2	Cliq	0.5	189	0	269	17	235	2472	29	527	982	15.8	0.10	0.06
	FC3	Cliq	0.45	211	0	565	37	524	4624	46	1070	928	15.1	0.11	0.04
	FC4	Cliq	0.4	245	0	1327	92	1317	9527	78	2413	890	14.5	0.14	0.03
	FC5	Cliq	0.35	302	0	3543	256	3777	21917	144	6123	874	13.8	0.17	0.02

Csill: composition of sillicate liquid after each immiscibility; Ccarb: composition of carbonate liquid after each immiscibility

															Annexe B
			F	Ce	Lu	Nb	Ta	Rb	Sr	Y	Zr	Ce/Lu	Nb/Ta	Rb/Sr	Y/Zr
	Immiscib1	Ccarb Csill	0.01 0.01	5208 111	1 0	700 136	11 9	1 118	10156 1348	144 18	182 286	4269 709	64.0 15.7	0.0001 0.09	0.79 0.06
	Immiscib2	Ccarb Csill	0.011 0.011	5345 114	1 0	1325 257	22 17	3 238	17328 2299	212 27	338 529	3836 637	61.4 15.1	0.0002 0.10	0.63 0.05
	Immiscib3	Ccarb Csill	0.012 0.012	5679 121	2 0	2772 537	47 37	6 531	32204 4273	333 42	686 1075	3483 578	58.8 14.4	0.0002 0.12	0.49 0.04
	Immiscib4	Ccarb Csill	0.013 0.013	6308 134	2 0	6488 1257	116 91	16 1334	65912 8747	562 71	1548 2424	3212 533	56.0 13.8	0.0002 0.15	0.36 0.03
	Immiscib5	Ccarb Csill	0.014 0.014	7412 158	2 0	6119 3341	115 255	16 3830	60110 19987	510 131	1556 6154	4154 503	53.0 13.1	0.0003 0.19	0.33 0.02
								215!

Table 4

 4 Output trace element composition of mixt parental liquid of model B

			Ce	Lu	Nb	Ta	Rb	Sr	Y	Zr
		X %	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5
		D1	0.045	0.115	0.05	0.075	0.002	0.04	0.15	0.24
		C0	7412	1.78	6119	115	16	60110	510	1556
		CA	158	0.31	3341	255	3830	19987	131	6154
		CA/C0	0.02	0.18	0.55	2.21	240.00	0.33	0.26	3.96
		r	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2
		F	Ce	Lu	Nb	Ta	Rb	Sr	Y	Zr	Ce/Lu	Nb/Ta	Rb/Sr	Y/Zr
	Cliq	0.9	8192	1.96	6846	134	124	66992	560	1843	4176	51.09	0.002	0.30
	C0	1	7412	1.78	6119	115	15.96	60110	510	1556	4154	53.03	0.00	0.33
			C0:

calculated liquid from immiscibility 5 from model A CA: calculated liquid from immiscibility 5 from model A r: rate of mingling; X: 50% cpx D1: Partition coefficient of minerals Cliq : mixt liquid composition after 0.1% of Cpx crystallization as parental liquid for model B

	Annexe B
	216!

Table 5

 5 Output trace element composition of crystal crystallization and immiscibility model B

				Ce	Lu	Nb	Ta	Rb	Sr	Y	Zr	Ce/Lu Nb/Ta Rb/Sr Y/Zr
		50% Cpx	X %	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	-	-	-	-
	Partition coefficient minerals	D	0.229 0.7 0.0125 0.016 0.0085 0.125	0.33	0.1175	-	-	-	-
	Calculated mixt liquid	C0	8192 1.96 6846	134	124	66992	560	1843	4176	51.09	0.002	0.30
			D sil/carb	0.12 0.26	0.02	0.05	0.06	0.80	0.10	0.11
	Cliq: Composition of initial liquid after each fractional crystallization and immiscibility
			f	Ce	Lu	Nb	Ta	Rb	Sr	Y	Zr	Ce/Lu Nb/Ta Rb/Sr Y/Zr
	CF1	Cliq	0.95	8522 1.99 7202	141	131	70067	579	1928	4278	51.10	0.00	0.30
	CF2	Cliq	0.96	4732 1.58	151	27.10 33.05 71084	275	985	2988	5.58	0.00	0.28
	CF3	Cliq	0.97	4496 1.55 97.26 22.78 28.72 72817	256	929	2896	4.27	0.00	0.28
	CF4	Cliq	0.98	4238 1.52 61.98 18.96 24.71 73925	236	869	2793	3.27	0.00	0.27
	CF5	Cliq	0.99	3963 1.48 39.10 15.62 21.04 74387	216	805	2682	2.50	0.00	0.27

Csill: composition of sillicate liquid after each immiscibility; Ccarb: composition of carbonate liquid after each immiscibility

  The average of apatite and clinopyroxene equilibrium recalculated liquids is used to calculate the partition coefficient between silicate and carbonate melts for numerical modelling explained in supplementary data B2.

										Annexe B Annexe B
	-
			F	Ce	Lu	Nb	Ta	Rb	Sr	Y	Zr	Ce/Lu Nb/Ta Rb/Sr Y/Zr
	Immiscib1	Ccarb Csill	0.08 0.08	38670 6.10 6941 4585 1.56 145.13 26.03 31.74 68590 267.42 553 570 86118 2746	9015 950	6341 2931	12.54 0.0066 0.30 5.58 0.0005 0.28
	Immiscib2	Ccarb Csill	0.01 0.01	37033 6.00 4514 4391 1.54 94.38 22.11 27.87 70902 250.39 470 501 89021 2571	8582 905	6176 2855	9.61 4.27	0.0056 0.30 0.0004 0.28
	Immiscib3	Ccarb Csill	0.01 0.01	35184 5.88 2906 4172 1.51 60.75 18.58 24.22 72630 232.82 395 435 91190 2391	8095 853	5986 2767	7.36 3.27	0.0048 0.30 0.0003 0.27
	Immiscib4	Ccarb Csill	0.01 0.01	33164 5.74 1851 3933 1.47 38.71 15.46 20.84 73735 215.00 329 374 92579 2208	7567 798	5774 2669	5.63 2.50	0.0040 0.29 0.0003 0.27
	Immiscib5	Ccarb Csill	0.01 0.01	31016 5.58 1156 3678 1.44 24.42 12.74 17.75 74196 197.20 268 316 92341 2012	6948 739	5560 2562	4.31 1.92	0.0034 0.29 0.0002 0.27
					218						! !
	! !

Table 1 Representative major element composition of inclusion-free apatite

 1

	Rock type		Si-poor carbonatite			!"#$"%&'%($)*+(,",-'
	Sample	INH642.2 INH642.7 INH642.10 INH642.15 INH170.4 INH170.6 INH170.8 INH170.12
	Type	Rim	Core	Rim	Rim	Core	Core	Middle	Rim
	SiO 2	1,50	1,85	2,46	0,66	4,91	5,05	5,23	4,95
	Fe 2 O 3	-	-	0,01	0,00	0,00	-	0,02	-
	CaO	51,01	53,23	54,61	58,02	50,41	50,44	50,07	49,09
	Na 2 O	-	-	0,02	0,00	0,00	-	0,00	-
	K 2 O	-	-	-	-	0,00	0,00	0,00	-
	P 2 O 5	36,17	37,38	35,29	42,05	31,43	31,03	30,52	31,33
	La 2 O 3	0,66	0,95	1,13	0,22	1,40	1,38	1,61	1,63
	Ce 2 O 3	1,89	2,31	2,78	0,73	3,15	3,23	3,55	3,59
	Pr 2 O 3	0,19	0,21	0,23	0,11	0,31	0,32	0,36	0,36
	Nd 2 O 3	0,91	1,03	1,13	0,54	1,31	1,33	1,46	1,46
	Sm 2 O 3	0,12	0,15	0,12	0,08	0,16	0,19	0,21	0,18
	Gd 2 O 3	0,09	0,10	0,11	0,07	0,09	0,14	0,12	0,13
	Dy 2 O 3	0,01	0,01	0,01	0,01	0,04	0,02	0,01	0,05
	Lu 2 O 3
	Y 2 O 3	0,14	0,13	0,14	0,11	0,22	0,22	0,25	0,25
	SrO	-	-	-	-	0	-	0,00	0,02
	ThO 2	0,02	0,06	0,12	0,00	0,24	0,24	0,23	0,25
	SO 2	0,23	0,11	0,41	0,05	1,76	1,55	1,64	1,41
	F	4,86	5,16	3,69	3,40	4,59	4,50	4,53	4,33
	Cl	0,00	0,00	0,00	0,00	0,03	0,05	0,05	0,04
	Total	97,80	102,7	102,24	106,04	100,06	99,68	99,84	99,07
	∑ REEox	3,85	4,75	5,50	1,75	6,47	6,60	7,31	7,41
	Numbers of ions on the basis of 24O			!!		!!
	Si	0,27	0,32	0,43	0,11	0,87	0,90	0,94	0,89
	Fe 2+	-	-	0,00	0	0	-	0,00	-
	Ca	9,82	9,82	10,26	10,16	9,59	9,68	9,63	9,50
	Na	-	-	0,01	0	0	-	0	-
	K	-	-	-	0	0,00	0,00	0,00	-
	P	5,50	5,45	5,24	5,82	4,73	4,70	4,64	4,79
	La	0,04	0,06	0,07	0,01	0,09	0,09	0,11	0,11
	Ce	0,12	0,15	0,18	0,04	0,21	0,21	0,23	0,24
	Pr	0,01	0,01	0,01	0,01	0,02	0,02	0,02	0,02
	Nd	0,06	0,06	0,07	0,03	0,08	0,08	0,09	0,09
	Sm	0,01	0,01	0,01	0,00	0,01	0,01	0,01	0,01
	Gd	0,01	0,01	0,01	0,00	0,01	0,01	0,01	0,01
	Dy	0,00	0,00	0,00	0,00	0,00	0,00	0,00	0,00
	Lu	-	-	-	-	-	-	-	-
	Sr	-	-	-	0	0	-	0	0,00
	Y	0,01	0,01	0,01	0,01	0,02	0,02	0,02	0,02
	Th	0,00	0,00	0,00	0,00	0,01	0,01	0,01	0,01
	S	0,04	0,02	0,07	0,01	0,29	0,26	0,28	0,24
	F	2,76	2,81	2,05	1,76	2,58	2,55	2,57	2,47
	Cl	0,00	0,00	0,00	0,00	0,01	0,02	0,02	0,01
	Total	18,65	18,72	18,42	17,97	18,52	18,57	18,58	18,42
	Ap: Apatite
		!

Table 2 Representative trace element composition of apatite Rock type Si-poor carbonatite

 2

	Sample	IC1-4B.35	IC1-4B.34	INH 642	INH 642	INH 694	INH 694.6	C3-9	INH693. 1	INH693. 2	INH693. 3	INH693. 6
	Mineral	Ap	Ap	Ap	Ap	Ap	Ap	Ap	Ap	Ap	Ap	Ap
	Type			Bulk		Bulk		Bulk
	Sc	0,05	0,22	-	-	-	-	-	0,61	0,40	0,66	0,43
	Ti	48,81	39,16	-	-	-	-	-	-	-	-	-
	V	4,68	5,18	-	-	-	-	-	10,71	6,96	6,62	5,86
	Rb	0,02	0,12	0,24	-	0,10	-	0,32	0,21	0,18	0,07	0,08
	Sr	5858	5980	4641	-	5588	125	2961	6189	6030	6868	7035
	Y	524	738	1171	-	804	106	848	1321	1067	639	723
	Zr	0,45	1,59	27,80	-	14,80	-	29,12	6,92	2,08	0,43	0,11
	Nb	0,01	0,03	0,18	-	2,41	-	1,27	0,25	0,10	0,16	0,14
	Ba	3,01	1,80	98,62	-	43,16	-	37,23	14,11	1,23	1,41	0,60
	La	1149	932	8230	4043	3523	2427	5128	2604	1358	1522	1212
	Ce	3514	3430	17977	9856	8572	5608	1163 1	11716	6516	5460	5320
	Pr	488	537	2124	909	1083	710	1489	1649	1090	828	831
	Nd	2219	2600	7962	435	4302	3202	5804	7166	4897	3637	3884
	Sm	427	547	1226	630	741	428	956	1172	1037	709	685
	Eu	82,12	110	221	-	140,79	-	181	290	245	130	143
	Gd	305	392	763	448	491	415	631	767	695	474	441
	Tb	30,20	41,10	67,27	-	45,18	-	63,23	76,06	73,23	46,49	49,29
	Dy	135	184	308	24	209	0	254	310	299	191	204
	Ho	18,42	25,83	42,30	-	28,97	-	35,68	43,72	42,04	25,52	27,06
	Er	37,95	53,41	87,61	-	60,50	-	70,13	83,62	80,02	47,68	52,58
	Tm	3,84	5,60	9,07	-	6,37	-	7,36	8,13	8,33	4,95	5,37
	Yb	21,02	29,17	42,88	-	30,65	-	35,10	37,39	35,77	23,69	24,92
	Lu	2,48	3,36	5,03	-	3,66	-	4,09	4,19	3,90	2,49	2,76
	Hf	0,04	0,05	0,14	-	0,05	-	0,18	0,08	0,06	0,02	0,01
	Ta	0,01	0,00	0,02	-	0,14	-	0,31	0,02	0,01	0,01	b.d.
	Pb	36,29	35,76	94,30	-	74,70	-	74,25	58,68	21,21	24,64	14,99
	Th	53	75	1060	-	896	110	1312	419	103	64	21
	U	2,49	5,12	49,86	-	50,42	-	92,85	11,54	8,03	2,32	6,31
	Nb/Ta	1,42	7,18	9,02	-	17,64	-	4,02	14,65	9,00	18,18	-
	Zr/Hf	12,61	30,58	199	-	272	-	162,3 9	87,59	34,67	22,18	7,55
	Ce/Lu	1419	1021	3575	-	2342	-	2842	2796	1671	2193	1928
	Rb/Sr	0,00	0,00	0,00	-	0,00	0,00	0,00	0,00	0,00	0,00	0,00
	Y/Zr	1155	464	42,13	-	54,30	-	29,1	190,8	513,1	1492,3	6883
	b.d.: below
	detection
	!			!

Table III .1 Representative major element composition of apatite with britholite Rock type Carbonatite

 III

	Sample	INH 604.44 INH 604.49 INH 604.54 INH 604a.8 INH 604a.3 INH 545.36 INH 545.13 IC2-9A.54
	Mineral	Ap	Ap	Ap	Ap	Ap	Ap	Ap	Ap
	Type	Core	Core	Rim	Core	Core	Core	Core	Core
	SiO2	3.21	3.02	4.60	2.53	5.10	3.35	5.99	2.45
	Fe2O3	-	-	-	0.12	0.00	0.00	-	-
	MnO	-	-	-	-	-	-	-	-
	CaO	50.2	50.2	47.8	51.5	46.3	48.6	48.4	52.4
	Na2O	-	-	-	0.01	0.09	0.00	0.01	-
	K2O	0.01	0.01	0.00	0.01	0.02	0.01	0.00	0.00
	P2O5	37.2	37.1	33.5	34.1	33.4	30.6	29.8	37.0
	La2O3	1.32	1.23	1.78	0.93	2.40	2.24	2.36	0.81
	Ce2O3	3.11	2.92	4.14	2.59	6.13	5.27	5.73	2.08
	Pr2O3	0.27	0.27	0.41	0.19	0.48	0.48	0.53	0.17
	Nd2O3	1.43	1.38	1.87	1.11	2.36	2.03	2.23	1.03
	Sm2O3	0.42	0.40	0.55	0.31	0.73	0.23	0.26	0.28
	Gd2O3	0.11	0.09	0.14	0.08	0.18	0.19	0.21	0.14
	Dy2O3	0.00	0.01	0.01	0.02	0.02	0.06	0.03	-
	Lu2O3	0.01	0.03	0.03	0.01	0.00	-	-	-
	Y2O3	0.13	0.12	0.17	0.10	0.20	0.25	0.32	0.12
	SrO	0.11	0.11	0.08	-	-	0.29	0.38	-
	ThO2	0.08	0.19	0.27	0.14	0.37	0.28	0.33	0.09
	SO2	0.57	0.56	0.72	0.56	0.74	1.16	1.36	0.68
	F	4.13	3.82	4.09	3.17	2.86	3.69	4.36	4.36
	Cl	0.17	0.32	0.26	0.06	0.13	0.02	0.04	0.04
	Total	102.5	101.7	100.5	97.5	101.5	98.8	102.3	101.7
	∑ REEox	6.79	6.46	9.08	5.34	12.51	10.74	11.67	4.63
	Numbers of ions on the basis of 24O
	Si	0.55	0.52	0.41	0.46	0.92	1.03	1.08	0.42
	Fe2+	-	-	-	0.02	0.00	-	-	-
	Mn	-	-	-	-	-	-	-	-
	Ca	9.25	9.33	9.97	10.09	8.93	9.43	9.33	9.68
	Na	-	-	-	0.00	0.03	0.00	0.01	-
	K	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
	P	5.42	5.45	5.25	5.28	5.09	4.69	4.54	5.40
	La	0.08	0.08	0.07	0.06	0.16	0.15	0.16	0.05
	Ce	0.20	0.19	0.17	0.17	0.40	0.35	0.38	0.13
	Pr	0.02	0.02	0.01	0.01	0.03	0.03	0.03	0.01
	Nd	0.09	0.09	0.07	0.07	0.15	0.13	0.14	0.06
	Sm	0.02	0.02	0.01	0.02	0.05	0.01	0.02	0.02
	Gd	0.01	0.01	0.01	0.01	0.01	0.01	0.01	0.01
	Dy	0.00	0.00	0.00	0.00	0.00	0.00	0.00	-
	Lu	0.00	0.00	-	0.00	0.00	-	-	-
	Sr	0.01	0.01	-	-	-	0.03	0.04	-
	Y	0.01	0.01	0.01	0.01	0.02	0.02	0.03	0.01
	Th	0.00	0.01	0.00	0.01	0.02	0.01	0.01	0.00
	S	0.09	0.09	0.08	0.10	0.12	0.20	0.23	0.11
	F	2.25	2.10	2.57	1.83	1.63	2.11	2.48	2.37
	Cl	0.05	0.09	0.00	0.02	0.04	0.01	0.01	0.01
	Total	18	18	19

Table III .1 Continued Rock type Carbonatite Syenite

 III

	Sample	IC2-9A.49	IC1-12.13	INH 455.5 INH 158.2	INH 3.24 .8	INH 3.24 .6	IC2-27B.	IC2-27B.
	Mineral	Ap	Ap	Ap	Ap	Ap	Ap	Ap	Ap
	Type	Core	Core	Core	Core	Core	Core	Core	Core
	SiO2	4.85	3.00	2.84	2.09	2.56	3.49	2.56	3.49
	Fe2O3	-	-	-	0.00	-	-	-	-
	MnO	-	-	-	0.01	-	-	-	-
	CaO	48.3	51.8	51.1	48.9	53.8	51.8	53.8	51.8
	Na2O	-	-	0.04	-	0.00	0.01	0.00	0.01
	K2O	0.00	-	-	0.01	0.00	0.01	0.00	0.01
	P2O5	31.9	35.4	37.3	35.3	37.9	33.4	37.9	33.4
	La2O3	1.86	1.11	1.41	0.91	0.78	1.44	0.78	1.44
	Ce2O3	4.83	2.54	2.93	1.67	2.12	3.84	2.12	3.84
	Pr2O3	0.45	0.29	0.35	0.17	0.25	0.38	0.25	0.38
	Nd2O3	2.32	1.31	1.53	0.90	1.14	1.72	1.14	1.72
	Sm2O3	0.64	0.35	0.44	0.25	0.30	0.52	0.30	0.52
	Gd2O3	0.17	0.10	0.17	0.05	0.16	0.10	0.16	0.10
	Dy2O3	0.10	0.06	0.01	-	0.05	0.02	0.05	0.02
	Lu2O3	0.01	-	-	-	-	-	-	-
	Y2O3	0.30	0.16	0.20	0.10	0.15	0.15	0.15	0.15
	SrO	-	-	-	0.07	-	-	-	-
	ThO2	0.36	0.04	0.10	0.06	0.16	0.39	0.16	0.39
	SO2	0.89	0.83	0.36	0.41	0.60	0.77	0.60	0.77
	F	4.12	4.06	4.34	4.63	3.91	4.16	3.91	4.16
	Cl	0.03	0.02	0.05	0.04	0.02	0.01	0.02	0.01
	Total	101.1	101.1	103.2	95.7	102.2	103.8	102.2	103.8
	∑ REEox	10.69	5.92	7.05	4.06	4.95	8.16	4.95	8.16
	Numbers of ions on the basis of 24O
	Si	0.87	0.52	0.49	0.38	0.43	0.62	0.43	0.62
	Fe2+	-	-	-	0.00	-	-	-	-
	Mn	-	-	-	0.00	-	-	-	-
	Ca	9.35	9.72	9.42	9.59	9.75	9.84	9.75	9.84
	Na	-	-	0.01	-	0.00	0.01	0.00	0.01
	K	0.00	-	-	0.00	0.00	0.00	0.00	0.00
	P	4.87	5.25	5.42	5.47	5.43	5.01	5.43	5.01
	La	0.12	0.07	0.09	0.06	0.05	0.09	0.05	0.09
	Ce	0.32	0.16	0.18	0.11	0.13	0.25	0.13	0.25
	Pr	0.03	0.02	0.02	0.01	0.02	0.02	0.02	0.02
	Nd	0.15	0.08	0.09	0.06	0.07	0.11	0.07	0.11
	Sm	0.04	0.02	0.03	0.02	0.02	0.03	0.02	0.03
	Gd	0.01	0.01	0.01	0.00	0.01	0.01	0.01	0.01
	Dy	0.01	0.00	0.00	-	0.00	0.00	0.00	0.00
	Lu	-	-	-	-	-	-	-	-
	Sr	-	-	-	0.01	-	-	-	-
	Y	0.03	0.01	0.02	0.01	0.01	0.01	0.01	0.01
	Th	0.01	0.00	0.00	0.00	0.01	0.02	0.01	0.02
	S	0.15	0.14	0.06	0.07	0.10	0.13	0.10	0.13
	F	2.35	2.25	2.36	2.68	2.09	2.33	2.09	2.33
	Cl	0.01	0.01	0.01	0.01	0.00	0.00	0.00	0.00
	Total	18	18	18

Table III .3 Representative major element composition of apatite with monazite inclusions Rock type Si-poor carbonatite

 III

	Sample	INH 693.1	INH 693.2	INH 693.3	INH 693.4	INH 693.5	INH 693.6	INH 693.7	INH 3.33 .23	INH 3.33 .25	INH 3.33 .26
	Mineral	Ap	Ap	Ap	Ap	Ap	Ap	Ap	Ap	Ap	Ap
	Type	Rim	Midd	Core	Core	Midd	Rim	Rim	Rim	Core	Rim
	SiO2	1.84	0.54	0.48	1.09	0.65	1.78	1.81	1.43	0.97	1.48
	Fe2O3	-	0.00	-	0.01	0.00	-	-	-	-	0.00
	MnO	-	-	-	-	-	-	0.00	-	-	-
	CaO	53.49	55.58	56.06	55.23	56.20	53.99	53.74	53.22	54.28	53.34
	Na2O	0.19	0.10	0.09	0.05	0.05	0.17	0.16	0.32	0.14	0.17
	K2O	-	-	-	-	0.00	0.00	-	0.00	0.00	-
	P2O5	36.73	40.25	40.43	39.21	39.63	36.64	35.53	38.00	39.09	37.97
	La2O3	0.53	0.19	0.18	0.38	0.19	0.68	0.63	0.31	0.28	0.37
	Ce2O3	1.94	0.77	0.67	1.48	0.82	2.17	2.09	1.48	1.28	1.69
	Pr2O3	0.24	0.08	0.08	0.17	0.14	0.24	0.23	0.20	0.18	0.26
	Nd2O3	1.39	0.55	0.50	0.85	0.62	1.24	1.30	1.22	0.86	1.33
	Sm2O3	0.39	0.17	0.14	0.24	0.18	0.36	0.36	0.35	0.24	0.35
	Gd2O3	0.22	0.09	0.07	0.13	0.03	0.13	0.09	0.24	0.07	0.16
	Dy2O3	0.08	0.04	0.02	0.05	0.01	0.04	0.01	0.04	0.01	0.07
	Lu2O3	0.03	0.01	0.01	0.02	0.02	0.02	-	-	0.02	-
	Y2O3	0.31	0.02	0.04	0.07	0.07	0.11	0.17	0.24	0.08	0.22
	SrO	-	-	-	-	-	-	-	-	-	-
	ThO2	0.08	0.03	0.00	0.01	-	0.11	0.07	0.10	0.03	0.07
	SO2	0.39	0.09	0.10	0.04	0.06	0.46	0.41	0.40	0.18	0.20
	F	3.99	3.83	4.26	3.94	4.37	4.08	4.22	3.93	4.37	3.95
	Cl	0.05	0.02	0.03	0.03	0.02	0.04	0.05	0.04	0.03	0.02
	Total	101.9	102.4	103.2	103.0	103.1	102.2	100.9	101.5	102.1	101.7
	∑ REEox	5.11	1.92	1.72	3.39	2.07	5.00	4.88	4.07	3.02	4.46
	Numbers of ions on the basis of 24O
	Si	0.32	0.09	0.08	0.19	0.11	0.31	0.32	0.25	0.17	0.26
	Fe2+	-	0.00	-	0.00	0.00	-	-	-	-	0.00
	Mn	-	-	-	-	-	-	0.00	-	-	-
	Ca	9.98	10.10	10.10	10.08	10.19	10.05	10.18	9.87	9.94	9.91
	Na	0.07	0.03	0.03	0.02	0.02	0.06	0.05	0.11	0.05	0.06
	K	-	-	-	-	0.00	0.00	-	0.00	0.00	-
	P	5.42	5.78	5.75	5.66	5.68	5.39	5.31	5.57	5.66	5.57
	La	0.03	0.01	0.01	0.02	0.01	0.04	0.04	0.02	0.02	0.02
	Ce	0.12	0.05	0.04	0.09	0.05	0.14	0.14	0.09	0.08	0.11
	Pr	0.01	0.00	0.00	0.01	0.01	0.02	0.01	0.01	0.01	0.02
	Nd	0.09	0.03	0.03	0.05	0.04	0.08	0.08	0.08	0.05	0.08
	Sm	0.02	0.01	0.01	0.01	0.01	0.02	0.02	0.02	0.01	0.02
	Gd	0.01	0.01	0.00	0.01	0.00	0.01	0.01	0.01	0.00	0.01
	Dy	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
	Lu	0.00	0.00	0.00	0.00	0.00	0.00	-	-	0.00	-
	Sr	-	-	-	-	-	-	-	-	-	-
	Y	0.03	0.00	0.00	0.01	0.01	0.01	0.02	0.02	0.01	0.02
	Th	0.00	0.00	0.00	0.00	-	0.00	0.00	0.00	0.00	0.00
	S	0.06	0.01	0.02	0.01	0.01	0.08	0.07	0.06	0.03	0.03
	F	2.20	2.06	2.26	2.12	2.34	2.24	2.36	2.15	2.36	2.16
	Cl	0.02	0.01	0.01	0.01	0.01	0.01	0.01	0.01	0.01	0.01
	Total	18	18	18

Table III .4 Representative major element composition of monazite

 III

								Annexe C
	Table III.4 Continued
	Rock type Rock type			Si-poor carbonatite Si-poor carbonatite
	Sample Sample	INH 693.14 INH 3.33 .1	INH 693.17 INH 3.33 .3	INH 693.18 INH 3.33 .12	INH 693.19 INH 3.33 .13	INH 693.20 INH 3.33 .28	INH 693.27 INH 3.33 .29	INH 693.29 INH 3.33 .27
	Mineral Mineral	Mnz Mnz	Mnz Mnz	Mnz Mnz	Mnz Mnz	Mnz Mnz	Mnz Mnz	Mnz Tho
	Type Type	Rg Rg	Rg Rg	Rg Incl	Rg Incl	Rg Incl	Incl Incl	Incl Incl
	SiO2 SiO2	1.37 0.96	0.74 1.34	1.21 1.97	1.28 1.72	1.27 0.78	0.72 1.17	1.23 13.82
	Fe2O3 Fe2O3	--	--	-0.32	--	--	--	--
	CaO CaO	0.31 0.28	0.29 0.28	0.30 1.29	0.36 0.27	0.37 0.20	0.34 0.30	0.36 0.44
	Na2O Na2O	--	--	--	--	--	--	-0.30
	K2O K2O	--	--	0.00 0.00	-0.00	0.00 -	-0.00	-0.02
	P2O5 P2O5	26.91 28.07	28.26 27.35	26.91 25.34	26.37 27.35	26.60 29.16	28.47 28.04	28.57 7.29
	La2O3 La2O3	22.02 17.40	20.51 16.78	20.81 18.56	21.08 18.99	21.36 15.43	20.86 18.46	22.52 4.37
	Ce2O3 Ce2O3	34.61 35.74	34.88 33.86	34.70 33.05	34.68 33.58	34.42 35.03	35.30 33.93	34.54 9.37
	Pr2O3 Pr2O3	1.77 2.32	1.95 2.27	1.94 1.91	1.89 2.02	1.83 2.59	1.87 2.07	1.63 0.62
	Nd2O3 Nd2O3	7.56 9.95	8.72 10.22	8.53 8.38	8.35 8.51	8.14 11.40	8.27 9.11	7.36 2.97
	Sm2O3 Sm2O3	2.56 2.96	2.75 2.91	2.79 2.61	2.66 2.69	2.56 3.19	2.38 2.88	2.31 0.93
	Gd2O3 Gd2O3	0.07 0.12	0.23 0.21	0.17 0.13	0.14 0.20	0.09 0.24	0.11 0.23	0.14 0.27
	Dy2O3 Dy2O3	-0.01	0.01 -	--	0.01 0.01	--	--	--
	Lu2O3 Lu2O3	0.02 -	--	-0.01	--	0.01 -	--	0.00 -
	Y2O3 Y2O3	-0.01	0.00 0.03	-0.03	-0.02	0.01 -	--	-0.48
	SrO SrO	0.06 0.05	0.09 0.08	0.06 0.04	0.07 0.07	0.07 0.06	0.12 0.07	0.09 0.05
	ThO2 ThO2	0.41 0.90	0.10 3.08	0.08 2.75	0.05 3.00	0.15 1.77	0.21 2.19	0.26 50.11
	SO2 SO2	1.39 0.78	0.86 0.67	1.28 1.17	1.41 0.93	1.41 0.32	0.77 0.78	1.28 0.23
	F F	0.53 0.47	0.55 0.46	0.50 0.47	0.45 0.56	0.47 0.42	0.49 0.40	0.52 0.17
	Cl Cl	0.01 0.01	0.01 0.01	0.01 0.01	0.01 0.01	0.02 0.01	0.01 0.01	0.01 0.02
	Total Total	99.59 100	99.96 99.56	99.31 98.06	98.83 99.92	98.79 100.6	99.91 99.65	100.8 91.45
	∑ REEox ∑ REEox	68.60 68.50	69.06 66.28	68.94 64.67	68.81 66.00	68.43 67.88	68.78 66.69	68.50 19.01
	Numbers of ions on the basis of 24O Numbers of ions on the basis of 24O
	Si Si	0.35 0.24	0.19 0.35	0.31 0.51	0.33 0.44	0.33 0.20	0.18 0.30	0.30 4.60
	Fe2+ Fe2+	--	--	-0.07	--	--	--	--
	Ca Ca	0.08 0.08	0.08 0.08	0.08 0.36	0.10 0.07	0.10 0.05	0.09 0.08	0.10 0.16
	Na Na	--	--	--	--	--	--	-0.20
	K K	--	--	0.00 0.00	-0.00	0.00 -	-0.00	-0.01
	P P	5.77 6.03	6.05 5.95	5.81 5.58	5.74 5.86	5.77 6.23	6.09 6.03	5.97 2.06
	La La	2.06 1.63	1.91 1.59	1.96 1.78	2.00 1.77	2.02 1.44	1.94 1.73	2.05 0.54
	Ce Ce	3.21 3.32	3.23 3.19	3.24 3.15	3.26 3.11	3.23 3.24	3.27 3.16	3.12 1.14
	Pr Pr	0.16 0.21	0.18 0.21	0.18 0.18	0.18 0.19	0.17 0.24	0.17 0.19	0.15 0.08
	Nd Nd	0.68 0.90	0.79 0.94	0.78 0.78	0.77 0.77	0.74 1.03	0.75 0.83	0.65 0.35
	Sm Sm	0.22 0.26	0.24 0.26	0.25 0.23	0.24 0.23	0.23 0.28	0.21 0.25	0.20 0.11
	Gd Gd	0.01 0.01	0.02 0.02	0.01 0.01	0.01 0.02	0.01 0.02	0.01 0.02	0.01 0.03
	Dy Dy	-0.00	0.00 -	--	0.00 0.00	--	--	--
	Lu Lu	0.00 -	--	-0.00	--	0.00 -	--	0.00 -
	Sr Sr	0.01 0.01	0.01 0.01	0.01 0.01	0.01 0.01	0.01 0.01	0.02 0.01	0.01 0.01
	Y Y	-0.00	0.00 0.00	-0.00	-0.00	0.00 -	--	-0.08
	Th Th	0.02 0.05	0.01 0.18	0.00 0.16	0.00 0.17	0.01 0.10	0.01 0.13	0.01 3.80
	S S	0.33 0.19	0.20 0.16	0.31 0.29	0.34 0.22	0.34 0.08	0.18 0.19	0.30 0.07
	F F	0.42 0.38	0.44 0.38	0.41 0.39	0.37 0.45	0.38 0.33	0.39 0.32	0.40 0.17
	Cl Cl	0.00 0.00	0.00 0.01	0.00 0.00	0.01 0.01	0.01 0.00	0.01 0.00	0.00 0.01
	Total Total	13 13	13 13	13 14	13 13	13 13	13 13	13 13
	Inc: inclusion; Rg: Rim grain
	!				233

Table III .5 Representative trace element composition of REE-inclusions Rock type

 III

	Sample	INH545.9 INH545.10	INH545.11	INH693.36	INH693.38
	Mineral	Bri	Bri	Bri	Mnz	Mnz
	Type	I.G	L	L	Rg	Rg
	Sc	0,47	1,67	1,04	0,12	0,03
	Ti	b.d.	29	b.d.
	V	2,92	8,12	3,50	3,70	4,42
	Rb	1,31	2,36	1,87	0,10	b.d.
	Sr	4088	7970	3588	373	191,93
	Y	7157	11969	9543	181	24,93
	Zr	277	597	268	2,15	0,16
	Nb	1,86	5,72	1,96	0,08	0,01
	Ba	8,11	41,96	30,11	2,10	0,67
	La	89229	136963	86859	35727	19652
	Ce	178743	268806	200929	40074	23259
	Pr	17557	28060	20172	3681	2001
	Nd	62403	99857	73405	11890	5433
	Sm	8161	12929	10238	1372	336
	Eu	1448	2312	1866	166	40,05
	Gd	4891	7789	6294	476	106
	Tb	442	717	582	25,90	5,02
	Dy	1895	3066	2531	67,41	11,80
	Ho	255	416	337	4,84	0,96
	Er	517	851	681	6,09	1,12
	Tm	55,72	92,68	73,84	0,29	0,06
	Yb	304	512	399	1,21	0,19
	Lu	33,03	55,20	42,56	0,06	0,01
	Hf	1,99	5,10	2,32	0,04	b.d.
	Ta	0,03	0,15	0,05	b.d.	0,00
	Pb	1651	3348	2535	25,08	29,04
	Th	8060	11781	6292	107,38	155,77
	U	2343	3229	1841	2,83	1,95
	Nb/Ta	54,71	37,63	42,61	-	-
	Zr/Hf	139	117	116	58,11	-
	Ce/Lu	5412	4870	4721	720753	3186179
	Rb/Sr	0,00	0,00	0,00	0,00	-
	Y/Zr	25,81	20,05	35,60	84,17	156,79
	b.d.: below detection		I.G:

Irregular shape grain; L: lamellar; Rg: Rim grain Annexe

									Annexe C
	Settings
	Accelerating Voltage			17.00 kV
	Specimen Tilt (degrees)		70.00	°Hit
	Rate				83.39 %
	Reanalysis Hit Rate			83.39 %
	Speed of Acquisition			63.03 Hz
	Phases for Acquisition
	Phase	a	b	c	Alpha	Beta	Gamma	Space	Database
								Group
	Apatite	9.41 Å	9.41 Å	6.91 Å	90.00 °	90.00 °	120.00 °		AM
	Britholite	9.68 Å	9.68 Å	7.07 Å	90.00 °	90.00 °	120.00 °		ICSD
	Britholite	9.39 Å	9.39 Å	6.90 Å	90.00 °	90.00 °	120.00 °		ICSD
	Deloneite	9.51 Å	9.51 Å	7.01 Å	90.00 °	90.00 °	120.00 °		ICSD
	(Ce)
	Fluorcaphite 9.49 Å	9.49 Å	7.00 Å	90.00 °	90.00 °	120.00 °		ICSD
	Calcite	4.99 Å	4.99 Å	17.06 Å	90.00 °	90.00 °	120.00 °		HKL
	Britholite	9.55 Å	9.55 Å	6.99 Å	90.00 °	90.00 °	120.00 °		ICSD
	Britholite	9.70 Å	9.70 Å	7.13 Å	90.00 °	90.00 °	120.00 °		ICSD
	(Ce)
	Britholite	9.63 Å	9.63 Å	7.06 Å	90.00 °	90.00 °	120.00 °		ICSD
	(Ce)
	Apatite	9.39 Å	9.39 Å	6.90 Å	90.00 °	90.00 °	120.00 °		AM
	Apatite	9.40 Å	9.40 Å	6.89 Å	90.00 °	90.00 °	120.00 °		AM
	Apatite	9.46 Å	9.46 Å	6.88 Å	90.00 °	90.00 °	120.00 °		ICSD
	Apatite	9.45 Å	9.45 Å	6.88 Å	90.00 °	90.00 °	120.00 °		ICSD
	Apatite	9.46 Å	9.46 Å	6.88 Å	90.00 °	90.00 °	120.00 °		ICSD
	Apatite	9.46 Å	9.46 Å	6.88 Å	90.00 °	90.00 °	120.00 °		ICSD
	!				236

C ! 235 Figure 1 a Apatite-britholite en LPNA. b Carte de chimie. c carte d'orientation de l'apatite et exsolutions de britholites selon l'axe IPFX. d orientation IPFX de la britholite

Table 1 :

 1 Continued Rock typeSi-rich Carbonatite

	!

Table 1 :

 1 Continued Rock typeSi-rich Carbonatite

	Sample
	Type	Middle	Rim	Rim	Rim	Rim	Rim	Core	Middle	Line1	Line1	Line1
	SiO2	31.40	31.69	31.70	31.45	31.08	31.30	31.20	31.40	31.03	30.76	31.16
	TiO2	0.01	0.02	0.01	0.01	0.01	0.01	0.01	0.02	0.01	0.02	0.01
	ZrO2	66.66	66.90	67.00	67.07	67.53	67.33	67.38	67.13	67.56	68.41	67.68
	FeO	0.05	0.05	0.02	0.01	0.01	0.01	b.d.	b.d.	0.01	0.01	b.d.
	CaO	0.06	0.02	0.03	0.07	0.04	0.03	0.02	0.01	0.03	0.09	0.03
	PbO	0.01	-	0.01	-	-	0.01	-	0.01	-	b.d.	-
	UO2	-	-	-	-	-	-	-	-	-	-	-
	ThO2	0.01	-	-	0.33	0.06	0.12	0.24	-	0.15	0.05	-
	Y2O3	-	-	-	-	-	-	-	-	-	-	-
	Yb2O3	-	-	-	-	0.01	0.08	0.02	0.01	-	0.05	-
	HfO2	0.55	0.54	0.57	0.55	0.56	0.55	0.55	0.56	0.54	0.56	0.54
	Total	98.75	99.22	99.33	99.48	99.30	99.43	99.42	99.13	99.32	99.95	99.42
	Numbers of ions on the basis of 16O
	Si	3.92	3.93	3.93	3.90	3.87	3.89	3.88	3.91	3.87	3.82	3.87
	Ti	0.001	0.001	0.001	0.001	0.001	0.001	0.001	0.002	0.001	0.001	0.001
	Zr	4.06	4.05	4.05	4.06	4.10	4.08	4.09	4.07	4.11	4.15	4.10
	Fe2+	0.005	0.005	0.002	0.001	0.001	0.001	-	-	0.001	0.001	-
	Ca	0.008	0.003	0.004	0.009	0.005	0.004	0.003	0.001	0.003	0.011	0.004
	Th	-	-	-	0.009	0.002	0.003	0.007	-	0.004	0.001	-
	Y	-	-	-	-	-	-	-	-	-	-	-
	Yb	-	-	-	-	0.000	0.003	0.001	0.000	-	0.002	-
	Hf	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02
	Total	8	8	8	8	8	8	8	8	8	8	8
	b.d. :below deection
	!		!

Numbers of ions on the basis of 16O Si

	Type	Line4	Line4	Line4	Line4	Line4	Line4	Line4	Line4	Line4	Rim	Middle
	SiO2	31.17	31.20	31.38	31.17	30.94	31.14	31.08	31.22	31.27	31.52	31.38
	TiO2	0.01	0.01	0.01	0.01	0.01	0.01	0.01	0.01	0.01	0.01	0.01
	ZrO2	66.89	66.55	66.80	66.46	66.55	66.65	66.87	66.77	66.86	67.08	67.14
	FeO	0.01	0.01	0.01	0.13	b.d.	b.d.	b.d.	0.01	b.d.	0.10	0.03
	CaO	0.01	0.04	0.00	0.02	0.05	0.02	0.02	0.03	0.03	0.05	0.02
	PbO	0.02	0.02	-	-	0.01	0.01	-	0.01	b.d.	-	-
	UO2	-	-	-	-	-	-	-	-	-	-	-
	ThO2	0.04	0.07	-	0.16	-	-	0.09	0.08	0.07	-	-
	Y2O3	-	-	-	-	-	-	-	-	-	-	-
	Yb2O3	0.03	-	-	0.04	-	0.08	-	-	-	0.05	0.05
	HfO2	0.55	0.57	0.54	0.58	0.58	0.56	0.58	0.57	0.58	0.50	0.46
	Total	98.76	98.50	98.76	98.58	98.16	98.50	98.64	98.72	98.84	99.30	99.10
		3.98	3.95	3.95	3.93	3.92	3.92	3.92	3.93	3.94	3.90	3.93
	Ti	0.001	0.001	0.001	0.001	0.000	0.001	0.001	0.000	0.001	0.001	0.000
	Zr	3.99	4.02	4.02	4.04	4.05	4.06	4.05	4.04	4.03	4.07	4.03
	Fe2+	0.002	0.001	0.001	0.001	0.001	0.002	0.001	0.001	0.001	0.001	0.003
	Ca	0.013	0.007	0.006	0.004	0.004	0.003	0.004	0.001	0.002	0.003	0.023
	Th	-	0.002	0.007	0.002	0.008	-	0.002	0.005	0.004	0.001	-
	Y	-	-	-	-	-	-	-	-	-	-	0.006
	Yb	-	0.003	-	-	-	-	-	-	-	-	0.002
	Hf	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02
	Total	8	8	8	8	8	8	8	8	8	8	8
	b.d. :below deection
	!		!

Numbers of ions on the basis of 16O Si

	Type	Rim	Core	Middle	Rim	Rim	Core	Rim	Core	Rim	Rim
	SiO2	31.20	25.46	31.24	31.58	31.71	31.57	31.37	31.72	31.56	31.98
	TiO2	0.02	b.d.	0.01	0.02	0.01	0.01	0.01	0.01	0.01	0.01
	ZrO2	67.23	56.32	67.14	66.28	66.63	66.85	67.60	66.61	66.34	65.69
	FeO	0.03	0.01	0.02	0.05	-	b.d.	0.01	0.01	0.08	0.12
	CaO	0.10	10.27	0.04	0.06	0.04	0.01	0.03	0.01	0.04	0.07
	PbO	-	0.01	b.d.	-	-	b.d.	-	0.01	-	-
	UO2	-	-	-	-	-	-	-	-	-	-
	ThO2	-	0.18	-	-	-	-	-	-	-	-
	Y2O3	-	-	-	-	-	-	-	-	0.02	-
	Yb2O3	-	-	-	0.02	-	-	0.11	-	0.01	-
	HfO2	0.55	0.52	0.56	0.58	0.56	0.48	0.49	0.49	0.47	0.46
	Total	99.12	92.79	99.00	98.58	98.94	98.92	99.63	98.87	98.53	98.32
		3.90	3.91	3.92	3.91	3.89	3.90	3.89	3.90	3.90	3.91	3.90
	Ti	0.001	0.001	0.001	0.001	0.001	0.001	0.001	0.001	0.001	0.001	0.001
	Zr	4.08	4.06	4.06	4.06	4.08	4.07	4.08	4.07	4.07	4.06	4.07
	Fe2+	0.001	0.001	0.001	0.014	-	-	-	0.001	-	0.01	0.004
	Ca	0.002	0.006	0.001	0.002	0.006	0.003	0.002	0.004	0.004	0.007	0.003
	Th	0.001	0.002	-	0.004	-	-	0.003	0.002	0.002	-	-
	Y	-	-	-	-	-	-	-	-	-	-	-
	Yb	0.001	-	-	0.001	-	0.003	-	-	-	0.002	0.002
	Hf	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02
	Total	8	8	8	8	8	8	8	8	8	8	8
	b.d. :below deection
	!		!

Numbers of ions on the basis of 16O Si

	Type	Rim	mant	core	core	Rim	Rim	core	core	Rim	Rim	core
	SiO2	31.29	31.23	31.15	31.08	31.26	31.33	31.12	31.16	31.16	31.09	31.38
	TiO2	0.02	0.02	0.01	0.02	0.01	0.02	0.02	0.02	0.02	0.02	0.02
	ZrO2	66.36	66.29	66.33	65.95	66.48	66.60	64.38	67.93	66.83	66.38	66.12
	FeO	0.03	0.02	0.04	0.04	0.04	0.08	0.07	0.07	0.05	0.01	b.d.
	CaO	0.01	0.02	0.02	0.01	0.01	0.01	0.29	0.16	b.d.	0.01	0.01
	PbO	0.10	0.13	0.07	0.33	0.14	0.07	0.04	0.03	0.06	-	0.02
	UO2	-	0.01	-	0.54	0.06	-	-	-	-	-	-
	ThO2	0.08	-	0.05	-	-	0.07	0.06	-	-	-	0.18
	Y2O3	-	0.02	0.01	0.12	0.01	0.04	0.03	0.01	0.03	-	b.d.
	Yb2O3	b.d.	0.11	-	b.d.	b.d.	0.01	b.d.	0.08	-	0.01	-
	HfO2	1.19	1.21	1.06	0.93	0.99	0.97	1.03	1.23	0.99	0.97	1.06
	Total	99.09	99.06	98.75	99.02	99.00	99.20	97.03	100.69	99.14	98.49	98.80
		3.89	3.47	3.89	3.94	3.94	3.93	3.89	3.94	3.94	3.98
	Ti	0.001	0.000	0.001	0.001	0.001	0.001	0.001	0.001	0.001	0.001
	Zr	4.08	3.75	4.08	4.03	4.04	4.05	4.09	4.04	4.04	3.99
	Fe2+	0.003	0.002	0.002	0.005	-	-	0.001	0.001	0.008	0.012
	Ca	0.013	1.502	0.005	0.009	0.005	0.001	0.004	0.001	0.005	0.010
	Th	-	0.006	-	-	-	-	-	-	-	-
	Y	-	-	-	-	-	-	-	-	0.002	-
	Yb	-	-	-	0.001	-	-	0.004	-	-	-
	Hf	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02
	Total	8	9	8	8	8	8	8	8	8	8
	b.d. :below deection
	!		!

Numbers of ions on the basis of 16O Si

	Table 1: Continued
	Rock type						Red Syenite
	Sample	IC2-6A. Z3.3	IC2-6A. Z3.4	IC2-6A. Z3.5	IC2-6A. Z4.1	IC2-6A. Z4.2	IC2-6A. Z4.3	IC2-6A. Z4.4	IC2-6A. Z4.5	IC2-6A. Z4.6	IC2-6A. Z5.1	IC2-6A. Z5.2
	Type	Rim	mant	Rim	Rim	mant	core	Rim	core	Rim	Rim	Rim
	SiO2	31.14	31.18	31.22	31.09	31.34	31.19	31.25	31.15	31.20	31.22	31.11
	TiO2	0.01	0.02	0.02	0.02	0.02	0.01	0.02	0.02	0.01	0.02	0.01
	ZrO2	66.51	66.59	66.37	66.67	66.95	66.49	66.67	66.80	66.81	66.55	66.87
	FeO	0.01	0.01	0.01	0.06	0.20	0.13	0.08	0.04	0.02	0.01	0.00
	CaO	0.01	0.01	0.02	0.01	0.01	0.01	0.01	0.01	0.01	b.d.	0.02
	PbO	b.d.	0.02	0.02	0.04	0.07	0.02	0.03	0.05	0.04	0.02	0.03
	UO2	-	-	-	-	-	-	-	-	-	-	-
	ThO2	-	0.03	-	-	0.11	0.09	0.26	-	-	-	0.02
	Y2O3	-	-	0.01	0.03	0.02	0.01	0.02	0.04	0.02	-	-
	Yb2O3	0.10	-	-	0.06	0.02	-	0.07	-	0.08	-	0.03
	HfO2	1.01	0.97	1.00	0.95	0.94	0.98	0.98	0.97	1.01	1.04	1.03
	Total	98.80	98.83	98.68	98.92	99.67	98.93	99.39	99.08	99.19	98.87	99.11
		3.91	3.91	3.90	3.90	3.91	3.91	3.95	3.85	3.89	3.90	3.92
	Ti	0.002	0.002	0.001	0.002	0.001	0.002	0.002	0.001	0.002	0.002	0.002
	Zr	4.04	4.04	4.05	4.03	4.05	4.05	3.98	4.09	4.07	4.06	4.03
	Fe2+	0.003	0.002	0.004	0.005	0.004	0.009	0.007	0.007	0.005	0.001	-
	Ca	0.002	0.003	0.003	0.001	0.001	0.002	0.040	0.021	0.001	0.002	0.001
	Th	0.002	-	0.001	-	-	0.002	0.002	-	-	-	0.005
	Y	-	0.001	0.001	0.008	0.001	0.003	0.002	0.000	0.002	-	-
	Yb	-	0.004	-	-	-	-	-	0.003	-	-	-
	Hf	0.04	0.04	0.04	0.03	0.04	0.03	0.04	0.04	0.04	0.03	0.04
	Total	8	8	8	8	8	8	8	8	8	8	8
	b.d. :below deection
	!		!

Numbers of ions on the basis of 16O Si

	Table 1: Continued
	Rock type						Red Syenite
	Sample	IC2-6A. Z5.3	IC2-6A. Z5.4	IC2-6A. Z5.5	IC2-6A. Z5.6	IC2-6A. Z5.7	IC2-6A. Z6.1	IC2-6A. Z6.2	IC2-6A. Z6.3	IC2-6A. Z6.4	IC2-6A. Z6.5	IC2-6A. Z6.6
	Type	Middle	Core	Middle	Rim	Rim	Rim	Middle	Core	Core	Rim	Rim
	SiO2	31.34	31.48	31.17	31.14	31.07	30.99	31.16	31.34	31.20	31.19	31.09
	TiO2	0.01	0.02	0.01	0.02	0.01	0.01	0.02	0.01	0.02	0.01	0.02
	ZrO2	66.51	66.23	66.35	66.60	66.58	69.17	67.15	66.71	66.59	66.71	66.31
	FeO	b.d.	-	0.02	0.01	0.02	0.02	0.01	0.01	0.01	0.02	0.01
	CaO	b.d.	0.01	0.02	0.01	0.05	0.01	0.02	b.d.	0.01	0.01	b.d.
	PbO	0.01	0.02	0.02	0.03	0.02	0.05	0.02	0.02	0.05	0.03	0.03
	UO2	-	-	-	-	-	-	-	-	-	-	-
	ThO2	0.13	0.13	-	-	-	0.12	0.15	-	-	-	0.02
	Y2O3	-	0.03	b.d.	0.04	0.02	0.01	0.02	0.01	0.02	0.02	0.02
	Yb2O3	0.02	0.04	-	0.01	-	0.05	-	0.03	-	-	-
	HfO2	1.03	1.07	1.07	1.02	1.07	0.98	0.98	1.01	1.03	1.01	1.03
	Total	99.05	99.02	98.66	98.88	98.84	101.41	99.53	99.13	98.94	99.00	98.53
		3.90	3.90	3.91	3.89	3.89	3.90	3.90	3.89	3.89	3.90	3.89
	Ti	0.001	0.002	0.002	0.002	0.002	0.001	0.002	0.002	0.001	0.002	0.001
	Zr	4.06	4.06	4.05	4.07	4.06	4.05	4.05	4.07	4.06	4.06	4.07
	Fe2+	0.001	0.001	0.001	0.007	0.021	0.014	0.008	0.004	0.002	0.001	0.000
	Ca	0.001	0.002	0.003	0.001	0.001	0.001	0.002	0.001	0.001	0.001	0.002
	Th	-	0.001	-	-	0.003	0.003	0.007	-	-	-	-
	Y	-	-	0.001	0.002	0.002	0.001	0.002	0.003	0.001	-	-
	Yb	0.004	-	-	0.002	0.001	-	0.003	-	0.003	-	0.001
	Hf	0.04	0.03	0.04	0.03	0.03	0.03	0.03	0.03	0.04	0.04	0.04
	Total	8	8	8	8	8	8	8	8	8	8	8
	b.d. :below deection
	!		!

Numbers of ions on the basis of 16O Si

	Table 1: Continued
	Rock type						Red Syenite
	Sample	IC2-6A. Z7.1	IC2-6A. Z7.2	IC2-6A. Z7.3	IC2-6A. Z7.4	IC2-6A. Z7.5	IC2-6A. Z7.6	IC2-6A. Z7.7	IC2-6A. Z7.8	IC2-6A. Z7.9	IC2-6A. Z7.10	IC2-6A. Z7.11
	Type	Rim	Core	Rim	Rim	Rim	Middle	Core	Rim	Rim	Rim	Rim
	SiO2	31.36	31.33	31.27	31.61	30.89	31.12	30.60	29.60	31.19	30.36	31.00
	TiO2	0.02	0.02	0.02	0.01	0.01	0.02	0.02	0.00	0.02	0.00	0.01
	ZrO2	66.80	66.26	66.42	67.03	66.09	66.21	65.86	62.92	66.69	61.95	66.34
	FeO	0.02	0.02	0.02	0.03	0.13	0.05	0.14	0.28	0.06	0.95	0.07
	CaO	0.01	0.02	0.02	0.07	0.24	0.02	0.10	0.42	0.00	1.40	0.01
	PbO	0.04	0.06	-	0.01	0.08	0.04	0.21	0.22	0.08	0.13	-
	UO2	-	-	-	-	-	-	0.17	0.21	-	-	-
	ThO2	-	-	-	-	0.12	-	0.13	-	-	-	-
	Y2O3	0.02	-	-	0.05	0.30	-	0.10	0.13	-	0.35	b.d.
	Yb2O3	-	-	0.07	0.03	0.15	0.01	-	0.01	0.08	0.10	0.05
	HfO2	1.06	1.18	1.08	1.04	0.98	1.21	1.15	1.07	1.15	0.99	0.96
	Total	99.31	98.89	98.90	99.88	98.99	98.69	98.48	94.86	99.28	96.22	98.44
		3.91	3.93	3.90	3.90	3.89	3.81	3.88	3.91	3.90	3.90	3.90
	Ti	0.001	0.002	0.001	0.001	0.001	0.001	0.002	0.001	0.002	0.001	0.002
	Zr	4.05	4.03	4.05	4.06	4.06	4.15	4.08	4.05	4.06	4.06	4.06
	Fe2+	0.000	-	0.002	0.001	0.002	0.002	0.001	0.001	0.001	0.002	0.002
	Ca	0.000	0.001	0.003	0.001	0.006	0.001	0.002	-	0.001	0.001	-
	Th	0.004	0.004	-	-	-	0.003	0.004	-	-	-	0.001
	Y	-	0.002	-	0.003	0.001	0.001	0.001	-	0.001	0.001	0.001
	Yb	0.001	0.001	-	-	-	0.002	-	0.001	-	-	-
	Hf	0.04	0.04	0.04	0.04	0.04	0.03	0.03	0.04	0.04	0.04	0.04
	Total	8	8	8	8	8	8	8	8	8	8	8
	b.d. :below deection
	!		!

Numbers of ions on the basis of 16O Si

	Type	Middle	Core	Middle	Rim	Rim	Rim	Core	Rim	Rim	Core	Rim
	SiO2	30.96	30.54	30.96	31.05	30.72	31.39	28.86	30.98	30.79	31.23	31.14
	TiO2	0.01	0.01	0.01	0.02	0.01	0.01	0.02	0.02	0.01	0.02	0.02
	ZrO2	67.11	66.26	66.37	66.42	64.93	66.60	63.05	67.21	65.90	66.78	66.80
	FeO	0.10	0.09	0.06	0.08	1.25	0.09	0.47	0.09	0.08	0.05	0.11
	CaO	0.03	0.02	b.d.	0.02	0.14	0.01	2.60	0.04	0.02	0.03	0.04
	PbO	0.15	0.11	0.14	-	0.13	0.04	0.16	0.01	0.15	0.01	0.10
	UO2	0.02	0.03	0.06	-	0.00	-	0.44	-	0.18	-	-
	ThO2	0.11	-	0.14	-	0.29	0.12	-	-	-	-	-
	Y2O3	0.05	0.01	0.11	-	0.11	-	0.12	b.d.	0.10	-	0.04
	Yb2O3	0.09	-	-	-	0.07	0.06	0.08	0.02	0.09	-	0.03
	HfO2	1.14	1.48	1.19	0.94	1.06	1.01	1.08	0.95	1.19	1.01	1.07
	Total	99.76	98.56	99.04	98.52	98.72	99.34	96.87	99.34	98.51	99.12	99.35
		3.90	3.92	3.91	3.91	3.87	3.90	3.87	3.88	3.89	3.91	3.89
	Ti	0.002	0.002	0.002	0.001	0.001	0.002	0.002	0.000	0.002	0.000	0.001
	Zr	4.05	4.04	4.05	4.04	4.04	4.05	4.06	4.02	4.06	3.89	4.06
	Fe2+	0.002	0.002	0.002	0.003	0.014	0.006	0.015	0.031	0.007	0.102	0.007
	Ca	0.001	0.003	0.003	0.010	0.033	0.003	0.014	0.059	-	0.194	0.002
	Th	-	-	-	-	0.003	-	0.004	-	-	-	-
	Y	0.001	-	-	0.003	0.020	-	0.007	0.009	-	0.024	-
	Yb	-	-	0.003	0.001	0.006	0.000	-	0.001	0.003	0.004	0.002
	Hf	0.04	0.04	0.04	0.04	0.04	0.04	0.04	0.04	0.04	0.04	0.03
	Total	8	8	8	8	8	8	8	8	8	8	8
	b.d. :below deection
	!		!

Numbers of ions on the basis of 16O Si

	Table 1: Continued
	Rock type						Red Syenite
	Sample	IC2-6A. Z8.2	IC2-6A. Z8.3	IC2-6A. Z8.4	IC2-6A. Z8.5	IC2-6A. Z8.6	IC2-6A. Z8.7	IC2-6A. Z8.8	IC2-6A. Z8.9	IC2-6A. Z9.1	IC2-6A. Z9.2	IC2-6A. Z9.3
	Type	Core	Rim	Rim	Rim	Rim	Core	Rim	Rim	Rim	Middle	Core
	SiO2	31.38	31.27	31.10	31.19	31.51	31.59	31.30	31.26	31.28	30.05	31.12
	TiO2	0.01	0.02	0.02	0.02	0.01	0.01	0.02	0.02	0.02	0.01	0.02
	ZrO2	66.53	66.79	65.53	66.40	66.45	66.22	66.73	66.48	66.66	69.39	67.05
	FeO	0.12	0.05	0.10	0.10	0.26	0.13	0.07	0.08	0.02	0.02	0.01
	CaO	0.01	0.02	0.06	0.01	0.01	0.01	0.01	0.01	0.01	0.02	b.d.
	PbO	0.06	0.05	0.07	0.05	0.01	0.02	0.07	0.03	0.02	0.05	0.05
	UO2	-	-	-	-	-	-	-	-	-	-	-
	ThO2	0.04	-	-	0.07	0.29	0.07	0.05	-	0.06	-	-
	Y2O3	b.d.	0.01	0.08	-	-	-	b.d.	-	-	0.01	0.02
	Yb2O3	-	0.10	0.04	-	-	0.01	-	-	0.01	0.05	-
	HfO2	1.18	1.06	1.01	1.05	0.96	1.12	0.94	1.12	0.95	1.00	0.94
	Total	99.35	99.36	98.00	98.89	99.51	99.18	99.19	98.99	99.01	100.59	99.21
		3.86	3.86	3.88	3.90	3.87	3.91	3.74	3.87	3.88	3.90	3.88
	Ti	0.001	0.001	0.001	0.002	0.001	0.001	0.002	0.001	0.001	0.001	0.002
	Zr	4.08	4.08	4.06	4.06	3.99	4.04	3.99	4.09	4.05	4.06	4.06
	Fe2+	0.010	0.010	0.006	0.008	0.132	0.010	0.051	0.010	0.008	0.005	0.012
	Ca	0.004	0.003	-	0.002	0.019	0.002	0.361	0.006	0.003	0.003	0.005
	Th	0.003	-	0.004	-	0.008	0.003	-	-	-	-	-
	Y	0.003	0.001	0.007	-	0.007	-	0.008	-	0.007	-	0.003
	Yb	0.003	-	-	-	0.003	0.002	0.003	0.001	0.003	-	0.001
	Hf	0.04	0.05	0.04	0.03	0.04	0.04	0.04	0.03	0.04	0.04	0.04
	Total	8	8	8	8	8	8	8	8	8	8	8
	b.d. :below deection
	!		!

Numbers of ions on the basis of 16O Si

	Table 1: Continued
	Rock type						Red Syenite
	Sample	IC2-6A. Z9.5	IC2-6A. Z9.6	IC2-6A-Z9.1	IC2-6A-Z9.2	IC2-6A-Z9.3	IC2-6A-Z9.4	IC2-6A-Z9.5	IC2-6A-Z9.6	IC2-6A-Z9.7	IC2-6A-Z9.8	IC2-6A-Z9.9
	Type	Middle	Rim	Line5	Line5	Line5	Line5	Line5	Line5	Line5	Line5	Line5
	SiO2	31.03	31.15	31.57	31.68	31.44	31.41	31.27	31.30	31.27	31.32	31.28
	TiO2	0.02	0.01	0.01	0.02	0.02	0.02	0.01	0.01	0.02	0.02	0.01
	ZrO2	66.83	66.93	65.63	65.60	65.39	65.40	64.99	65.43	65.23	65.65	65.56
	FeO	0.01	0.02	0.02	0.02	0.02	0.01	0.01	0.01	0.01	0.01	0.01
	CaO	0.01	0.01	0.01	0.01	0.01	0.02	0.01	0.01	0.01	0.01	0.01
	PbO	b.d.	-	b.d.	0.00	0.03	0.04	0.02	0.01	0.04	0.03	0.02
	UO2	-	-	-	-	-	-	-	-	-	-	-
	ThO2	-	0.10	0.16	-	-	b.d.	0.02	0.05	-	0.04	0.07
	Y2O3	-	b.d.	b.d.	-	-	-	-	-	0.01	0.01	0.01
	Yb2O3	0.08	-	-	-	-	0.09	-	-	0.01	0.12	-
	HfO2	1.01	0.93	1.00	1.03	1.04	1.05	1.03	1.02	1.01	1.02	1.00
	Total	98.99	99.15	98.47	98.39	97.97	98.07	97.39	97.87	97.65	98.23	98.01
		3.91	3.90	3.92	3.90	3.92	3.93	3.90	3.90	3.90	3.74	3.88
	Ti	0.001	0.002	0.002	0.002	0.001	0.001	0.002	0.001	0.001	0.001	0.001
	Zr	4.04	4.06	4.03	4.05	4.03	4.02	4.06	4.05	4.06	4.21	4.08
	Fe2+	0.012	0.005	0.011	0.010	0.027	0.013	0.008	0.008	0.002	0.002	0.001
	Ca	0.002	0.002	0.008	0.001	0.001	0.001	0.002	0.001	0.001	0.002	-
	Th	0.001	-	-	0.002	0.008	0.002	0.001	-	0.002	-	-
	Y	-	-	0.005	-	-	-	-	-	-	0.001	0.001
	Yb	-	0.004	0.001	-	-	-	-	-	-	0.002	-
	Hf	0.04	0.04	0.04	0.04	0.03	0.04	0.03	0.04	0.03	0.04	0.03
	Total	8	8	8	8	8	8	8	8	8	8	8
	b.d. :below deection
	!		!

Numbers of ions on the basis of 16O Si

	Table 1: Continued
	Rock type						Red Syenite
	Sample	IC2-6A-Z9.10	IC2-6A-Z9.11	IC2-6A-Z9.12	IC2-6A-Z9.13	IC2-6A-Z9.14	IC2-6A-Z9.15	IC2-6A-Z9.16	IC2-6A-Z9.17	IC2-6A-Z9.18	IC2-6A-Z9.19	IC2-6A-Z9.20
	Type	Line5	Line5	Line5	Line5	Line5	Line5	Line5	Line5	Line5	Line5	Line5
	SiO2	31.29	31.16	31.09	30.87	27.65	25.44	26.81	25.73	26.23	24.71	24.68
	TiO2	0.02	0.02	0.02	0.01	0.02	0.03	0.29	0.04	0.01	0.01	0.04
	ZrO2	65.66	65.64	65.52	65.77	67.00	61.97	59.32	63.26	65.03	65.95	51.14
	FeO	0.01	0.01	0.01	0.01	0.01	0.02	0.03	0.01	0.01	0.01	0.02
	CaO	0.01	0.01	0.01	b.d.	0.01	0.05	0.09	0.05	0.04	0.07	0.18
	PbO	0.03	0.05	0.04	0.04	0.05	0.04	0.04	0.03	0.03	-	0.01
	UO2	-	-	-	-	-	-	-	-	-	-	-
	ThO2	-	0.08	0.05	0.10	0.05	0.17	-	0.13	0.22	0.18	-
	Y2O3	0.02	b.d.	0.01	0.02	0.03	0.01	0.01	0.01	-	0.01	0.02
	Yb2O3	0.14	-	b.d.	-	0.13	0.07	0.08	0.10	0.09	-	-
	HfO2	0.99	0.98	0.98	0.99	1.04	1.01	1.01	1.07	1.11	1.06	0.97
	Total	98.18	97.97	97.76	97.84	96.04	88.83	87.69	90.45	92.79	92.05	77.09
		3.88	3.89	3.95	3.96	3.95	3.95	3.95	3.94	3.95	3.93	3.94
	Ti	0.002	0.001	0.001	0.002	0.002	0.002	0.001	0.001	0.002	0.001	0.001
	Zr	4.08	4.07	4.01	4.00	4.01	4.01	4.01	4.02	4.01	4.02	4.02
	Fe2+	0.002	0.002	0.002	0.002	0.002	0.001	0.001	0.001	0.001	0.001	0.001
	Ca	0.002	0.001	0.002	0.001	0.002	0.003	0.001	0.001	0.001	0.001	0.001
	Th	-	0.003	0.005	-	-	-	0.001	0.001	-	0.001	0.002
	Y	-	-	-	-	-	-	-	-	-	0.000	0.001
	Yb	0.003	-	-	-	-	0.003	-	-	-	0.005	-
	Hf	0.04	0.03	0.04	0.04	0.04	0.04	0.04	0.04	0.04	0.04	0.04
	Total	8	8	8	8	8	8	8	8	8	8	8
	b.d. :below deection
	!		!

Numbers of ions on the basis of 16O Si

	Table 1: Continued
	Rock type						Red Syenite
	Sample	IC2-6A-Z9.21	IC2-6A-Z9.22	IC2-6A-Z9.23	IC2-6A-Z9.24	IC2-6A-Z2.1	IC2-6A-Z2.2	IC2-6A-Z2.3	IC2-6A-Z2.4	IC2-6A-Z2.5	IC2-6A-Z2.6	IC2-6A-Z2.7
	Type	Line5	Line5	Line5	Line5	Line6	Line6	Line6	Line6	Line6	Line6	Line6
	SiO2	28.06	31.29	31.62	31.36	31.55	31.37	31.33	31.37	31.20	30.14	29.60
	TiO2	0.13	0.02	0.01	0.01	0.02	0.01	0.02	0.01	0.02	0.02	0.02
	ZrO2	63.06	64.24	65.19	65.06	64.92	64.30	64.26	65.38	65.61	65.36	65.68
	FeO	0.03	0.02	0.02	0.01	0.03	0.08	0.04	0.02	0.01	0.05	0.05
	CaO	0.07	0.01	b.d.	b.d.	0.03	0.10	0.04	0.01	0.03	0.17	0.15
	PbO	0.02	0.04	0.02	0.01	0.08	0.07	0.19	0.07	0.07	0.15	0.22
	UO2	-	-	-	-	-	-	0.11	-	-	0.07	0.31
	ThO2	0.13	-	-	-	0.03	-	0.07	0.16	-	-	0.03
	Y2O3	0.02	-	0.01	b.d.	-	0.05	0.05	0.01	b.d.	0.06	0.06
	Yb2O3	-	0.01	-	0.01	0.02	-	0.02	-	0.08	0.06	0.12
	HfO2	1.07	1.01	1.00	1.00	1.36	1.31	1.37	1.12	1.09	1.06	0.99
	Total	92.61	96.66	97.90	97.50	98.06	97.41	97.56	98.17	98.14	97.16	97.23
		3.93	3.93	3.93	3.90	3.64	3.63	3.81	3.61	3.60	3.45	3.95
	Ti	0.002	0.002	0.002	0.001	0.002	0.003	0.031	0.004	0.001	0.001	0.005
	Zr	4.02	4.03	4.03	4.05	4.31	4.31	4.11	4.33	4.35	4.49	3.99
	Fe2+	0.001	0.001	0.001	0.001	0.001	0.002	0.003	0.002	0.001	0.001	0.003
	Ca	0.001	0.001	0.001	0.001	0.001	0.007	0.013	0.007	0.007	0.011	0.032
	Th	-	0.002	0.001	0.003	0.002	0.005	-	0.004	0.007	0.006	-
	Y	0.002	-	0.001	0.002	0.002	0.001	0.001	0.001	-	-	0.001
	Yb	0.005	-	-	-	0.005	0.003	0.003	0.004	0.004	-	-
	Hf	0.04	0.04	0.04	0.04	0.04	0.04	0.04	0.04	0.04	0.04	0.04
	Total	8	8	8	8	8	8	8	8	8	8	8
	b.d. :below deection
	!		!

Numbers of ions on the basis of 16O Si

	Table 1: Continued
	Rock type								Red Syenite
	Sample	IC2-6A-Z2.8	IC2-6A-Z2.9	IC2-6A-Z2.10	IC2-6A-Z2.11	IC2-6A-Z2.12	IC2-6A-Z2.13	IC2-6A-Z2.14	IC2-6A-Z2.15	IC2-6A-Z2.16	IC2-6A-Z2.17	IC2-6A-Z2.18	IC2-6A-Z2.19	IC2-6A-Z2.20
	Type	Line6	Line6	Line6	Line6		Line6	Line6	Line6	Line6	Line6	Line6	Line6	Line6	Line6
	SiO2	24.90	26.04	30.79	30.18		29.35	28.64	30.92	31.61	31.19	31.40	31.93	30.73	32.05
	TiO2	0.03	0.02	0.01	0.02		0.02	0.02	0.01	0.01	0.01	0.01	0.02	0.00	0.03
	ZrO2	63.96	61.20	66.12	66.22		66.06	66.25	63.88	66.37	66.60	66.62	66.68	61.65	64.04
	FeO	0.06	0.07	0.03	0.03		0.05	0.17	0.05	0.04	0.05	0.06	0.06	0.21	0.17
	CaO	0.48	0.29	0.02	0.04		0.09	0.81	0.37	0.02	0.03	0.01	0.03	0.51	0.29
	PbO	0.19	0.18	0.27	0.27		0.26	0.13	0.06	0.04	0.10	0.14	0.08	0.30	0.06
	UO2	0.34	0.12	0.30	0.38		0.39	-	-	-	-	0.02	-	0.28	-
	ThO2	0.17	-	-	-		0.12	0.22	0.04	0.17	-	0.01	-	0.08	0.02
	Y2O3	0.06	0.05	0.08	0.08		0.07	0.02	b.d.	-	0.05	0.04	0.02	0.36	0.36
	Yb2O3	0.05	0.03	0.06	0.08		0.07	-	0.08	-	0.04	0.06	0.08	0.05	0.01
	HfO2	0.98	1.03	1.00	0.96		0.96	0.99	1.04	1.02	1.01	0.97	0.98	0.95	0.99
	Total	91.25	89.04	98.68	98.28		97.48	97.27	96.48	99.30	99.10	99.37	99.90	95.38	98.18
		3.79	3.98	3.97		3.96	3.97	3.97	3.97	3.94	3.93	3.86	3.81
	Ti	0.013	0.002	0.001	0.001	0.002	0.001	0.002	0.001	0.002	0.002	0.002
	Zr	4.15	3.98	3.99		4.00	3.98	3.97	3.97	4.01	4.03	4.08	4.12
	Fe2+	0.003	0.002	0.002	0.002	0.003	0.009	0.004	0.002	0.001	0.005	0.005
	Ca	0.010	0.002	0.000	0.001	0.004	0.014	0.006	0.001	0.003	0.024	0.021
	Th	0.004	-	-			-	0.001	-	0.002	0.005	-	-		0.001
	Y	0.001	-	0.001		-	-	0.004	0.003	0.001	-	0.004	0.004
	Yb	-	-	-			-	0.001	-	0.001	-	0.003	0.002	0.005
	Hf	0.04	0.04	0.04		0.04	0.05	0.05	0.05	0.04	0.04	0.04	0.04
	Total	8	8	8		8	8	8	8	8	8	8	8
	b.d. :below deection
	!		!

Numbers of ions on the basis of 16O Si

		3.50	3.69	3.88	3.83	3.78	3.71	3.95	3.93	3.90	3.91	3.94	3.98	4.01
	Ti	0.003	0.002	0.001	0.002	0.002	0.001	0.001	0.001	0.001	0.001	0.002	-	0.002
	Zr	4.39	4.23	4.06	4.10	4.15	4.18	3.98	4.02	4.06	4.04	4.01	3.90	3.90
	Fe2+	0.008	0.008	0.003	0.004	0.005	0.018	0.005	0.004	0.005	0.006	0.006	0.023	0.018
	Ca	0.073	0.044	0.002	0.005	0.013	0.112	0.051	0.003	0.003	0.002	0.004	0.070	0.038
	Th	0.005	-	-	-	0.003	0.007	0.001	0.005	-	-	-	0.002	0.001
	Y	0.005	0.004	0.005	0.005	0.005	0.001	-	-	0.003	0.003	0.002	0.025	0.024
	Yb	0.002	0.001	0.002	0.003	0.003	-	0.003	-	0.001	0.002	0.003	0.002	-
	Hf	0.04	0.04	0.04	0.03	0.04	0.04	0.04	0.04	0.04	0.03	0.03	0.04	0.04
	Total	8	8	8	8	8	8	8	8	8	8	8	8	8
	b.d. :below deection

terres rares dans les carbonatites sont la bastnäsite, la monazite et le xénotime qui présentent des minéraux primaires et hydrothermaux par plusieurs processus d'enrichissement supergènes(Mariano et Mariano Jr,

;[START_REF] Harlov | Apatite and fluids: a fingerprint for metasomatic processes Elements[END_REF][START_REF] Chen | Geochemistry of Monazite within Carbonatite Related REE Deposits[END_REF].

détecteur HKL NordlysNano EBSD pour l'analyse cristallographique et un détecteur EDS X-Max N 20mm 2 à spectrométrie à rayon X pour l'analyse chimique qualitative. Une tension d'accélération de 15 à 20 kV, un courant de faisceau d'environ 5 nA, une taille de pas de 2,7 et 10 µm et une distance de travail de 25 mm sont les conditions d'analyses utilisées. La déviation angulaire pour les mesures est de 20º entre le faisceau d'électrons et la surface de l'échantillon pour atteindre une intensité maximale de diffraction. Les données sont réduites en bruit à l'aide d'une correction pour remplir les pixels non indexés «Wild spikes» en fonction des pixels voisins à l'aide du logiciel CHANNEL5 (Oxford Instruments HKL).Des cartes de phases et des cartes de 11 éléments (Th, Ce, La, Nd, P, Si, Al, Ca, S, Cl, et C) ont été réalisées afin de mettre en évidence les propriétés chimiques des apatites et des exsolutions en britholite et la distribution des éléments dans les minéraux. Les cartographies microstructurales et les figures de pôles ont été réalisées afin de mettre en évidence l'orientation cristallographique des minéraux. Les cartographies d'orientation représentent l'orientation cristallographique de chaque pixel par une couleur fonction de la figure de pôles inverses, selon un des trois axes principaux (X, Y, Z). A partir de l'orientation cristallographique de chacun des pixels, il est dès lors possible de déterminer l'orientation cristallographique préférentielle (Crystallographic Preferred Orientation CPO), qui est définie par la fabrique des minéraux et indique l'orientation dominante.

Contactecarbonatitepegmatite IC1-2B X X X X X IC1-2C X X X X X ? X IC1-3A carbonatite pegmatitique X X X X X X IC1-3B X X X X X X X Fl Fluorite dans FK ? IC1-3C contact carb + pegmatite pegmatitique X IC1-3D feldspath pegmatitique pegmatitique X X X Petits cristaux de Cpx+All IC1-3E X IC1-3F X X X X Fk altéré IC1-3G X X X X IC1-4A Carbonatite bréchique grenue à grains fins X X X X IC1-4B X X X X X Cpx altéré IC1-4C X X X X X X contact avec syenite IC1-5A Carb+Syenite grenue X X X X X IC1-5B Carb+Syenite grenue X X X X X X IC1-7A Dolerite grenue X X plagio IC1-11 filon de quartz grenue X Filon de quartz IC1-12A Syenite rouge grenue X X X X X X Minéral doré? IC1-12 Carbonatite bréchique grenue X X X X X ? Gt FK altéré IC1-12E Carb+Syenite grenue X X X X X X X X Gt IC1-12D grenue X X X X X X X Gt IC1-12B grenue X X X X X X X Fl ? IC1-12C grenue X X X X X X X IC1-13 Syénite blanche grenue X X X X X XAp en inclusion dans Cpx IC1-13B pegmatite de syénite grenue X X X X X

Cpx déstabilisé IC2-7B pegmatite de syénite grenue X X X X X ? X +Micas IC2-9A Carb bréchique grenue porphyroide X X X X X X X X Gt IC2-9B X X X X X X X X Gt IC2-9C Carb + syenite X X X X X X X X X Gt inclusion de syenite dans la carbonatite IC2-10A Carb + Syenite grenue X ? X X X X Gt IC2-10B Carb + Syenite grenue X X X X X X X Gt IC2-10C Carb + Syenite grenue X X X X X Gt des FK en points triples IC2-11A carbonatite pegmatitique X X X X X X X X Gt inclusion de syenite dans la carbonatite IC2-11B Carb + Syenite pegmatitique X X X X X X X IC2-11C Carb + Syenite pegmatitique X X X X X X X IC2-11D Carb + Syenite pegmatitique X X X X X X X X Gt Qtz autour du Cpx IC2-15A Syénite rouge grenue X X X X X ? X Petits cristaux d'apatite sans inclusions IC2-15B Syénite + dolérite grenue X X X X ? X IC2-20A Carb bréchique grenue X X X X X allanite rouge dans les fissures d'apatite IC2-20B X X X X X cumulats de Cpx IC2-21 carbonatite pegmatitique X X X X X allanite rouge dans les fissures d'apatite IC2-27A Syénite blanche grenue X X X X X X X IC2-27B X X X X X X XTable 1 (suite) composition des carbonatites et syénites d'Ihouhaouene

Minéral doré? IC3-19A Carbonatite pegmatitique X X X X X X X carbonatite en poche IC3-19B contact Carbsyenite grenue X X X X X X X IC3-20 Carbonatite pegmatitique X X X X X X IC3-21A Carbonatite pegmatitique X X X IC3-21B Carbonatite pegmatitique X X X X X X IC3-10 Syénite blanche grenue X ? X X X X X X IC3-12B Syénite blanche grenue X X X X X X X X X GtMinéral doré? Table 1 (suite) composition des carbonatites et syénites d'Ihouhaouene

Remerciements

Acknowledgements This study was financially supported by the FP7-PEOPLE-IRSES project MEDYNA (2014-2017) "Maghreb-EU research staff exchange on geodynamics, geohazards, and applied geology in Northwest Africa", the French Embassy of Algiers through a PROFAS B+ research grant to A.D (2016-2017) and by the French National Institute of Earth Sciences (INSU-SYSTER 2016). We thank the authorities, field guided and drivers of Ahaggar National Park (Tamanghasset), and M. Amara for their valuable assistance during field campaigns. The help of C. Martin, L. Causse and B. Boyer for analytical work is gratefully acknowledged. We thank C. Nevado and D. Delmas for their appreciated technical assistance, Justine Villard and Rabia Benchabane for their support.

Chapitre II : Processus magmatiques ! '(!

Supplementary Data B2 illustration

P-T-X conditions of the chosen experimental studies:

The compositions of equilibrium melt calculated from clinopyroxene and apatite REE and trace elements are determined from experimental partition coefficients (mineral/melt) that obey the Henry's Law and concentrations are function of the intensity of the process.

We chose partition coefficient between:

-