Matthieu Harlaux
email: matthieu.harlaux@unige.ch

Julien Mercadier

Christian Marignac

Johan Villeneuve

Bernard Mouthier

Michel Cuney

Origin of the atypical Puy-les-Vignes W breccia pipe (Massif Central, France) constrained by trace element and boron isotopic composition of tourmaline

Keywords: Tourmaline, Boron isotopes, Trace elements, Tungsten deposit, Breccia pipe, French Massif Central

Introduction

The stability of tourmaline in a large number of geological environments, from sedimentary to hydrothermal, metamorphic, and magmatic settings, makes it an excellent monitor for determining the physico-chemical conditions and the processes involved during its crystallization [START_REF] Dutrow | Tourmaline: a geological DVD[END_REF][START_REF] Von Goerne | Experimental determination of Na-Ca distribution between tourmaline and fluid in the system CaO-Na2O-MgO-Al2O3-SiO2-B2O3-H2O[END_REF]. The chemical and isotopic compositions of tourmaline can, for instance, yield information about the temperature, composition and source of the fluids [START_REF] Von Goerne | Experimental determination of Na-Ca distribution between tourmaline and fluid in the system CaO-Na2O-MgO-Al2O3-SiO2-B2O3-H2O[END_REF][START_REF] Marschall | Tourmaline isotopes: no element left behind[END_REF][START_REF] Slack | Tourmaline as a recorder of ore-forming processes[END_REF]. Tourmaline is a common mineral in granite-related W-Sn deposits, which dominantly consist of wolframite-cassiterite-bearing hydrothermal veins spatially associated with granitic intrusions and represent economically important producers of W and Sn [START_REF] Baker | A comparison of graniterelated tin, tungsten, and gold-bismuth deposits: implications for exploration[END_REF][START_REF] Černý | Granite-related Ore Deposits[END_REF]. In these magmatichydrothermal systems, tourmaline generally represents an accessory mineral phase, locally abundant, in evolved granites and related pegmatites, greisens, quartz veins, and breccia pipes [START_REF] London | Chemical variation and significance of tourmaline from southwest England[END_REF][START_REF] Williamson | Geochemical constraints from zoned hydrothermal tourmalines on fluid evolution and Sn mineralization: an example from fault breccias at Roche[END_REF][START_REF] Jiang | Trace and rare-earth element geochemistry in tourmaline and cassiterite from the Yunlong tin deposit, Yunnan, China: implication for migmatitichydrothermal fluid evolution and ore genesis[END_REF][START_REF] Mlynarczyk | Zoned tourmaline associated with cassiterite: implications for fluid evolution and tin mineralization in the San Rafael Sn-Cu deposit, southeastern Peru[END_REF][START_REF] Lerouge | Conditions of formation and origin of fluids of quartztourmaline veins in the La Châtaigneraie tungstiferous district (Massif Central, France): fluid inclusions and stable isotopes[END_REF][START_REF] Mahjoubi | Structural, mineralogical, and paleoflow velocity constraints on Hercynian tin mineralization: the Achmmach prospect of the Moroccan Central Massif[END_REF][START_REF] Duchoslav | Changes in tourmaline composition during magmatic and hydrothermal processes leading to tin-ore deposition: The Cornubian Batholith, SW England[END_REF][START_REF] Codeço | Chemical and boron isotopic composition of hydrothermal tourmaline from the Panasqueira W-Sn-Cu deposit[END_REF][START_REF] Hong | Tourmaline-rich features in the Heemskirk and Pieman Heads granites from western Tasmania, Australia: Characteristics, origins, and implications for tin mineralization[END_REF]. The spatial association between tourmalinization and the occurrence of W-Sn deposits is thus well documented worldwide.

Their genetic relationship is, however, debated since cases of intense tourmalinization without associated mineralization are known (e.g., [START_REF] Marignac | Fluid evolution in an unmineralized greisen-tourmaline system in the Ment granite (central Morocco): a fluid-inclusion study[END_REF][START_REF] London | Chemical variation and significance of tourmaline from southwest England[END_REF][START_REF] Demirel | Geology and chemical variations in tourmaline from the quartz-tourmaline breccias within the Kerkenez granite-monzonite massif, Central Anatolian Crystalline Complex, Turkey[END_REF]. Several questions remain open about (i) the source of boron, (ii) the origin of the hydrothermal fluids, and (iii) the role of these fluids in W-Sn oreforming processes.

In granite-related W-Sn deposits, tourmaline may form during the magmatic stage as a latecrystallizing phase from the silicate melt, during the magmatic-hydrothermal transition as veins, breccias, replacements, or cavity-filling mineral precipitating from exsolved magmatic fluids, or during later hydrothermal episodes involving external fluids (meteoric, metamorphic, etc). Many studies considered the hydrothermal fluids and metals (W, Sn) to be of magmatic origin derived from evolved peraluminous granites (e.g., [START_REF] Audétat | Magmatic-hydrothermal evolution in a fractionating granite: A microchemical study of the Sn-W-F-mineralized Mole Granite (Australia)[END_REF][START_REF] Williamson | Source and partitioning of B and Sn in the Cornubian batholith of southwest England[END_REF][START_REF] Hulsbosch | Fluid fractionation of tungsten during granite-pegmatite differentiation and the metal source of peribatholitic W quartz veins: Evidence from the Karagwe-Ankole Belt (Rwanda)[END_REF][START_REF] Harlaux | Geochemical signature of magmatic-hydrothermal fluids exsolved from the Beauvoir rare-metal granite (Massif Central, France): insights from LA-ICPMS analysis of primary fluid inclusions[END_REF]Harlaux et al., , 2018a)). However, the origin of boron and tourmaline in granite-related W-Sn deposits remains controversial. A magmatic origin of the boron-rich fluids was proposed for the Panasqueira W-Sn deposit (Portugal) based on the chemical and isotopic compositions of tourmaline [START_REF] Codeço | Chemical and boron isotopic composition of hydrothermal tourmaline from the Panasqueira W-Sn-Cu deposit[END_REF][START_REF] Launay | Deciphering fluid flow at the magmatic-hydrothermal transition: A case study from the world-class Panasqueira W-Sn-(Cu) ore deposit (Portugal)[END_REF]. Mixing between magmatic and meteoric fluids was proposed for the Sn deposits of the Cornubian Batholith (England) using the same approach [START_REF] Williamson | Geochemical constraints from zoned hydrothermal tourmalines on fluid evolution and Sn mineralization: an example from fault breccias at Roche[END_REF][START_REF] Drivenes | Late-magmatic immiscibility during batholith formation: assessment of B isotopes and trace elements in tourmaline from the Land's End granite[END_REF][START_REF] Duchoslav | Changes in tourmaline composition during magmatic and hydrothermal processes leading to tin-ore deposition: The Cornubian Batholith, SW England[END_REF]. Mass balance calculations and geochemical modelling suggested, however, that the boron budget in the Sn deposits of the Cornubian Batholith cannot be derived from the granitic melts alone, but that an additional source from the metamorphic country rocks is required [START_REF] Williamson | Source and partitioning of B and Sn in the Cornubian batholith of southwest England[END_REF]. A mixed magmatic-metamorphic origin or a metamorphic-dominated origin of the fluids were proposed for other W-Sn deposits based on mineral chemistry, fluid inclusion, and stable isotope data (e.g., [START_REF] Blamart | A comparative thermobarometric (chemical and isotopic) study of a tourmalinized pelite and its Sn-Be vein, Walmès, Morocco[END_REF]Vallance et al., 2001;[START_REF] Chicharro | Origin, ore forming fluid evolution and timing of the Logrosán Sn-(W) ore deposits (Central Iberian Zone, Spain)[END_REF][START_REF] Dewaele | Genesis of the vein-type tungsten mineralization at Nyakabingo (Rwanda) in the Karagwe-Ankole belt, Central Africa[END_REF]Van Daele et al., 2018).

This study provides new constraints for the boron and fluid source(s) involved in the formation of granite-related W-Sn deposits, based on the Puy-les-Vignes wolframite-bearing breccia pipe in the French Massif Central (FMC). Like the majority of W-Sn deposits in the European Variscan belt, the tourmalinization at Puy-les-Vignes resulted from multi-stage hydrothermal alterations related to pre-ore fluid-rock interactions, formation of the W mineralization, and post-ore fracturing episodes. Tourmaline from Puy-les-Vignes therefore allows us to investigate the fluid evolution of the ore-forming hydrothermal system during pre-, syn-, and post-mineralization stages. Here, we present a complete characterization of tourmaline combining detailed paragenetic and textural observations, with in situ analysis of chemical (major, minor, and trace elements) and boron isotope compositions. Our results indicate the preponderant role of high-temperature fluid-rock interactions between the metamorphic basement and boron-rich hydrothermal fluids for tourmaline formation at Puyles-Vignes. We further discussed the magmatic vs. metamorphic origin of the fluids during the evolution of this atypical W-mineralized hydrothermal system.

Geological setting

The northwestern French Massif Central

The Puy-les-Vignes W deposit (Lat. 45°49'34"N, Long. 1°31'51"E) is located in the Limousin area in the northwestern FMC (Fig. 1), which belongs to the internal part of the European Variscan belt that formed during the continental collision between Gondwana and Laurussia through the Upper Paleozoic (Faure et al., 2009a and references therein). The regional structure of the FMC consists of a stack of metamorphic nappes that developed diachronously from Late Silurian to Early Carboniferous time. Three major tectonic units are recognized from top to bottom and from north to south (Faure et al., 2009a and references therein): (i) the Upper Gneiss Unit (UGU), which is composed of migmatitic ortho-and paragneisses derived from Cambrian to Ordovician protoliths (ca. 530 to 480 Ma; [START_REF] Alexandrov | Datation U-Pb à la microsonde ionique des zircons de l'unité supérieure de gneiss dans le Sud Limousin, Massif central[END_REF]Berger et al., 2010a;[START_REF] Chell-Michou | Pre-Cadomian to late-Variscan odyssey of the eastern Massif Central, France: Formation of the West European crust in a nutshell[END_REF], high-pressure and hightemperature metamorphic units (eclogite, granulite), and the so-called "leptyno-amphibolite complex" composed of an Ordovician metamorphosed bimodal magmatic association; (ii) the Lower Gneiss Unit (LGU) that consists of ortho-and paragneisses similar to those of the UGU, that were inherited from Late Ediacarian protoliths (ca. 620 to 550 Ma; [START_REF] Alexandre | U-Pb zircon SIMS ages from the French Massif Central and implication for the pre-Variscan tectonic evolution in Western Europe[END_REF][START_REF] Melleton | Precambrian protoliths and Early Paleozoic magmatism in the French Massif Central: U-Pb data and the North Gondwana connection in the west European Variscan belt[END_REF][START_REF] Chell-Michou | Pre-Cadomian to late-Variscan odyssey of the eastern Massif Central, France: Formation of the West European crust in a nutshell[END_REF]; and (iii) the Para-Autochtonous Unit (PAU), dominated by metasedimentary rocks (micaschists, metagreywackes, and quartzites) of greenschist-to lower amphibolite-facies, that were deposited between the Neoproterozoic and Early Cambrian (ca. 650 to 530 Ma; [START_REF] Melleton | Precambrian protoliths and Early Paleozoic magmatism in the French Massif Central: U-Pb data and the North Gondwana connection in the west European Variscan belt[END_REF]. To the south, these metamorphic units are overthrust above the sedimentary rocks of the Paleozoic fold-andthrust belt and foreland basin in the external zone (Faure et al., 2009a). The FMC hosts numerous hydrothermal W-Sn deposits, which are spatially associated with Carboniferous peraluminous biotite-cordierite or two-mica granites [START_REF] Marignac | Ore deposits of the French Massif Central: insight into the metallogenesis of the Variscan collision belt[END_REF][START_REF] Cuney | The timing of W-Sn rare-metals mineral deposit formation in the Western Variscan chain in their orogenic setting: the case of the Limousin area (Massif Central, France). In: The Timing and Location of Major Ore Deposits in an Evolving Orogen[END_REF][START_REF] Bouchot | Late Variscan mineralizing systems related to orogenic processes: the French Massif Central[END_REF]. Most of these W-Sn occurrences correspond to intra-or perigranitic quartz-wolframite-cassiterite veins and stockworks, greisens, and scheelite skarns. U-Pb dating of wolframite from several peri-granitic vein-type deposits in the FMC indicates that W mineralization formed during at least three main episodes extending over a period of 40 million years, ranging from syn-orogenic compression in the Early Carboniferous at ca. 335 Ma to post-orogenic extension in the Permian at ca. 295 Ma (Harlaux et al., 2018b).

The Puy-les-Vignes W breccia pipe

The Puy-les-Vignes deposit represents the only known W-bearing hydrothermal breccia pipe in the FMC and is hosted in migmatitic biotite-sillimanite paragneisses of the St-Léonard-de-Noblat gneiss unit, which is structurally correlated with the LGU and is located on the southern flank of the Thaurion anticline (Faure et al., 2009a). The deposit was the secondranked tungsten mine in France during the 20 th century with a past production of ca. 4,000 t WO3 at an average grade of 0.5% WO3. Remaining W resources may be significant since only half of the breccia pipe was mined. The former economic mineralization was limited to wolframite-bearing quartz veins, although the whole breccia body represents a potential lowgrade ore containing disseminated wolframite [START_REF] Weppe | Contribution à la géologie minière et à la minéralogie minière. Les gisements de wolfram de Leucamp, Puy-les-Vignes[END_REF]. The Puy-les-Vignes breccia pipe is located close to two peraluminous granitic intrusions (Fig. 1A): (i) the Auriat biotitemuscovite granite in the northeast dated at 324 ± 1 Ma (U-Pb on zircon; [START_REF] Gebauer | U/Pb zircon and monazite dating of mafic-ultramafic complex and its country rocks. Example: Sauviat-sur-Vige, French Massif Central[END_REF], and (ii) the Aureil biotite-cordierite granite in the southwest dated at 346 ± 14 Ma (Rb-Sr on whole-rock; [START_REF] Duthou | Les granitoïdes du Haut Limousin (Massif central français), chronologie Rb/Sr de leur mise en place; le thermo-métamorphisme carbonifère[END_REF]. Several other W showings are known in the surroundings of Puyles-Vignes (Fig. 1A), including quartz-wolframite veins (Le Moulard, Les Clauds, Etivaud, Chassagnat, Beynat, Lifarnet), as well as a second possible wolframite-bearing breccia pipe at Les Caillaudoux [START_REF] Weppe | Contribution à l'étude des gîtes de tungstène français : Puy-les-Vignes (Haute Vienne)[END_REF][START_REF] Weppe | Contribution à la géologie minière et à la minéralogie minière. Les gisements de wolfram de Leucamp, Puy-les-Vignes[END_REF]. The Puy-les-Vignes breccia pipe has an oval shape with dimensions 80 x 340 m at surface and is cut into two parts by a N30°E sinistral strikeslip fault (so-called "faille limite") with a 120-m horizontal displacement (Fig. 1B). The pipe is located at the intersection of two NE-trending dykes of microgranite and one N-trending dyke of lamprophyre, typically 1 to 4 m thick, which crosscut the enclosing gneisses, but are fragmented within the breccia.

The Puy-les-Vignes deposit has been interpreted by [START_REF] Weppe | Contribution à l'étude des gîtes de tungstène français : Puy-les-Vignes (Haute Vienne)[END_REF][START_REF] Weppe | Contribution à la géologie minière et à la minéralogie minière. Les gisements de wolfram de Leucamp, Puy-les-Vignes[END_REF] as a gravitational collapse breccia that evolved in several steps. A first stage of hydraulic fracturing and mass collapse produced a matrix-supported breccia composed by polygenetic and heterometric clasts of the country rocks (mainly gneisses and granites) cemented by hydrothermal quartz representing about 10% of the total volume of the breccia. The clasts are angular to subangular, centimetric to pluri-metric in size, and are rimmed by an aureole of tourmalinite (tourmaline±quartz), the thickness of which varies from a few millimeters to ten centimeters (Fig. 2A), and up to complete tourmalinization of the fragments. A second stage of mass collapse resulted in the formation of quartz-filled decollements, some delineating the brecciacountry rocks boundaries ("gaine" or "croiseurs") and others forming planar-curved veins ("plateures") within the former breccia. A third stage led to the formation of a NE-trending network of sub-parallel quartz-wolframite-sulfide veins ("filons") dipping at high-angle (>50°), which crosscut the entire breccia pipe and the enclosing gneisses. These veins are about 400 m long with variable thickness of 0.2 to 1 m, and they were the main host for the economic W mineralization, with grades ranging from 0.2 to 2% WO3 [START_REF] Weppe | Contribution à l'étude des gîtes de tungstène français : Puy-les-Vignes (Haute Vienne)[END_REF][START_REF] Weppe | Contribution à la géologie minière et à la minéralogie minière. Les gisements de wolfram de Leucamp, Puy-les-Vignes[END_REF][START_REF] Mouthier | La mine de tungstène de Puy-les-Vignes (Haute-Vienne)[END_REF]. 40 Ar-39 Ar dating of muscovite associated with wolframite yielded a plateau age of 323.4 ± 0.9 Ma [START_REF] Cuney | The timing of W-Sn rare-metals mineral deposit formation in the Western Variscan chain in their orogenic setting: the case of the Limousin area (Massif Central, France). In: The Timing and Location of Major Ore Deposits in an Evolving Orogen[END_REF], whereas U-Pb dating of wolframite from a mineralized vein ("filon A", level -270 m) yielded a slightly younger concordia age of 317.7 ± 0.7 Ma for the W mineralization (Harlaux et al., 2018b). Although the underground workings extended to 300 m below surface in the former mine, the vertical extent of the deposit has not been reached and no granitic body has been found at depth. Nevertheless, it is likely that the breccia pipe is located above the apex of an unexposed granite as described for other mineralized breccia pipes (e.g., [START_REF] Sillitoe | Ore-related breccias in volcanoplutonic arcs[END_REF][START_REF] Ren | Magmatic and hydrothermal history of the porphyry-style deposits of the Ardlethan tin field, New South Wales, Australia[END_REF][START_REF] Somarin | Hydrothermal alteration and mineralisation of the Glen Eden Mo-W-Sn deposit: a leucogranite-related hydrothermal system, Southern New England Orogen, NSW, Australia[END_REF][START_REF] Yang | Orthomagmatic origin for the Ilkwang Cu-W breccia-pipe deposit, southeastern Kyongsang Basin, South Korea[END_REF][START_REF] Solomovich | Geology and mineralization of the Uchkoshkon tin deposit associated with a breccia pipe, Eastern Kyrgyzstan[END_REF].

The paragenetic sequence of the Puy-les-Vignes deposit is divided into six main stages (Harlaux et al., 2015a): (1) Early hydrothermal alteration of the host-rocks characterized by pervasive greisenization (exo-greisen), forming a quartz-muscovite±tourmaline assemblage, and massive tourmalinization, was followed by hydraulic brecciation and mass collapse producing a quartz-tourmaline matrix-supported breccia; (2) W mineralization associated with hydraulic fracturing and formation of quartz-wolframite-arsenopyrite-tourmaline veins that crosscut the breccia pipe and enclosing rocks; (3) Fe-Cu-Zn mineralization mainly composed by veins and overgrowths of pyrite, chalcopyrite, enargite, and minor sphalerite, which overprint the quartz-wolframite-arsenopyrite veins; (4) Tourmaline-adularia-chlorite microbreccias that locally affect the wolframite-bearing quartz veins and are associated with accessory minerals of hydrothermal zircon, xenotime, monazite, Nb-Fe-W-rich rutile, and Nb-Ti-Y-HREE-W-U oxides. This mineral assemblage has been interpreted as having formed by magmatic-hydrothermal fluids derived from an hypothetic peralkaline granitic body concealed at depth that intruded later after the W mineralization (Harlaux et al., 2015b); (5) A minor and discrete stage of Bi-Au mineralization is associated with the deposition of native bismuth, bismuthinite, electrum, and Bi-Ag-Se-Te sulfosalts, in micro-cavity and micro-crack infillings within the mineralized quartz veins; (6) Late hydrothermal scorodite (FeAsO4.2H2O) and illite alteration followed by supergene alteration forming secondary minerals of tungstite and Fe-oxides/hydroxides.

Analytical methods

Scanning electron microscope

Mineralogical observations of tourmaline were performed at the Service Commun de Microscopies Electroniques et de Microanalyses (SCMEM) of GeoRessources laboratory (Vandoeuvre-lès-Nancy, France) using a Jeol J7600F scanning electron microscope (SEM) equipped with a SDD-type energy dispersive X-ray spectrometer (EDS) coupled to an Oxford Wave wavelength dispersive X-ray spectrometer (WDS). Backscattered electron (BSE) images were obtained on polished thin sections with an acceleration voltage of 15 kV, adjusting the electronic brightness to reveal the internal zoning in tourmaline. SEM was used to study the internal textures of tourmaline and to select crystals for the in situ chemical and isotopic analyses. Microanalyses were performed along profiles in selected grains of tourmaline to determine the major element variations along micrometre-scale zoning. The major elements measured were calibrated using the same standards as for the electron microprobe analyses (see below).

Electron microprobe

The major and minor element composition of tourmaline was determined using a Cameca SX100 electron microprobe analyzer (EMPA) at SCMEM, operated with an acceleration voltage of 15 kV, a beam current of 12 nA, and a beam diameter of 5 µm. The following standards were analyzed using WDS spectrometers: albite (Si, Na), corundum (Al), olivine (Mg), hematite (Fe), ilmenite (Mn, Ti), orthose (K), andradite (Ca), and Cr2O3 (Cr). Counting times were 10 s on element peaks and 5 s on background. Limits of detection are: 500 ppm for Si, Al; 600 ppm for Na, Ca; 400 ppm for Mg, K, Ti; 1700 ppm for Fe; 1600 ppm for Mn; and 900 ppm for Cr. Analytical error was <1% for most elements. Structural formulae of tourmaline were calculated using the Excel spreadsheet from The Open University, UK [START_REF] Tindle | Tourmaline in petalite-subtype granitic pegmatites: evidence of fractionation and contamination from the Pakeagama Lake and Separation Lake areas of northwestern Ontario, Canada[END_REF] normalizing to 31 anions and assuming stoichiometric 3 atoms for B and 4 atoms for OH+F, based on the general formula XY3Z6(T6O18)(BO3)3V3W, where X=Na + , Ca 2+ , K + , and vacancy (X☐); Y=Fe 2+ , Mg 2+ , Mn 2+ , Al 3+ , Li + , Fe 3+ , and Cr 3+ ; Z= Al 3+ , Fe 3+ , Mg 2+ , Ti 4+ , and Cr 3+ ; T=Si 4+ , Al 3+ , and B 3+ ; B=B 3+ ; V=OH -, and O 2-; and W=OH -, F -, and O 2- [START_REF] Henry | Nomenclature of the tourmaline-supergroup minerals[END_REF]. Fe2O3 was calculated assuming all extra charges to be Fe 3+ , whereas all deficiency in charge was assigned to presence of O 2-in the W-site. The chemical compositions of tourmaline are reported in weight per cent oxides (wt.%) and the structural formulae are expressed in atoms per formula unit (apfu). The results presented here correspond to approximately 400 spot microanalyses on the different generations of tourmaline. X-ray element maps were acquired with an acceleration voltage of 15 kV, a beam current of 100 nA, and a beam diameter of 1 μm. The elements Fe, Mg, Ti, Ca, and F were measured with dwell times of 0.2 s each and an acquisition step of 1 µm, for a total map size of 148 x 129 µm.

Laser ablation -inductively coupled plasma -mass spectrometry

The concentrations of minor and trace elements in tourmaline were measured by laser ablation -inductively coupled plasma -mass spectrometry (LA-ICP-MS) at GeoRessources laboratory using a Agilent 7500c quadrupole ICP-MS coupled with a 193 nm GeoLas ArF Excimer laser (MicroLas, Göttingen, Germany). Laser ablation was performed on polished thin sections with a constant 5 Hz pulse frequency and a constant fluence of 6 J/cm 2 . LA-ICP-MS spot analyses were performed using variable laser beam diameters between 24 and 90 µm, depending on the size of zoning in tourmaline. Helium was used as carrier gas to transport the laser-generated particles from the ablation cell to the ICP-MS and argon was added as an auxiliary gas via a flow adapter before the ICP torch. Typical flow rates of 0.5 L/min for He and 0.9 L/min for Ar were used. The certified reference material NIST SRM 610 (concentrations from [START_REF] Jochum | Determination of reference values for NIST SRM 610-617 glasses following ISO guidelines[END_REF] was used as an external standard for calibration of all analyses, and was analyzed twice at the beginning and at the end of each set of samples, following a bracketing standardization procedure. The reference material NIST SRM 612 (concentrations from [START_REF] Jochum | Determination of reference values for NIST SRM 610-617 glasses following ISO guidelines[END_REF] was used as a control standard to verify the quality of the analyses and of the standardization. LA-ICP-MS calibration was optimized for highest sensitivity on the whole m/Q range, while maintaining Th/U ~ 1 and ThO/Th <0.5%, as determined on NIST SRM 610. The following 40 isotopes were measured with a dwell time of 10 ms for each: 7 Li, 9 Be, 29 Si, 45 Sc, 47 Ti, 51 V, 53 Cr, 59 Co, 60 232 Th, and 238 U. In these conditions, the cycle time was about 496 ms. Analytical background was recorded for 30 s at the beginning of each analysis followed by acquisition of the LA-ICP-MS signal of tourmaline for 40-60 s. Data reduction and absolute quantification of signals were performed using the software StalQuant developed at the ETH Zürich, Switzerland. For each LA-ICP-MS analysis, the Si content previously determined by EMPA was used as internal standard.

Limits of detection (LOD) were calculated using the 3σ criterion from [START_REF] Longerich | Laser ablation inductively coupled plasma mass spectrometric transient signal data acquisition and analyte concentration calculation[END_REF].

Secondary ion mass spectrometry

Boron isotope compositions of tourmaline were measured by secondary ion mass spectrometry (SIMS) using a Cameca IMS 1280-HR instrument at the CRPG-CNRS (Vandoeuvre-lès-Nancy, France). Analyses were performed on the same polished thin sections analyzed by LA-ICP-MS with a 20 nA beam of primary ions O -accelerated at 13 kV. The secondary ions 10 B + and 11 B + were accelerated at 10 kV and were measured in monocollection with a mass resolution M/ΔM=2000. Each calculated isotopic ratio 11 B/ 10 B corresponds to 30 cycles of measurement with counting times of 8 s per cycle on mass 10 and of 4 s per cycle on mass 11. The ablation spot size was fixed to 20 µm. Instrumental mass fractionation (IMF) was determined and corrected using two tourmaline reference materials corresponding to dravite (Harvard #108796) and schorl (Harvard #112566) described by [START_REF] Dyar | Reference minerals for the microanalysis of light elements[END_REF] and [START_REF] Leeman | Boron isotopic analysis of proposed borosilicate mineral reference samples[END_REF]. Each standard was measured several times during the analytical SIMS session following a standard-sample-standard bracketing procedure. The summary of the SIMS B isotope analyses on the tourmaline reference materials is given in the Electronic Supplementary Material. After correction of IMF, the measured 11 B/ 10 B ratios were reported in δ 11 B notation (in ‰) relative to the NIST SRM 951, whose 11 B/ 10 B ratio is 4.04362 [START_REF] Catanzaro | Standard reference materials: boric acid isotopic and assay standard reference materials[END_REF]. The external reproducibility (2σ) is about 0.6‰ on dravite and schorl standards. The external error used is that of the relevant reference material, and the total uncertainty is the quadratic sum of the internal and external errors. The total errors on individual analysis are typically ± 0.4‰ (2σ).

Results

Paragenesis and internal textures of tourmaline

Tourmalinization represents the most important hydrothermal alteration in the Puy-les-Vignes deposit. It occurred from the early hydrothermal alteration stage that followed the formation of the collapse breccia pipe and continued until silicification and vein opening leading to the deposition of wolframite, as well as during later fracturing episodes. Four generations of hydrothermal tourmaline (Tur 1 to Tur 4) are identified based on crosscutting relationships and detailed textural observations.

Greisen tourmaline (Tur 1)

This tourmaline is only found in the internal part of greisenized host-rock clasts (mainly gneisses) and it represents the earliest generation identified in the Puy-les-Vignes deposit. Tur 1 forms sub-euhedral crystals of green-brownish colour in plane-polarized light, ranging from 50 to 100 µm in size, which are disseminated in clusters within the quartz and muscovite assemblage of the greisen (Fig. 2B). On BSE images, Tur 1 shows an internal zoning composed of three successive zones (Fig. 3A): (i) a medium grey core forming the main part of the grains and showing a relatively homogeneous texture; (ii) a light grey irregular rim, a few to tens of µm-wide, surrounding the core with textural evidence of corrosion. The corerim interface is thus interpreted as a dissolution-precipitation front; (iii) a dark overgrowth of tens of µm wide that surrounds the tourmaline grains in apparent continuity with the rim.

Tourmalinites (Tur 2)

This second generation of tourmaline is related to the most important stage of tourmalinization at Puy-les-Vignes. It corresponds to the formation of black aureole of tourmalinite (tourmaline±quartz) on the rims of the host-rock clasts (gneisses and granites) composing the breccia body. The tourmalinite rims are of variable thickness, ranging from a few millimetres to tens of centimetres, up to complete tourmalinization of the clasts (Fig. 2A).

The contact between the tourmalinite and the quartz forming the breccia matrix is sharp and crack-seal textures are common along the tourmaline-quartz borders. This indicates that silicification of the breccia was synchronous to the mass collapse and occurred after formation of the tourmalinite. At the microscopic scale, the tourmalinite rim is composed of aggregates of prismatic grains cemented by limpid macrocrystalline quartz. There are some textural differences between gneissic and granitic clasts. Tourmaline on gneissic clasts (Tur 2a) consists of sub-euhedral crystals with an orange-brownish to greenish colour in planepolarized light and ranging from 50 to 500 µm in size (Fig. 2C). They typically display zoning composed of three successive zones on BSE images (Fig. 3B): (i) a dark grey core (<50 µm in size) showing a patchy texture; (ii) a discrete and irregular bright rim, of a few micrometres thickness, that locally replaces the core; and (iii) an overgrowth in continuity with the rim that forms the largest part of the tourmaline grains and is characterized by a micrometre-scale oscillatory zoning. X-ray element maps show that the core has higher Mg and Ca contents than the overgrowth, which is generally Fe-rich but with fluctuating Fe and Mg contents corresponding to the oscillatory zoning (Fig. 4). Intracrystalline variations in Ti contents reflect sector zoning. Tourmaline on granitic clasts (Tur 2b) forms larger crystals, ranging from 100 µm up to a few millimetres, which have a green-brownish colour in planepolarized light (Fig. 2D). On BSE images, the crystals show more complex internal textures composed of the following zones (Fig. 3C): (i) a dark grey core showing some sector zoning and patchy texture; (ii) a light grey rim in continuity with the core and showing oscillatory zoning at the micrometre-scale; (iii) a dark overgrowth with a relatively homogeneous texture surrounding the rim; (iv) a bright external corrosion, which crosscuts and partially replaces the previous zones. This late tourmaline shows a particularly fine-scale growth zoning (Fig. 3D).

Acicular tourmaline (Tur 3)

This third tourmaline generation was only found within the quartz of the breccia matrix and in wolframite-bearing quartz veins, where it is locally intergrown with wolframite suggesting it is syn-mineralization. Tur 3 forms large elongated euhedral crystals with a green-bluish colour or colourless in plane-polarized light. Most crystals range from 500 µm to a few millimetres in size, but the largest ones reach a few centimetres (Fig. 2E). Acicular tourmaline is found either as isolated or fan-like aggregates disseminated within the quartz, or as fibrous crystals directly overgrown on the wall-rock selvages. The tourmaline crystals are commonly fractured within the quartz, suggesting that the quartz-tourmaline breccia and veins underwent a late brittle deformation episode. The internal texture of acicular tourmaline is composed of (i) a large core forming the main part of the crystals, and (ii) a rim a few µm-thick that shows growth zoning. Tourmaline sections perpendicular to the c-axis typically show sector zoning (Fig. 3E).

Microbreccia tourmaline (Tur 4)

This last generation is restricted to a late tourmaline-adularia-chlorite microbreccia episode that postdates the W mineralization. The microbreccia is composed of a dense aggregate of prismatic tourmaline grains, which are cemented by adularia and chlorite, with minor muscovite. The tourmaline crystals have an orange-brownish to bluish colour in plane-polarized light and range from 50 to 500 µm in size (Fig. 2F). Tur 4 is internally-zoned (Fig. 3F) with: (i) a medium grey core showing a patchy texture; (ii) a light grey rim, of several tens of µm thick, forming the largest part of the grains. The core-rim interface is irregular and shows evidences of corrosion-dissolution; (iii) a dark overgrowth with micrometre-scale zoning in continuity with the previous rim.

Chemical composition and crystal chemistry of tourmaline

Major and minor elements

Representative chemical compositions of tourmaline from Puy-les-Vignes are summarized in Table 1 and the complete dataset is provided in the Electronic Supplementary Material. The different generations of hydrothermal tourmaline have overall similar chemical compositions, with some variations in the major elements Fe (0.5-1.7 apfu), Mg (0.7-2.1 apfu), and Al (5.6-6.9 apfu), as well as for the minor elements Na (0.4-0.8 apfu), Ti (<0.3 apfu), and Ca (<0.2 apfu). Tourmaline belongs mostly to the alkali group and plots within the field of metasedimentary rocks in the Al-Fe-Mg diagram (Fig. 5). Only a minority of tourmaline belongs to the X-vacant group and plots along the field of granites and pegmatites (Fig. 5).

Tourmaline compositions correspond dominantly to the dravite-schorl solid solution, with a few analyses corresponding to the foitite-Mg-foitite solid solution (Fig. 6). The compositional variations of tourmaline are related to variable ratios of Fe/(Fe+Mg)=0.23-0.69 and X☐/(X☐+Na)=0.12-0.61, which are mainly attributed to the exchange vectors Fe 2+ +1Mg 2+ -1 and (☐Al 3+ )+1(Na + Mg 2+ )-1 (Fig. 6).

In detail, the different tourmaline generations show chemical variations of the opticallydistinguished zones. Pre-ore Tur 1 has variable Fe/(Fe+Mg)=0.28-0.64 and X☐/(X☐+Na)=0.12-0.49, which reflects compositional zoning. The core and overgrowth are characterized by similar dravitic compositions with low Fe/(Fe+Mg) values (0.28-0.54), whereas the rims have higher Fe/(Fe+Mg) values (0.56-0.64). Tur 2a hosted in gneissic clasts has relatively homogeneous major element compositions corresponding to dravite with minor variations in Fe/(Fe+Mg)=0.33-0.57 and X☐/(X☐+Na)=0.28-0.57. Tur 2b hosted in granitic clasts has more variable compositions with Fe/(Fe+Mg)=0.23-0.64 and X☐/(X☐+Na)=0.21-0.60. The range is mainly due to differences between the core zone and overgrowth (Fe/(Fe+Mg)=0.23-0.36) and the rims (Fe/(Fe+Mg)=0.44-0.64). Syn-ore Tur 3 has dravitic composition with homogeneous compositions having Fe/(Fe+Mg)=0.24-0.43 and X☐/(X☐+Na)=0.31-0.51. Post-ore Tur 4 has compositions intermediate between foitite and dravite with an extended range of Fe/(Fe+Mg)=0.26-0.58 and X☐/(X☐+Na)=0.16-0.61 ratios.

The cores are distinguished by high X☐/(X☐+Na)=0.46-0.61 with schorl compositions, whereas the rims and overgrowths have more dravitic compositions with lower X☐/(X☐+Na)=0.16-0.50 and higher Ti contents (up to 0.26 apfu).

Trace elements

Average trace element compositions of tourmaline from Puy-les-Vignes are summarized in Table 2 and the complete dataset is given in the Electronic Supplementary Material. ppm), total REE (0.3-15 ppm), Sn (7-147 ppm), and Pb (0.7-19 ppm) (Fig. 7). In multi-element diagrams normalized to the upper continental crust (UCC from [START_REF] Rudnick | Composition of the Continental Crust[END_REF], the different tourmaline generations show similar trace element patterns with relative enrichments in Sc, V, Cr, Be, Bi, and Zn between 2 and 100 times higher than the UCC values, and relative depletions in Sr, Ba, Cs, Rb, Y, Nb, Ta, Zr, Ti, U, Th, Mo, Sn, Pb, and Cu between 5 and 100 times lower than the UCC values (Fig. 8). Principal component analysis (PCA) has been applied in order to understand the compositional variations of tourmaline and to identify trace element correlations. PCA is a multivariate statistical technique that provides dimensionality-reduction of correlated variables into a reduced set of orthogonal linear combinations (so-called principal components), maximizing the variance and minimizing information loss [START_REF] Izenman | Modern multivariate statistical techniques. Regression, classification, and Manifold learning[END_REF]. PCA is a classical method of multivariate statistics that is particularly useful for treating large geochemical datasets such as LA-ICP-MS trace element analyses of minerals (e.g., Winderbaum et al., 2012;[START_REF] Belissont | LA-ICP-MS analyses of minor and trace elements and bulk Ge isotopes in zoned Ge-rich sphalerites from the Noailhac-Saint-Salvy deposit (France): Insights into incorporation mechanisms and ore deposition processes[END_REF].

Boron isotopic compositions of tourmaline

The boron isotopic compositions of tourmaline from Puy-les-Vignes are reported in Table 3.

The δ 11 B values of tourmaline (n=46) range in total from -13.3‰ to -7.8‰ with a mean value of -11.4 ± 1.5‰ (Fig. 11). The within-sample variations are typically 1-3‰ and are related to growth zoning. Greisen-hosted Tur 1 has δ 11 B values between -11.1‰ and -7.8‰ (mean = -9.2 ± 1.0‰, n=11) with the cores having lower δ 11 B values compared to the rims and overgrowths. Pre-ore Tur 2a has δ 11 B values ranging from -13.1‰ to -11.1‰ (mean = -11.9 ± 0.6‰, n=8) with no significant boron isotopic zonation. Syn-ore Tur 3 also has homogeneous δ 11 B values ranging from -13.2‰ to -12.1‰ (mean = -12.7 ± 0.3‰, n=12) without distinction between core and rim. Finally, Tur 4 has δ 11 B compositions between -13.3‰ and -10.3‰

(mean = -11.8 ± 0.9‰, n=15) with no isotope zoning.

Discussion

Intracrystalline zoning and compositional variations in tourmaline

Tourmaline from the Puy-les-Vignes deposit shows internal zoning and variations in major, minor, and trace elements. The majority of tourmaline grains have cores surrounded by rims and overgrowths, which display both sector and concentric zoning. The core-rim interface is commonly marked by dissolution evidences, whereas the overgrowth typically shows oscillatory zoning at the micrometre-scale. The formation of oscillatory zoning is a typical feature of hydrothermal minerals and has generally been interpreted to result from external and/or internal controls [START_REF] Shore | Oscillatory zoning in minerals; a common phenomenon[END_REF]. In the first case (external control), oscillations may be caused by periodic changes in the external environment due to varying fluid conditions such as chemical composition, pressure, or temperature (e.g., [START_REF] Holten | Statistical characteristics and origin of oscillatory zoning in crystals[END_REF]. In the second case (internal control), the oscillations are related to self-organized processes during the crystalline growth, which are controlled by absorption-diffusion mechanisms at the crystal-fluid interface (e.g., L' Heureux and Jamtveit, 2002) or by micromorphological instabilities of the growing face (e.g., [START_REF] Shtukenberg | Micromorphological instability of a growing face as a source of oscillatory zoning in crystals[END_REF].

Oscillatory zoning may also result from a combination of both external and internal controls, whereby crystal-scale variations are related to bulk changes in the hydrothermal fluid whereas fine-scale modulations are caused by growth-rate-controlled incorporation of trace elements [START_REF] Barker | Oscillatory zoning and trace element incorporation in hydrothermal minerals: insights from calcite growth experiments[END_REF]. Quantitative microanalyses performed along an oscillatory zoning in a representative tourmaline crystal show chemical evolution trends at the growth-band scale (Fig. 12). The external overgrowth shows a succession of rhythmic growth bands (dark and light) on BSE images, each of them being marked by a systematic Fe increase (0.93-1.18 apfu) and Mg decrease (1.27-1.09 apfu). The oscillatory zoning corresponds therefore to an increasing trend of the Fe/(Fe+Mg) ratio (0.42-0.52) along the growth direction. The compositional changes marking the transition between the growth bands could not be caused by a continuous fractionation trend of a single fluid in closed-system, which is expected to yield rather continuous variations with a decreasing Fe/(Fe+Mg) ratio over time. By contrast, the increasing Fe/(Fe+Mg) ratio along the compositional zoning is interpreted as reflecting rapid crystal growth or dynamic changes in the external fluid conditions. This interpretation is supported by (i) the formation of the breccia pipe by a collapse mechanism indicating rapidly changing fluid overpressure conditions, (ii) the density of euhedral tourmaline crystals composing the tourmalinite rims suggesting that the hydrothermal fluid was oversaturated relative to tourmaline allowing homogeneous and possibly rapid nucleation, and (iii) the dissolution evidences at the core-rim interface attesting that the fluid responsible was locally out-of-equilibrium and reacted with the pre-existing tourmaline by a dissolution-precipitation mechanism. Multi-stage formation of tourmaline at Puy-les-Vignes is thus demonstrated by growth zoning and crosscutting relationships, arguing for successive boron-rich fluid circulation episodes in a dynamic hydrothermal system.

Tourmaline composition as indicator of fluid chemistry

The major and trace element composition of tourmaline is a reliable geochemical monitor of its forming environment and has been used to trace the fluid evolution and sources in magmatic-hydrothermal systems (e.g., [START_REF] Jiang | Trace and rare-earth element geochemistry in tourmaline and cassiterite from the Yunlong tin deposit, Yunnan, China: implication for migmatitichydrothermal fluid evolution and ore genesis[END_REF][START_REF] Marks | Trace element systematics of tourmaline in pegmatitic and hydrothermal systems from the Variscan Schwarzwald (Germany): the importance of major element composition, sector zoning, and fluid or melt composition[END_REF][START_REF] Drivenes | Late-magmatic immiscibility during batholith formation: assessment of B isotopes and trace elements in tourmaline from the Land's End granite[END_REF][START_REF] Yang | Tourmaline as a recorder of magmatic-hydrothermal evolution: an in situ major and trace element analysis of tourmaline from the Qitianling batholith, South China[END_REF][START_REF] Duchoslav | Changes in tourmaline composition during magmatic and hydrothermal processes leading to tin-ore deposition: The Cornubian Batholith, SW England[END_REF][START_REF] Hong | Tourmaline-rich features in the Heemskirk and Pieman Heads granites from western Tasmania, Australia: Characteristics, origins, and implications for tin mineralization[END_REF][START_REF] Dutrow | Tourmaline compositions and textures: reflections of the fluid phase[END_REF].

Precipitation of tourmaline from aqueous fluids requires high boron contents (>0.5-1.0 wt.% B2O3) and acidic-to-near neutral conditions (pH<6) that favor trigonal coordination of boron in the fluid [START_REF] Morgan | Experimental reactions of amphibolite with boron-bearing aqueous fluids at 200 MPa: implications for tourmaline stability and partial melting in mafic rocks[END_REF][START_REF] Henry | Metamorphic tourmaline and its petrologic applications[END_REF]. Tourmaline compositions from Puy-les-Vignes plot along the dravite-schorl solid solution and have relatively low Na contents (average 0.6 apfu) and high X-site vacancies (average 0.4 apfu), suggesting precipitation from a low-salinity fluid (von Goerne et al., 2001[START_REF] Von Goerne | Experimental determination of Na-Ca distribution between tourmaline and fluid in the system CaO-Na2O-MgO-Al2O3-SiO2-B2O3-H2O[END_REF][START_REF] Dutrow | Tourmaline compositions and textures: reflections of the fluid phase[END_REF]. Assuming a temperature of 500°C, a salinity of ca. 3 wt.% NaCl eq can be estimated

for the fluid in equilibrium with the assemblage tourmaline + quartz + chlorite (von Goerne et al., 2001). The dominant substitution mechanisms observed in tourmaline are Fe 2+ +1Mg 2+ -1 and (☐Al 3+ )+1(Na + Mg 2+ )-1 (Fig. 6), with no contribution of the Fe 3+ +1Al 3+ -1 exchange vector in the Al vs. Fe diagram (not shown), thus suggesting low Fe 3+ /Fe 2+ ratios and reduced fluid conditions. These conclusions are supported by fluid inclusion studies of quartz associated with the tourmalinite (Tur 2) that reported low-salinity (2-5 wt.% NaCl eq), high-temperature (>500°C), and elevated CO2-CH4-N2 contents [START_REF] Alikouss | Contribution à l'étude des fluides crustaux : approche analytique et expérimentale[END_REF], pointing to fluid compositions controlled by the graphite-water equilibrium with C-rich metasediments under reduced hydrothermal conditions [START_REF] Ramboz | The P-V-T-X-fO2 evolution of H2O-CO2-CH4bearing fluid in a wolframite vein: Reconstruction from fluid inclusion studies[END_REF][START_REF] Dubessy | Advances in C-O-H-N-S fluid geochemistry based on micro-Raman spectrometric analysis of fluid inclusions[END_REF]. The different tourmaline generations show considerable overlap in their major and trace element contents (Figs. 5 to 8) and lack distinct chemical signatures allowing discrimination of clusters. This may reflect the role of fluid-rock interaction processes as already proposed in several studies [START_REF] Hazarika | Diverse tourmaline compositions from orogenic 40 gold deposits in the Hutti-Maski greenstone belt, India: implications for sources of oreforming fluids[END_REF][START_REF] Kalliomäki | Major and trace element geochemistry of tourmalines from Archean orogenic gold deposits: Proxies for the origin of gold mineralizing fluids?[END_REF]. Incorporation of major and trace elements in hydrothermal tourmaline is fundamentally controlled by the tourmaline-fluid partition coefficients, which depend on crystal chemistry constraints and external conditions [START_REF] Von Goerne | Experimental determination of Na-Ca distribution between tourmaline and fluid in the system CaO-Na2O-MgO-Al2O3-SiO2-B2O3-H2O[END_REF]. Several studies reported that the major and trace element contents of tourmaline mirror the host-rock composition and local fluid-rock interactions [START_REF] Henry | Tourmaline as a petrogenetic indicator mineral: an example from the staurolite-grade metapelites of NW Maine[END_REF][START_REF] Raith | Boron metasomatism and behaviour of rare earth elements during formation of tourmaline rocks in the eastern Arunta Inlier, central Australia[END_REF][START_REF] Marks | Trace element systematics of tourmaline in pegmatitic and hydrothermal systems from the Variscan Schwarzwald (Germany): the importance of major element composition, sector zoning, and fluid or melt composition[END_REF][START_REF] Hazarika | Diverse tourmaline compositions from orogenic 40 gold deposits in the Hutti-Maski greenstone belt, India: implications for sources of oreforming fluids[END_REF][START_REF] Kalliomäki | Major and trace element geochemistry of tourmalines from Archean orogenic gold deposits: Proxies for the origin of gold mineralizing fluids?[END_REF]. High concentrations (>100 ppm) of V, Cr, and Sr, and low concentrations (<50 ppm) of Li and Sn in tourmaline from Puy-les-Vignes suggest an input of these elements from metasedimentary-volcanic rocks rather than magmatic sources [START_REF] Jiang | Trace and rare-earth element geochemistry in tourmaline and cassiterite from the Yunlong tin deposit, Yunnan, China: implication for migmatitichydrothermal fluid evolution and ore genesis[END_REF][START_REF] Galbraith | Assessment of tourmaline compositions as an indicator of emerald mineralization at the Tsa da Glisza Prospect, Yukon Territory[END_REF]van Hinsberg and Schumacher, 2011;[START_REF] Marks | Trace element systematics of tourmaline in pegmatitic and hydrothermal systems from the Variscan Schwarzwald (Germany): the importance of major element composition, sector zoning, and fluid or melt composition[END_REF][START_REF] Hazarika | Diverse tourmaline compositions from orogenic 40 gold deposits in the Hutti-Maski greenstone belt, India: implications for sources of oreforming fluids[END_REF][START_REF] Yang | Tourmaline as a recorder of magmatic-hydrothermal evolution: an in situ major and trace element analysis of tourmaline from the Qitianling batholith, South China[END_REF][START_REF] Kalliomäki | Major and trace element geochemistry of tourmalines from Archean orogenic gold deposits: Proxies for the origin of gold mineralizing fluids?[END_REF]. In particular, Li and Sr have been proposed as suitable indicators for discriminating between a magmatic and metamorphic origin of hydrothermal tourmalines [START_REF] Kalliomäki | Major and trace element geochemistry of tourmalines from Archean orogenic gold deposits: Proxies for the origin of gold mineralizing fluids?[END_REF]. Using the Li/Sr ratio as a proxy for the fluid source, we compared the composition of tourmaline from Puy-les-Vignes for selected trace elements with worldwide tourmaline hosted in granites, metasediments, and metavolcanics (Fig. 13). Despite some variations, tourmaline from Puy-les-Vignes has trace element contents overlapping with the compositional field of metamorphic tourmaline, which is also in agreement with its major element compositions falling into the field of metasediments in the Al-Fe-Mg diagram (Fig. 5). This would indicate that hydrothermal tourmalines from Puy-les-Vignes were dominantly formed from fluids that interacted with metavolcanic and metasedimentary host-rocks. In order to evaluate the potential sources of the trace elements, we compared the average composition of tourmaline from Puy-les-Vignes with the whole-rock compositions of the main host-rock lithologies in the northwestern FMC, composed of peraluminous granites, gneisses, and metabasic rocks (Fig. 14). Tourmaline shows intermediate trace element patterns with similar enrichments in granitophile elements (Be, U, Sn, W, Bi, U) and transition metals (Sc, V, Cr, Zn, Ni) compared to evolved peraluminous granites and gneisses, and metabasic rocks, respectively.

This finding is relevant since peraluminous granites and gneissic-amphibolite rocks are known in a distance <5 km around the Puy-les-Vignes deposit (Fig. 1). The REE pattern of tourmaline is marked by enrichments in HREE over LREE, with a positive Eu anomaly, and it is clearly different from the REE spectra of peraluminous granites and gneisses but resembles those of metabasic rocks. The REE patterns of tourmaline have been shown to reflect the REE composition of their host-rock lithologies and the effects of fluid-rock interactions (e.g., [START_REF] Torres-Ruiz | Origin and petrogenetic implications of tourmaline-rich rocks in the Sierra Nevada (Betic Cordillera, southeastern Spain)[END_REF][START_REF] Marks | Trace element systematics of tourmaline in pegmatitic and hydrothermal systems from the Variscan Schwarzwald (Germany): the importance of major element composition, sector zoning, and fluid or melt composition[END_REF][START_REF] Yang | Tourmaline as a recorder of magmatic-hydrothermal evolution: an in situ major and trace element analysis of tourmaline from the Qitianling batholith, South China[END_REF][START_REF] Duchoslav | Changes in tourmaline composition during magmatic and hydrothermal processes leading to tin-ore deposition: The Cornubian Batholith, SW England[END_REF][START_REF] Kalliomäki | Major and trace element geochemistry of tourmalines from Archean orogenic gold deposits: Proxies for the origin of gold mineralizing fluids?[END_REF][START_REF] Hong | Tourmaline-rich features in the Heemskirk and Pieman Heads granites from western Tasmania, Australia: Characteristics, origins, and implications for tin mineralization[END_REF]. The depletion in LREE over HREE and the low total REE contents of Puy-les-Vignes tourmaline may reflect (i) variable fluid/rock ratios during the tourmalinization process [START_REF] Torres-Ruiz | Origin and petrogenetic implications of tourmaline-rich rocks in the Sierra Nevada (Betic Cordillera, southeastern Spain)[END_REF][START_REF] Pesquera | Petrographic, chemical and B-isotopic insights into the origin of tourmaline-rich rocks and boron recycling in the Martinamor Antiform (Central Iberain Zone[END_REF], (ii) LREE incorporation in accessory phases (rutile, monazite, zircon) co-crystallizing with tourmaline in the fluid, or (iii) presence of micro-inclusions (zircon, rutile, titanite, etc.) in tourmaline [START_REF] Jiang | Trace and rare-earth element geochemistry in tourmaline and cassiterite from the Yunlong tin deposit, Yunnan, China: implication for migmatitichydrothermal fluid evolution and ore genesis[END_REF][START_REF] Hazarika | Diverse tourmaline compositions from orogenic 40 gold deposits in the Hutti-Maski greenstone belt, India: implications for sources of oreforming fluids[END_REF]. The positive Eu anomaly (Eu/Eu*=2-4)

indicates the predominance of Eu 2+ in the fluid and its preferential partitioning over Eu 3+ into the X-site of tourmaline [START_REF] Von Goerne | Experimental determination of Na-Ca distribution between tourmaline and fluid in the system CaO-Na2O-MgO-Al2O3-SiO2-B2O3-H2O[END_REF]. This would also indicate a reducing nature of the fluids, in accordance with the inferred low Fe 3+ /Fe 2+ ratios. In summary, the major and trace element compositions of tourmaline possibly records a mixed magmatic-metamorphic signature resulting from fluid-rock interaction processes yielding to two possible interpretations: (i) the fluid was of magmatic origin, exsolved from a crystallizing peraluminous melt, and strongly interacted with the metamorphic host-rocks during formation of the breccia pipe; or (ii) the fluid was of metamorphic origin, possibly produced by devolatilization reactions, and leached out metals from the granitic basement during hightemperature fluid-rock interactions. Considering the inferred low fluid salinity and reducing conditions, a metamorphic-hydrothermal origin seems more likely.

B isotope constraints on the fluid source(s): magmatic vs. metamorphic origin

The total range of δ 11 B values in tourmaline from Puy-les-Vignes is large, varying from -13.3‰ to -7.8‰ (average δ 11 B = -11.4‰), with most of the tourmaline having δ 11 B values <-10‰ (Fig. 11). These δ 11 B values cannot unambiguously distinguish between a granitic and a metamorphic source of boron due to the large isotopic overlap of these two reservoirs [START_REF] Marschall | Tourmaline isotopes: no element left behind[END_REF][START_REF] Trumbull | Boron Isotopes -The Fifth Element. Advances in Isotope Geochemistry, tourmaline and fluid at 300 to 700°C and 200 MPa[END_REF]. Previous boron isotope studies on tourmaline from W-Sn deposits in the European Variscan belt reported δ 11 B values ranging from -15‰ to +2‰ with a mean around -10‰, and concluded that boron was dominantly derived from magmatic fluids exsolved from peraluminous granitic melts [START_REF] Smith | The boron isotopic composition of tourmaline as a guide to fluid processes in the southwestern England orefield: an ion microprobe study[END_REF][START_REF] Pesquera | Petrographic, chemical and B-isotopic insights into the origin of tourmaline-rich rocks and boron recycling in the Martinamor Antiform (Central Iberain Zone[END_REF][START_REF] Jiang | Chemical and boron isotopic variations of tourmaline in the Hnilec graniterelated hydrothermal system, Slovakia: Constraints on magmatic and metamorphic fluid evolution[END_REF][START_REF] Ribeiro Da Costa | Tourmaline occurrences within the Penamacor-Monsanto granitic pluton and host-rocks (Central Portugal): genetic implications of crystal-chemical and isotopic features[END_REF][START_REF] Drivenes | Late-magmatic immiscibility during batholith formation: assessment of B isotopes and trace elements in tourmaline from the Land's End granite[END_REF][START_REF] Codeço | Chemical and boron isotopic composition of hydrothermal tourmaline from the Panasqueira W-Sn-Cu deposit[END_REF]. Recent SIMS data from the Panasqueira W-Sn deposit (Portugal)

show that tourmaline has δ 11 B values comprised between -12.7‰ and -3.7‰ (average δ 11 B = -9‰), which has been interpreted as a boron source derived from a S-type granite [START_REF] Codeço | Chemical and boron isotopic composition of hydrothermal tourmaline from the Panasqueira W-Sn-Cu deposit[END_REF]. Generally, the boron isotopic composition of tourmaline is controlled by (i) the composition of the boron source, (ii) the temperature of formation, and (iii) the fluid/rock ratio [START_REF] Palmer | Boron isotopic composition of tourmaline from massive sulfide deposits and tourmalinites[END_REF]. Based on existing tourmaline-fluid boron isotope fractionation factors from [START_REF] Meyer | Boron-isotope fractionation between tourmaline and fluid: an experimental re-investigation[END_REF], valid for T=400-700°C and P=200 MPa, it is possible to estimate the isotopic composition of the hydrothermal fluid in equilibrium with tourmaline depending on temperature. Fluid inclusion data from hydrothermal quartz associated with the tourmalinite (Tur 2) yielded trapping conditions at temperatures of 540 ± 50°C and pressures of 2.5 ± 0.5 kbar [START_REF] Alikouss | Contribution à l'étude des fluides crustaux : approche analytique et expérimentale[END_REF]. This is consistent with the Zr-in-rutile temperatures of 530 ± 35°C estimated for W-bearing rutile intergrown with the tourmalinite [START_REF] Harlaux | Tungsten and Rare-metal (Nb, Ta, Sn) Hydrothermal Metallogenic Systems in the Late-Variscan Orogenic Context: Example of the French Massif Central[END_REF].

Assuming a crystallization temperature of 500°C and an average δ 11 B = -11.4‰ for tourmaline, the fluid in isotopic equilibrium would have a δ 11 B = -9.5‰ using tourmalinefluid boron isotope fractionation factors [START_REF] Meyer | Boron-isotope fractionation between tourmaline and fluid: an experimental re-investigation[END_REF]. A magmatic fluid origin can be tested by calculating the isotopic composition of a boron-rich peraluminous granitic melt, which would have produced a magmatic fluid with a δ 11 B = -9.5‰. At 650°C, a boron isotope fractionation factor of 5‰ can be predicted between the granitic melt and the aqueous fluid [START_REF] Hervig | Isotopic and elemental partitioning of boron between hydrous fluid and silicate melt[END_REF], considering a 50:50 proportion of trigonal-tetrahedral coordination of boron in the melt (see discussion by Trumbull et al., 2013). This would imply a δ 11 B = -14.5‰ for the hypothetical granitic source, which falls in the typical range of S-type granites [START_REF] Trumbull | Boron Isotopes -The Fifth Element. Advances in Isotope Geochemistry, tourmaline and fluid at 300 to 700°C and 200 MPa[END_REF]. A metamorphic fluid origin is also possible since metasediments generally contain high amounts of boron >80 ppm on average and up to 100s ppm [START_REF] Ishikawa | Boron isotope systematics of marine sediments[END_REF][START_REF] Leeman | Geochemistry of boron and its implications for crustal and mantle processes[END_REF][START_REF] Nakano | Boron isotope geochemistry of metasedimentary rocks and tourmalines in a subduction zone metamorphic suite[END_REF][START_REF] Wilke | B and Li Proterozoic metapelites from the Black Hills, U.S.A.: Implications for the origin of leucogranitic magmas[END_REF][START_REF] Trumbull | Boron Isotopes -The Fifth Element. Advances in Isotope Geochemistry, tourmaline and fluid at 300 to 700°C and 200 MPa[END_REF]. Metamorphic dehydration reactions and fluid-rock interactions represent two possible processes that may efficiently extract boron from metasediments (e.g., [START_REF] Nakano | Boron isotope geochemistry of metasedimentary rocks and tourmalines in a subduction zone metamorphic suite[END_REF][START_REF] Kawakami | Boron in metapelites controlled by the breakdown of tourmaline and retrograde formation of borosilicates in the Yanai area, Ryoke metamorphic belt[END_REF][START_REF] Von Goerne | Experimental determination of Na-Ca distribution between tourmaline and fluid in the system CaO-Na2O-MgO-Al2O3-SiO2-B2O3-H2O[END_REF]. During prograde metamorphism, the muscovite-breakdown reaction of metapelitic rocks produces a low-salinity, reduced, and boron-rich metamorphic fluid [START_REF] Moran | Boron depletion during progressive metamorphism: implications for subduction processes[END_REF][START_REF] Dutrow | Tourmaline-rich pseudomorphs in sillimanite zone metapelites: Demarcation of an infiltration front[END_REF]Dutrow andHenry, 1996, 2012). Such a hydrothermal fluid equilibrated with boron-rich metasediments would contain about 0.2 wt.% B2O3 at 500°C and 1 kbar [START_REF] Weisbrod | Experimental study of tourmaline solubility in the system Na-Mg-Al-Si-B-O-H. Applications to the boron content of natural hydrothermal fluids and tourmalinization processes[END_REF]. Devolatilization of metasediments also induces a high boron isotope fractionation of about -10‰ between mica and fluid at 500°C with preferential partitioning of 11 B into the expelled metamorphic fluid [START_REF] Wunder | The geochemical cycle of boron: constraints from boron isotope partitioning experiments between mica and fluid[END_REF]. Considering that the metamorphic fluid had a δ 11 B = -9.5‰, this would imply that the muscovite-bearing rock would have a very light boron isotope composition of δ 11 B = -19‰, which falls in the range of metasedimentary rocks [START_REF] Ishikawa | Boron isotope systematics of marine sediments[END_REF][START_REF] Peacock | Boron isotopic composition of subduction-zone metamorphic rocks[END_REF][START_REF] Nakano | Boron isotope geochemistry of metasedimentary rocks and tourmalines in a subduction zone metamorphic suite[END_REF][START_REF] Romer | Lithium and boron isotopic fractionation in sedimentary rocks during metamorphism-the role of rock composition and protolith mineralogy[END_REF][START_REF] Berryman | Tourmaline as a petrogenetic indicator in the Pfitsch Formation, Western Tauern Window, Eastern Alps[END_REF]. To sum up, a magmatic or a metamorphic fluid origin is possible for tourmaline from Puy-les-Vignes according to the boron isotope data.

Evolution of the hydrothermal system in the Puy-les-Vignes W deposit

Tourmaline formation at Puy-les-Vignes occurred during the pre-ore hydrothermal alteration stage preceding the main brecciation-collapse episode and continued up to vein opening leading to deposition of wolframite. This boron metasomatism thus represents a protracted process throughout the history of the deposit formation. As previously discussed, the trace element and boron isotopic composition of tourmaline suggest the dominant role of fluid-rock interactions between the metamorphic basement and boron-rich hydrothermal fluids. The fluid evolution of the Puy-les-Vignes ore-forming hydrothermal system is discussed in the following based on geological constraints.

Early greisenization stage (ca. 324 Ma)

Greisen-hosted Tur 1 is interpreted to have formed during the earliest hydrothermal episode known at Puy-les-Vignes, which corresponds to the greisenization of the St-Léonard-de-Noblat paragneisses. Greisen formation is typically related to high-temperature alteration by acidic magmatic fluids released from the apical part of a crystallizing intrusion (Černý et al., 2005). Exsolution of a magmatic volatile phase from a water-saturated and boron-rich (>1 wt.% B2O3) peraluminous granitic melt would preferentially partition boron and other lithophile incompatible elements (Li, Rb, Cs, Sn, W, etc.) into the fluid [START_REF] Audétat | Magmatic-hydrothermal evolution in a fractionating granite: A microchemical study of the Sn-W-F-mineralized Mole Granite (Australia)[END_REF][START_REF] Hervig | Isotopic and elemental partitioning of boron between hydrous fluid and silicate melt[END_REF][START_REF] Thomas | The behaviour of boron in a peraluminous granite-pegmatite system and associated hydrothermal solutions: a melt and fluidinclusion study[END_REF][START_REF] Schatz | Partitioning of boron among melt, brine and vapour in the system haplogranite-H2O-NaCl at 800°C and 100 MPa[END_REF]. In this regard, Tur 1 has the highest concentrations in Rb (10-80 ppm), Cs (1-5 ppm), and W (4-20 ppm) among all tourmaline. No granitic intrusion spatially and genetically connected to the breccia pipe is known at Puy-les-Vignes. The closest and the only contemporaneous intrusion is the Auriat granite, which is located at about 5 km in the northeast of the deposit (Fig. 1A) and is dated at 324 ± 1 Ma (U-Pb on zircon; [START_REF] Gebauer | U/Pb zircon and monazite dating of mafic-ultramafic complex and its country rocks. Example: Sauviat-sur-Vige, French Massif Central[END_REF]. A continuous core drilling of 1000 m through the Auriat granite revealed a vertical zoning marked by an upward enrichment in incompatible trace elements (Li, Rb, Cs, Ta, Th, U) reflecting a magmatic differentiation trend, which was later affected by successive hydrothermal alteration events during the Late Carboniferous to Permian [START_REF] Arniaud | Geochemistry of Auriat granite (Massif Central, France)[END_REF][START_REF] Parneix | Hydrothermal alteration of an old geothermal system in the Auriat granite (Massif Central, France): petrological study and modelling[END_REF]. In particular, late-magmatic tourmaline has been described as an interstitial phase or filling intracrystalline cracks in plagioclase and K-feldspar from the upper part of the Auriat granite [START_REF] Parneix | Hydrothermal alteration of an old geothermal system in the Auriat granite (Massif Central, France): petrological study and modelling[END_REF]. These observations would suggest that the granitic melt contained >2 wt.% B2O3 allowing crystallization of late-magmatic tourmaline at temperature <750°C [START_REF] Wolf | Boron in granitic magmas: stability of tourmaline in equilibrium with biotite and cordierite[END_REF]. Regional geophysical data indicate a NE-SW zone of lower gravity anomaly towards Puy-les-Vignes, suggesting a possible extension of the Auriat granite under the deposit [START_REF] Melleton | Promotion des districts miniers métropolitains[END_REF]. In addition, NE-trending dykes of microgranite crosscutting the enclosing gneisses are located at the intersection with the breccia pipe [START_REF] Weppe | Contribution à l'étude des gîtes de tungstène français : Puy-les-Vignes (Haute Vienne)[END_REF][START_REF] Weppe | Contribution à la géologie minière et à la minéralogie minière. Les gisements de wolfram de Leucamp, Puy-les-Vignes[END_REF]. One of these dykes has been dated at 324.7 ± 2.4 Ma ( 40 Ar-39 Ar on muscovite;

Harlaux, 2016), which is compatible with the age of the Auriat granite. These arguments suggest therefore that a peraluminous granitic cupola, possibly related to the nearby Auriat granite, exists beneath the Puy-les-Vignes deposit. This unexposed granite was likely responsible for the release at ca. 324 Ma of early magmatic-hydrothermal fluids, which would have strongly interacted with the overlying gneisses leading to distal greisenization and forming disseminated Tur 1.

Main tourmalinization stage (ca. 324-318 Ma)

The main tourmalinization stage at Puy-les-Vignes produced a tourmaline-rich crackle breccia affecting the enclosing paragneisses and forming the tourmalinite rims (Tur 2), which is interpreted to have resulted from intense fluid-rock interactions between boron-rich hydrothermal fluids and the host-rocks in a fluid-dominated system (i.e. high fluid/rock ratios). This episode is temporally constrained between 324 Ma ( 40 Ar-39 Ar on muscovite; Ma (650-750°C, 0.7 GPa) and during the Early Carboniferous at ca. 360-350 Ma (550-600°C, 0.8-1 GPa) (Faure et al., 2009a and references therein). Previous works reported that the LGU gneisses in the northern FMC reached the muscovite-breakdown reaction during the prograde metamorphic path, resulting in a biotite-sillimanite-stable assemblage, whereas boron partitioned into the expulsed fluid (van Hinsberg and Schumacher, 2011). This is in good agreement with the mineralogical composition of the migmatitic biotite-sillimanite gneisses of the St-Léonard-de-Noblat unit, implying that those were boron-depleted during the Middle Devonian -Early Carboniferous prograde metamorphism prior to the formation of the Puyles-Vignes deposit. Consequently, the St-Léonard-de-Noblat paragneisses cannot be considered as a viable source of boron for the massive tourmalinization stage that occurred after 324 Ma. An alternative source could be the Dronne micaschists that belong to the PAU located below the LGU, at the bottom of the three-nappe pile system of the FMC. In the northern FMC, the PAU crops out locally in tectonic windows surrounded by higher-grade rocks from the LGU and UGU, and has only been subjected to low-grade metamorphism (Faure et al., 2009a). During the Late Carboniferous (ca. 320-315 Ma), syn-orogenic crustal melting and high-grade metamorphism were coeval in the Limousin area as indicated by the emplacement of two-mica leucogranites into the UGU and LGU and the formation of cordierite-sillimanite migmatites [START_REF] Lafon | Géochronologie U-Pb et leucogranites varisques: cas des massifs de Grandrieu (Lozère) et de la Porcherie (Limousin), Massif Central Français[END_REF][START_REF] Cartannaz | Characterization of wrench tectonics from dating of syn-to post-magmatism in the north-western French Massif Central[END_REF][START_REF] Gébelin | Syntectonic crustal melting and high-grade metamorphism in a transpressional regime, Variscan Massif Central, France[END_REF]Faure et al., 2009b;[START_REF] Gardien | Thermal maturation and exhumation of a middle orogenic crust in the Livradois area (French Massif Central)[END_REF]. release of overpressured magmatic fluids from a crystallizing intrusion beneath the deposit is a possible explanation [START_REF] Sillitoe | Ore-related breccias in volcanoplutonic arcs[END_REF][START_REF] Pollard | Contrasting evolution of fluorine-and boronrich tin systems[END_REF]. This mechanism has generally been proposed for the formation of magmatic-hydrothermal breccia pipes associated with W-Sn mineralization (e.g., [START_REF] Ren | Magmatic and hydrothermal history of the porphyry-style deposits of the Ardlethan tin field, New South Wales, Australia[END_REF][START_REF] Somarin | Hydrothermal alteration and mineralisation of the Glen Eden Mo-W-Sn deposit: a leucogranite-related hydrothermal system, Southern New England Orogen, NSW, Australia[END_REF][START_REF] Yang | Orthomagmatic origin for the Ilkwang Cu-W breccia-pipe deposit, southeastern Kyongsang Basin, South Korea[END_REF][START_REF] Solomovich | Geology and mineralization of the Uchkoshkon tin deposit associated with a breccia pipe, Eastern Kyrgyzstan[END_REF]. The trace element composition of wolframite from Puy-les-Vignes has shown increasing concentrations in granitophile elements (Nb, Ta, Sn, Li) from surface down to 300 m at depth, which has been interpreted as the chemical footprint of the spatial proximity with an underlying leucogranite (Harlaux et al., 2018a). Such trend may indicate wolframite precipitation from magmatic or metamorphic fluids having interacting with the basement. This interpretation is likely since several studies reported the importance of fluidrock interaction as a major process for deposition of wolframite (e.g., [START_REF] Dewaele | Genesis of the vein-type tungsten mineralization at Nyakabingo (Rwanda) in the Karagwe-Ankole belt, Central Africa[END_REF][START_REF] Chicharro | Origin, ore forming fluid evolution and timing of the Logrosán Sn-(W) ore deposits (Central Iberian Zone, Spain)[END_REF][START_REF] Lecumberri-Sanchez | Fluid-rock interaction is decisive for the formation of tungsten deposits[END_REF]. In absence of any evidences arguing for a direct genetic connection of the Puy-les-Vignes breccia pipe to an unexposed leucogranite emplaced at 318 Ma, the origin (magmatic vs. metamorphic) of the ore-forming hydrothermal fluids must be kept open.

5.4.4. Post-ore hydrothermal stage (ca. 300 Ma)

Tur 4 associated with the adularia and chlorite microbreccia formed during a late hydraulic fracturing episode that post-dated the W mineralization. This event is constrained at 301.3 ± 1.5 Ma ( 40 Ar-39 Ar on adularia; [START_REF] Harlaux | Tungsten and Rare-metal (Nb, Ta, Sn) Hydrothermal Metallogenic Systems in the Late-Variscan Orogenic Context: Example of the French Massif Central[END_REF], i.e. more than 20 Ma after the emplacement of the Auriat granite. This age is coeval with the late-Variscan generalized extensional tectonics in the FMC that resulted from the late-orogenic uplift and thinning of the continental crust (Faure et al., 2009a). The 300-305 Ma period is synchronous to the formation of orogenic Au deposits in the Limousin area, which were produced by mixing of metamorphic and meteoric fluids [START_REF] Boiron | Mixing of metamorphic and surficial fluids during the uplift of the Hercynian upper crust: consequences for gold deposition[END_REF][START_REF] Bouchot | Late Variscan mineralizing systems related to orogenic processes: the French Massif Central[END_REF]. Since no episode of granitic magmatism is known in the Limousin during this period, it is likely that Tur 4 was formed by boron-rich fluids equilibrated with the metamorphic pile. This would imply that that the boron isotope composition of metamorphic tourmaline is indistinguishable from the one of tourmaline formed from magmatic-hydrothermal fluids and that caution should be applied when interpreting the fluid sources in granite-related deposits based only on boron isotope compositions of tourmaline.

Conclusions

Tourmaline is an important alteration mineral in the Puy-les-Vignes W deposit occurring We conclude that the trace element and boron isotopic composition of tourmaline from the Puy-les-Vignes deposit was dominantly controlled by fluid-rock interaction between magmatic and/or metamorphic fluids and the country rocks. ratio compared to compositions of worldwide tourmaline hosted in granites [START_REF] Drivenes | Late-magmatic immiscibility during batholith formation: assessment of B isotopes and trace elements in tourmaline from the Land's End granite[END_REF][START_REF] Yang | Tourmaline as a recorder of magmatic-hydrothermal evolution: an in situ major and trace element analysis of tourmaline from the Qitianling batholith, South China[END_REF][START_REF] Duchoslav | Changes in tourmaline composition during magmatic and hydrothermal processes leading to tin-ore deposition: The Cornubian Batholith, SW England[END_REF][START_REF] Hong | Tourmaline-rich features in the Heemskirk and Pieman Heads granites from western Tasmania, Australia: Characteristics, origins, and implications for tin mineralization[END_REF]Kalliomäki et al., 2017), metasediments (van Hinsberg andSchumacher, 2011;[START_REF] Hazarika | Diverse tourmaline compositions from orogenic 40 gold deposits in the Hutti-Maski greenstone belt, India: implications for sources of oreforming fluids[END_REF][START_REF] Kalliomäki | Major and trace element geochemistry of tourmalines from Archean orogenic gold deposits: Proxies for the origin of gold mineralizing fluids?[END_REF]Trumbull et al., 2019), and metavolcanics [START_REF] Galbraith | Assessment of tourmaline compositions as an indicator of emerald mineralization at the Tsa da Glisza Prospect, Yukon Territory[END_REF][START_REF] Hazarika | Diverse tourmaline compositions from orogenic 40 gold deposits in the Hutti-Maski greenstone belt, India: implications for sources of oreforming fluids[END_REF][START_REF] Kalliomäki | Major and trace element geochemistry of tourmalines from Archean orogenic gold deposits: Proxies for the origin of gold mineralizing fluids?[END_REF].

Figure captions

Tur 2a

Core Rim Overgrowth

Tur 2b

Core LGU Para-and orthogneisses (n=38) UGU Para-and orthogneisses (n=10)

UGU Leptyno-amphibolite complex (n=25)

UGU Ophiolites and eclogites (n=47)

Puy-les-Vignes tourmaline Puy-les-Vignes tourmaline

Puy-les-Vignes tourmaline

Puy-les-Vignes tourmaline

  Tourmaline is overall characterized by low concentrations (<0.1 to 10 ppm) of Co, Ni, Cu, Rb, Y, REE, Zr, Nb, Mo, Cs, Ba, Ta, W, Pb, Bi, Th, and U, intermediate concentrations (10s to 100 ppm) of Li, Be, Sc, Sr, and Sn, and high concentrations (100s to >1000 ppm) of Ti, V, Cr, and Zn (Fig.7). The different generations of hydrothermal tourmaline show slightly compositional zoning principally marked by variations in Sc (5-228 ppm), Ti (580-7780 ppm), V (64-804 ppm), Cr (9-13060 ppm), Ni (20-135 ppm), Zn (39-280 ppm),

  Results of thePCA are represented by a two-dimensional projection of the two first principal components (PC1 vs. PC2), which describe the statistical correlations between the investigated variables on a correlation circle. Classical PCA has been applied to the log-transformed LA-ICP-MS dataset of trace element contents in tourmaline (n=116 spot analyses). A total of 18 variables has been selected for the PCA including the main trace elements (Li, Sc, Ti, V, Cr, Co, Zn, Sr, Y, Zr, Nb, Sn, LREE, HREE, W, Pb, Th, U) determined by LA-ICP-MS. Other trace elements at very low concentrations (<1 ppm) or below the limits of detection were not included. PCA applied to each individual generation of tourmaline led to the same group correlations than PCA applied to the complete tourmaline dataset. The projection of the PC1 vs. PC2 planes accounts for 53% of the element content variability. Four groups of element correlation clusters are discriminated by the PCA (Fig.9). A first group is composed of HREE, Y, Zr, Th, and U, which correspond to trivalent and tetravalent high field strength elements. A second group includes Li, Ti, LREE, Sr, and Pb, which correspond mostly to monovalent and bivalent large ion lithophile elements. A third group consists of Nb, Sn, and W, which are tetravalent to hexavalent high field strength elements. A fourth group includes Sc and V, which are anticorrelated with the second group. Finally, the elements Co, Cr, and Zn plot individually, without correlations between each other. Site occupancy in tourmaline is controlled by the charge-to-radius ratios of the elements, with incorporation of 1+ and some 2+ elements (Na, K, Ca, Li, Sr, Pb, etc) in the X-site, 3+, 4+ and some 2+ elements (Fe, Mg, Mn, Co, Ni, Cu, Zn, Sc, Cr, V, Ga, REE, Ti, Hf, Zr, U, etc) in the Y-and Z-sites[START_REF] Von Goerne | Experimental determination of Na-Ca distribution between tourmaline and fluid in the system CaO-Na2O-MgO-Al2O3-SiO2-B2O3-H2O[END_REF]. The statistical correlation clusters identified by PCA therefore reflect partly the crystallochemical control for the incorporation of trace elements in tourmaline. Variation diagrams of selected trace elements (Fig.10) show overlapping concentrations between the different tourmaline generations precluding the discrimination of distinct clusters. Positive correlations between Li vs. Ti, Sr vs. Sn, Sn+W vs. Nb+Ta, Sc vs. V, Pb vs. Sr, or LREE vs. Sr, confirm the results from the PCA.

  [START_REF] Cuney | The timing of W-Sn rare-metals mineral deposit formation in the Western Variscan chain in their orogenic setting: the case of the Limousin area (Massif Central, France). In: The Timing and Location of Major Ore Deposits in an Evolving Orogen[END_REF] and 318 Ma (U-Pb on wolframite;Harlaux et al., 2018b), but it likely occurred soon after the crystallization of the Auriat granite. The St-Léonard-de-Noblat paragneisses belong to the LGU, which experienced successively two episodes of medium-pressure and medium-temperature metamorphism during the Middle Devonian at ca. 385-375

  Although an unexposed peraluminous leucogranite is a possible source for the boron-rich hydrothermal fluids at Puy-les-Vignes, a metamorphic fluid origin cannot be ruled out. We propose that devolatilization of the deepseated Dronne micaschists in the underlying PAU during the Late Carboniferous may also represent a potential mechanism for generating boron-rich metamorphic fluids at depth. Whatever the origin of the fluids (magmatic or metamorphic), the formation of the Puy-les-Vignes quartz-tourmaline crackle breccia would have been the result of a strong focusing of boron-rich hydrothermal fluids rising upwards at the intersection of crustal faults, yielding to hydraulic fracturing and brecciation of the overlying gneiss carapace, filling the cavities between the clasts, and forming the tourmalinite rims (Tur 2) during fluid-rock interactions. 5.4.3. Hydrothermal W mineralization stage (ca. 318 Ma) Hydraulic brecciation and mass collapse of the tourmalinite crackle breccia produced a matrix-supported quartz-tourmaline breccia pipe, followed by fluid-assisted reopening and formation of the network of quartz-wolframite±tourmaline (Tur 3) veins. The age of the W mineralization episode is constrained at 317.7 ± 0.7 Ma (U-Pb wolframite age; Harlaux et al., 2018b), i.e more than 6 Ma after the emplacement of the Auriat granite. The mechanism responsible for the brecciation-collapse of the overlying gneisses is unknown. Explosive

  during pre-, syn-, and post-mineralization stages. The different generations of hydrothermal tourmaline (Tur 1 to Tur 4) belong to the dravite-schorl series and have similar major and trace element compositions plotting in the field of metamorphic rocks. The variable enrichments in granitophile elements and transition metals in tourmaline suggest a mixed magmatic-metamorphic origin likely related to high-temperature fluid-rock interactions between the metamorphic basement and boron-rich, low salinity, and reduced hydrothermal fluids. Boron isotope variations (δ 11 B = -13.3‰ to -7.8‰) in tourmaline cannot unambiguously distinguish between a magmatic and a metamorphic origin of the hydrothermal fluids. According to existing geochronological data and geological constraints, the Puy-les-Vignes breccia pipe is interpreted to result from a multi-stage evolution involving both magmatic and metamorphic fluids. The release of magmatic-hydrothermal fluids from an unexposed peraluminous leucogranitic cupola at ca. 324 Ma, possibly related to the nearby Auriat granite, is proposed as the main mechanism responsible for formation of greisen tourmaline (Tur 1). Massive tourmalinization and hydraulic fracturing of the host-rocks resulted from extensive interactions between boron-rich hydrothermal fluids and the metasedimentary rocks leading to formation of the tourmalinite rims (Tur 2). Fluid-assisted reopening and collapse of the former tourmalinite at ca. 318 Ma yielded to a superimposed matrix-supported quartz-tourmaline breccia pipe and formation of wolframite-bearing quartz veins and syn-ore tourmaline (Tur 3). Finally, post-ore hydraulic fracturing by boron-rich metamorphic fluids resulted in formation of tourmaline microbreccias (Tur 4) at ca. 300 Ma.

Fig. 1 .

 1 Fig. 1. (A) Geological setting and location of the Puy-les-Vignes (PLV) deposit in the Limousin area, northwest French Massif Central (FMC) (modified from[START_REF] Chenevoy | Carte géologique à 1/50 000 Saint-Léonard-de-Noblat et notice explicative[END_REF]. (B) Close-up sketch of the breccia pipe structure at surface (modified from[START_REF] Weppe | Contribution à l'étude des gîtes de tungstène français : Puy-les-Vignes (Haute Vienne)[END_REF].

Fig. 2 .

 2 Fig. 2. Mineralogical and textural features of tourmaline from the Puy-les-Vignes deposit. (A) Typical clast of greisenized gneiss (Gr) rimmed by a cm-thick aureole of black tourmalinite and cemented by quartz (sample PLV-7571). (B) Greisen tourmaline (Tur 1) disseminated in cluster within secondary quartz and muscovite assemblage (sample PLV-02-08a; planepolarized transmitted light). (C) Tourmalinite on a gneissic clast (Tur 2a) composed by the aggregation of tourmaline crystals cemented by macrocrystalline quartz (sample PLV-02-01a; plane-polarized transmitted light). (D) Tourmalinite on a granitic clast (Tur 2b) showing a sharp contact with the quartz of the breccia (sample PLV-02-04a; plane-polarized transmitted light). (E) Acicular tourmaline (Tur 3) disseminated in a wolframite-bearing quartz vein (sample PLV-02-01c; plane-polarized transmitted light). (F) Microbreccia tourmaline (Tur 4) cemented by adularia and chlorite (sample PLV-02-13b; plane-polarized transmitted light).Mineral abbreviations according to the IMA: Ad=Adularia, Chl=Chlorite, Fe-ox=Fe-oxide, Ms=Muscovite, Qtz=Quartz, Tur=Tourmaline.

Fig. 3 .

 3 Fig. 3. Backscattered electron images of tourmaline from the Puy-les-Vignes deposit. (A) Greisen tourmaline (Tur 1) associated with secondary quartz and muscovite (sample PLV-02-08a). (B) Tourmaline on a gneissic clast (Tur 2a), composed by a core and rim surrounded by an overgrowth showing oscillatory zoning (sample PLV-02-01a). (C) Tourmaline on a granitic

Fig. 4 .

 4 Fig. 4. Backscattered electron image (BSE) of a zoned tourmaline from a tourmalinized gneissic clast (Tur 2a) and corresponding X-ray element maps for Mg, Fe, Ti, Ca, and F (sample PLV-02-01a).

Fig. 5 .Fig. 6 .Fig. 7 .

 567 Fig. 5. Chemical compositions of tourmaline from Puy-les-Vignes plotted in the Ca-X☐-

Fig. 8 .

 8 Fig. 8. Multi-element diagrams of tourmaline from Puy-les-Vignes normalized to the upper continental crust (UCC from Rudnick and Gao, 2003). The coloured fields correspond to the minimum and maximum values range. Trace elements are grouped by geochemical affinity (after Decrée et al., 2013).

Fig. 9 .

 9 Fig. 9. Principal component analysis (PCA) of the LA-ICP-MS log-transformed dataset of trace element contents in tourmaline from Puy-les-Vignes (n=116 spot analyses, 18 variables).See text for discussion.

Fig. 10 .

 10 Fig. 10. Variation diagrams of selected trace elements in tourmaline from Puy-les-Vignes.

Fig. 11 .

 11 Fig. 11. Boron isotope compositions of tourmaline from Puy-les-Vignes. (A) Histogram showing the δ 11 B distribution of the different tourmaline generations (Tur 1 to Tur 4) with distinction of the intracrystalline zones (core, rim, overgrowth). (B) δ 11 B variations in tourmaline ordered by generations (Tur 1 to Tur 4). The δ 11 B value of -11.4 ± 1.5‰ represents

Fig. 12 .

 12 Fig. 12. Compositional zoning in a single grain of tourmaline from a massive tourmalinite (Tur 2a; sample PLV-02-01a). (A) Backscattered electron image of a tourmaline grain sectioned perpendicular to the c-axis. Internal zoning is underlined with black dashed lines. (B) Detail view of the oscillatory zoning at the micrometre-scale along the external overgrowth with location of the microanalyses. (C) Corresponding compositional variations in tourmaline along the zoning expressed in atom per formula unit (apfu).

Fig. 13 .

 13 Fig. 13. Selected trace elements in tourmaline from Puy-les-Vignes as function of the Li/Sr

Fig. 14 .

 14 Fig. 14. Average trace element and REE compositions of tourmaline from Puy-les-Vignes compared to the whole-rock compositions of the main lithologies in the northwestern French Massif Central, normalized to the upper continental crust values (UCC from Rudnick and Gao, 2003). The lines correspond to the average of the data and the coloured fields correspond to the minimum and maximum value ranges. Source of the data: St-Sylvestre granite: Villaros and Pichavant (2019), Leger et al. (1990) -Guéret granite: Cartannaz (2005) -Lower Gneiss Unit (LGU) para-and orthogneisses: Cartannaz (2005), van Hinsberg and

  Ni, 63 Cu, 66 Zn, 85 Rb, 88 Sr, 89 Y, 90 Zr, 93 Nb, 95 Mo, 118 Sn, 133 Cs, 137 Ba, 139 La, 140 Ce, 141 Pr, 146 Nd, 147 Sm, 153 Eu, 157 Gd, 159 Tb, 163 Dy, 165 Ho, 166 Er, 169 Tm, 172 Yb, 175 Lu, 181 Ta, 182 W, 208 Pb, 209 Bi,

Al Al 50 Fe 50 Al 50 Mg 50

	A		Tur 1	Al Elbaite	E
			1
	Calcic group	Foitite		Mg-foitite
			2	7
	X-vacant group	Alkali group	Schorl		Dravite
			3	6	8	Uvite
		Na+K	Al 50 Fe 50		Al 50 Mg 50
	Ca
	B			Elbaite	F
			1
	Calcic group	Foitite		Mg-foitite
			2	7
	X-vacant group	Alkali group	Schorl		Dravite
			3	6	8	Uvite
	X	Na+K
	Ca
	Calcic group
	X-vacant group	Alkali group
	X	Na+K

C Al Al 50 Fe 50 Al 50 Mg 50

			Elbaite	G
		1
		Foitite		Mg-foitite
		2	7
		Schorl		Dravite
		3	6	8	Uvite
	Ca
	D
	Calcic group
	X-vacant group	Alkali group
	X	Na+K

Al Al 50 Fe 50 Al 50 Mg 50

	Core
	Rim
	Overgrowth
		Elbaite	H
	1
	Foitite		Mg-foitite
	2	7
	Schorl		Dravite
	3	6	8	Uvite

Table 1 .

 1 Average major element compositions (in wt.% and apfu) of tourmaline from Puy-les-Vignes analyzed by EMPA.

	Table 1. (continued)

Table 2 .

 2 Average trace element concentrations (in ppm) in tourmaline from Puy-les-Vignes determined by LA-ICP-MS.

Table 2 .

 2 (continued)

	Sample	Zone	11 B/ 10 B	δ 11 B (‰)	± 2σ (‰)
	Greisen tourmaline (Tur 1)
	PLV-02-08a_02	Core	3.892	-11.06	0.36
	PLV-02-08a_09	Core	3.896	-10.07	0.40
	PLV-02-08a_06	Core	3.896	-10.00	0.33
	PLV-02-08a_08	Core	3.897	-9.63	0.44
	PLV-02-08a_10	Rim	3.903	-9.41	0.56
	PLV-02-08a_11	Rim	3.904	-9.16	0.40
	PLV-02-08a_01	Rim	3.906	-8.65	0.40
	PLV-02-08a_03	Rim	3.907	-8.45	0.37
	PLV-02-08a_04	Rim	3.907	-8.42	0.36
	PLV-02-08a_05	Overgrowth	3.903	-8.17	0.25
	PLV-02-08a_07	Overgrowth	3.904	-7.78	0.33
		Average (n=11)	-9.16	0.98
	Tourmalinite on gneissic clast (Tur 2a)
	PLV-02-01a_03	Core	3.884	-13.08	0.32
	PLV-02-01a_01	Core	3.888	-12.07	0.28
	PLV-02-01a_07	Core	3.889	-11.69	0.34
	PLV-02-01a_08	Rim	3.890	-11.55	0.34
	PLV-02-01a_02	Overgrowth	3.887	-12.15	0.28
	PLV-02-01a_04	Overgrowth	3.888	-12.03	0.26
	PLV-02-01a_05	Overgrowth	3.890	-11.46	0.38
	PLV-02-01a_06	Overgrowth	3.891	-11.14	0.41
		Average (n=8)	-11.90	0.59
	Acicular tourmaline (Tur 3)
	PLV-02-01c_07	Core	3.884	-13.05	0.32
	PLV-02-01c_05	Core	3.884	-12.99	0.31
	PLV-02-01c_12	Core	3.885	-12.89	0.30
	PLV-02-01c_01	Core	3.885	-12.76	0.35
	PLV-02-01c_10	Core	3.885	-12.71	0.32
	PLV-02-01c_06	Core	3.886	-12.62	0.26
	PLV-02-01c_03	Core	3.888	-12.11	0.29
	PLV-02-01c_11	Rim	3.883	-13.21	0.30
	PLV-02-01c_08	Rim	3.885	-12.91	0.35
	PLV-02-01c_02	Rim	3.886	-12.62	0.26
	PLV-02-01c_09	Rim	3.886	-12.42	0.40
	PLV-02-01c_04	Rim	3.887	-12.25	0.38
		Average (n=12)	-12.71	0.33
	Breccia tourmaline (Tur 4)
	PLV-02-13b_14	Core	3.889	-13.02	0.40
	PLV-02-13b_13	Core	3.891	-12.45	0.43
	PLV-02-13b_01	Core	3.892	-12.29	0.36
	PLV-02-13b_07	Core	3.892	-12.18	0.49
	PLV-02-13b_03	Rim	3.888	-12.08	0.39
	PLV-02-13b_12	Rim	3.888	-12.04	0.44
	PLV-02-13b_02	Rim	3.888	-11.97	0.31
	PLV-02-13b_05	Rim	3.894	-10.44	0.38
	PLV-02-13b_11	Rim	3.895	-10.30	0.67
	PLV-02-13b_06	Overgrowth	3.883	-13.26	0.37
	PLV-02-13b_04	Overgrowth	3.886	-12.43	0.33
	PLV-02-13b_15	Overgrowth	3.889	-11.75	0.38
	PLV-02-13b_10	Overgrowth	3.890	-11.55	0.44
	PLV-02-13b_09	Overgrowth	3.894	-10.52	0.42
	PLV-02-13b_08	Overgrowth	3.894	-10.51	0.49
		Average (n=15)	-11.79	0.94

Table 3 .

 3 Boron isotopic compositions of tourmaline from Puy-les-Vignes measured by SIMS.

									10 2
	10 -1 10 Sn + W (ppm) 1		Tourmaline hosted in metamorphic rock		Tourmaline hosted in granite		Nb + Ta (ppm) 10 -1 1 10	rock metamorphic Tourmaline hosted in			Tourmaline hosted in granite
	10 -2	-3	10 -2	10 -1	1	10	10 2	10 3	10 -2 10 -3	10 -2	10 -1	1	10	10 2	10 3
					Li / Sr								Li / Sr
									10 2
			Tourmaline
	Cr + V (ppm)		hosted in metamorphic rock			Tourmaline hosted in		Y + REE (ppm)	1 10	Tourmaline rock metamorphic hosted in			Tourmaline granite hosted in
	10						granite
	1	-3	10 -2	10 -1	1	10	10 2	10 3	10 -3 10 -1	10 -2	10 -1	1	10	10 2	10 3
					Li / Sr								Li / Sr

Acknowledgements

This work was supported by the French National Research Agency through the national LABX-21-RESSOURCES21, and has also taken part of the project ERAMIN "New Ores".

The authors would like to thank Dr. Hossein Ahmadzadeh and the Musée Minéralogique de l'Ecole des Mines d'Alès (France) for supplying samples of collection from the Puy-les-Vignes mine. We also thank Sandrine Mathieu, Dr. Andreï Lecomte, Dr. Olivier Rouer, and Dr. Chantal Peiffert (GeoRessources, Vandoeuvre-lès-Nancy, France) for technical support in providing analytical data with SEM, EMPA, and LA-ICP-MS. We are also grateful to Dr.

Andrey Gurenko and Dr. Etienne Deloule (CRPG-CNRS, Vandoeuvre-lès-Nancy, France) for their help during the SIMS analyses. Constructive reviews and suggestions by Dr. Robert Trumbull and another anonymous reviewer greatly improved the quality of the manuscript.

We also thank the Editor-in-Chief Prof. Franco Pirajno for the editorial handling.

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Greisen tourmaline (Tur 1)