Pauline Corentin
email: pauline.corentin@u-bourgogne.fr

Jean-François Deconinck

Pierre Pellenard

Francis Amédro

Ludovic Bruneau

Elise Chenot

Bertrand Matrion

Emilia Huret

Philippe Landrein

Environmental and climatic controls of the clay mineralogy of Albian deposits in the Paris and Vocontian basins (France)

Keywords: Clay minerals, Albian, Paris Basin, Vocontian Basin, Palaeoclimate

niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Most often, the reconstruction of Cretaceous climates is based on an estimate of the ocean surface or deep water temperatures from a variety of proxies including δ 18 O, TEX86 and more recently ∆47 [START_REF] Friedrich | Evolution of middle to Late Cretaceous oceans-A 55 m.y. record of Earth's temperature and carbon cycle[END_REF][START_REF] O'brien | Cretaceous sea-surface temperature evolution: Constraints from TEX86 and planktonic foraminiferal oxygen isotopes[END_REF][START_REF] Meyer | Climate of the Late Cretaceous North American Gulf and Atlantic Coasts[END_REF]. The global climate evolution during the Albian is well known in terms of temperatures inferred from numerous δ 18 O data measured on foraminifera and belemnite guards [START_REF] Friedrich | Evolution of middle to Late Cretaceous oceans-A 55 m.y. record of Earth's temperature and carbon cycle[END_REF].

After the late Aptian 'coldhouse' climate [START_REF] Herrle | Calcareous nannofossils from the Aptian-Lower Albian of southeast France: palaeoecological and biostratigraphic implications[END_REF][START_REF] Pirrie | Cool early Albian climates; new data from Argentina[END_REF][START_REF] Bodin | Large igneous provinces and organic carbon burial: Controls on global temperature and continental weathering during the Early Cretaceous[END_REF][START_REF] Rodríguez-López | Glacial dropstones in the western Tethys during the late Aptian-early Albian cold snap: Palaeoclimate and palaeogeographic implications for the mid-Cretaceous[END_REF], the Albian stage is characterized by a regular increase in temperature from the base to the top. This trend continued until the Cretaceous thermal maximum that occurred around the Cenomanian/Turonian boundary [START_REF] O'brien | Cretaceous sea-surface temperature evolution: Constraints from TEX86 and planktonic foraminiferal oxygen isotopes[END_REF][START_REF] Huber | The rise and fall of the Cretaceous Hot Greenhouse climate[END_REF].

The estimation of the fluctuations in the hydrological cycle and the intensity of the precipitation during the Albian is discussed much less often [START_REF] Föllmi | Early Cretaceous life, climate and anoxia[END_REF], even though this stratigraphic interval corresponds to dramatic changes in the Earth's history. Albian environments are notably characterized by a radiation of angiosperms and their development in floodplain areas and by the emergence of a narrow humid equatorial climatic belt in comparison with the earlier stages of the Early Cretaceous during which the equatorial humid belt was absent [START_REF] Chumakov | Climate belts of the mid-Cretaceous time[END_REF][START_REF] Poulsen | Response of the mid-Cretaceous global oceanic circulation to tectonic and CO2 forcings[END_REF][START_REF] Chaboureau | Tectonic-driven climate change and the diversification of angiosperms[END_REF]. A warm and humid belt around the equator is deduced from the common occurrence of bauxite and coal during the Albian [START_REF] Chumakov | Climate belts of the mid-Cretaceous time[END_REF]. This re-organization of the climatic belts is likely a consequence of the widening of the South and North Atlantic Oceans which thereby introduced a source of moisture [START_REF] Chaboureau | Tectonic-driven climate change and the diversification of angiosperms[END_REF]. Therefore, it appears that the Albian was a pivotal period from a climatic point of view that may have had consequences on the hydrological cycle.

In the Anglo-Paris Basin, Albian seawater temperatures were estimated using δ 18 O analysis of the belemnite guards and fish teeth from the Wissant section outcropping in the Boulonnais area (northwest of the Paris Basin, Bomou et al., 2016, Fig. 1). The measured temperatures on the belemnite guards (bottom waters) range from 13.5 to 19.3°C with an increase from the middle to late Albian. The δ 18 O values for the phosphate in the fish teeth indicate temperatures (from intermediate or sea surface waters) that varied between 22° and 28°C with a similar trend. Increasing temperatures during the Albian are consistent with the long-term global warming recorded from the Albian to the Cenomanian using either δ 18 O measured in the foraminiferal test or the TEX86 proxy [START_REF] Friedrich | Evolution of middle to Late Cretaceous oceans-A 55 m.y. record of Earth's temperature and carbon cycle[END_REF][START_REF] O'brien | Cretaceous sea-surface temperature evolution: Constraints from TEX86 and planktonic foraminiferal oxygen isotopes[END_REF][START_REF] Kanungo | A brief warming event in the late Albian: evidence from calcareous nannofossils, macrofossils, and isotope geochemistry of the Gault Clay Formation, Folkestone, southeastern England[END_REF]. However, although moisture is a key palaeoclimate parameter, the changes in humidity and weathering conditions that occurred during the Albian are much less documented [START_REF] Ufnar | The mid-Cretaceous water bearer: Isotope mass balance quantification of the Albian hydrologic cycle[END_REF]Herrle et al., 2003b;[START_REF] Horikx | Vegetation dynamics, angiosperm radiation and climatic changes in the Lusitanian Basin (Portugal) during Albian times[END_REF]. Our objective is therefore to improve knowledge on humidity/aridity conditions prevailing during the Albian using clay mineral assemblages from sediments deposited in two distinct provinces: the Paris basin (Boreal Province) and the Vocontian basins (Tethyan Province).

Geological context

During the Albian, the Anglo-Paris Basin was an epicontinental sea connecting the Boreal domain to the north-west and the Tethyan domain to the south-east. It was located at a latitude close to 35°N within a mid-latitude warm humid belt (Fig. 1, [START_REF] Boucot | Phanerozoic paleoclimate: An atlas of lithologic indicators of climate[END_REF][START_REF] Amédro | L'étage Albien dans sa région-type, (Aube, France) : une synthèse dans un contexte sédimentaire global[END_REF][START_REF] Gély | Le bassin parisien, un nouveau regard sur la géologie[END_REF]. The Albian deposits from the type locality (stratotype, department of Aube, south-east of the Paris Basin) were only known by temporary outcrops or quarries where only a few metres of the sedimentary succession can be observed [START_REF] Amédro | L'Albien du bassin anglo-parisien: Ammonites zonation phylétique, séquences[END_REF][START_REF] Amédro | Une coupe lithologique synthétique dans l'Albien-type de l'Aube[END_REF]2008[START_REF] Haq | Cretaceous eustasy revisited[END_REF]. Consequently, a complete continuous succession could not be established in this part of the Paris Basin. Recently, boreholes were drilled by ANDRA (French agency for nuclear waste disposal) in the department of Aube, allowing the whole lower to middle Albian clayey succession to be examined. The sedimentary series belongs to the so-called 'Argiles tégulines de Courcelles' unit which overlies the Aptian and lowermost Albian greensands, the so-called 'Sables Verts de l'Aube'. In one of the boreholes, the succession encompasses the lowermost part of the overlying 'Marnes de Brienne' of late Albian age.

The Paris Basin was bordered to the south-west by the Armorican Massif and the French Massif Central, and to the north-east by the London-Brabant Massif (Fig. 1, [START_REF] Amédro | L'étage Albien dans sa région-type, (Aube, France) : une synthèse dans un contexte sédimentaire global[END_REF][START_REF] Amédro | Le Crétacé du Bassin parisien[END_REF]. At that time, north-west Europe was made up of large islands inherited from the Variscan orogeny. Although clay minerals are likely to be deposited very far from their detrital source, the French Massif Central and the London-Brabant Massif were probably the main sources of detrital clay mineral since coeval detrital sandy deposits of the Paris Basin originated from these massifs [START_REF] Amédro | Le Crétacé du Bassin parisien[END_REF]). These massifs were located at slightly different latitudes and are made up of distinct parent rocks, therefore, significant differences in the composition of clay assemblages can be expected.

The Vocontian Basin was located on the northern margin of the Tethys Ocean, around 30°N at a somewhat lower palaeoaltitude and closer to the semi-arid belt than the Paris Basin (Chumakov et al., 1995, Hay and[START_REF] Hay | New thoughts about the Cretaceous climate and oceans[END_REF]Fig. 1). This basin was surrounded by shallow platforms except to the east where it was largely opened to the Tethys Ocean (Fig. 1).

Lower to middle Albian deposits (Blue Marls Formation) are well-exposed in several sections [START_REF] Bréhéret | L'Aptien et l'Albien de la Fosse vocontienne (des bordures au bassin). Évolution de la sédimentation et enseignements sur les événements anoxiques[END_REF][START_REF] Gale | The uppermost Middle and Upper Albian succession at the Col de Palluel, Hautes-Alpes, France: an integrated study (ammonites, inoceramid bivalves, planktonic foraminifera, nannofossils, geochemistry, stable oxygen and carbon isotopes, cyclo-stratigraphy)[END_REF]. The Col de Pré-Guittard section was chosen for this study considering its location in the western part of the Vocontian Basin, far from thermal influences that would transform detrital clay minerals. This reference section is also clearly defined with biostratigraphy [START_REF] Kennedy | Integrated stratigraphy across the Aptian-Albian boundary in the Marnes Bleues, at the Col de Pré-Guittard, Arnayon (Drôme), and at Tartonne (Alpes-de-Haute-Provence), France, a candidate Global Boundary Stratotype Section and Point for the base of the Albian Stage[END_REF][START_REF] Kennedy | Integrated stratigraphy across the Aptian/Albian boundary at Col de Pré-Guittard (southeast France): A candidate Global Boundary Stratotype Section[END_REF][START_REF] Petrizzo | Abrupt planktic foraminiferal turnover across the Niveau Kilian at Col de Pré-Guittard (Vocontian Basin, southeast France): new criteria for defining the Aptian/Albian boundary[END_REF], and was approved recently as the Albian Global Boundary Stratotype Section and Point (GSSP) [START_REF] Kennedy | The Global Boundary Stratotype Section and Point (GSSP) for the base of the Albian Stage, of the Cretaceous, the Col de Pré-Guittard section, Arnayon, Drôme, France[END_REF].

Lithology and biostratigraphy

Boreholes from the Paris Basin

Two boreholes (AUB111 and AUB220) located close to Juzanvigny, and one borehole drilled close to Vallentigny (AUB240) were studied (Fig. 2). Samples were taken every meter in the borehole AUB240 and every 50 centimeters in the boreholes AUB111 and AUB220.

The distance between boreholes AUB111 and AUB220 is only 1 km. One of the cores (AUB111, Fig. 3) has been described in detail including a precise biostratigraphic scheme on the basis of the abundant ammonite fauna [START_REF] Amédro | Les forages de Juzanvigny (Aube, France) : litho-biostratigraphie des formations du Barrémien à l'Albien moyen dans l'est du bassin de Paris et datations par les ammonites[END_REF] following the ammonite biozonation proposed by [START_REF] Amédro | L'étage Albien dans sa région-type, (Aube, France) : une synthèse dans un contexte sédimentaire global[END_REF]. Lower to middle Albian deposits (Argiles tégulines de Courcelles) essentially consist of bioturbated clays and silty clays with occasional pyrite and phosphate nodules [START_REF] Knight | Phosphates and phosphogenesis in the Gault Clay (Albian) of the Anglo-Paris Basin[END_REF]. Phosphate nodules are either scattered or in the form of thin horizons that may be correlated at a regional scale. The base of the unit is more or less sandy, with increasingly more abundant glauconite further down the core, until the boundary with the Aptian greensands (Sables Verts de l'Aube Formation).

Borehole AUB 220 shows a sedimentary succession quite similar to that described in borehole AUB111, but it can be used to provide more descriptions further upward in the series (Figs. 4 and 5; Supplementary Appendix). In addition, the recovery across the boundary between the Sables Verts de l'Aube and the Argiles tégulines de Courcelles is better than in the AUB111 borehole. Notably, a condensed horizon composed of a 10 cm-thick phosphatic crust corresponding to a hardground is particularly well preserved in this borehole (Fig. 5). The age of the deposits recovered in the lower part of the two boreholes is not well established. In this part of the Paris Basin, the Sables Verts de l'Aube unit is considered to be Aptian in age [START_REF] Amédro | Une coupe lithologique synthétique dans l'Albien-type de l'Aube[END_REF] because of the occurrence of the benthic foraminifera Verneuilinoides subfiliformis which suggests that the Sables verts de l'Aube belong to the Hypacanthoplites jacobi Zone from the upper Aptian [START_REF] Damotte | Ostracodes et Foraminifères de l'Aptien inférieur du sondage du Bois du Perchois (Aube)[END_REF][START_REF] Mutterlose | The Vöhrum section (northwest Germany) and the Aptian/Albian boundary[END_REF].

The phosphatic crust corresponds to a condensed interval that, according to previous studies on outcrops located in the same region, likely includes the Leymeriella tardefurcata and Leymeriella regularis ammonite zones (Amédro andMatrion 2007, 2014). At the base of the two boreholes, the 5 m-thick interval between the phosphatic crust and the first occurrence of D. mammillatum is not well dated as only Beudanticeras sp. have been found. This interval probably successively corresponds to the Sonneratia kitchini, Cleoniceras floridum and Hemisonneratia puzosiana zones compared with the sections outcropping to the south-east of the Paris Basin (Destombes in [START_REF] Rat | L'Albien de l'Aube[END_REF][START_REF] Amédro | La zone d'ammonite à Protohoplites (Hemisonneratia) puzosianus et sa position dans la zonation réactualisée de l'Albien inférieur du bassin anglo-parisien[END_REF][START_REF] Amédro | Corrélations dans l'Albien de l'Yonne et de l'Aube, France (lithologie et ammonites)[END_REF]. Above this poorly dated interval, the borehole is precisely dated by numerous ammonites which can be used to draw an accurate biostratigraphic scheme (Figs. 345). The two boreholes can be easily correlated in particular by using marker beds that include horizons of phosphate nodules and bio-events [START_REF] Amédro | L'Albien type de l'Aube (France) : première description litho-biostratigraphique de la totalité des Argiles tégulines de Courcelles[END_REF].

The change from the Aptian greensands, deposited in shoreface, estuarine or fluviodeltaic environments [START_REF] Guillocheau | Meso-Cenozoic geodynamic evolution of the Paris Basin: 3D stratigraphic constraints[END_REF], to the Argiles tégulines de Courcelles deposited in offshore environments clearly indicates a deepening of the depositional environments as a consequence of the early Albian transgression from the south-west through the Burgundy high (Pictet et al., 2018). This transgressive trend is also expressed by the occurrence of cosmopolitan ammonites indicating the opening of the Burgundy threshold (Fig. 1).

The third borehole, AUB240 (Fig. 2), shows a similar lithological succession but the upper part of the borehole has permitted the recovery of the topmost part of the Argiles tégulines de Courcelles and the lowermost part of the Marnes de Brienne (Fig. 7). The recognition of marker beds between the three boreholes allows precise correlations to be drawn [START_REF] Amédro | L'Albien type de l'Aube (France) : première description litho-biostratigraphique de la totalité des Argiles tégulines de Courcelles[END_REF]. In the upper part of this borehole, all ammonite zones were recognized except the Dipoloceras cristatum Zone which is condensed and corresponds to the occurrence of a phosphate nodule bed [START_REF] Amédro | L'Albien type de l'Aube (France) : première description litho-biostratigraphique de la totalité des Argiles tégulines de Courcelles[END_REF].

The Col de Pré-Guittard section (Vocontian Basin)

The Col de Pré-Guittard section (Fig. 8) shows the lower to middle Albian sedimentary succession, which is part of the Blue Marls Formation. It mainly consists of hemipelagic blue-grey marls punctuated by several marker beds and bundles of micritic limestones used as marker horizons to refine the correlations throughout the basin [START_REF] Friès | Dynamique du bassin subalpin méridional de l'Aptien au Cénomanien[END_REF][START_REF] Bréhéret | L'Aptien et l'Albien de la Fosse vocontienne (des bordures au bassin). Évolution de la sédimentation et enseignements sur les événements anoxiques[END_REF]. Organic matter-rich layers (black shales) are also common, the most prominent of these being the Paquier horizon corresponding to the sedimentary expression of Oceanic Anoxic Event (OAE) 1b (Bréhéret, 1985 a and b;[START_REF] Tribovillard | Organic facies of the Early Albian Niveau Paquier, a key black shales horizon of the Marnes Bleues Formation in the Vocontian Trough (Subalpine Ranges, SE France)[END_REF][START_REF] Hart | The Albian stage and substage boundaries[END_REF][START_REF] Erbacher | Correlating environmental changes during early Albian oceanic anoxic event 1B using benthic foraminiferal paleoecology[END_REF]Herrle et al., 2003b). The section has been measured from the Aptian/Albian transition (Kilian bundle) to the lowermost middle Albian. Samples were taken every metre.

Because different ammonite biozonations (Boreal vs Tethyan) are used in sections from the Paris Basin and the Vocontian Basin, correlations are difficult, however a comparison between the ammonite biozones used in both study areas is given in Table 1. Notably, the D. [START_REF] Gale | The uppermost Middle and Upper Albian succession at the Col de Palluel, Hautes-Alpes, France: an integrated study (ammonites, inoceramid bivalves, planktonic foraminifera, nannofossils, geochemistry, stable oxygen and carbon isotopes, cyclo-stratigraphy)[END_REF], but here, the absence of ammonite in the lower levels does not allow to recognise the total vertical distribution of this species. The appearance of O. roissyanum is however well documented both in northern France [START_REF] Amédro | Stratigraphie séquentielle des successions albiennes du bassin anglo-parisien et du bassin de Mons (Belgique)[END_REF] and Kent in south-east England (Young et al., 2010), from the Hoplites dentatus Zone.

Therefore, the O. roissyanum Total Range Zone used in this paper comprises successively the Hoplites dentatus, Anahoplites intermedius, Dimorphoplites niobe and D. biplicatus zones in the Anglo-Paris Basin.

Methods

Mineralogy

A total of 400 samples were analysed using X-Ray Diffraction (XRD). After moderate grinding in a mortar, powdered samples were decarbonated with a 0.2N HCl solution. The < 2 µm fraction (clay-sized particles) was extracted with a syringe after decantation of the suspension for 95 minutes following Stokes' law; this fraction was then centrifuged. Clay residue was then smeared on oriented glass slides and run in a Bruker D4 Endeavour diffractometer with CuKα radiations, a LynxEye detector and a Ni filter with a voltage of 40 kV voltage and an intensity of 25 mA (Biogéosciences laboratory, University of Burgundy, France). Goniometer scanning ranged from 2.5° to 28° for each analysis. Three runs were performed for each sample to discriminate the clay phases: 1) air-drying; 2) ethylene-glycol solvation; and 3) heating at 490°C, as recommended by [START_REF] Moore | X-Ray diffraction and the identification and Analysis of Clay Minerals[END_REF] (Fig. 9).

Clay minerals were identified using their main diffraction (d001) peak and by comparing the three diffractograms obtained. The following main clay minerals were identified (Fig. 9) : a R0 type illite-smectite mixed-layer (17 Å based on a glycolated run condition) referred to as smectite for the following sections; a R1 type illite-smectite mixed-layer (around 11.5 Å in air-drying conditions and 13 Å after ethylene-glycol solvation); chlorite (14.2 Å, 7.1 Å, 4.7 Å and 3.54 Å peaks); illite (10 Å, 5 Å, 3.33 Å peaks); kaolinite (7.18 Å and 3.58 Å peaks) and vermiculitic clays including true vermiculite (14 Å in air-drying conditions, 14.5-15 Å after ethylene-glycol solvation and 10 Å peaks after heating) and chlorite-vermiculite mixed-layers.

The relative proportions of clay minerals are estimated using peak intensity ratios, the most relevant of these being the ratio between the 7.18 Å and 17 Å peaks corresponding to kaolinite + chlorite/smectite (K+C/S). The error of this method is approximatively ± 5 %. This ratio can be taken as an estimate of the humidity vs aridity.

Fifteen samples have been measured for CaCO3 content on the AUB 111 borehole with a Bernard's calcimeter device (uncertainty of ~1%). No measurement were done in the Vocontian Basin as [START_REF] Bréhéret | L'Aptien et l'Albien de la Fosse vocontienne (des bordures au bassin). Évolution de la sédimentation et enseignements sur les événements anoxiques[END_REF], previously performed it. We only compared the GRS signal that we measured on the field with the CaCO3 content given by [START_REF] Bréhéret | L'Aptien et l'Albien de la Fosse vocontienne (des bordures au bassin). Évolution de la sédimentation et enseignements sur les événements anoxiques[END_REF].

Spectral gamma ray (SGR)

SGR measurements were taken on the Col de Pré-Guittard section every 50 cm at the same position as for the samples collected for XRD. Field SGR measurements were taken with a constant 1-min acquisition time using a Geofyzica-Statis-Geo GS-512 spectrometer with a Cesium 137 scintillation detector. For all readings, the detector was placed against outcrop surfaces that had been cleaned of weathered material and smoothed. A scintillometer arrangement was used to produce an energy spectrum for the natural gamma rays emitted from an outcrop. This spectrum was interpreted electronically to yield concentrations of the principal gamma ray sources involved, namely potassium (K), thorium (Th) and uranium (U).

K and Th are usually concentrated in clay minerals whereas U is associated with organic matter [START_REF] Myers | Understanding Jurassic organic-rich mudrocks -new concepts using gamma-ray spectrometry and palaeoecology: examples from the Kimmeridge Clay of Dorset and the Jet Rock of Yorkshire[END_REF]. SGR values are given in ppm (eq. U). Measurement reproducibility is assessed at 5% (1σ) by repeating the same measurement 30 times [START_REF] Martinez | Astrochronology of the Valanginian Stage from reference sections (Vocontian Basin, France) and palaeoenvironmental implications for the Weissert Event[END_REF]). The spectral gamma ray is an effective tool for the preliminary assessment of the degrees of palaeoweathering (clay content) and is therefore commonly used for palaeoclimate reconstructions [START_REF] Ruffell | Do spectral gamma ray data really reflect humid-arid palaeoclimates? A test from Palaeogene Interbasaltic weathered horizons at the Giant's Causeway, N. Ireland[END_REF].

Results

Paris Basin

In the Argiles tégulines de Courcelles unit, the CaCO3 proportions are between 10% and 15% except in some marly limestones where the CaCO3 content reaches 40%. Smear slides performed on some clayey samples show abundant nannofossils which are likely responsible for the CaCO3 content. Consequently, clay minerals represent a significant amount of the deposits.

Clay mineralogy

The clay mineral assemblages of the AUB111 borehole are mainly composed of illite (28% on average), vermiculitic clays (10% on average), smectite (22% on average) and kaolinite (26% on average). They also contain chlorite (≤ 5%), R1 type illite-smectite mixedlayers and chlorite-vermiculite mixed-layers, which are both estimated to be 5% or less (Fig. 3). The composition of the mineralogical assemblages along the borehole allows to distinguish three different intervals. At the base of the borehole, from 69.10 to 63.96 m, the first poorly-dated interval is characterized by abundant smectite (up to 70%), illite, and very low proportions of kaolinite. Some illite-rich samples occur in the glauconitic interval, close to the transition with the greensands. The presence of glauconite in the deposits is confirmed by the observation of smear slides. Above, the second interval is marked from 63.96 to 13.35 m by increasing proportions of kaolinite and illite together with vermiculitic clays in significant proportions (up to 15%), while the smectite proportion decreases. In this interval, the proportions of illite generally range between 20 and 30%, with occasionally more abundant proportions reaching 40% (Fig. 3). The disappearance of vermiculitic clays and the higher proportions of smectite (~ 40%) characterize the third interval, above 13.35 m while the percentages of kaolinite and illite decrease. The transition from the second to the third interval occurs around the transition from the A. intermedius to D. niobe ammonite zones.

The clay mineralogy of the AUB220 borehole is quite similar to that described in AUB111 indicating that the clay mineralogy of the Argiles Tégulines de Courcelles is, as expected, homogeneous at a kilometer scale (Figs. 4 and5). The increase in smectites content in the third interval is better expressed, since this borehole includes an upper part of the Argiles tégulines de Courcelles (Figs. 4 and5).

In the upper part of borehole AUB240, a fourth interval is observed from 8.75 to 27.3 m marked by a decrease in smectite while increasing proportions of illite, vermiculitic clays and kaolinite are observed in the pricei Zone (Fig. 7). Therefore, within the Argiles tégulines de Courcelles, the D. niobe/D. biplicatus time-equivalent interval is characterized by a smectite-rich sedimentation compared to the rest of the formation. This evolution in the clay assemblages confirms the low-resolution clay mineral data published by [START_REF] Fauconnier | Répartition des Péridiniens de l'Albien du bassin de Paris. Rôle stratigraphique et liaison avec le cadre sédimentologique[END_REF] and [START_REF] Pomerol | Minéralogie des argiles albiennes du sud du Pays d'Othe (sud-est du bassin de Paris). Modalités du passage latéral Sables de la Puisaye-Argiles Tégulines[END_REF].

Vocontian Basin

The clay mineral assemblages of the Col de Pré-Guittard section are mainly composed of smectite (63% on average), illite (19% on average) and kaolinite (11% on average). They also contain about 5% of chlorite (Fig. 10). Traces of R1 type illite-smectite mixed-layers and chlorite-vermiculite mixed-layers may be present (≤ 2%) in some samples and although they were taken into account in the calculation, they are not represented in Figure 10. The clay composition is marked by a gradual smectite decrease from 70% from the base to 60% at the top of the section. This decrease corresponds to a clear increase in kaolinite with values in the order of 5% down section to values greater than 15% above. Interestingly, as in the Paris Basin, sedimentary rocks located around the Aptian/Albian boundary are depleted in kaolinite. The proportion of kaolinite increases during the L. tardefurcata ammonite Zone but remains generally below 10%, while in the D. mammillatum Zone, the proportions of kaolinite are higher than 10%.

According to [START_REF] Bréhéret | L'Aptien et l'Albien de la Fosse vocontienne (des bordures au bassin). Évolution de la sédimentation et enseignements sur les événements anoxiques[END_REF], the CaCO3 content is approximately 20% at the base of the section and increases to approximately 40% at the top, which is consistent with our SGR measurements that show a reverse long-term trend with decreasing values from the base to the top of the section (Fig. 10). This expected inverse relationship between the SGR measurements and the CaCO3 content was already observed in the Aptian part of the Blue Marls Formation [START_REF] Ghirardi | Multi-proxy orbital chronology in the aftermath of the Aptian Oceanic Anoxic Event 1a : Palaeoceanographic implications (Serre Chaitieu section, Vocontian Basin, SE France)[END_REF].

Discussion

Influence of burial diagenesis

Burial diagenesis may transform clay mineral assemblages leading to a misreading of the original paleoclimatic and paleoenvironmental signal. Before examining the environmental significance of the clay minerals, it is important to ensure that they are dominantly detrital without any significant influence of burial diagenesis.

In the Paris Basin, the post-Albian geological history includes the deposition of the Upper Cretaceous chalk, the maximum thickness of which probably never exceeded 1000 m.

At least 700 m of the Cenomanian to lower Campanian chalk was preserved in the depocentre of the Paris Basin [START_REF] Robaszynski | Stratigraphy and stage boundaries in a type-section of the Late Cretaceous chalk from the East Paris basin: The "Craie 700 boreholes[END_REF] but the total thickness was greater since the upper Campanian to Maastrichtian chalks have been dissolved (the Maastrichtian chalk is known as reworked pebbles) and eroded during the latest Cretaceous. Consequently, the Upper Cretaceous chalk is separated from the Cenozoic deposits by a major unconformity truncating Late Cretaceous folds [START_REF] Guillocheau | Meso-Cenozoic geodynamic evolution of the Paris Basin: 3D stratigraphic constraints[END_REF]. In the eastern part of the Paris Basin, the chalk series was probably thinner but this was difficult to evaluate. Detailed reconstructions of the thermal evolution of the eastern part of the Paris Basin indicate that even in the Late Jurassic, the maximum burial temperature reached by the end of the Cretaceous never exceeded 50-60°C [START_REF] Pellenard | Contrôle géodynamique de la sédimentation argileuse du Callovien-Oxfordien moyen dans l'Est du Bassin de Paris : influence eustatique et volcanique[END_REF][START_REF] Blaise | Reconstruction of low temperature (<100° C) burial in sedimentary basins: A comparison of geothermometer in the intracontinental Paris Basin[END_REF][START_REF] Mangenot | Basin-scale thermal and fluid flow histories revealed by carbonate clumped isotopes (Δ47) -Middle Jurassic carbonates of the Paris Basin depocentre[END_REF]. Consequently, in the overlying Albian deposits, the temperature remained low; this is confirmed by the abundance of smectite, as these minerals are known to be particularly sensitive to burial diagenesis and are transformed into R1 illite-smectite mixed-layers and illite through illitization processes at temperatures over 60-70°C [START_REF] Merriman | Patterns of very low-grade metamorphism in metapelitic rocks[END_REF][START_REF] Lanson | Diagenetic smectite-to-illite transition in clay-rich sediments: a reappraisal of X-ray diffraction results using the multi-specimen method[END_REF][START_REF] Środoń | K-Ar dating of the Lower Palaeozoic K-bentonites from the Baltic Basin and the Baltic Shield: implications for the role of temperature and time in the illitization of smectite[END_REF][START_REF] Dellisanti | Use of Tmax as a thermal maturity indicator in orogenic successions and comparison with clay mineral evolution[END_REF]. As a result, the abundance of smectite from the lowermost part of the studied boreholes indicates that the temperatures never exceeded 60-70°C and that the clay minerals are mostly primary and detrital in origin.

In the Vocontian Basin, for the same reasons, the abundance of smectite indicates a negligible influence of burial diagenesis on the clay mineralogy. Numerous studies have shown that in the western part of the Vocontian Basin, the influence of diagenesis on clay minerals from Lower Cretaceous formations is weak [START_REF] Deconinck | Héritage et diagenèse des minéraux argileux dans les alternances marno-calcaires du Crétacé inférieur du domaine subalpin[END_REF][START_REF] Ferry | Diagenèse croissante des argiles dans les niveaux isochrones de l'alternance calcaire-marne valanginienne du bassin vocontien. Zonation géographique[END_REF]Deconinck andDebrabant, 1985, Levert and[START_REF] Levert | Diagenèse argileuse complexe dans le mésozoïque subalpin révélée par cartographie des proportions relatives d'argiles selon des niveaux isochrones[END_REF]. In the Col de Pré-Guittard section, Rock-Eval analyses performed on organic matter-rich horizons show that Tmax values are comprised between 417 and 437°C indicating that organic matter is immature or at the onset of the oil window, thereby confirming that the influence of thermal diagenesis remained weak on this section [START_REF] Bréhéret | L'Aptien et l'Albien de la Fosse vocontienne (des bordures au bassin). Évolution de la sédimentation et enseignements sur les événements anoxiques[END_REF].

Authigenic clay minerals

Detrital clay assemblages may be modified by the authigenesis of clay minerals formed either during early or late successive diagenetic steps. Authigenic glauconite (ironrich illite) is common in Albian deposits notably at the transition between the greensands and the Argiles tégulines de Courcelles that is at the base of the boreholes studied in the Paris Basin. Although glauconite granules are much coarser than the clay fraction, after grinding the samples, glauconitic illite is inevitably partly incorporated in the clay fraction and could be responsible for some abnormally high proportions of illite thus corresponding to a mixture of detrital and authigenic minerals (Fig. 3). This likely occurs at the base of the boreholes at the transition between the Sables verts de l'Aube and the Argiles tégulines de Courcelles.

A detailed study of clay minerals from similar Albian deposits (Gault clay) from the Wissant section in the Boulonnais area (Northwest of the Paris basin) shows that the clay fraction includes two types of smectites corresponding to beidellite (dioctahedral Al-Fe smectite). The first type, showing a fleecy shape under transmission electron microscope (TEM), is considered to be detrital, while the second displays a lathed shape due to the development of crystalline overgrowths indicating authigenesis [START_REF] Holtzapffel | Smectites authigènes et glauconitisation dans les Argiles du Gault (Albien du Boulonnais)[END_REF][START_REF] Steinberg | Characterization of overgrowth structures formed around individual clay particles during early diagenesis[END_REF]. It is hypothesized that crystalline overgrowths are the result of an early diagenetic recrystallization of detrital smectites and may represent an early stage of glauconitization. Lath-shaped smectites are widespread in Meso-Cenozoic deposits [START_REF] Holtzapffel | Respective influence of detrital supply and marine diagenesis on the formation of Albo-Aptian and Paleogene smectites in the North-Atlantic Range[END_REF][START_REF] Deconinck | Diversity of smectite origins in Late Cretaceous sediments: example of chalks from northern France[END_REF] and result from dissolution/recrystallization processes in relatively closed environments [START_REF] Clauer | Morphological, chemical, and isotopic evidence for an early diagenetic evolution of detrital smectite in marine sediments[END_REF].

However, the development of this type of authigenic minerals does not seem to significantly modify the composition of the detrital clay fractions.

In both studied areas, we therefore consider that the clay minerals are mainly detrital and originated from the erosion of nearby emerged lands, knowing that 1) glauconitic illite may be associated with detrital illite, notably in the Paris Basin at the transition between the Sables Verts de l'Aube and the Argiles tégulines de Courcelles and 2) authigenic smectite may have marginally enhanced the total proportion of smectites in specific closed environments.

Origin of clay minerals

Although clay particles may be transported over long distances [START_REF] Chamley | Clay Sedimentology[END_REF], during the Albian, a large part of the clay minerals potentially originated from the landmasses composed of the French Massif Central and the Armorican massifs, and from the London-Brabant Massif which were the main emerged lands around the studied areas (Fig. 1). Clay minerals were likely transported to the sea mainly by rivers and then deposited by decantation relatively far from the shoreline. In the Paris basin, the erosion of the two massifs probably fed the sedimentation, whereas the clays from the Vocontian Basin had to come from the basement and the sedimentary cover of the French Massif Central and other emerged lands located to the south (Corso-Sarde microcontinent?, Fig. 1).

The lithology of the London-Brabant Massif and the French Massif Central is different. These massifs are both inherited from the Variscan orogeny, but magmatic and high-grade metamorphic rocks (granitoids, migmatites, and gneiss) are predominant in the French Massif Central, whereas low-grade metamorphic and sedimentary rocks dominated in the London-Brabant Massif (schists, slates, limestones and shales; [START_REF] Fielitz | Pre-and synorogenic burial metamorphism in the Ardenne and neighbouring areas (Rhenohercynian zone, central European Variscides)[END_REF][START_REF] Han | Palaeozoic clay mineral sedimentation and diagenesis in the Dinant and Avesnes basins (Belgium, France): relationships with variscan tectonism[END_REF]. Therefore, a different nature can be expected from the contributions of clay minerals originating from these two massifs. In addition, they were not located at the same latitudes, and according to the estimated precipitation rates during the 'Mid-Cretaceous' [START_REF] Ufnar | The mid-Cretaceous water bearer: Isotope mass balance quantification of the Albian hydrologic cycle[END_REF]2004), the French Massif Central was located between 25 and 30°N close to an arid to semi-arid climatic belt extending southward toward Portugal and West Africa [START_REF] Fenner | Middle and Late Albian geography, oceanography, and climate and the setting of the Kirchrode I and II borehole sites[END_REF][START_REF] Heimhofer | Coastal sediments from the Algarve: low-latitude climate archive for the Aptian-Albian[END_REF], while the London-Brabant Massif was located between 30 and 35°N in a more humid tropical belt.

Primary clay minerals

Primary clay minerals, i.e. chlorite and illite, are mainly formed through weathering processes of metamorphic and igneous rocks yet these minerals can be also reworked from a sedimentary basement [START_REF] Chamley | Clay Sedimentology[END_REF][START_REF] Weaver | Clays, muds and shales[END_REF]). In Albian deposits, chlorite never exceeds 5% of the clay fraction which is common in Cretaceous sedimentary rocks that have not undergone a deep burial (Deconinck et al., 1985;[START_REF] Kühn | Mineralogy of the upper Albian sediments from the Kirchrode I borehole with special emphasis on the clay mineralogy[END_REF]. The scarcity of chlorite is explained by the overall warm and humid climate that prevailed at that time, as chlorite is easily weathered under such climate conditions (Deconinck et al., 1985). Illite primarily characterizes the mechanical erosion of a mica-rich crystalline basement (notably muscovite). The common occurrence of significant amounts of this mineral is explained by its reworking from the Variscan igneous and metamorphic massifs. The higher illite abundance in the Paris Basin (close to 30%) than in the Vocontian Basin (close to 20%) likely results from the differential settling processes of clay minerals: illite is preferentially deposited nearshore whereas smectites, because of their better buoyancy, are exported further out in the ocean [START_REF] Gibbs | Clay mineral segregation in the marine environment[END_REF][START_REF] Chamley | Clay Sedimentology[END_REF]. This difference is then explained by the distinct palaeogeographical context of the two sedimentary basins, as the Col de Pré-Guittard Formation was likely in a more distal position compared with the emerged lands than the boreholes located in the eastern part of the Paris Basin.

Origin of kaolinite

There are two possible origins of kaolinite in the deposits. Kaolinite may originate from soils where it accumulated due to the partial hydrolysis of silicates including feldspars and other minerals which can be easily weathered [START_REF] Chamley | Clay Sedimentology[END_REF]; it is subsequently transported and integrated into marine sediments. Kaolinite may be also reworked from older kaolinite-bearing sedimentary rocks or palaeoalterations [START_REF] Deconinck | Eocene to Pleistocene clay mineral sedimentation off New Jersey, western North Atlantic (sites 903 and 905[END_REF][START_REF] Thiry | Palaeoclimatic interpretation of clay minerals in marine deposits : an outlook from the continental origin[END_REF]. In the first case, kaolinite is indicative of a warm and humid climate responsible for strong hydrolysis, whereas in the second case, kaolinite is only indicative of a significant runoff on the continents. In both cases, the occurrence of kaolinite indicates a humid climate [START_REF] Chamley | Clay Sedimentology[END_REF][START_REF] Ruffell | Comparison of clay mineral stratigraphy to other proxy palaeoclimate indicators in the Mesozoic of NW Europe[END_REF][START_REF] Dera | Distribution of clay minerals in Early Jurassic Peritethyan seas: Palaeoclimatic significance inferred from multiproxy comparisons[END_REF][START_REF] Bougeault | Climatic and palaeoceanographic changes during the Pliensbachian (Early Jurassic) inferred from clay mineralogy and stable isotope (C-O) geochemistry (NW Europe)[END_REF].

However, when kaolinite is reworked from ancient rocks, it can be expected to observe a covariation with illite as this mineral results from the same process, whereas when kaolinite originates from soils, its evolution through time should be decoupled from that of illite.

A clear covariation of illite and kaolinite is observed in the Paris Basin, suggesting that kaolinite is dominantly reworked from kaolinite-bearing rocks and palaeoalterations rather than from soils formed at the time of sedimentation. After the Purbeckian (latest Jurassic/earliest Cretaceous) regressive facies [START_REF] Brigaud | Sedimentary architecture, depositional facies and diagenetic response to intracratonic deformation and climate change inferred from outcrops for a pivotal period (Jurassic/Cretaceous boundary, Paris Basin, France)[END_REF], the Paris Basin corresponded to a continental area where early Cretaceous Wealden facies accumulated. At that time, the surrounding massifs, remnants of the Variscan orogeny, were deeply weathered with the formation of kaolinite-rich soils, saprolites and bauxites over the French Massif Central, the London-Brabant Massif and the Armorican Massif [START_REF] Thiry | Altération bauxitique associée aux argiles à chailles sur la bordure sud-est du bassin de Paris[END_REF]. Apatite fission-track thermochronology performed on the Ardennes Massif suggests that the sedimentary cover of the London-Brabant Massif was eroded during the Late Jurassic and Early Cretaceous [START_REF] Barbarand | Post-Paleozoic evolution of the northern Ardenne Massif constrained by apatite fission-track thermochronology and geological data[END_REF]. A major alteration phase favoured by a tectonic rejuvenation in the southern part of the London-Brabant Massif took place during the Early Cretaceous and then this massif underwent a kaolinitic alteration [START_REF] Quesnel | Paleoweathering and paleosurfaces from northern and eastern France to Belgium and Luxembourg: geometry, dating and geodynamic implications[END_REF][START_REF] Yans | An overview of the saprolites of Belgium and their potential kaolinitic supplies to Mesozoic and Cainozoic sediments[END_REF][START_REF] Thiry | Altération bauxitique associée aux argiles à chailles sur la bordure sud-est du bassin de Paris[END_REF][START_REF] Thiry | Continental France and Belgium during the early Cretaceous: paleoweatherings and paleolandforms[END_REF]. In agreement with the Mid-Cretaceous study of the Isle of Wight [START_REF] Gale | The stratigraphy and petrography of the Gault Clay Formation (Albian, Cretaceous) at Redcliff, Isle of Wight[END_REF][START_REF] Ruffell | Tectonic controls on the variation in thickness and mineralogy of pebble-beds in the Lower Greensand Group (Aptian-Albian) of the Isle of Wight, southern England[END_REF], we suggest that clay minerals from the Albian deposits of the Anglo-Paris Basin preferentially originated from the north (i.e. the London-Brabant Massif). However, Lower Cretaceous bauxitic profiles have also been identified in the French Massif Central [START_REF] Thiry | Altération bauxitique associée aux argiles à chailles sur la bordure sud-est du bassin de Paris[END_REF], which could constitute an additional source of reworked kaolinite. Therefore, the high proportions of kaolinite in the Albian deposits of the Paris Basin could be explained by the erosion of the kaolinite-rich weathering profile developed over the Variscan massifs during the Early Cretaceous. As detrital clays including kaolinite may be reworked from older rocks or from palaeoalterations, their climatic significance may be questioned [START_REF] Jeans | Age, origin and climatic signal of English Mesozoic clays based on K/Ar signatures[END_REF], but overall, the illite and kaolinite dominated clay assemblages of the Albian in the Paris Basin point to a significant runoff and consequently humid climate conditions.

In the Vocontian Basin, kaolinite proportions increase slightly from the base to the top of the section, whereas the proportions of illite remain stable. This suggests that kaolinite and illite deposited in the Vocontian Basin primarily originated from distinct sources. Illite likely originated from the crystalline basement whereas kaolinite was probably at least partly derived from soils or palaeoweathering profiles developed over the French Massif Central or other further away areas. These mineralogical features suggest slightly increasing humidity during the early Albian.

Origin of smectite

Smectites seem predominantly detrital, whether in the Albian in the Boulonnais area or southern England [START_REF] Holtzapffel | Smectites authigènes et glauconitisation dans les Argiles du Gault (Albien du Boulonnais)[END_REF]1987;[START_REF] Gale | The stratigraphy and petrography of the Gault Clay Formation (Albian, Cretaceous) at Redcliff, Isle of Wight[END_REF]. Their Al-Fe beideillite composition suggests a reworking from soils developed on the Variscan massifs under a warm and seasonally humid climate [START_REF] Chamley | Clay Sedimentology[END_REF]. These minerals are abundant in a poorlydated interval likely corresponding to the L. tardefurcata/L. regularis ammonite Zone in the lowermost part of the Argile tégulines de Courcelles (Figs. 345). Smectites are also abundant in the uppermost middle Albian corresponding to the D. niobe and D. biplicatus ammonite zones and 7). During these intervals, smectite-rich sedimentation suggests that the semi-arid climatic belt expanded northward.

Origin of vermiculitic clays

In the Paris Basin, the Argiles tégulines de Courcelles contain significant amounts of vermiculitic clays, in association with illite and kaolinite whereas these minerals are almost absent from the Vocontian Basin. These clay minerals are relatively unusual in Mesozoic marine sedimentary rocks, although vermiculite is also mentioned in coeval middle Albian deposits (Gault Clay) from the Isle of Wight in England [START_REF] Gale | The stratigraphy and petrography of the Gault Clay Formation (Albian, Cretaceous) at Redcliff, Isle of Wight[END_REF]. Therefore, vermiculitic minerals are likely deriving together with illite and kaolinite from a source that could possibly be the London-Brabant Massif (Fig. 11A). This mineral may originated from soils formed under cold-temperate climate [START_REF] Li | Clay mineral assemblages in the Zhaotong Basin of southwestern China: Implications for the late Miocene and Pliocene evolution of the South Asian monsoon[END_REF], but such climatic conditions seem unlikely at relatively low latitudes during the Albian. We therefore suggest that vermiculitic clays are reworked from the basement (moderate weathering of chlorite) or from palaeoalterations.

Environmental controls of the early/middle Albian clay sedimentation

The mineralogical composition of the clay assemblages is the result of a complex interplay of the lithology of the emerged landmasses, their reliefs and tectonic instability, sealevel fluctuations and climate (e.g., [START_REF] Chamley | Clay Sedimentology[END_REF].

In the Paris Basin, clay sedimentation largely dominated by illite and kaolinite suggests that the London-Brabant Massif was submitted to significant runoff conditions.

Between 30 and 35°N, corresponding to the palaeolatitudes of the London-Brabant Massif, precipitation rates are estimated between 1000 and 1500 mm/yr [START_REF] Ufnar | The mid-Cretaceous water bearer: Isotope mass balance quantification of the Albian hydrologic cycle[END_REF], which is high enough to produce erosional soil processes, the erosion of Lower Cretaceous kaoliniterich palaeoalterations and the bedrock. These conditions were probably responsible for a significant detrital flux of clay minerals such as illite and kaolinite (Fig. 11). As the temperatures were also high (>20°C for these palaeolatitudes, based on δ 18 O values; O'Brien et al., 2017), chlorite was likely rapidly transformed into vermiculite and interstratified minerals including chlorite-vermiculite which are identified in small quantities in the Albian sedimentary rocks [START_REF] Herbillon | Weathering of chlorite in a soil derived from a chloritoschist under humid tropical conditions[END_REF][START_REF] Proust | Supergene vermiculitization of a magnesian chlorite: iron and magnesium removal processes[END_REF][START_REF] Righi | Characterization of Hydroxy-Interlayered Vermiculite and Illite/Smectite Interstratified Minerals from the Weathering of Chlorite in a Cryorthod[END_REF][START_REF] Banfield | Atomic-resolution transmission electron microscope evidence for the mechanism by which chlorite weathers to 1:1 semi-regular chloritevermiculite[END_REF].

The two smectite-rich intervals identified in the Albian of the Paris Basin, the first one close to the Aptian/Albian transition and in the lowermost Albian and the second from the A. intermedius to the D. biplicatus ammonite zones in the lower middle Albian, clearly indicate that the erosional processes were less intense. A decreasing intensity of erosion may be linked to rising sea level or to a shift from humid to more arid conditions. At the base of the succession in the lower Albian, the long-term transgressive trend may be responsible for the smectite-rich sedimentation, but this trend lasted during the entire Albian [START_REF] Haq | Cretaceous eustasy revisited[END_REF] while abundant illite and kaolinite replaced the smectite-rich sedimentation. The comparison of clay assemblages with short-term sea level curves [START_REF] Haq | Cretaceous eustasy revisited[END_REF] did not show any relationship between clay assemblages and sea level fluctuation. In addition, in the study area, the timeequivalent interval for the D. niobe and D. biplicatus zones is known to correspond to a low relative sea level [START_REF] Amédro | L'étage Albien dans sa région-type, (Aube, France) : une synthèse dans un contexte sédimentaire global[END_REF]. Consequently, smectite-rich sedimentation does not seem to be the result of a rising sea level. However, these particular intervals, previously identified in the Boulonnais area [START_REF] Holtzapffel | Smectites authigènes et glauconitisation dans les Argiles du Gault (Albien du Boulonnais)[END_REF]1987) and in southern England (Isle of Wight, [START_REF] Gale | The stratigraphy and petrography of the Gault Clay Formation (Albian, Cretaceous) at Redcliff, Isle of Wight[END_REF] can be explained by more arid climate conditions. As the Aptian-Albian transition is known to be a cool interval (Millán et al., 2014 and references therein), the hydrological cycle was probably slower during this period which is consistent with dryer conditions reflected by smectite-rich sedimentation intervals. Such climate conditions are also suggested in southern Portugal (Algarve) where mineralogical and palynological data indicate more aridity [START_REF] Heimhofer | Coastal sediments from the Algarve: low-latitude climate archive for the Aptian-Albian[END_REF]. The smectite-rich sedimentation in the upper part of the middle Albian (A. intermedius to D. biplicatus zones) may be also explained by a semi-arid climate and a cooling trend suggested by calcareous nannofossils and the isotope chemistry of the Gault Clay from south-eastern England [START_REF] Kanungo | A brief warming event in the late Albian: evidence from calcareous nannofossils, macrofossils, and isotope geochemistry of the Gault Clay Formation, Folkestone, southeastern England[END_REF]. Such climate conditions are also known in northern Spain before more humid conditions occurred during the late Albian [START_REF] Sender | Preliminary data on a new Albian flora from the Valle del Río Martínn Teruel, Spain[END_REF][START_REF] Coiffard | Early Cretaceous Angiosperm Invasion of Western Europe and Major Environmental Changes[END_REF]. In the Lusitanian Basin, in the time-equivalent interval, coupled palynological and clay mineral data indicate drier conditions characterized by the abundance of Classopollis and by decreasing proportions of kaolinite balanced by increasing proportions of illite-smectite mixed-layers [START_REF] Heimhofer | Climate and vegetation history of western Portugal inferred from Albian near-shore deposits (Galé Formation, Lusitanian Basin)[END_REF].

In the Vocontian Basin, the Aptian/Albian transition is also characterized by kaolinitedepleted deposits which is consistent with drier conditions (Fig. 11B). The proportions of this mineral slightly increased during the L. tardefurcata ammonite Zone but stayed relatively low. A significant increase occurs in the D. mammillatum Zone, partly time equivalent to the O. subhilli and H. steinmanni zones from the Paris Basin, which represents the upper half of the D. mammillatum Zone (see Table 1 and Fig. 11B). This trend is comparable with the increase of kaolinite recorded in the Paris Basin (Fig. 11B) and likely reflects wetter climatic conditions as a consequence of the emergence of a humid equatorial belt during the Albian [START_REF] Chumakov | Climate belts of the mid-Cretaceous time[END_REF]. There may be several possible explanations for the significant difference between the percentages of kaolinite in the Paris Basin (between 25 and 30%) and Vocontian Basin (between 10 and 15%). It is well-known that differential settling processes of clay minerals favour the nearshore deposition of kaolinite whereas smectite, because of its better buoyancy, is deposited further out in the ocean (Deconinck et al., 1985;[START_REF] Godet | Platform-induced clay-mineral fractionation along a northern Tethyan basin-platform transect: implications for the interpretation of Early Cretaceous climate change (Late Hauterivian-Early Aptian)[END_REF]. In addition, clay minerals deposited in the Vocontian Basin may originated from distinct detrital sources, some of which are located southward (Corso-sarde micro-continent?) in the semi-arid climatic belt where smectite should form in soils.

Surprisingly, clay assemblages do not display any particularity in the stratigraphic interval encompassing the organic matter-rich Paquier horizon (OAE1b) in the Col de Pre-Guittard section. However, the K+C/S ratio increases slightly around this level. Most works show that the temperature increased sharply during this event and some authors suggest that the monsoonal climate enhanced the humidity and detrital supply during this peculiar event (Herrle et al., 2003a and b;[START_REF] Hofmann | Climateocean coupling off North-West Africa during the Lower Albian: The Oceanic Anoxic Event 1b[END_REF][START_REF] Jenkyns | Geochemistry of oceanic anoxic events[END_REF][START_REF] Sabatino | High-resolution chemostratigraphy of the late Aptian-early Albian oceanic anoxic event (OAE 1b) from the Poggio le Guaine section (Umbria-Marche Basin, central Italy)[END_REF], which is consistent with our clay mineralogical results.

In the Paris Basin, the upper Albian deposits (pricei Zone) again show a kaolinite-and illite-rich clay fraction (Fig. 6) indicating a return to more humid climate conditions. The base of the late Albian is characterized by a warm event recorded during the D. cristatum Zone [START_REF] Kanungo | A brief warming event in the late Albian: evidence from calcareous nannofossils, macrofossils, and isotope geochemistry of the Gault Clay Formation, Folkestone, southeastern England[END_REF]. Unfortunately, this stratigraphic interval is condensed in the boreholes studied here, but the above mentioned warming event [START_REF] Kanungo | A brief warming event in the late Albian: evidence from calcareous nannofossils, macrofossils, and isotope geochemistry of the Gault Clay Formation, Folkestone, southeastern England[END_REF] may be responsible for an accelerated hydrological cycle and consequently enhanced erosional processes on the London-Brabant Massif during the overlying M. pricei Zone. Alternatively, the tectonic instability of the London-Brabant Massif during the early late Albian [START_REF] Owen | The Stratigraphy of the Gault in the Thames Estuary and its Bearing on the Mesozoic Tectonic History of the Area[END_REF]) could be also responsible for the concomitant increase in illite and kaolinite.

Conclusions

The clay mineralogy of the Albian deposits in the Paris and Vocontian basins shows some common features suggesting at least a regional climatic control of the clay sedimentation as well as specific characteristics attributable to certain local conditions. Finally, the warm climates of the Albian also seem to be characterized by fluctuations in humidity with significant impacts on the continental weathering processes. Tethyan ammonite zonation [START_REF] Owen | Correlation of Albian European and Tethyan ammonite zonations and the boundaries of the Albian Stage and substages: some comments[END_REF][START_REF] Kennedy | Integrated stratigraphy across the Aptian-Albian boundary in the Marnes Bleues, at the Col de Pré-Guittard, Arnayon (Drôme), and at Tartonne (Alpes-de-Haute-Provence), France, a candidate Global Boundary Stratotype Section and Point for the base of the Albian Stage[END_REF][START_REF] Gale | The uppermost Middle and Upper Albian succession at the Col de Palluel, Hautes-Alpes, France: an integrated study (ammonites, inoceramid bivalves, planktonic foraminifera, nannofossils, geochemistry, stable oxygen and carbon isotopes, cyclo-stratigraphy)[END_REF]

FIGURE CAPTIONS

mammillatum

  Zone used in the Vocontian Basin includes the S. kitchini, C. floridum, H. puzosiana, Otohoplites subhilli and Hoplites (Isohoplites) steinmanni zones. During the Albian, the Paris Basin belonged to the Northern European Faunal Province of the Boreal Domain, characterized by the presence of rich populations of Hoplitidae that followed each other (including genera Sonneratia, Hemisonneratia, Otohoplites, Hoplites, Anahoplites, and Dimorphoplites), allowing the definition of many biozones. The Vocontian Basin, located on the northern margin of the Tethyan Domain, contains more occasional and less diversified faunas at the top of the lower Albian and in the middle Albian (Douvilleiceras, then Lyelliceras and Oxytropidoceras). At the top of the lower Albian, the correlation between the two basins is based on the vertical distribution of the species Douvilleiceras mammillatum which appears just above the L. regularis Zone and disappears at the top of the Lyelliceras lyelli Zone (or Subzone). In the middle Albian, Oxytropidoceras roissyanum is known at Col de Palluel at the top of this Substage

  The kaolinite-depleted interval around the Aptian/Albian transition and in the lowermost Albian suggests that a relatively cool and dry climate was likely responsible for a slow-down of the hydrological cycle. From the D. mammillatum Zone in the Vocontian Basin and at least from the H. puzosiana to the A. intermedius Zone in the Paris Basin, increasing proportions of kaolinite and/or illite suggest increased precipitation rates and a more constant humid climate. This change may be the consequence of the re-organization of the climatic belts, particularly the emergence of the equatorial humid zone favouring a warm humid belt at latitudes between 25 and 35°N. In the Paris Basin, kaolinite is primarily reworked from Lower Cretaceous palaeoalterations and from unmetamorphosed rocks outcropping on the London-Brabant Massif, whereas in the Vocontian Basin, this mineral may be also reworked from soils developed over the Central Massif and other continental masses located southwards. In both cases, increasing proportions of kaolinite are indicative of increased runoff triggered by a more humid climate and a southward shift of the mid-latitude warm humid belt. During the late-middle Albian (at least in the D. niobe and D. biplicatus ammonite zones), the smectite-rich sedimentation in the Paris Basin suggests a latitudinal expansion of the semi-arid climatic belt which is consistent with palaeobotanical data. During the late Albian (M. pricei Zone), illite and kaolinite contents increase again indicating either a return to a more humid climate and/or the influence of a tectonic instability of the London-Brabant Massif. The occurrence of vermiculitic clays restricted to the Anglo-Paris Basin suggests that this mineral originated from the London-Brabant Massif. Finally, the smectite-rich sedimentation recorded in the Vocontian Basin compared with the Paris Basin illustrates the significant role played by the differential settling of clay minerals from nearshore to offshore environments and by palaeogeography.

Figure 1 .

 1 Figure 1. Palaeogeographic map (Albian) showing the location of the studied areas and the boundary between the semi-arid and the mid latitude warm-humid belts defined by Chumakov et al. (1995). Abbreviations: AM = Armorican Massif, BT = Burgundy threshold, MC = Massif Central, IbM = Iberian Massif, LBM = London-Brabant Massif, CS = Corso-Sarde microcontinent (modified from Amédro and Matrion, 2014).

Figure 2 .

 2 Figure 2. Location of the boreholes studied to the south-east of the Paris Basin (Amédro et al., 2019).

Figure 3 .

 3 Figure 3. Lithology, biostratigraphy and clay mineralogy of the AUB 111 borehole. Abbreviations: SVA = 'Sables Verts de l'Aube', APT = Aptian, (K+C)/S = (kaolinite+chlorite)/smectite.

Figure 4 .

 4 Figure 4. Lithology, biostratigraphy and clay mineralogy of the AUB220 borehole. The detailed lithological description and the biostratigraphic data were published by Amédro et al. (2017). Abbreviations : SVA = 'Sables Verts de l'Aube', APT = Aptian, (K+C)/S = (kaolinite+chlorite)/smectite.

Figure 5 .

 5 Figure 5. Correlation between AUB111, AUB220 and AUB240 boreholes Figure 6. Phosphatic crust corresponding to a hardground at the transition between the 'Sables Verts de l'Aube' (Greensands) and the Argiles tégulines de Courcelles Formation in borehole AUB220 (74.50 m in depth).

Figure 7 .

 7 Figure 7. Lithology, biostratigraphy and clay mineralogy of the AUB 240 borehole. The detailed lithological description is given in Amédro et al. (2019). (K+C)/S = (kaolinite+chlorite)/smectite.

Figure 8 .

 8 Figure 8. Detailed geographical location of the Col de Pré-Guittard section and field views of this section.

Figure 9 .

 9 Figure 9. Diffractograms obtained for the sample AUB220 -25,50 m. The minerals identified are : S = smectite (I/S R0), V = vermiculitic clays, C =chlorite, I = illite, K = kaolinite, C/V = interstratified chlorite -vermiculite, Qtz = quartz.

Figure 10 .

 10 Figure 10. Lithology, clay mineralogy and spectral gamma ray of the Col de Pré-Guittard section. (K+C)/S = (kaolinite+chlorite)/smectite.

Figure 11 .

 11 Figure 11. A. Palaeogeographic map, facies (modified after Amédro and Matrion, 2014) and inferred detrital clay mineral sources in the Paris and Vocontian basins. IW = Isle of Wight, LBM = London-Brabant Massif. B. Correlation between the AUB 220 borehole (Paris Basin) and the Col de Pré-Guittard section (Vocontian Basin).

Table 1 .

 1 Correspondences between the ammonite biozonations from the Paris and Vocontian basins. The appearance of the foraminfer Microhedbergella renilaevis is marked in the H. jacobi zone. Abbreviations: U. Apt. = upper Aptian, H. jacobi = Hypacanthoplites jacobi, Micr. renil. = Microhedbergella renilaevis, L. schrammeni = Proleymeriella schrammeni, L. germanica = Leymeriella germanica, L. tardefurcata = Leymeriella tardefurcata, L. regularis = Leymeriella regularis, S. kitchini = Sonneratia kitchini, C. floridum = Cleoniceras floridum, H. puzosiana = Hemisonneratia puzosiana, O. subhilli = Otohoplites subhilli, H. steinmanni = Hoplites (Isohoplites) steinmanni, D. mammillatum = Douvilleiceras mammillatum, L.l. = Lyelliceras lyelli, L. ps. = Lyelliceras pseudolyelli, H. benettianus = Hoplites (Hoplites) benettianus, H. dentatus = Hoplites dentatus, A. intermedius = Anahoplites intermedius, D. niobe = Dimorphoplites niobe, D. biplicatus = Dimorphoplites biplicatus, O. roissyanum = Oxytropidoceras roissyanum, D. cristatum = Dipoloceras cristatum, M. pricei = Mortoniceras pricei, M. inflatum = Mortoniceras inflatum.

Acknowledgements

We would like to thank Claude Aurière, who is in charge of Andra's core storage, for his help in studying the boreholes. Alexis Godet and an anonymous reviewer are also gratefully acknowledged for their constructive remarks.