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Microstructural features control the petrophysical properties of rocks. Of these, pore size is particularly sensitive when non-wetting fluids saturate the reservoir. The pore networks and physical properties (helium, water and mercury saturation porosity, bulk density, nitrogen permeability, P-wave velocity and thermal conductivity) of different rock types from a productive Upper Cretaceous (Coniacian) reservoir in the tunisian offshore are measured on hydrocarbon-washed samples. The facies sampled of Douleb Member are wackestone, packstone and grainstone textures as well as dolostone, dolomitized packstone and anhydrite textures. Based mainly on the results obtained by mercury injection, the porous facies of the Coniacian Douleb Member are characterized by a complex pore system with a large morphological and pore size variability in the rock. Porosity values range from 0.3 to 23.6%, bulk densities vary from 2.05 to 2.92 g.cm−3. The permeability is variable from 3760 mD to values below 0.01 mD (measurement limit of the device). P-wave propagation velocity values range from 2060 to 6084 m.s−1 and thermal conductivity varies from 1.43 to 3.77 W.m−1.K−1. The oil-impregnated facies with the best petrophysical characteristics are mainly the rudist-rich limestones and dolomites of the first unit (U1) of the Douleb Member. The well-sorted grainstones with small rudist debris and peloids have the best reservoir qualities. Porosity is the first order characteristic that controls petrophysical properties. The variability of permeability values around this first-order relationship is attributed to variations in the size of the pore access thresholds and connectivity. The variability in velocities is due to the shape of the voids, while the variability in thermal conductivity measurements is due to the nature of the contacts between the grains.

International audience; The Cretaceous marine transgression proceeded through successive steps from the Albian to the Turonian (dated with ammonites). The onlapping wedge begins with coastal transgressiveeregressive short-term sequences on massive, probably fluvial sandstones to be correlated with the very thick continental Lower Cretaceous succession found in the Puerto Cansado well in the Tarfaya sub-basin to the north. A second step, of probable Cenomanian age, reached the Palaeozoic basement. A third, more pronounced step occurred during the earliest Turonian with platy laminated limestone overlain by marlstone bearing pyritized ammonites. At early Turonian peak transgression, a marine connection was possibly established between the Atlantic and the Tethyan margins, between the Anti-Atlas and the Reguibat Shield. From large-scale correlation integrating what occurred along the southwestern shoulder of the Atlas rift, the South Moroccan Atlantic margin may have undergone a short-lived tectonic uplift around the Cenomanian eTuronian boundary.

International audience; Two new sections covering the CenomaniandTuronian transition have been studied at the foot of the Kasserine platform in the northeastern Mellegue basin (Jebels Serj and Bargou). They show, in the uppermost part of the Cenomanian Fahdene Formation, a Pre-Bahloul unit overlain by the well-known Bahloul black shale. Combined foraminiferal and isotope data of the sections complement other published results: (1) extinction of rotaliporids atop of the Pre-Bahloul bed during the build-up of the CenomaniandTuronian Boundary Event (CTBE) d 13 C positive shift, (2) Heterohelix bloom during the deposition of the Bahloul black shale, (3) filament event during d 13 C return to normal values, and (4) first occurrence of Helvetoglobotruncana helvetica during the transition to the marlstone of the Annaba Formation. The Bahloul black shale is here divided into three units, U1 to U3 which are compared with the other sections of the Mellegue basin. The bulk of this paper is a comparison of the two new sections with revisited nearby sections of the Mellegue basin, as well as with those published from the south Tunisian Gafsa trough and Saharan Atlas of Algeria. The comparison suggests that the pre-Bahloul of the Mellegue basin is correlatable with the transgressive fine-grained limestone bed underlying the CTB black shale in the corridors between isolated , keep-up platform carbonates of the Ouled Nail in Algeria, as well as the fine-grained limestone bed overlying upper Cenomanian shallow-water deposits of southern Tunisia. Its sequence stratigraphic significance in the Mellegue basin should therefore be recognized as a deeper-water equivalent of a transgressive systems tract, instead of being interpreted as a lowstand or highstand as it is by other authors. If correct, the inception of the CTBE d 13 C shift would correspond to a transgression over most of Algeria and Tunisia, as observed in the North American Western Interior.

Constrained by both foraminifera and isotope data, the Zeitoun and Nahr Ibrahim sections in northern Lebanon record a steady flooding of the Cenomanian carbonate platform during the uppermost Cenomanian-lower Turonian interval. The flooding began just before the inception of the CTBE δ13C positive shift. It is marked by the deposition of finely bedded to laminated, fine-grained limestone overlying platformal carbonates. This scenario is entirely different to what has been published in northern Israel, where repeated emergences are instead recorded during the event. A survey of published data from nearby Middle East countries to North Africa suggests that the CTBE is accompanied on a larger scale, especially along the Syrian Arc, by tectonic disturbances responsible for sequence stratigraphic heterogeneity and palaeogeographic changes. Detailed analysis of available data makes it possible to extract from the sedimentary record four sequence stratigraphic scenarios implying two phases of heterogeneity bounding the event, and responsible for the outphasing of relative sea level changes in some sensitive areas. These disturb a stepped early Cenomanian to early Turonian overall transgressive trend recorded in some large stable areas, often used to support the concept of Mesozoic eustasy. The discussion focuses on the global processes that are possibly involved. The hypothesized tectonic pulse does not explain the CTBE. It is just another set of data to be taken into account in the search for causes.

International audience; The definition of the Cenomanian stage was based on the description of several type 34 sections scattered in the vicinity of Le Mans (Sarthe, France). Despite limited exposures 35 nowadays, the area remains a reference for the palaeontology of the Cenomanian due to its 36 outstanding richness in marine macrofossils, especially molluscs, bryozoans, brachiopods and 37 echinoderms. The publication in 2015 of the volume dedicated to the Cenomanian stratotype 38 yielded the opportunity to restudy the last accessible outcrops. This paper provides a high39 resolution stratigraphic scheme and palaeoenvironmental reconstruction for the middle and 40 late Cenomanian interval in its type area. La Garenne Quarry is a window on the middle Cenomanian, where Praeglobotruncana rillella nov. sp. has been identified. The δ 13 41 Ccarb and δ 18 42 Ocarb record of a Cenomanian–Turonian succession close to Le Mans is correlated with the 43 type section of Pueblo (Colorado). Isotopic and biotic events highlight the presence of several 44 hiatuses in the sedimentary record of Le Mans especially around the Cenomanian–Turonian boundary with a dramatic truncation of the plateau of high δ 13 45 Ccarb values. Coiling reversal 46 events among the surface dwellers Muricohedbergella delrioensis, indicate sea surface 47 temperature changes with transient coolings, including the Plenus cold event, and warm 48 conditions at the Cenomanian–Turonian boundary. Sandy to chalky facies have yielded 49 empty, well-preserved shells of foraminifera allowing the description of Dicarinella 50 falsohelvetica nov. sp. Oxygen isotopic analyses performed on right- and left-coiled M. 51 delrioensis reveal a systematic offset during cold events which lead to discuss about the 52 potential occurrence of cryptic species in the Mesozoic.

International audience; The present study is based on core petrographical analyses of an oil-producing Turonian carbonate reservoir in the Sfax area (central-eastern onshore of Tunisia). Sedimentological studies show that these Early-Middle Turonian carbonates consist of shallow marine bioclastic limestones, sometimes partly dolomitised, and are rich in rudists which can be associated to other bivalves, gastropods, oncoliths, benthic foraminifers and calcisphers. Facies are organised into metre-scale shallowing upward cycles, each comprising three units corresponding, from base to top, to the following: bedded, slightly argillaceous wackestones containing floating rudist debris and sometimes calcisphers; alternation of massively bedded partly dolomitised packstones rich in entire joined rudists and finely bedded wackestones-packstones containing miliolids, oncoliths and gastropods; and micritic carbonates, partly argillaceous, nodular shaped and laminated. In terms of reservoir properties, the highest values of helium porosity (reaching 27%) and permeability (reaching 700 mD) were measured in rudist-rich carbonates. Pores, which are partly filled with oil, mainly correspond to the Radiolitid cells. In addition, some diagenetic features such as dolomitisation, dedolomitisation and dissolution have created additional pores and have clearly enhanced the reservoir potential of these rudist-rich carbonates.

The Turonian-Coniacian rudist-bearing carbonates are characterized by their good quality as reservoir rocks. They produce oil and gas in several fields in eastern onshore and offshore of Tunisia. These rudist-rich facies are featured by a developed porosity (intragranular, intergranular, intercrystalline and matrix porosity especially between micritic grains). In terms of reservoir properties, the highest values of helium-porosity (reaching 24%) and nitrogen-permeability (reaching 1200 mD) were measured in rudist-rich carbonates. In addition, some diagenetic features such as dolomitisation and dissolution have created additional pores and have clearly enhanced the reservoir potential of these rudist-rich carbonates. On the other side, some diagenetic processes such as cementation, silicification and compaction have led to the destruction of the pore system and the decrease of porosity and permeability values.

The first two calcarenite units at the base of the Urgonian limestones on the southern edge of the platform bear different depositional geometries depending on place (Cirque d’Archiane to Montagnette and Rocher de Combau). The lower calcarenite unit (Bi5 of Arnaud H. 1981. De la plate-forme urgonienne au bassin vocontien. Le Barrémo-Bédoulien des Alpes occidentales entre Isère et Buëch (Vercors méridional, Diois oriental et Dévoluy). Géologie Alpine, Grenoble, Mémoire 12: 3. Disponible sur https://tel.archives-ouvertes.fr/tel-00662966/document), is up to 200 m thick and shows three different patterns, in terms of accommodation space, from the western Archiane Cirque to the Montagnette to the east. On the western side of the Cirque, the unit begins on slope fine-grained limestone with thin sigmoïdal offlap geometry, suggesting little available space after a relative sea level fall. It is overlain by thick progradational/aggradational, then purely aggradational calcarenite capped by a coral and rudist-bearing bed. This bed is, therefore, interpreted as a maximum (although moderate) flooding facies. The depositional geometry is different on the eastern side of the Cirque, where a progradational pattern in the lower part of the unit is interrupted by a rotational movement affecting the depositional profile. The deformation promoted aggradation updip and retrogradation downdip as a result of starvation. The inferred growth fault updip (thought to be responsible for the change) began to function earlier at the Montagnette, explaining the huge calcarenite clinoforms found there, filling a deeper saddle created in the depositional profile. The same fault probably was reactivated later during the deposition of the overlying, thinner Bi6-1 unit, which appears at Rocher de Combau with an uncommon tidal facies at the base. A rotational bulge, created by the inferred growth fault, would have protected a small area behind it to spare the local calcarenite deposition from the waves for a while. These two examples show that sequence stratigraphic interpretation may differ from one place to the other, and even show opposite trends due to this kind of disturbance.

The Vocontian Basin (SE France) which presents lower Aptian expanded successions characterized by major lithological changes, is particularly suitable to determine palaeoenvironmental changes occurring across the OAE 1a. A multidisciplinary study (sedimentology, CaCO3, TOC, carbon and oxygen stable isotopes, micropalaeontology, cyclostratigraphy) was carried out in the Notre-Dame-de-Rosans section in order to establish a detailed chronological framework of these changes. The OAE 1a corresponds to carbon isotope segments C3–C6, and it lasted for 1.2 Myr. A first drop in the carbonate production occurs 500 kyr before the OAE 1a (upper part of the carbon isotope segment C2), and could result from both onset of “Urgonian” carbonate platform demise and associated reducing export of platform-derived sediments into the basin, and nannoconid crisis. A second drastic drop (crash) in the carbonate production is recorded within the lower part of the OAE 1a (latter part of segment C3 to C5) and is explained by a strong dissolution. This study then shows that the onset of the major carbonate crisis, that occurs before the OAE 1a, could be due to both rise in sea-level and in marine surface water fertility, whereas its “acme” that occurs within the OAE 1a, could be related to CO2-induced ocean acidification. Black shales of the “Niveau Goguel” occur in the upper part of the OAE 1a and represent the lower part of segment C6. Surface-waters primary producers are principally represented by cyanobacteria, whereas nannofossil primary productivity is reduced, and deep-water anoxia prevailed during the deposition of “the Niveau Goguel”. The last 300 kyr of the OAE 1a are characterized by a partial recovery of both nannofossil primary productivity and pelagic carbonate production, which sharply increase just after the end of the event. This study also shows that organic-rich layers associated to the OAE 1a are diachronous in the Tethyan realm.

The Cenomanian–Turonian Boundary Event (CTBE) event is not associated with a transgression on the southern margin of the Subalpine Basin, but with a steady shallowing-up trend beginning in the lower half of the δ 13 C positive shift. The SW–NE Rouaine Fault had a complex role, first in isolating a black shale basin to the west and a large, deep submarine plateau devoid of black shale to the east, then by a strike-slip movement that induced a forced progradation to the north of the southern platform in the eastern compartment. This compressive tectonic reactivation of the southern margin began around the deposition of the local equivalent of the Plenus bed of boreal basins, as shown by correlation supported by both isotope and palaeontological data. Other local data are pieced together to suggest that the whole of SE France underwent a short-lived transpressive tectonic pulse around the Cenomanian–Turonian boundary, probably connected with the early compressive movement of Africa vs. Europe. On a larger scale, other published data suggest that this pulse could be a global one. It is coeval with renewed thrust loading, volcanism and transgression in the North-American Western Interior, local emergences during the event along the eastern Atlantic margin, suggesting a slight tendency to inversion of the margin, and a tilting to the east of the North-Africa plate that could explain the large transgression recorded from Morocco to Tunisia on the Saharan Craton. New isotope and palaeontological (coiling ratio of Muricohedbergella delrioensis ) data from SE France suggest that two coolings of suprabasinal importance occurred just before and during the build-up of the d 13 C shift, including the boreal “Plenus Marls“, especially its middle limestone bed and its SE France equivalent. Regarding the extinction of the genus Thalmaninella and Rotalipora and during the event, neither anoxia nor climate changes can fully explain the palaeontological crisis, given that Rotalipora cushmani crosses the first phase of anoxia without harm, as well as the two coolings, not only in SE France but on a large scale, as shown by the correlation of the published data. This extinction needs alternative explanations as we challenge both anoxia and climate as major causes.

International audience; Several transects made of correlated stratigraphic sections and well logs have been constructed spanning southern Tunisia and the Algerian Sahara (Tinrhert) for comparison with earlier results obtained in the Saharan Atlas. The study is based on fades analysis, sedimentology, biostratigraphy focused on ammonites and foraminifers) as well as whole rock geochemistry (delta C-13). These suggest that the entire northern Sahara Platform underwent marine flooding that commenced just prior to the onset of the global positive delta C-13 shift documented for the Cenomanian-Turonian boundary. This flooding occurred in two phases. The first phase is expressed by the deposition of deeper-water, light-coloured bioturbated mudstones overlying the shallow-water deposits comprising the local Cenomanian successions. But in some places in the Central Sahara (Hassi Messaoud area, Tihemboka Arch) as well as in the Saharan Atlas, shallow-water carbonates kept up locally with the relative sea-level rise to build up isolated carbonate platforms. The topographic lows or saddles between these areas could have been formed through differential accumulation rates. During the second phase, flooding resumed and black shales were deposited over the mudstones in the saddles. The occurrence of black shales in these saddles is limited to the northern edge of the platform (Saharan Atlas of Algeria, Gafsa Trough in southern Tunisia). On the platform, this phase is represented by the same kind of mudstones deposited during the first phase of the flooding (southern Tunisia), or by ammonite-rich chalks in the intra-cratonic basin of the Tinrhert (southern Algeria). Black-shale deposition ceased in the early Turonian. Based on the delta C-13 curve, the latest Cenomanian flooding of the Sahara Platform is roughly coeval with that documented for the US Western Interior. During the first phase of the transgression, that is before the occurrence of the large Whiteinella of the W. archeocretacea Zone in the black shale unit, planktic foraminifers are dominated by small globulose forms of the Hedbergella delrioensis type, associated with Heterohelicidae. Keeled forms (rotaliporids, dicarinellids) are scarce and always very small when present. Perhaps these dwarfed forms were adapted to the restricted environments of the extensive intracratonic seaways crossing the Saharan Platform to the Benoue Trough in Nigeria.

International audience; Among some modern and recent fossil species of planktonic foraminifera, the proportion of left-to right-coiled shells in a population appears to be temperature-dependent; the relative abundance of each morphotype reflecting ecological preferences. A similar relationship is identified among Muricohedbergella delrioensis (Carsey, 1926) at the Cenomanian-Turonian stage boundary in mid-latitude sites of the Western Interior Seaway, including the Pueblo type section. The increase of sinistral M. delrioensis in the assemblage is related to higher  18 O carb values and decrease in inner porosity which suggests that changes in the coiling direction in this morphospecies could represent a new proxy for constraining Sea Surface Temperature (SST) variations. As surface dwellers, muricohedbergellids were not ACCEPTED MANUSCRIPT 2 affected by Oceanic Anoxic Event (OAE2) and provide a continuous paleoclimatic signal throughout the Cenomanian-Turonian boundary interval. Furthermore, genetic evidence obtained from extant foraminifera indicates that shifts of coiling ratios in planktonic foraminifera species can express the signature of distinct genetic types, which are revealed through their opposite coiling directions. Coiling direction could be a genetic trait, implying that cryptic species may occur in the Mesozoic.

International audience; This paper provides the sedimentological, palaeontological and biostratigraphical characteristics of a newly discovered lignite-bearing sedimentary succession in western France. The lignitic bed, which is reminiscent of some Wealden facies in southern England, is located in Angeac in the Charentes region. The plant remains occur as three-dimensionally preserved mesofossils (cuticles, charred ferns and seeds, cones and twigs) and larger pieces of wood. The deposits contain variable amounts of such material and at one horizon in particular, an outstanding accumulation of dinosaur teeth and bones. Among the vertebrate remains are the longest sauropod femur (ca. 220 cm) yet found and bones representing an ornithomimosaur herd of at least eight individuals. The palynomorph content of the clay associated with the bones and lignitic material indicates a Hauterivian Barremian age. The abundance in the fossil assemblage of freshwater unionoid bivalves, some preserved in life position, the presence of freshwater algae, and the scarcity of brackish or marine species indicate that the depositional environment was a swamp only very occasionally connected to the sea. The forest bordering the swamp was dominated by cheirolepidiaceous trees co-occurring with a diverse assemblage of ferns

EnglishA series of sections from the Ouled Nail, Hodna and Aures massifs of Algeria have been studied to analyse the palaeogeographic evolution of the eastern part of the Saharan Atlas prior to and after the Cenomanian/Turonian (C/T) boundary event. Three periods are distinguished in the interval studied. During the middle to late Cenomanian, an overall ramp setting prevailed from the Saharan platform to the deeper environments of the Saharan Atlas. The latest Cenomanian and the earliest Turonian was marked by an episode of marked palaeogeographic change. Prior to the deposition of C/T boundary black shales, a rise in sea level occurred. Shallow-water carbonates were locally able to accommodate the sea-level rise. A "keep-up" response created a palaeogeography made up of isolated carbonate platforms separated by saddles, where a 1-20 m thick bed of deeper water mudstones was deposited as the lateral equivalent of the platform carbonates. At a larger scale, these saddles probably acted as corridors that allowed marine communication with the intra-Saharan basins (Tinrhert, Tademait basins). Correlations show that the boundary black shales later filled up the saddles of the Saharan Atlas, and onlapped the carbonate platforms, before the deposition of lower Turonian open marine marls that everywhere blanket the successions. During the early to late Turonian, the palaeogeography again changed to restore a N-S oriented ramp setting, similar to that of the middle Cenomanian. Correlation with the deeper-water facies of nearby northern Tunisia, suggests that the uppermost Cenomanian mudstone immediately underlying the black shale facies in the Saharan Atlas is the lateral equivalent of the uppermost bed of the Fahdene Formation (the so-called "pre-Bahloul") underlying the Bahloul black shale facies in the Tunisian Kalaat Senan reference section. Our platform-to-basin correlations show that the base of this bed is a regional transgressive surface, not a type II sequence boundary as suggested by previous authors. Finally, it is proposed that this mudstone bed correlates with Bed 63 of the Pueblo global reference section in the North American western Interior Basin, which also marks the beginning of the strong C/T boundary transgression. francaisUne douzaine de coupes levees dans les massifs des Ouled Nail, du Hodna et de l'Aures permettent de decrire l'evolution paleogeographique particuliere de ce domaine situe sur la flexure nord-saharienne, au moment de la crise de la limite Cenomanien-Turonien. Trois periodes sont distinguees. Au cours de la premiere (Cenomanien moyen-superieur p.p.), une paleogeographie globalement de rampe s'etablit entre la plate-forme saharienne et le domaine plus profond de l'Atlas saharien. La seconde periode couvre le passage Cenomanien-Turonien (C/T). Elle est marquee par un changement paleogeographique tres net. Juste avant le depot des black shales de la limite C/T, une elevation moderee du niveau marin relatif se produit. Les carbonates de plate-forme sont localement capables d'accommoder cette elevation. Il en resulte une paleogeographie particuliere faite des plates-formes carbonatees isolees, separees par des ensellements ou se depose, en equivalent lateral de facies, une couche de calcaires fins de 15 metres a moins d'un metre d'epaisseur selon les endroits. A plus grande echelle, ces ensellements ont pu constituer des corridors assurant la communication des bassins intra-sahariens de meme âge (Tinrhert, Tademait) avec la Tethys. Nos correlations montrent que les black shales qui terminent cette seconde periode se sont deposes uniquement dans ces ensellements qu'ils remplissent totalement, avant le retour a une sedimentation marneuse generalisee au cours du Turonien inferieur. Au cours de la periode suivante, couvrant le reste du Turonien, s'effectue la restauration d'un profil globalement de rampe orientee sud-nord, avec les carbonates de plate-forme progradant et retrogradant regulierement sur ce profil. Les correlations effectuees avec la coupe de reference de Kalaat-Senan en Tunisie du Nord suggerent que la couche de calcaire fin du Cenomanien terminal de l'Atlas saharien, sous les black shales, et dont l'epaisseur diminue de l'Aures vers le bassin du Mellegue, soit un equivalent lateral du banc calcaire (« pre-Bahloul ») qui surmonte la formation Fahdene et precede l'installation du facies Bahloul en Tunisie. Dans ce cas, la base de cette couche calcaire n'a pas la valeur regionale d'une limite de sequence de type II comme il a ete anciennement propose mais au contraire une valeur de surface de transgression. Nous proposons egalement de correler cette couche calcaire avec le banc 63 de la coupe de reference de Pueblo dans le bassin interieur nord-americain ou ce banc marque egalement le debut de la transgression, apres le depot des shales de Hartland.

International audience; An integrated stratigraphic study was conducted on a Kimmeridgian succession of 3rd-order cycles including marls and limestones in a shelf context at Bure (Paris Basin). The study was possible due to the exceptional opportunity provided by well-boring activities related to the construction of an underground laboratory of the French National Agency for Radioactive Waste Management (ANDRA). Studies of macrofossils, microfossils, sedimentology, clay mineralogy, isotopic composition (C, O) of shells and organic molecular geochemistry lead to a detailed description of the stratigraphic column, which allows us to address the history of sea-level and climate changes. Six transgressive-regressive cycles are recognised in the studied Kimmeridgian succession. In these 3rd-order cycles, the deepest environments are systematically represented by marls and organic-rich sediments whilst the shallowest are represented by limestones. These cycles do not correspond to changes in temperatures or carbonate production rates at a regional or global scale. On the contrary, long-term palaeontological, sedimentological, and geochemical changes during the Early Kimmeridgian are interpreted as climatically induced. These climatic changes are considered as responsible for bringing significant granular carbonate production to an end, in contrast to carbonate mud that was deposited in alternation with marls throughout the Late Kimmeridgian.

International audience; Seven sections, covering the upper Albian to lowermost Turonian, have been correlated from full-marine to continental-dominated deposits across a passive margin, along a transect 425 km long, from the present-day Atlantic coast to the ``Pre-African Trough'' between the Anti-Atlas and the High-Atlas. The thickness of the Cenomanian succession changes from around 500 metres in the fully marine sections to 250 metres in mostly continental facies in the western High-Atlas, about 150 km updip, to a few tens of metres in the Bou Tazoult area. The strata thicken again eastwards into the Pre-African Trough where they can be traced without major facies changes to the Kem Kem embayment and to the Bechar area in Algeria. Over all this eastern area, continental facies are overlain by the fully-marine shallow-water deposits of the Cenomanian-Turonian boundary interval. A first major conclusion is that fluvial aggradation in high-frequency transgressive-regressive sequences is coeval with the seaward-shift of the shoreline, in accordance with the genetic sequence stratigraphic model of GALLOWAY (1989). Both the flatness of the depositional profile and the corresponding very low energy of the marine environment during the transgressions account for the blanket of red continental clays on top of marine facies in updip depositional sequences, which is then preserved under the marine transgressive surface of the next sequence. A second major conclusion is that the high-frequency transgressive-regressive (T-R) sequences do not look like classical parasequences bounded by transgression surfaces. They usually exhibit a surface created by a sea-level fall within the regressive half-cycle. This is interpreted in the following way: regressions did not operate through a regular seaward-shift of the shoreline, but through stepped sea-level falls. The very low slope of the depositional ramp is thought to have enhanced the sequence stratigraphic record of such stepped regressions. Short-term, high-frequency sequences are organized into medium-frequency T-R sequences (seven in the Cenomanian) which show an overall aggrading and slowly retrograding pattern along the whole transect. Comparisons with other basins show that medium-frequency sequences do not fit the third-order depositional sequences described elsewhere, casting doubts about a eustatic mechanism for their deposition.

International audience; A synthetic study was carried out based on sedimentological, palaeontological, geochemical and mineralogical data of the upper Cenomanian lower Turonian carbonate platform of the Preafrican Trough (eastern Morocco) in order to (1) propose a 3D representation of the platform and constrain the temporal framework of the dysoxic/anoxic episodes recorded during the OAE2, (2) define and discuss the prevailing climate on the platform during this period, and (3) make comparisons with other Cenomanian Turonian platforms. During the late Cenomanian, both before and during the CCIE (Cenomanian Carbon Isotope Excursion), the platform displayed an east west polarity. Three third-order sequences of transgression regression can be defined. Dysoxic conditions were developed in the sediments and the bottom waters of the deepest environment (mid- to outer-ramp setting), in the western part of the platform. Well-oxygenated waters were present in the eastern part of the platform (peritidal zone to mid-ramp environment). The climate was arid before the CCIE, becoming warm with contrasted seasons during the CCIE. This climate is associated with a low palaeoproductivity over the entire platform, along with the presence of photozoan followed by heterozoan carbonate-producers, as found also in other parts of the Saharan platform. However, such conditions are not in accordance with many studies which suggest a wet climate during the CCIE, leading to intense chemical weathering of the continent favouring the appearance of high palaeoproductivity at a global scale and the establishment of dysoxic/anoxic conditions. In the Preafrican Trough, poorly-oxygenated waters spread outwards from the deep basins and covered the platform in response to sea-level rise. Many disturbances are recorded in the platform succession during the early Turonian, after the CCIE. Indeed, just after the C/T boundary, the development of an outer-ramp environment over the entire Preafrican Trough reflects flooding of the platform, linked to the end of the major Cenomanian transgression and the presence of eutrophic conditions which disrupted carbonate-producing organisms. This high palaeoproductivity, due to considerable nutrient input, led to the establishment of highly dysoxic/conditions in the bottom and intermediate waters, causing the disappearance of the majority of the Cenomanian palaeontological groups, except for the opportunist benthic and planktonic foraminifera which proliferated. Part of the nutrient input could be due to the presence of a hot and wet climate that may have led a slight increase in the degree of chemical weathering of the continent. Nevertheless, many lines of evidence, such as the decrease of the detrital influx during the early Turonian and the reduction of the weatherable continental areas after the Cenomanian transgression, suggest the existence of another source of nutrient inputs. Combined with the presence of dysoxic/anoxic conditions during the lower Turonian in several regions of the tropical Central Atlantic, the occurrence of these nutrient inputs may be linked to the volcanism/hydrothermalism of the Caribbean LIP and the mid-ocean ridges.

International audience; Once interpreted as a deep-water canyon infilling and later as some kind of tempestite deposit, the Tithonian breccias of Cause are here reinterpreted as a small lobe deposit, emplaced at the mouth of a gully cutting into a slope between two deep-water terraces in the eastern part of the subalpine basin. The breccias belong to two basic categories: mostly grain-supported and occasionally mud-supported. Spectacular large-scale oblique geometries (apparent lateral accretions) are observed in the grain-supported breccias, both within the infilling of the lower feeder channel and in the updip part of the lobe. Detailed analyses of these geometries show that they correspond to progradational features. Both laterally and in a more distal position on the lobe, these progradational bodies evolve into a pile of unsorted massive breccias, sometimes showing a crude, even stratification. We thus propose a depositional model for the grain-supported breccias, linking the two facies as follows: the deposition of a gravity flow begins at the toe-of-slope (mouth of the tributary gully) by a progradational head which evolves downslope and laterally to a splay of massive or crudely stratified breccia. The internal oblique stratification flattens distally over a distance of a few kilometres. Elementary beds pile up in morphological compensation to build the 100 m thick breccia body of Case. Because the breccias are derived from the gravity-reworking of deep-water nodular carbonates, there is no sand-sized material available in the depositional system, or only a little probably produced through an erosive clast grain diminution process during transport. This explains why the thick breccia beds pass quickly eastward to thin-bedded mud turbidites.

International audience; Upper Cretaceous conglomerates, sandstones and calcarenites outcropping in the Glandage syncline (Les Gas Gorge) belong to two superimposed ``turbidite'' systems, the first being the shortest (about two hundred metres thick, five kilometres wide, and a mere ten kilometres long). Both onlap a SW-NE oriented palaeoslope created by faulting in the latest Turonian on the southern edge of the Vercors carbonate platform. The first system is Coniacian in age, the second probably Campanian. This study deals only with the first system which comprises, in stratigraphic order, classical sandstone turbidites, clast-supported conglomerates, and coarse-grained, cross-bedded, sandy calcarenites. The transition between the last two lithologies is progressive, allowing the mechanisms, responsible for apparent lateral accretions found pervasively in both the conglomerates and the calcarenites, to be understood. Here, cross-bedding is not the result of changes in the direction of accretion in ``lateral bars'' or in oblique infillings of sinuous channels, as is often suggested in other similar deep-water carbonate systems. Each event bed comprises a prograding conglomeratic head plug, blanketed in continuous sedimentation by forward spreading bioclastic calcarenites. The superimposition of such mixed beds gives rise to a low-angle cross-stratification, an unusual feature for a system interpreted as a base-of-slope apron. Conglomerates were probably deposited through a granular flow mechanism at a strong hydraulic jump at the base of the slope. Associated calcarenites show supercritical flow features. The undulating transverse architecture of its large head onlapping the paleoslope suggests it is a multi-apex apron. The sandstone-conglomerate-calcarenite succession of the depositional sequence is interpreted as overall transgressive after the late Turonian tectonic phase that led to the exposure of the Vercors carbonate platform updip.

The Cenomanian/Turonian boundary black shale has been traced in southeastern French subalpine ranges in several sections correlated over tens of kilometres, both on a bed-by-bed basis and with the control of δ13C isotope curves. Correlations show a thickness increase slopeward and a slight increase in the time span of black shale deposition basinward. They also show that the Vergons section cannot be used as a local reference section for Ocean Anoxic Event 2 (OAE2) because it has probably been affected by synsedimentary sliding. Finally they show that the vertical range of the Whiteinella archaeocretacea Zone changes considerably over short distances. This could be easily understood in widely separated basins but is harder to explain at such a local scale. In addition, using results obtained in the US Western Interior Basin, we question the validity of this Partial Range Zone.

Five altered volcanic-ash beds have been correlated near the Cenomanian-Turonian stage boundary through much of the Western Interior Basin. These instantaneous events constitute independent chronostratigraphic marker-beds enabling the synchroneity of lithological, biological or geochemical records to be tested. In this way, the Greenhorn Sea is a unique place where the potentiality of this high-resolution stratigraphic tool is illustrated. The Cenomanian-Turonian interval is the ideal period for this sort of study because major oceanic changes, including the global expansion of the oxygen minimum zone, are recognised across OAE2 event, involving the disappearance of Rotalipora, complex keeled foraminifera which previously occupied deep oceanic waters. Biostratigraphic data coupled with bentonite correlation, in several sections of Colorado, show the diachronism of the occurrences of R. cushmani and H. helvetica. Consequently, the extension of the W. archaeocretacea partial range zone is extremely variable at the regional scale. Thus, this association has a low temporal value. Planktonic foraminiferal analyses also reveal an A. multiloculata event in the M. mosbyense zone. During tens of thousands of years, this species, plentiful in the Western Interior Basin, multiplies and prevails on Rotalipora before a gradual decline. Rotalipora gave rise to Anaticinella by the atrophy of its keel. Thus, Anaticinella may stay in shallower habitats and avoid the expansion of the oxygen minimum zone. However, even if this adaptation allowed a return to the surface water, this selective advantage would not be enough for Anaticinella to survive the ecologically drastic modifications. Extinction of Anaticinella and its ancestor Rotalipora occurred contemporaneously. Carbon stable isotope analyses show that main paleoceanographic events have occurred at Pueblo during the Cenomanian-Turonian stage boundary. The initial rapid increase and first peak of δ13C indicate the first anoxic event (event 1) before a decrease in values and a main manganese enrichment which are the evidence for a well-oxygenated environment (event 2). This assumption is supported by the occurrence of an abundant and diversified benthic community at the same interval. The second increase in δ13C proxies signs the rise of anoxia (event 3). The temporal distribution of these events with the bentonite marker beds and the ammonite biostratigraphy attest to the synchroneity of events 2 and 3 over 600 km between the Pueblo and Lohali Point sections. The absence of event 1 at Lohali Point in the S. gracile zone implies the existence of a hiatus. Thus, thanks to the five bentonite marker beds, extending from the S. gracile to the M. nodosoides ammonite zone over 2 Ma, we have not only achieved precise regional correlation but, dealing with facies variations, our observations also indicate gaps in the sedimentary record. Thus, in detail, some thin levels expressed in Pueblo (reference section) cannot be correlated in any other eastern sections. Furthermore, supposed continuous sections may contain important hiatuses. An example is given at El Vado (New Mexico) where two bentonite marker beds are missing. In spite of the lack of significant planktonic foraminifera, the indications provided by bentonite geometries and by nannofossils reveal the existence of a hiatus of at least 850 kyr. It could be explained by the location of the area along the trend of a tectonic forebulge linked to the Sevier orogeny. This bathymetric high had great consequences on the currents flows in this large interior sea where tethysian and boreal water masses competed.

Micropaleontological analysis and sedimentological studies were undertaken on the Turonian to the Coniacian strata of the western part of the Vocontian Basin near Nyons, Southeast France, in order to understand the evolution of paleoenvironments. Microfacies examination shows an alternation of two types of deposits: (1) sediments dominated by abundant sponge spicules, echinoderm fragments and quartz packstones–wackestones, suggesting a shallow water environment, and (2) sediments dominated by abundant calcispheres and planktic foraminifera, providing evidence of a deeper water environment. The biostratigraphy is based on a systematic analysis of planktic foraminifera (about 50 taxa). The first appearance of Dicarinella primitiva , associated with Marginotruncana tarfayaensis and Marginotruncana sinuosa , indicates the beginning of the Coniacian. Ostracoda corroborate the Coniacian age given by planktic foraminifera. Amongst the benthic foraminifera, Nodosariidae, Verneuilinidae and Eggerellidae are the most common families represented by the fauna. The qualitative and quantitative changes of benthic and planktic foraminifera population parameters provide precise information about the paleoenvironmental conditions (paleobathymetry, sediment composition, dissolved oxygen). The biological system reflects high-frequency sea level fluctuations. A possible glacially and/or tectonically induced mechanism is discussed in order to explain this kind of variations.

On the North-Provence margin, an omission surface with Rhizocorallium often characterizes the sub-Aptian discontinuity between Eocretaceous carbonates and Aptian-Albian marls. This discontinuity is recorded in various successions described along a palaeoslope joining the Vocontian Basin and the Provence platform, between the Jabron valley in the west and the Var valley in the east. The successions including Aptian marls always exhibit an omission surface with Rhizocorallium. Through this area, the Aptian discontinuity equates to at least part of the Goguel Level. The latter is represented by black shales occurring in the Vocontian Basin at the top of Deshayesi zone and is a regional expression of the global anoxic event OAE1a. Thus, the surface with Rhizocorallium can be regarded, on the North-Provence margin, as a marker coincident with the onset of the anoxic event which, in the Vocontian basin, succeeded to a nannoconid crisis. Representing a short event, the surface is also a marker of various processes: (1) current activity, deduced from a dominant orientation of Rhizocorallium. The Barremian-early Aptian carbonate succession is strongly eroded by the formerly more active currents along the Peipin Channel, south-east of Sisteron; these currents also led to the omission of the Bedoulian (= carbonate Lower Aptian) to upper Valanginian series from the top of the hemipelagic palaeoreliefs in the eastern Castellane arc; (2) tectonic activity in the Lower Aptian, marked by N080 degrees to N100 degrees extension faults and slumping of a semi-lithified carbonate sediment. Slumped material and fault scarps are burrowed with Rhizocorallium; (3) differential lithification of the Barremian limestones which has led to distinctive types of current erosion.

Resume A partir de la repartition des associations de foraminiferes, etudiee a la limite Cenomanien-Turonien dans le bassin vocontien, il a ete possible de mettre en evidence des periodes dominees par des strateges r et d'autres par des strateges K. Pendant la crise, les morphotypes globuleux prennent le pas sur les morphotypes carenes plus complexes. Cette alternance semble directement liee au cycle de reproduction et done a la profondeur du milieu, pour les foraminiferes planctoniques. En ce qui concerne les foraminiferes benthiques, la crise se marque par une baisse drastique de la diversite et par la manifestation d'une strategie opportuniste. L'analyse sequentielle des depots permet de mettre en evidence des oscillations du niveau marin a haute frequence qui se superposent a la grande transgression de 3o ordre, de la limite Cenomanien-Turonien. Pour expliquer un tel phenomene, nous envisageons deux hypotheses: la tectonique a haute frequence et le glacio-eustatisme. Ainsi, en confrontant les donnees biologiques avec les donnees sedimentologiques, nous mettons en evidence que la strategie r se developpe pendant la partie transgressive, alors que la strategie K caracterise plutot les phases regressives des cycles de 3o ordre.

Resume Des analyses micropaleontologiques associees a une etude sedimentologique ont ete entreprises dans le Turonien et le Coniacien du bassin vocontien occidental (Region de Nyons, S. E. France) afin de preciser le cadre paleoenvironnemental, mettant en evidence le caractere singulier de la region. L'examen des microfacies revele l'alternance de deux types de depots. Ils sont representes par des packstones-wackestones riches en spicules de spongiaires, debris d'echinodermes et quartz suggerant des apports en provenance de la plate-forme, d'une part et par des wackestones riches en calcispheres et foraminiferes planctoniques temoignant d'influences du bassin, d'autre part. L'analyse systematique des foraminiferes representes par une cinquantaine de taxa, permet de preciser la biostratigraphie avec, notamment, l'apparition de Dicarinella primitiva associee a Marginotruncana tarfayaensis et M. sinuosa qui datent le debut du Coniacien. Parmi les benthiques, les Nodosariidae ainsi que les Verneuilinidae, et les Eggerellidae correspondent aux familles les plus representatives. L'inventaire des ostracodes est egalement effectue; ces derniers confirment l'âge donne par les foraminiferes planctoniques. L'evolution qualitative et quantitative de divers parametres caracterisant les populations de foraminiferes benthiques et planctoniques fournit des precisions sur les conditions paleoenvironnementales (paleobathymetrie, nature des substrats, oxygene dissous). Cette etude micropaleontologique fine permet donc, non seulement de preciser le cadre biostratigraphique mais aussi une meilleure caracterisation et comprehension de la succession des milieux de depots que l'analyse de facies n'avait pas revele.

International audience; Carbon and oxygen isotope fractionations between calcite and aragonite were investigated by analyzing marine gastropods and bivalves that lived under temperate to tropical climates. Species that secrete both aragonite and calcite layers were studied to ensure similitude of changes in the isotopic composition of water, in diet, and in metabolic activity during shell growth. Aragonite and calcite layers from the adult parts of the shell were identified and mapped by using Raman spectroscopy. Powder samples were obtained by micro-drilling under a stereo microscope. Thirty-six pairs of aragonite-calcite samples were obtained from ten gastropod and five bivalve species. Biogenic aragonite is C-13-enriched by 0.95 +/- 0.81%. and O-18-enriched by 0.37 +/- 0.65%. relative to co-existing biogenic calcite. Direction and magnitude of the carbon isotope fractionation are compatible with those already determined by using low-temperature experimental approaches. The observed oxygen isotope difference between biogenic aragonite and calcite is assigned to the difference (similar to 0.4 parts per thousand) in the acid fractionation factor values that must be taken into account during digestion of carbonate polymorphs at 90 degrees C. It is concluded that biogenic calcium carbonate polymorphs precipitate close to, but not in isotopic equilibrium with seawater. Therefore, empirical oxygen isotope fractionation equations that were established on the basis of modern mollusc shells and ambient waters should be preferred for the calculation of aquatic paleotemperatures.

International audience; This paper documents for the first time microfossils in Upper Cretaceous (Santonian) amber from Martigues. Filamentous structures assigned to Prokaryotes and Eukaryotes are described. We show that the distribution of these filaments is closely related to the two types of amber encountered: red translucent, drop-shaped pieces and opaque to milky nuggets. The diversity and the constant occurrence of filaments in all studied pieces of amber reflect an exceptional filamentous resinicolous micro-world.

International audience; Detailed correlations across Tithonian carbonate breccia deposits in the Drome River area (northern part of the so-called "Vocontian Through") suggest the depositional system was that of an elongated deep-water lobe, up to 70 km long and 20 to 30 km wide, for a thickness reaching 200 m. The Drome lobe, as it is now called, is mainly made of slope to basinal mudstones breccias with minor platform components, interpreted as debris flow and mud flow deposits, associated with slump deposits. It is basically a base-of-slope system, whose elongated depositional area implies it was a "point-sourced" gravity system, thus perhaps connected to a small canyon cut onto the western slope of the basin. But the mostly mudstone material of the breccias also suggests that the walls of this inferred canyon were the main supplier of the lobe, not the carbonate platform proper. The updip part of the lobe has a complex internal geometry as the deposition of breccia bed packages is interrupted by scourings locally 50 m-deep, indicating maybe a canyon mouth environment. The middle part of the lobe is dominated by pure vertical aggradation of breccia beds with minor intervening erosion. In the downdip part of the system a morphological compensation mechanism occurs as breccia beds tend to spread laterally. A huge slump carrying large mudstone olistoliths ends the breccia deposition at the beginning of the Berriasian. This megaslump deposit was mostly emplaced on the right side of the breccia lobe supporting the idea of a depositional relief. Our observations thus show that previous interpretations as a submarine canyon infilling or as shallow-water breccias formed in-situ by cyclic loading under attenuating hurricane waves approaching the platform are not consistent with our observations. The internal geometry of the system studied brings new data about a poorly-studied kind of "turbidite" systems that of deep-water carbonate breccias

We present new radiometric ages in order to constrain the calibration of the Cretaceous time scale. They have been obtained from volcanic tuffs sampled at Hokkaido (Japan) within the Northwest Pacific marine succession of the Yezo Group, and are compared with ages from the Western Interior and Boreal basins. The good coherency between the U-Pb, Ar-40/Ar-39 and K/Ar chronometers when applied simultaneously and their comparison with previous determinations, argue for the previously proposed global synchronicity of biotic events. The U-Pb ages allow us to identify that a thermal event has affected some of the K/Ar ages through argon diffusion. Furthermore, the very low uncertainties associated with the U-Pb ages argue for the use of this technique for calibrating the geologic time scale. We obtain an age of 84.9 +/- 0.2 Ma from the base of the Campanian, which provides an upper bound for the Santonian-Campanian limit. The Cenomanian-Turonian limit is dated here at 94.3 +/- 0.3 Ma using U-Pb applied to zircons from the North-Pacific basin, and at 94.2 +/- 1.0 Ma using Ar-40/Ar-39 applied to a Western Interior basin tuff. The Albian-Cenomanian is constrained here between 99.7 +/- 03 and 99.7 +/- 1.3 Ma using, the ID-TIMS and LA-ICPMS U-Pb techniques, respectively. The age of 112.6 +/- 1.1 Ma proposed here for the Aptian-Albian limit is supported by both Ar-40/Ar-39 and K-Ar data. Finally, the approach followed here combining the U-Pb and K/Ar and Ar-40/Ar-39 isotopic dating allowed us to limit the systematic biases inherent to each approach. The very low absolute uncertainties associated with the U-Pb ages, further reinforces the use of this technique for calibrating the Cretaceous time scale.

The evolution of benthic foraminiferal assemblages at the Cenomanian-Turonian boundary in southeastern France is analysed. The biostratigraphic framework is clearly defined and the associations of benthic Foraminifera characterizing various palaeogeographic domains compared. During the Cenomanian-Turonian crisis, typical Cenomanian carbonate platform assemblages disappeared and were replaced by new associations in mid-Turonian times. In basinal environments an opportunistic adaptative strategy occurred during the crisis, followed by a recolonization of substrates by the same taxa.

Resume L'etude micropaleontologique des plates-formes a rudistes du Santonien du Sud-Est de la France a abouti a la mise en evidence d'un nouveau taxon: Spirolina cretacea nov. sp. (sous-ordre: Miliolina) qui a ete observe sur plusieurs coupes situees dans differents secteurs de Provence. L'analyse bibliographique concernant les Spirolines mesozoiques permet de mettre en doute l'attribution a ce genre des especes jurassiques et cretacees anciennement decrites. La presence du genre Spirolina des le Cretace, outre son interet biostratigraphique, fournit egalement d'interessantes informations sur les paleoenvironnements; elle permet en effet de caracteriser des milieux de depots calmes, situes en domaine de plate-forme proximale.

International audience; Correlations of four sections, constrained by stable isotope stratigraphy and micropalaeontology, along a 80 km-long, E/W-oriented transect from the western High-Atlas to the present-day coast (Taghazoute), show that the Cenomanian Turonian boundary event (CTBE) occurred within shallow-water, oyster-bearing limestones and marls, and not in the overlying black shale. The age of the laminated shale is early Turonian as the planktonic marker Helvetoglobotruncana helvetica is found from its first centimetres upward. The underlying deposits hosting the CTBE event are bounded by two unconformities interpreted as emersion surfaces, and represent the strongest seawardshifts of facies in the local Cenomanian sedimentary wedge. The delta(13)C anomaly is only recorded in the coastal Taghazoute section, not in other sections landward, meaning that the CUBE occurred here during a short transgressive phase within an overall regressive trend. The lower Turonian black shale of the Taghazoute section is transgressive onto the second unconformity and pass landward to white, evenly laminated, chert-bearing mudstones, then to bioturbated mudstones in the easternmost sections of the transect (western High-Atlas)

Resume L'analyse des foraminiferes benthiques de la coupe de Vergons (S.E. France) s'inscrit dans un travail pluridisciplinairesur la limite Cenomanien-Turonien, dans le but de comprendre les evenements anoxiques constates. Sur le plan paleontologique, 67 taxa sont presentes; ils completent les connaissances sur les microfaunes benthiques des milieux profonds du Cenomano-Turonien. La presence d'especes connues a des niveaux stratigraphiques plus anciens ouvre des perspectives pour d'eventuelles etudes phylletiques. Les repartitions stratigraphiques observees permettent d'envisager, apres comparaisons avec les secteurs voisins, la mise en evidence de marqueurs a l'echelle regionale. Des phenomenes de remaniements sont constates dans la Zone a Whiteinella archaeocretacea. L'evolution qualitative et quantitative des assemblages de foraminiferes benthiques apporte des precisions sur les paleoenvironnements; les biotopes correspondent a des substrats vaseux developpes sur le talus continental. Les variations de la diversite specifique, de la taille des individus et de la morphologie des tests, fournissent des indications sur les modifications du taux d'oxygene dissous, au moment des depots. Dans les milieux sous-oxygenes, des relations sont envisagees entre l'abondance de certains groupes (Buliminacea) et leur morphologie interne. D'une facon generale, une forte hypoxie se manifeste episodiquement a la base de la Zone a W. archaeocretacea et ces conditions alternent avec des periodes de moindre sous-oxygenation. Apres un retour progressif a des conditions d'oxygenation normale (analogues a celle de la zone a Rotalipora cushmani), on constate a nouveau, au sommet de la Zone a W. archaeocretacea et dans la Zone a Helvetoglobotruncana helvetica, l'existence de petites passees noires totalement depourvues de microfaune benthique et interpretees comme de breves periodes de forte hypoxie.

International audience; The fossil record of planktonic foraminifera is a key source of data on the evolution of marine plankton. One of the most distinctive groups of Cretaceous foraminifera, the rotaliporids, widely used as a stratigraphic index, has always been considered to be a monophyletic clade. New data on the coiling direction and persistent morphological features of the late rotaliporids from the Upper Cenomanian of the Western Interior Seaway, USA, and the Vocontian Basin of southeast France is used as a phylogenetic proxy. Dealing with key morphological features, the coiling pattern of these keeled morphotypes proves that the rotaliporids group is polyphyletic and composed of Thalmanninella, that displays a dextral-coiling preference, and Rotalipora s.s., that have a proportionate-coiling mode. The stratigraphically youngest rotaliporids with keels co-occur with globular forms; and all morphologies transitional between these morphotypes are observed. The ontogenetic relationships between them are investigated, indicating that loss of the keel was a selective advantage that enabled those rotaliporids to remain in the surface water, thereby avoiding the expansion of the oxygen minimum zone. Two species are observed: Thalmanninella multiloculata and Rotalipora planoconvexa. These species are interpreted as having arisen by neoteny from Thalmanninella greenhornensis and Rotalipora cushmani respectively.

International audience; Amber usually contains inclusions of terrestrial and rarely limnetic organisms that were embedded in the places were they lived in the amber forests. Therefore, it has been supposed that amber could not have preserved marine organisms. Here we report the first known amber-preserved marine microfossils. Diverse marine diatoms as well as radiolarians, sponge spicules, a foraminifer, and a larval spine of a sea urchin were found in Late Albian and Early Cenomanian amber samples of southwestern France. The highly fossiliferous resin samples solidified ca. 100 million years ago on the floor of coastal mixed forests dominated by conifers. The amber forests of southwestern France grew directly along the coast of the Atlantic Ocean and were influenced by the nearby sea: shells and remnants of marine organisms were probably introduced by wind, spray or high tide from the beach or the sea onto the resin flows.

Paleoecological studies carried out in the Carbonate bank with Rudists of La Cadiere d'Azur (Southeast France) and adjacent perideltaic areas have been made in order to define some stages during the evolution of the formation. For each period, type of ostracode assemblage can be proposed. This is undertaken by analysis using both a more precised systematics and especially quantitative methodology, particularly the factorial analysis of correspondances. One purpose of this study is to justify the paleoecological interpretations and moreover to conclude on the autecology of ostracode species. Lastly, it is suggested that carbonate rate (i.e. water content in calcium), turbulence of sea-waters (influencing the grain-size of terrigenous deposits) and perhaps depth are locally important controlling factors of ostracode diversity.

A detailed lithologic and biostratigraphic framework was determined for 4 Cenomanian sections, allowing correlations from the boarder of the upper slope to the platform and the lower slope of the vocontian basin. Over 800 samples provided planktonic and benthic foraminifera associations for a biostratigraphic and paleogeographic succession. There was a diachronisme between the ammonites and the foraminifera biozonation. Indeed, Thalmanninella reicheli, the marker of the middle Cenomanian substage had a short extension,overlapping with the Mantelliceras mantelli, ammonite of the Inferior Cenomanian. Moreover Rotalipora cushmani, the foraminifer marker for the Upper Cenomanian,appeared before Acanthoceras, an ammonite of the Middle Cenomanian. Basal Cenomanian, Middle Cenomanian, and CTB were registered by local lithologic discontinuities resulting from the lowering of the relative sea level in the boarder of the upper slope section. Correlated with the lithologic events, the benthic opportunist foraminifera dominated the associations from the Inferior Cenomanian of the upper slope and platform sections, and from the middle part of the Upper Cenomanian of the deep sea sections. Dysoxic periods (Albian-Cenomanian boundary, MCE, and OAE2) as detected by δ13C anomalies, also corresponded to the regression levels. Benthic Foraminifera responsiveness to sea water depth and anoxia was faster than δ13C variations. CTBE was lithologically registered by black shakes deposits in the deep sea section, but the end of the Rotalipora extension was the marking event in all sections., Quatre coupes ont été étudiées dans les séries marno-calcaires de talus et de bassin profond de la "fosse vocontienne" au Cénomanien. Le travail effectué à partir de plus de 800 échantillons dans lesquels les associations de foraminifères planctoniques et benthiques ont été étudiées a montré des particularités biostratigraphiques, et paléogéographiques. En effet, il existe un diachronisme dans l’extension verticale de Thalmanninella reicheli et dans l’apparition du marqueur de la base du Cénomanien supérieur (Rotalipora cushmani). T. reicheli a une extension verticale courte, mais située dans le Cénomanien inférieur peu élevé d’après les faunes d’ ammonites associées; R. cushmaniapparait avant les ammonites marquant le Cénomanien moyen (Acanthoceras). Les chutes du niveau marin relatif enregistrées par des discontinuités lithologiques dans la coupe de la marge du talus au Cénomanien basal, dans la partie moyenne du Cénomanien, et au passage Cénomanien-Turonien sont également repérées par la dominance des assemblages de foraminifères benthiques opportunistes, d’abord dans les coupes de marge et de plate-forme méridionale, ensuite dans les coupes de bassin profond. Ces passages correspondent aussi à des évènements dysoxiques, liés à l’anomalie du δ13C. L’évolution des foraminifères benthiques s’avère très sensible à profondeur de l’eau et à la dysoxie,leur réponse étant plus rapide que la variation du δ13C. La régression forcée au passage Cénomanien-Turonien correspond à des dépôts de black shales dans la coupe du bassin le plus profond, traduisant l’événement anoxique OAE2. La fin de l’ extension de Rotalipora cushmani, définit le sommet de l’étage dans les 4 coupes.

During the Cenomanian-Turonian boundary interval, over 2Ma, five altered volcanic-ash beds, which are isochronous time-line, have been correlated over tens of thousands of square kilometres through the US Western Interior Basin from Arizona to Kansas and from Texas up to South Dakota while passing by the Pueblo type section (Colorado). These instantaneous events constitute independent chronostratigraphic marker-beds enabling the robustness of lithologica, biological (planktic and benthic foraminefera, calcareous nannofossils) or geochemical (S13C, S18C) records to be tested as tool for high resolution correlations. As suggested by our scheme, differences obseved between supposed continuous sections could be related, with some hiatuses in the sedimentary record. If correct, one hiatus may have been as long as 800 Kyrs. The onset and most of the fine-scale features of carbon-isotope excursion identified at pueblo are recognised over long distances even in the more coastal sections where bed by bed correlations become more difficult. Thus, this tool appears extremely robust if the hiatuses are precisely constrained. Some bioevents as the benthic zone or the Heterohelix event are synchronous at the scale of the Western Interior Basin and they could be used as global stratigraphic tools; they also coincide with events recorded by S13Ccarb (respectively phase of oxygenation and second rise of the anoxia). On the basis of this high resolution scheme, we show that the filament event, the last occurences of R. cushmani as well as the first occurence of H. helvetica are strongly diachronous at the basin scale. Thus the W. archaeocretacea Partial Range Zone, in which is the Cenomanian-Turonian boundary, has a variable duration. If it is reduced at almost nothing at Pueblo (