CAMPANIAN CALCAREOUS NANNOFOSSIL BIOSTRATIGRAPHY OF EASTERN KOPPEH-DAGH BASIN (NORTH EAST OF IRAN), TETHYAN REALM

Tethyan calcareous nannofossil assemblages have been recorded from three sections of the Abtalkh Formation including the type section at Abtalkh village and two others (Padeha and Jalilabad) in the east Koppeh-Dagh Basin, north east of Iran. The formation studied is expanded with a thickness of up to 1770 m at the type locality in the middle of eastern Koppeh-Dagh spanning biozones UC15bTP to UC16 while in the Padeha (973.5 m thick) in east and Jalilabad (1316 m thick) section in the west the formation spans biozones UC14dTP–UC15aTP to of UC16. The zonation erected indicates an age of early–latest Campanian for the Abtalkh Formation. The recorded assemblages are of low-latitude to intermediate forms suggesting placement of the Koppeh-Dagh Basin in low to intermediate latitudes during Campanian

Constraints on the duration of the early Toarcian T-OAE and evidence for carbon-reservoir change from the High Atlas (Morocco)

International audienceThe Toarcian oceanic anoxic event (T-OAE, ~183 Ma) marks a geologically brief and severe global warming, associated with a profound perturbation in the global carbon cycle. The carbon cycle perturbation has been documented worldwide in marine and continental sedimentary records with a pronounced negative carbon isotope excursion (CIE) in the long-term d 13 C profile. However, the cyclostratigraphically inferred duration of the CIE, which was mainly derived from the Paris (France) and Lusitanian (Portugal) basins, remains controversial, resulting in two notably different estimates of 300-500 and 900 kyr. Here, we present an early Toarcian cyclostratigraphic record from the High Atlas in Morocco (Talghemt section), based on high-resolution d 13 C and %CaCO 3 data, which capture the Pliensbachian-Toarcian (Pl-To) transition event and the T-OAE, and strongly correlate to previous d 13 C key records. Orbital tuning based on the short and long, stable 405 kyr (g2-g5) eccentricity cycles, provides a duration of ~400 to ~500 kyr for the T-OAE. This duration is very close to that previously inferred from the Sancerre Core in the Paris Basin (300 to 500 kyr), and similar to that recently revised from the Peniche section (Lusitanian Basin, Portugal) (~472 kyr). In addition, the 405 kyr %CaCO 3 timescale at Talghemt calibrates high-frequency d 13 C variations at the Pl-To transition and the initiation part of the T-OAE to the obliquity cycle band, thus concuring with previous studies for obliquity forcing during these time intervals. The 405 kyr calibrated O1 obliquity period (~30 kyr) is shorter than the astronomically predicted one (~35 kyr), hence supporting the hypothesis of shortened obliquity periods during the Early Jurassic, and providing constraints on Earth's tidal dissipation factor during this geologic epoch. Finally, a remarkable phase change between %CaCO 3 and d 13 C orbitally paced cycles is observed for the first time at the T-OAE, suggesting a change in the carbon reservoir in relation with volcanically released greenhouse gases and major carbonate crisis. However, this phase shift is not observed at the Pl-To event implying different causal mechanisms on the carbon cycle perturbation between the Pl-To and T-OAE events

Nitrogen isotope record of a perturbed paleoecosystem in the aftermath of the end-Triassic crisis, Doniford section, SW England

International audience[1] The Triassic-Jurassic transition (TJ) is characterized by successive perturbations of the carbon cycle during a time of biotic disruption as recorded by the carbon isotopic composition of organic matter (δ13Corg). The nitrogen isotopic composition of sedimentary organic matter (δ15Norg) constitutes a key parameter to explore the functioning of the ecosystem during carbon cycle perturbations and biological crises, because it provide information on seawater redox conditions and/or nutrient cycling. Here we report the first continuous δ15Norg record across the TJ transition at the Doniford Bay section (Bristol Channel Basin, UK), combined with δ13Corg, kerogen typology and carbon (δ13Cmin) and oxygen (δ18Omin) isotopic composition of bulk carbonates. The end Triassic is characterized by a major negative excursion both in δ13Corg and δ13Cmin, very low TOC (Total Organic Carbon, wt%) and high δ15Norg values, associated with a sea level lowstand. A second δ13Corg negative excursion occurs during the lower Hettangian. This interval is characterized by phases of carbonate production increase alternated with phases of exceptional accumulations of type I organic matter (up to 12%) associated with lower δ15Norg and δ13Corg. This alternation likely reflects a succession of nutrient input increase to the basin leading to enhanced productivity and eutrophication, which promoted a primary production driven by organic-walled prokaryotic organisms. The following OM export increase generates anaerobic conditions within the basin. These events occur between periods of relatively good seawater column ventilation and nutrient recycling boosting the carbonate producer recovery. Ecosystems remain perturbed in the Bristol Channel Basin during the aftermath of the end-Triassic crisis

Définition des unités chronostratigraphiques mondiales et échelle des temps : pour des conventions simples et limitées favorisant la mise en oeuvre des connaissances disponibles

Ce travail discute quatre aspects de la terminologie stratigraphique considérés comme inappropriés et propose des améliorations concernant : (1) le système de double terminologie avec des termes propres pour chacun des aspects temporel et géométrique des corps de roche ; (2) l’assertion selon laquelle le Point Stratotypique Mondial (PSM) définit la base d’un étage qui coïncide avec le sommet de l’étage précédent au lieu de tout simplement : la limite d’étage ; (3) la répugnance devant la désignation de sections additionnelles (auxiliaires) qui accroîtraient la connaissance d’un PSM et pourraient ainsi élargir le domaine de corrélation immédiate ; (4) le système actuel de subdivision différent pour le Précambrien (limites définies par des âges) et pour le Phanérozoïque (limites définies par des PSM) est accepté mais un troisième système (des limites propres à chaque outil de corrélation) est proposé pour les dépôts âgés de 3 à 5 Ma. Par ailleurs, si le travail encourage l’utilisation universelle d’un nombre restreint de conventions, il met en garde contre une prolifération de celles-ci pour des unités qui, en devenant plus courtes, deviennent plus malaisées à reconnaître. On souligne enfin que la distinction doit rester très claire entre ces conventions qui sont une affaire d’administration et de consensus et la connaissance, un domaine où la libre expression des opinions est indispensable

Enrichment of redox-sensitive trace metals (U, V, Mo, As) associated with the late Hauterivian Faraoni oceanic anoxic event

The Faraoni Level is a short-lived oxygen-deficient event that took place during the latest Hauterivian. In order to improve our understanding of the palaeoenvironmental conditions that occurred during this event, we have analysed the contents of several redox-sensitive trace elements (U, V, Mo, As, Co, Cd, Cu, Zn, Ni, Pb, Cr) from bulk limestone samples of late Hauterivian-early Barremian age from three reference sections. U, V, Mo and As show consistent and significant enrichments during the Faraoni event whereas the other redox-sensitive trace elements analysed here are not systematically enriched. In order to explain this discrepant behaviour, we propose that the Faraoni Level was deposited during a period of anoxic conditions near the sediment-water interface. The distinctive peaks in U, V, Mo and As contents are traceable throughout the three studied sections and represent a good correlation tool which helps to identify the Faraoni Level and its equivalents in the western Tethyan realm and outside of the Tethys. For example, a peak in U contents in upper Hauterivian sediments of the northwestern Pacific realm (ODP leg 185, site 1149) may well be an expression of the Faraoni event in this particular basi

The significance of macrophage phenotype in cancer and biomaterials

The aim of this study was to evaluate the osteogenic response of human adipose-derived stromal cells (ADScs) to mesoporous titania (TiO2) coatings produced with evaporation-induced self-assembly method (EISA) and loaded with magnesium. Our emphasis with the magnesium release functionality was to modulate progenitor cell osteogenic differentiation under standard culture conditions. Osteogenic properties of the coatings were assessed for stromal cells by means of scanning electron microscopy (SEM) imaging, colorimetric mitochondrial viability assay (MTT), colorimetric alkaline phosphates activity (ALP) assay and real time RT-polymerase chain reaction (PCR). Using atomic force microscopy (AFM) it was shown that the surface expansion area (Sdr) was strongly enhanced by the presence of magnesium. From MTT results it was shown that ADSc viability was significantly increased on mesoporous surfaces compared to the non-porous one at a longer cell culture time. However, no differences were observed between the magnesium impregnated and non-impregnated surfaces. The alkaline phosphatase activity confirmed that ADSc started to differentiate into the osteogenic phenotype after 2 weeks of culturing. The gene expression profile at 2 weeks of cell growth showed that such coatings were capable to incorporate specific osteogenic markers inside their interconnected nano-pores and, at 3 weeks, ADSc differentiated into osteoblasts. Interestingly, magnesium significantly promoted the osteopontin gene expression, which is an essential gene for the early biomaterial-cell osteogenic interaction