The Early Toarcian oceanic anoxic event (OAE) is associated with a rapid and severe environmental change whose causes are still a matter of debate. A new paleoenvironmental interpretation is ...proposed, based on a multidisciplinary dataset (chemical, mineralogical and paleontological) obtained from a borehole drilled by Andra (French National Radioactive Waste Management Agency) in the Lower Toarcian of the eastern Paris Basin (France).
During the earlymost Toarcian (Tenuicostatum Zone), the presence of well oxygenated sea-water is reflected by an abundant and diverse fauna, along with paleoredox proxies (U/Al, Mo/Al and V/Al) typical of oxidizing conditions, associated with predominant mechanical weathering on the continent. At the base of the Serpentinum Zone, an important paleoenvironmental change is marked by an initial phase of organic matter enrichment (~12% TOC) during the negative shift of δ13C (Carbon Isotope Excursion: CIE). Euxinic/anoxic conditions, indicated by cobalt enrichment and the development of framboidal pyrite, lead to the disappearance of the benthic and pelagic fauna and allow organic matter to be preserved in the sediments. At this time, the low concentration of paleoproductivity proxies (Cd, P, Ni and Zn) suggests weak chemical weathering on the continent due to a rather arid climate. Low concentrations of Sr and coccoliths are due to an input of fresh water probably coming from the Arctic through the Laurasian seaway. Thus, the isolation of the Paris Basin from the Tethyan realm and the influx of freshwater favour haline stratification and the preservation of organic matter.
Following the CIE, oxygen concentration gradually increases up to a maximum flooding surface dated as coeval with the Serpentinum Zone, Elegantulum Subzone. Paleoproductivity proxies indicate a weak primary productivity.
The top of the Lower Toarcian is characterized by a second enrichment in organic matter (~12% TOC) due to an important input of nutrients. This enhanced primary production generates euxinic/anoxic conditions in the sediment and in part of the water column, leading to a high enrichment in paleoredox proxies (Mo, U, V, Co) and causing the sudden disappearance of the benthic fauna and a progressive decline of the pelagic fauna. The metal enrichment is related to intense chemical weathering on the continent due to a more humid climate.
► Chemical disturbance during T-OAE and CIE in NW Europe ► No metal enrichment, low productivity during CIE due to rather dry climate ► Pelagic fauna and flora density controlled by salinity variations during CIE ► Normal oxygenation conditions briefly reappear just after CIE during maximum flooding. ► Metal enrichment, high productivity after CIE due to humid climate after CIE
The early Bajocian environmental crisis is marked by floral and faunal turnovers, and a positive carbon excursion recognized in both marine and continental archives. In the basinal setting of the ...Central High Atlas Basin, it is concomitant to a drastic drop of carbonate content, interpreted as a result of a severe carbonate demise event in neritic settings. In order to provide a carbonate platform perspective of this demise event, we have investigated a proximal–distal transect consisting of five sections of the Errachidia Platform, which represents upper neritic settings on the southern margin of the basin. New nannofossils and brachiopod findings, supported by organic matter carbon isotope chemostratigraphy, allow for the establishment of a high-resolution chronostratigraphic framework of the Errachidia Platform and a detailed reconstruction of carbonate factory evolution during the late Aalenian to middle Bajocian interval. The early Bajocian (Propinquans Zone) environmental crisis triggered a severe demise event which restricted carbonate production to supra-to intertidal settings, where microbial and peloidal limestones are the only trace of carbonate production. As a consequence, most of the platform is dominated by extended marl deposits that are usually interpreted as hemipelagic deposits. This observation demonstrates that caution must be exerted when interpreting the depositional environments of marl-dominated successions during time of neritic carbonate factory demise.
•Neritic carbonate factory restricted to nearshore environments during drowning event.•Characterized by microbial and peloidal limestones.•Original biostratigraphic and chemostratigraphic data for the Bajocian of the Central High Atlas.•New lithostratigraphic scheme for the Errachidia Platform.
We describe several new unconformable marine Miocene outcrops on the Lower Cretaceous of the Mediterranean coast of Saint-Martin Iceland (Gruissan, Aude). None had been identified to date. They are ...evidence of a maximum Neogene marine transgression on the Languedoc margin of the Lion Gulf in the Langhian (15,9 - 13,65 My).
Nous décrivons plusieurs nouveaux affleurements de Miocène marin discordants sur le Crétacé inférieur de la façade méditerranéenne de l'Île Saint-Martin (Gruissan, Aude). Aucun n'avait été identifié à ce jour. Ils sont les témoins, au Langhien (15,9-13,65 Ma), d'un maximum de la transgression marine du Néogène sur la marge languedocienne du Golfe du Lion.
The Réalmont basin (Tarn, France) is a Stephano-Permian (Upper Carboniferous, Permian) molasses- filled basin of limited extent, located in the southwestern part of the Massif Central. Four ...sedimentary units are identified, Grey Serie, Stephanian, Gray and Dew Series, with Autunian facies, Red Series and Red Conglomeratic Series, with Saxono-Thuringian facies. Despite the absence of radiometric dating due to the lack of interstratified volcanic rock, the age of these continental deposits could be specified. We present an attempt to correlate sedimentary episodes with the main tectonic and magmatic events that occurred in the continental Réalmont domain.
Le bassin de Réalmont (Tarn, France) est un bassin à remplissage molassique stéphano-permien (Carbonifère supérieur, Permien) d'étendue limitée, situé dans la partie sud-occidentale du Massif Central. Sont identifiées quatre unités sédimentaires, Série grise, stéphanienne, Série grise et rosée, à faciès autunien, Série rouge et Série conglomératique rouge, à faciès saxono-thuringien. Malgré l'absence de datation radiométrique due au manque de roche volcanique interstratifiée, l'âge de ces dépôts continentaux a pu être précisé. Nous présentons une tentative de corrélation entre les épisodes sédimentaires et les principaux événements tectoniques et magmatiques qui se sont produits dans le domaine continental de Réalmont.
The paleogene molasses (Eocen, Oligocen) which fill the Castrais and Albigeois basins (eastern Aquitaine, France) contain several conglomerate spreads with elements of Paleo-Pyrenean origin, which ...have been assimilated by the authors to the “Poudingues de Palassou” of the northern edge of the central Pyrenees. These levels, better named in the Tarn under the name « Poudingues de type Puylaurens », range from the Upper Eocene (Bartonian, Priabonian) to the Rupelian. If the syntectonic origin of the Eocene-age conglomerates is proven, the climatic origin of the Rupelian-age conglomerates is more likely. These conglomerates also bear witness to the existence since the Bartonian of a paleorelief prefiguring the Montagne Noire.
Les molasses paléogènes (Eocène, Oligocène) qui comblent les bassins du Castrais et de l'Albigeois (Aquitaine orientale) renferment plusieurs épandages conglomératiques à éléments d'origine paléo-pyrénéenne qui ont été assimilés par les auteurs aux « Poudingues de Palassou » de la bordure nord des Pyrénées centrales. Ces niveaux, mieux nommés dans le Tarn sous le terme de « Poudingues de type Puylaurens », s'y échelonnent de l'Eocène supérieur (Bartonien, Priabonien) au Rupélien. Si l'origine syntectonique des conglomérats d'âge éocène est avérée, l'origine climatique des conglomérats d'âge rupélien est plus vraisemblable. Ces conglomérats paléogènes témoignent aussi de l'existence depuis le Bartonien, d'un paléorelief préfigurant la Montagne Noire.
The paleogene molasses (Eocen, Oligocen) which fill the Castrais and Albigeois basins (eastern Aquitaine, France) contain several conglomerate spreads with elements of Paleo-Pyrenean origin, which ...have been assimilated by the authors to the “Poudingues de Palassou” of the northern edge of the central Pyrenees. These levels, better named in the Tarn under the name « Poudingues de type Puylaurens », range from the Upper Eocene (Bartonian, Priabonian) to the Rupelian. If the syntectonic origin of the Eocene-age conglomerates is proven, the climatic origin of the Rupelian-age conglomerates is more likely. These conglomerates also bear witness to the existence since the Bartonian of a paleorelief prefiguring the Montagne Noire.
Les molasses paléogènes (Eocène, Oligocène) qui comblent les bassins du Castrais et de l'Albigeois (Aquitaine orientale) renferment plusieurs épandages conglomératiques à éléments d'origine paléo-pyrénéenne qui ont été assimilés par les auteurs aux « Poudingues de Palassou » de la bordure nord des Pyrénées centrales. Ces niveaux, mieux nommés dans le Tarn sous le terme de « Poudingues de type Puylaurens », s'y échelonnent de l'Eocène supérieur (Bartonien, Priabonien) au Rupélien. Si l'origine syntectonique des conglomérats d'âge éocène est avérée, l'origine climatique des conglomérats d'âge rupélien est plus vraisemblable. Ces conglomérats paléogènes témoignent aussi de l'existence depuis le Bartonien, d'un paléorelief préfigurant la Montagne Noire.
We describe several examples of the marine Neogene transgression on the Lower Cretaceous from Saint- Martin Island (Gruissan, Aude). Little was known of the composition of the Miocene there. Molassic ...limestones with Chlamys tournali of Burdigalian age are overlaid by limestone and sandstone marl with Crassostrea gryphoides of Lower Langhian age. One of these outcrops, located south-west of Gruissan, had not been described to date.
Nous décrivons plusieurs témoins de la transgression du Néogène marin sur le Crétacé inférieur de l'Île Saint-Martin (Gruissan, Aude). La composition du Miocène y était peu connue. Des calcaires molassiques à Chlamys tournali, d'âge burdigalien, y sont surmontés par des calcaires et marnes gréseuses à Crassostrea gryphoides, d'âge langhien inférieur. L'un de ces affleurements, situé au sud-ouest de Gruissan, n'avait pas été décrit à ce jour.
Located in the western part of the Bédarieux basin, the Lower Jurassic (Pliensbachian, Toarcian) of the surroundings of Boussagues (La Tour-sur-Orb, Hérault) offers a reduce, condensed and ...discontinuous sedimentary series representative of the southern end of the Cevenol hight
Situé dans la partie occidentale du bassin de Bédarieux, le Jurassique inférieur (Pliensbachien, Toarcien) des environs de Boussagues (La Tour-sur-Orb, Hérault) offre une série sédimentaire réduite, condensée et discontinue représentative d’un haut fond qui s’inscrit dans l’extrémité méridionale du Seuil cévenol.
The nasal tissues have the main consecutive roles of moistening and heating the air entering the respiratory tract and detecting odor via the activation of olfactory receptors in the neuro-olfactory ...epithelium. Initially, nasal toxicology was investigated to better assess the risk of nasal injuries caused by environmental toxicants or their active metabolites. Later, the characterization of the nasal toxicological barrier was a research concern for the purposes of intranasal drug delivery. Both fields allowed for an increase in our knowledge of the nasal xenobiotic-metabolizing enzymes and transporters that are highly expressed in this tissue. In addition to airborne toxicants or drugs, the main substrates for these proteins are natural volatiles known as odorants that emanate from our daily environment (food, perfume, plants, materials, congeners, etc.). Accordingly, another emerging field of interest has been developed that aims to understand the function of odorant-metabolizing enzymes (OMEs) in olfaction. Early in this field of research, OMEs were suspected to participate in the clearance of odorants from the receptor environment to avoid their saturation and thus maintain the sensitivity of neuronal detection. Other roles of OMEs that could significantly modulate olfaction were also considered, such as the involvement of odorant primary metabolites in the olfactory response. By combining enzymatic, physiological and sensory experimental approaches, recent advances have markedly improved our understanding of the contributions of OMEs to the olfactory process. This review combines recent data from the literature regarding nasal OME identification, localization, and activity and highlights the function of OMEs in olfaction.
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