83 research outputs found
De l'importance des dissolutions partielles dans des ooĂŻdes calcaires : Exemple des oolithes hauteriviennes de Suisse
In the Canton of Vaud (Switzerland), two Hauterivian oolitic units were penetrated by a borehole. In both units, the ooids are partly leached. More specifically, the ooid cortices were partly leached and some ooid nuclei appear suspended in the middle of cortical moldic cavities created by leaching, rather than having fallen to the bottom of these cavities before the final cementation take place. We demonstrate that these ooids were originally calcitic, not aragonitic, not "two-phase" nor "bimineral". This leaching is not an early diagenetic feature related to subaerial exposure, but a late diagenetic feature, possibly related to the migration of acidic pore waters, brought about by Alpine tectonics and/or karstification
Commentaires sur "Estimating the impact of early diagenesis on isotope records in shallow-marine carbonates: A case study from the Urgonian platform in western Swiss Jura" par A. Godet et al. [Palaeogeography Palaeoclimatology Palaeoecology 454 (2016) 125-138]
A recent paper by Godet et al. on Urgonian carbonates from the Swiss Jura concluded that diagenesis may hinder chemostratigraphic correlations of deep- to shallow-water facies. Although we agree with this conclusion we question their arguments and interpretations. These authors correctly identified diagenesis as the key factor, but we question the timing of events in their paragenetic sequence. In particular, they reported the leaching of originally calcitic oolitic cortices but failed to discuss this puzzling feature properly. In addition, the backbone of their argument is the stratigraphic correlation of a specific sequence from three dominantly shallow-water sections together with a basinal reference section. However, a reliable alternative biostratigraphic framework shows that this attempt of long-distance correlation might be erroneous.Une publication récente de Godet et al. sur les carbonates urgoniens du Jura suisse concluait que la diagenÚse pouvait compromettre les corrélations chimiostratigraphiques des faciÚs distaux vers les proximaux. Bien que nous soyons d'accord avec cette conclusion, nous nous interrogeons sur les arguments des auteurs et leurs interprétations. Ils ont bien identifié la diagénÚse comme étant le facteur déterminant, mais nous mettons en doute la chronologie des événements de leur séquence paragénétique. Ils ont notamment signalé la dissolution de cortex d'ooïdes originellement calcitiques mais n'ont pas abordé sous un bon angle cet élément étonnant. De plus, leur argumentaire s'appuie sur la corrélation stratigraphique d'une séquence spécifique identifiée dans trois coupes aux faciÚs essentiellement peu profonds avec une coupe de bassin utilisée comme référence. Toutefois, un autre cadre biostratigraphique plus robuste que celui utilisé par Godet et al. suggÚre que leur tentative de corrélations sur de longues distances est erronée
The Cretaceous of the Swiss Jura Mountains: an improved lithostratigraphic scheme
In the course of the HARMOS project of the Swiss Geological Survey, the lithostratigraphic subdivisions of the Cretaceous sedimentary rocks outcropping in the Swiss Jura Mountains were revisited. New formation names are proposed where only inadequate facies terms existed so far. As in some cases outcrop conditions in the Swiss Jura do not allow for logging complete sections to characterise the formations, type localities in neighbouring France have been chosen. The following formations (Fm.) are defined to describe the Cretaceous lithological units (from bottom to top): Goldberg Fm., Pierre-ChĂątel Fm., Vions Fm., Chambotte Fm., Vuache Fm., Grand Essert Fm., Gorges de lâOrbe Fm., Vallorbe Fm., Perte du RhĂŽne Fm., Narlay Fm. Dating of the formations is based on biostratigraphy (ammonites, echinids, dasycladalean algae, foraminifera, calpionellids, dinocysts, nannofossils). The fossils indicate Berriasian through to Coniacian ages. The lithostratigraphic units describe the general evolution from a shallow, peritidal platform to deeper-water shelf environments, then the installation of a carbonate platform, and finally the drowning of this platform followed by the predominance of pelagic conditions. The common lateral and vertical changes in facies and sedimentation rates as well as numerous hiatuses within the formations testify to a complex interplay of tectonics, climate, and sea level that controlled the Swiss Jura realm during the Cretaceous
Barremian ammonite fauna from L'Estellon section (Baronnies, SE France): preli-minary biostratigraphic results
The study of the ammonite fauna in the L'Estellon section (DrÎme department, SE France) allows us to date episodes with gravitational deposition in this area of the "Vo-contian Trough". They span most of the Barremian Stage, from the Nicklesi Zone up to the Giraudi Zone. We did not identify any Bedoulian redeposits, the "Bedoulian ridge" auct. being latest Barremian in age.L'étude de l'ammonitofaune de la coupe de L'Estellon (département de la DrÎme, France) permet de dater les épisodes de la sédimentation gravitaire dans ce secteur de la "Fosse vocontienne". Ils couvrent pratiquement l'ensemble du Barrémien, depuis la Zone à Nicklesi jusqu'à celle à Giraudi. Nous n'y avons pas caractérisé de resédimentation bédoulienne, la "barre bédoulienne" auct. Cor-respondant au Barrémien terminal
La Formation du Grand Essert (Jura franco-suisse; Valanginien supérieur p.p. à Hauterivien supérieur basal)
Le terme de Formation du Grand Essert a Ă©tĂ© proposĂ© en 2016 pour remplacer ceux de « Marnes dâHauterive » auct. et « Pierre jaune de NeuchĂątel » auct. attribuĂ©s Ă lâ« Hauterivien » auct. dans le Jura franco-suisse. Lâobjet de cette note est, dans un premier temps, de dĂ©crire et dâinterprĂ©ter la lithologie de la coupe-type reprĂ©sentative de cette nouvelle formation, dâune Ă©paisseur de 112,5 m, relevĂ©e dans la localitĂ©-type du Grand Essert le long de la route D991, entre Confort et ChĂ©sery, sur la rive gauche de la vallĂ©e de la Valserine (Jura mĂ©ridional, Ain, France). La Formation du Grand Essert comprend, Ă la base, le Membre dâHauterive composĂ© de 52 m de marnes dans lesquelles apparaissent des bancs et des nodules calcaires contenant souvent des grains de quartz et de glauconie. Les faciĂšs indiquent un milieu calme en dessous de la limite de lâaction des vagues de beau temps, avec lâapport pĂ©riodique de matĂ©riel bioclastique allochtone. Au-dessus, le Membre de NeuchĂątel dâune Ă©paisseur de 60,5 m se compose de calcaires bioclastiques localement quartzo-glauconieux. Au sein de ce membre sâintercale un horizon marneux dâorigine marine, les Marnes des Uttins. Les bancs calcaires montrent des structures sĂ©dimentaires entrecroisĂ©es qui suggĂšrent la prĂ©sence de courants tidaux. Dans un deuxiĂšme temps, les auteurs proposent des corrĂ©lations basĂ©es sur la biostratigraphie (ammonites et dinokystes) et lâanalyse sĂ©quentielle, entre la coupe-type et dâautres coupes et forages publiĂ©s dans le Jura franco-suisse. La corrĂ©lation avec une coupe du Bassin vocontien (Haut Vergons) permet de discuter jusquâĂ quel point lâenregistrement sĂ©dimentaire de la Formation du Grand Essert Ă©tait contrĂŽlĂ© par des fluctuations du niveau marin. Finalement, les ammonites et dinokystes permettent de bien dater la Formation du Grand Essert qui sâĂ©tend du Valanginien supĂ©rieur pro parte jusquâĂ la base de lâHauterivien supĂ©rieur. Le Membre dâHauterive commence dans la zone Ă Peregrinus. Lâintervalle Peregrinus-Furcillata est partout fortement condensĂ© (comme la partie sommitale de la Formation du Vuache sous-jacente dans le Jura neuchĂątelois) tandis que les sĂ©diments de la zone Ă Radiatus sont bien reprĂ©sentĂ©s. La limite entre le Membre dâHauterive et le Membre de NeuchĂątel se situe dans la zone Ă Loryi. Le Membre de NeuchĂątel occupe la partie supĂ©rieure de la zone Ă Loryi et toute la zone Ă Nodosoplicatum. La limite Nodosoplicatum / Sayni se trouve au sein de la partie sommitale du Membre de NeuchĂątel. La base de la Formation des Gorges de lâOrbe sus-jacente est datĂ©e de la zone Ă Sayni
L'Estellon (Baronnies, France), une "Pierre de Rosette" pour la biostratigraphie de l'Urgonien
Des associations d'organismes habituellement caractéristiques de faibles tranches d'eau
(des orbitolinidés et des algues, en particulier) ont été identifiées dans des faciÚs relativement profonds
de la "fosse vocontienne" (SE de la France), oĂč ces Ă©lĂ©ments ont Ă©tĂ© transportĂ©s gravitairement et
précocement resédimentés. Dans un tel contexte paléoenvironnemental, ces associations benthiques
peuvent ĂȘtre directement calibrĂ©es sur les zones d'ammonites. D'aprĂšs ces nouvelles observations,
entre autres résultats, la premiÚre apparition de Palorbitolina lenticularis ainsi que celles de quatre
représentants du genre Orbitolinopsis, soi-disant typiques de l'Aptien inférieur, sont datées du Barrémien
inférieur. De fait la plupart des espÚces d'orbitolinidés connues dans le Barrémien supérieur sont
déjà présentes au Barrémien inférieur à L'Estellon. Concernant les plates-formes urgoniennes, les schémas
de corrélations couramment utilisés, qui s'appuient sur des distributions biaisées (tronquées) d'orbitolinidés
-- et par conséquent les conclusions et hypothÚses qui en sont dérivées --, nécessitent au
moins des révisions en profondeur, sinon un rejet définitif.Shallow-water assemblages of transported ("freshly reworked") bioclasts (mainly orbitolinids
and dasycladales) are observed in the deeper facies of the "Vocontian Trough" (SE France). There
these benthic assemblages can be directly correlated with ammonite zones. These new finds give an
Early Barremian age to the earliest record of Palorbitolina lenticularis as well as those of four so-called
"typical Early Aptian" representatives of the genus Orbitolinopsis. Actually most orbitolinid species recorded
from the Late Barremian interval are now found present in Lower Barremian strata at L'Estellon.
Some currently used correlation schemes for the Urgonian platforms, that are based on partial stratigraphic
distribution ranges for the orbitolinids, --and consequently derived conclusions and hypotheses-
- require at least in-depth revisions when they are not definitively refuted.The study of the ammonite
fauna in the L'Estellon section (DrĂŽme department, SE France) allows us to date episodes with gravitational
deposition in this area of the "Vocontian Trough". They span most of the Barremian Stage,
from the Nicklesi Zone up to the Giraudi Zone. We did not identify any Bedoulian redeposits, the
"Bedoulian ridge" auct. being latest Barremian in age
Proteomic Analysis of S-Acylated Proteins in Human B Cells Reveals Palmitoylation of the Immune Regulators CD20 and CD23
S-palmitoylation is a reversible post-translational modification important for controlling the membrane targeting and function of numerous membrane proteins with diverse roles in signalling, scaffolding, and trafficking. We sought to identify novel palmitoylated proteins in B lymphocytes using acyl-biotin exchange chemistry, coupled with differential analysis by liquid-chromatography tandem mass spectrometry. In total, we identified 57 novel palmitoylated protein candidates from human EBV-transformed lymphoid cells. Two of them, namely CD20 and CD23 (low affinity immunoglobulin epsilon Fc receptor), are immune regulators that are effective/potential therapeutic targets for haematological malignancies, autoimmune diseases and allergic disorders. Palmitoylation of CD20 and CD23 was confirmed by heterologous expression of alanine mutants coupled with bioorthogonal metabolic labeling. This study demonstrates a new subset of palmitoylated proteins in B cells, illustrating the ubiquitous role of protein palmitoylation in immune regulation
De novo TBR1 variants cause a neurocognitive phenotype with ID and autistic traits:report of 25 new individuals and review of the literature
TBR1, a T-box transcription factor expressed in the cerebral cortex, regulates the expression of several candidate genes for autism spectrum disorders (ASD). Although TBR1 has been reported as a high-confidence risk gene for ASD and intellectual disability (ID) in functional and clinical reports since 2011, TBR1 has only recently been recorded as a human disease gene in the OMIM database. Currently, the neurodevelopmental disorders and structural brain anomalies associated with TBR1 variants are not well characterized. Through international data sharing, we collected data from 25 unreported individuals and compared them with data from the literature. We evaluated structural brain anomalies in seven individuals by analysis of MRI images, and compared these with anomalies observed in TBR1 mutant mice. The phenotype included ID in all individuals, associated to autistic traits in 76% of them. No recognizable facial phenotype could be identified. MRI analysis revealed a reduction of the anterior commissure and suggested new features including dysplastic hippocampus and subtle neocortical dysgenesis. This report supports the role of TBR1 in ID associated with autistic traits and suggests new structural brain malformations in humans. We hope this work will help geneticists to interpret TBR1 variants and diagnose ASD probands
Recherches stratigraphiques dans l'Est du Massif des Bornes (Haute-Savoie)
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