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1.
Abdelkader Ouali Mehadji Serge Elmi Patrick Rachebœuf Larbi Mekahli 《Comptes Rendus Geoscience》2004,336(14):1283-1292
In the Saoura, the brachiopod shell beds, so-called niveau coralligène, correspond to a major shell deposit dated to the Late Emsian. Brachiopods and crinoids dominate the benthic assemblage that contains also corals, bryozoans, trilobites, goniatites, and orthocones. This major level has a large geographic distribution and it is characterized by a wide brachiopod diversity due to time-averaging, taphonomic feedback and alternate bottom conditions changing from soft to shelly and firm. This kind of brachiopod association is linked to a transgressive onlap system. At regional extent, we can correlate this major shell bed to similar shell deposits from the Ahnet-Mouydir, Tindouf, and Zemmour areas. It indicates an important transgressive event underlined by change in the sedimentation from detritic deposits to carbonate sediments. To cite this article: A. Ouali Mehadji et al., C. R. Geoscience 336 (2004). 相似文献
2.
The survey of sedimentological and lithostratigraphic Liassic facies of the Todrha–Dades area (southwestern part of the central High Atlas) permits to establish new data on the Tagoudite formation. Its environment deposit and its micropalaeontological content are evidenced in relation with the geodynamic evolution of the High Atlas Basin during the Early Toarcian. To cite this article: M. Ettaki, E.H. Chellaï, C. R. Geoscience 337 (2005). 相似文献
3.
Three microbialite forms are recognized in the Lower-Cambrian succession of Irherm area in the western Anti-Atlas (Morocco). Stromatolites, which correspond to non-calcified shallow marine laminated microbialites, are well developed in the basal Lower-Cambrian succession. Occurrence of calcified microbial thrombolites, in the middle part of this succession, reflects an increasing sea level from the peritidal zone to the subtidal environment. In the upper part of this succession, a second increasing water depth event and the development of branching archaeocyathan reefal framework lead to dendritic microbialite emergence. To cite this article: M. Benssaou, N. Hamoumi, C. R. Geoscience 336 (2004). 相似文献
4.
Joseph Canérot Jacques Bauer Michel Bilotte Chantal Bourdillon Jean-Paul Colin Elie-Jean Debroas Françoise Magniez Francis Mediavilla Yves Ternet 《Comptes Rendus Geoscience》2004,336(10):951-958
By us considered as Albo-Aptian in age and generated through halokinetic processes, the Bosmendiette breccias have been recently interpreted as Selandian (Palaeocene) globigerine-bearing sediments deposited in sub-marine canyons within a deep trough crossing the Pyrenees, from the Mediterranean Sea to the Atlantic Ocean. These breccias are really azoic in their lower part and contain a scarce microfauna including radolarians and benthic foraminifera at the top of the formation. They are unconformably covered by the Urgo-Aptian limestones and marls and indicate, under opening marine conditions, Lower Cretaceous collapse movements and northward sliding of the Jurassic slumped cover, related to the growth of the Béloscare–Apoura diapir. To cite this article: J. Canérot et al., C. R. Geoscience 336 (2004). 相似文献
5.
The current structure of the central Tunisian Atlas fossilizes the different tectonic events that have succeeded and that have structured this region. The Lower Cretaceous of this sector reflects, through variations of thickness and facies, the importance of the tectonic activity during this period. The tectonic study detailed in this sector has revealed the existence of structures from the kilometric scale down to the metric one related to a compressive regime that has dominated the studied zone at least from the Upper Hauterivian until the Lower Aptian. 相似文献
6.
Jean-Marie Dautria Delphine Bosch Jean-Michel Liotard 《Comptes Rendus Geoscience》2006,338(8):527-536
Lherzolite xenoliths with calcite-rich microgranular secondary aggregates (0.1–1 mm) have been sampled in a Messinian breccia pipe from the northeastern part of the Languedoc volcanic province (South France). Their study shows that the carbonate crystallized at low pressure from a silico-carbonated melt resulting from partial melting of diopside and spinel at depth. This melting has been induced by injection, shortly before the eruption, of CO2 and H2O-rich fluids, stored probably within the upper lithospheric mantle and reset in motion by the magma ascension. These fluids would derive from decarbonation of levels of deeper lithospheric mantle previously metasomatized by carbonatitic melts. To cite this article: J.-M. Dautria et al., C. R. Geoscience 338 (2006). 相似文献
7.
Jean-François Becq-Giraudon 《Geodinamica Acta》2013,26(4):219-224
RésuménLa coexistence de flores à cachet autunien et de flores à cachet Stéphanien dans une même formation et dans plusieurs bassins limniques du Paléozoïque supérieur du Massif central est attribuée.à des variations de paléoenvironnement : les flores “autuniennes” sont des flores méso- à xérophiles poussant sur les reliefs bordiers des bassins ou dans les zones hautes de ces derniers, alors que les flores “stéphaniennes” sont des flores hygrophiles des plaines d’inondation des zones basses. Le changement climatique qui marque le passage du Carbonifère au Per-mien, et qui se traduit par une certaine aridification, amène une évolution radicale de la composition des flores, les ensembles floristiques méso- et xérophiles devenant prédominants. Ceci démontre l’importance des conditions paléoécologiques sur la répartition et la succession des flores permocarbonifères. Il découle de tout ceci que la stratigraphie du Paléozoïque supérieur du Massif central, basée sur les successions de flores, n’est pas en mesure de fournir un cadre chronologique précis aux événements structuraux de l’époque. 相似文献
8.
François Baudin Nicolas Fiet Rodolfo Coccioni Simone Galeotti 《Cretaceous Research》1998,19(6):701-714
The Selli Level is a marker-bed in the Umbria-Marche Apennines that represents the regional sedimentary expression of the Lower Aptain Oceanic Anoxic Event 1a. This one to three-metre-thick interval shows a remarkable uniformity on a regional scale, with a green to grey marly lower part overlain by black shales. Bulk geochemical studies and an examination of palynofacies were carried out on three sections in order to characterise the distribution and nature of the organic matter in the Selli Level which has been poorly known hitherto. The organic content is medium (0.5 to 2.9% TOC) in the basal part and higher (4.5% on average, and up to 18% TOC) in the black shales. Pyrolysis and palynological data indicate that the organic matter is mainly of marine origin. The geochemical characteristics of the Selli Level are compared to other, more or less organic-rich marker-beds in the Cretaceous succession of the Umbria-Marche Apennines.
Abstract
Le Niveau Selli est un niveau-repère des Apennins d'Ombrie-Marches qui correspond à l'enregistrement régional de l'événement anoxique océanique 1a. Ce niveau, épais de un à trois mètres, présente une remarquable uniformité à l'échelle régionale avec une partie inférieure argileuse, verdâtre à grise, surmontée par des black shales. Des analyses géochimiques et l'examen des palynofacies ont été entreprises sur trois coupes afin de caractériser le contenu en matière organique du niveau Selli, jusqu'à présent mal connu. Les teneurs en carbone organique sont moyennes (0,5 à 2,9% COT) dans la partie basale et élevées (4,5% en moyenne et jusque 18% COT) dans les black shales. Les résultats de pyrolyse et des observations palynologiques indiquent que la matière organique est essentiellement d'origine marine. Les caractéristiques géochimiques du niveau Selli sont comparées aux autres niveaux repères, plus ou moins riches en carbone organique, qui émaillent la série du Crétacé du basin d'Ombrie-Marches. 相似文献9.
Stéphane Bodin Jean Vermeulen Alexis Godet Karl B. Föllmi 《Comptes Rendus Geoscience》2006,338(10):727-733
The Chopf Member is a glauconitic, phosphate-bearing succession that occurs in the distal part of the Helvetic Alps (eastern Switzerland). The recent discovery of age-diagnostic ammonites within this horizon allows for its attribution to the lower part of the Gerhardtia sartousiana zone (middle Late Barremian). This new age corresponds to a maximal age for the onset of the Schrattenkalk Fm. in this area, and is coeval with the onset of the Urgonian facies in other parts of the western Tethyan realm. This new age allows also for a more precise dating of Late Barremian curves. To cite this article: S. Bodin et al., C. R. Geoscience 338 (2006). 相似文献
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