Les forages de Juzanvigny (Aube, France): lithobiostratigraphie des formations du Barrémien à l'Albien moyen dans l'est du bassin de Paris et datations par les ammonites

RESUME Dans le departement de l'Aube, region stratotypique de l'etage Albien, plusieurs forages realises en 2013 ont traverse la plus grande partie des Argiles tegulines de Courcelles ou « Gault » auct. (Albien inferieur et moyen), les Sables verts de l'Aube (Aptien superieur), les Argiles a Plicatules (Aptien inferieur), les Sables et argiles bariolees (Barremien superieur) et la partie superieure des Argiles ostreennes (Barremien inferieur). Une description lithologique detaillee de la succession est realisee dans le but d'ameliorer la connaissance du Cretace inferieur de la bordure orientale du bassin de Paris dont les affleurements sont peu nombreux et discontinus. En ce qui concerne l'…

Lower Cretaceous formations (Berriasian/Valanginian to Albian) from the East of the Paris Basin: lithostratigraphy and depositional environments.

The Paris Basin is a Meso-Cenozoic intracontinental basin characterised during the Early Cretaceous by a continental evolution. However, in its southeastern part, due to transgres­sions originating from the Tethys, the Lower Cretaceous conti­nental deposits were occasionally interrupted by the deposition of marine sediments. In this area, the sedimentary succession includes above the Lower Tithonian “Calcaires du Barrois”, the transgressive “Sables de Soulaines” Formation on the Late Jurassic emersion surface. This formation showing facies characteristic of a tidal flat is reputed to be Valanginian in age, but there is no dating element and could as well begin in the Late Berriasian. Above,…

Evolution climatique au Jurassique inférieur (Sinémurien supérieur) de la zone Nord-Ouest européenne, déduit de la minéralogie des argiles et des isotopes du carbone

International audience

Impact of basin burial and exhumation on Jurassic carbonates diagenesis on both sides of a thick clay barrier (Paris Basin, NE France).

27 pages; International audience; Several diagenetic models have been proposed for Middle and Upper Jurassic carbonates of the eastern Paris Basin. The paragenetic sequences are compared in both aquifers to propose a diagenetic model for the Middle and Late Jurassic deposits as a whole. Petrographic (optical and cathodoluminescence microscopy), structural (fracture orientations) and geochemical (δ18O, δ13C, REE) studies were conducted to characterize diagenetic cements, with a focus on blocky calcite cements, and their connection with fracturation events. Four generations of blocky calcite (Cal1-Cal4) are identified. Cal1 and Cal2 are widespread in the dominantly grain-supported facies of t…

Environmental and climatic controls of the clay mineralogy of Albian deposits in the Paris and Vocontian basins (France)

18 pages; International audience; High-resolution clay mineral analyses were performed on lower and middle Albian deposits from the Paris and Vocontian basins in order to specify the weathering conditions that prevailed at that time. The clay mineral assemblages are composed of small proportions of chlorite and vermiculitic clays associated with abundant illite, R0 type illite-smectite mixed-layers (smectite) and kaolinite. Clay minerals originated from the physical alteration and chemical weathering of rocks and soils outcropping on the Variscan massifs bordering the studied areas. In the Paris Basin, the covariation of illite and kaolinite suggests the reworking of these latter minerals f…

First record of early Aptian Oceanic Anoxic Event 1a from the Paris Basin (France) - Climate signals on a terrigenous shelf

Abstract In 2013, Andra (French National Radioactive Waste Management Agency) drilled boreholes to the south-east of the Paris Basin, to characterise Aptian and Albian clayey formations, including the ‘Argiles a Plicatules’ Formation dated as early Aptian. One of these boreholes intersected this formation with an excellent recovery allowing detailed biostratigraphy (ammonites), sedimentology, clay mineralogy, isotope geochemistry (δ13Corg) and Rock-Eval analyses to be performed. The base of the formation corresponds to transgressive dark-grey silty clays with iron oolites and plant debris indicating a coastal environment evolving up-section to upper offshore environments. Higher in the succ…

Characterization and origin of permeability-porosity heterogeneity in shallow-marine carbonates: from core scale to 3D reservoir dimension (Middle Jurassic, Paris Basin, France).

21 pages; International audience; Nuclear magnetic resonance (NMR), stable isotope geochemistry of micro-sampled cores, NMR well-logs and 3D modeling are used to investigate the carbonate permeability-porosity heterogeneity along 230 m-thick limestones of the Paris Basin. Despite the global low porosity and permeability of the limestones, two aquifers units with porosity greater than 15% were identified. These two aquifers are very different in terms of pore through radii and NMR signal. The first one (A1: Aquifer 1) is a 7 m-thick mudstone unit, dominated by extended microporosity with pore throat radii of 0.25 μm to 0.3 μm. The second one (A2: Aquifer 2) is a 15 m-thick oolitic grainstone…

Evolution climatique au Jurassique inférieur (Sinémuriensupérieur) de la zone Nord-Ouest européenne, déduit de laminéralogie des argiles et des isotopes du carbone

National audience; L’étude des minéraux argileux et des isotopes stables (carbone) du Sinémuriensupérieur du bassin de Cardigan Bay (forage de Mochras, Pays de Galles) et du bassinde Paris (forage de Montcornet, France) permet de mettre en évidence les conditionsenvironnementales et climatiques dominantes à cette période. Dans les deux bassins,situés à des paléolatitudes proches (30 à 35°N), les assemblages de minéraux argileuxcomprennent des chlorites, des illites, des interstratifiés illite-smectite (IS R1), dessmectites et des kaolinites dans des proportions variables. L'influence de la diagenèsed’enfouissement et de l'authigénèse étant négligeable dans les deux forages, lesminéraux argi…

Enregistrement du cycle du carbone à la transition Oxfordien inférieur-moyen dans l'est du Bassin de Paris

Lower Aptian climate and recording of the oceanic anoxic event 1a on the terrigenous shelf of the Paris Basin.

Emersion generalisee intra-maastrichtienne de la plate-forme de Gavrovo-Tripolitza (Grece); effets sur les populations de foraminiferes Rhapydionininae

Abstract The reliability of biostratigraphic correlations in neritic carbonate platforms is often questioned because the benthic fauna on which biozonation is based are particularly sensitive to environmental change. It is crucial to know whether a population change corresponds strictly to a facies change. Conversely, there arise the questions of determining how populations are renewed over time and how new species appear even if facies associations remain unchanged. This is the case with the Gavrovo-Tripolitza zone of Greece, an isolated shallow carbonate platform surrounded by two oceanic domains (Pindos-Olonos Zone and Ionian Zone). The absence or scarcity of faunas generally used in Upp…