Evolution tectonique méso-cénozoïque du bassin de Paris: contraintes stratigraphiques 3D

Abstract 3D stratigraphic geometries of the intracratonic Meso-Cenozoic Paris Basin were obtained by sequence stratigraphic correlations of around 1 100 wells (well-logs). The basin records the major tectonic events of the western part of the Eurasian Plate, i.e. opening and closure of the Tethys and opening of the Atlantic. From earlier Triassic to Late Jurassic, the Paris Basin was a broad subsiding area in an extensional framework, with a larger size than the present-day basin. During the Aalenian time, the subsidence pattern changes drastically (early stage of the central Atlantic opening). Further steps of the opening of the Ligurian Tethys (base Hettangian, late Pliensbachian;...) and…

Numerical evidence for thermohaline circulation reversals during the Maastrichtian

[1] The sensitivity of the Maastrichtian thermohaline circulation to the opening/closing of marine communications between the Arctic and North Pacific oceans is investigated through a set of numerical experiments using the model CLIMBER-2 (Earth Model of Intermediate Complexity). We show here that the opening or closing of an Arctic-Pacific marine gateway induces transitions between different equilibrium states of the thermohaline circulation. Sensitivity tests of the inferred modes of thermohaline circulation to atmospheric CO2 level changes have also been explored. An abrupt switch in deep convection from high northern to high southern latitudes, a change consistent with isotopic evidence…

Late Cretaceous changes in continental configuration: toward a better-ventilated ocean?

International audience; Oceanic anoxic events (OAEs) are large-scale events of oxygen depletion in the deep ocean that happened dur-ing pre-Cenozoic periods of extreme warmth. Last global OAE occurred at the Cenomanian-Turonian boundary(OAE2) prior to the Late Cretaceous long term cooling. Ever since, and despite the occurrence of warming events,Earth no more experienced such large-scale anoxic conditions. Here we explore the role of major continentalconfiguration changes occurring during the Late Cretaceous on oceanic circulation modes through numerical sim-ulations using a General Circulation Model (GCM), that we confront to existing neodymium isotope data ("Nd).Except from a continuous d…

Palynofacies and calcareous nannofossils in the Upper Kimmeridgian, southeastern Paris basin (France)

AbstractThe Upper Kimmeridgian Members “Calcaires blancs supérieurs” and the “Marnes à exogyres supérieures” of the southeastern Paris basin were investigated for their palynofacies and calcareous nannofossils. These members display alternating limestone-marl lithotypes and represent shallow marine palaeoenvironments. The lower carbonate member is interpreted as a proximal palaeoenvironment (palaeobathymetry = 5 to 10 m), where storm and swell deposits were prevalent and the salinity was occasionally weak. The relative richness of brown phytoclasts in this part is favoured by good preservation related to restricted conditions. These conditions would explain the dominance of the nannofoss…

Jurassic evolution of the Arabian carbonate platform edge in the central Oman Mountains

International audience; The Jurassic Sahtan Group exposed in northern Oman was deposited in shallow marine environments at the edge of the Arabian Platform facing the Neo-Tethys (Hamrat Duru Basin). The upper Sahtan Group is made up of a mixed siliciclastic-carbonate unit overlain by pure carbonate deposits, assigned to a Bathonian and Early Callovian age on the basis of brachiopods and foraminifers. These carbonate depositional systems were composed of outer oolitic shoals that underwent subaerial exposure, and a deeper, somewhat restricted, gently dipping shelf interior. Oolitic material was shed off the platform edge into the deep-sea depositional complex of the Guweyza Formation. The Sa…

The role and contribution of eustasy as a triggering force of the onset of Oceanic Anoxic Events: A case study of the early Aptian OAE1a in the Tethyan margin of Tunisia

<p>Oceanic Anoxic Events (OAEs) are short-lived global carbon cycle perturbations characterized by significant changes in the chemistry, temperature and circulation of the oceans of the world. The forcing mechanisms behind these events remain a subject of discussion, especially for the Jurassic and Cretaceous periods. Typically, these events are thought to be triggered by a contemporaneous emplacement of a large igneous province (LIP) associated with a significant release of CO<sub>2</sub> into the atmosphere and leading to rapid global warming. In turn, induced sharp climatic change promotes an acceleration of the hydrological cycle which intensifi…

Deep basin record evolution of chemical weathering and physical erosion as response to the tectonic uplift of the South African Plateau during the upper Cretaceous

<p>During the upper Cretaceous the South African Plateau underwent an uneven uplift period that coincided with the onset of a long-term climate cooling. This uplift recorded two pulses, an early pulse during the Turonian that affected the eastern margin and a later pulse occurred during the Campanian affecting the western margin (van der Beek et al., 2002; Braun et al., 2014; Baby et al., 2020). We aim here to determine the response of physical erosion and chemical weathering to this tectonic event, that may have played a role in the long-term climate cooling by promoting silicate weathering and associated atmospheric CO<sub>2</sub> drawdown. In thi…

Variation of relief, siliciclastic flux and stratigraphic architecture of sedimentary basins: a database for the African passive margins

Vertical movements of the Paris Basin (Triassic-Pleistocene): from 3D stratigraphic database to numerical models