Dominique Fortwengler

Contrôle géodynamique de la sédimentation argileuse du Callovien-Oxfordien moyen dans l'Est du bassin de Paris: influence eustatique et volcanique

The Middle Callovian to Middle Oxfordian clay deposits drilled in the eastern Paris Basin (borehole HTM 102, ANDRA) show a strong mineralogical change occurring in the lowermost Oxfordian (Scarburgense subzone, Mariae zone). Such a change probably results from the initial development of connections between the young Atlantic Ocean and the Paris Basin. A bentonitic layer identified close to the boundary between Lower and Middle Oxfordian and also recognized in the subalpine Basin (South-East of France) at the same age, reflects a volcanic activity probably resulting from an extensional regime located in the North Sea.

Integrated Stratigraphy of the Potential Candidate Oxfordian GSSP at Thuoux and Saint-Pierre d’Argençon (France)

The Thuoux and Saint-Pierre d’Argencon sections (Subalpine Basin, southeastern France) are proposed as a potential GSSP candidate for the Callovian–Oxfordian boundary. Several aspects of stratigraphy that have recently been applied in the two selected sections are discussed, including ammonite and nannofossil biostratigraphy, palynology, physical stratigraphy, and cyclostratigraphy.

Thuoux and Saint-Pierre d’Argençon Sections (Subalpine Basin, Southeastern France): Case Studies of Ammonite Biostratigraphy for the Potential Candidate Callovian–Oxfordian GSSP

The Thuoux and Saint-Pierre d’Argencon sections (Subalpine Basin, southeastern France) display a thick silty–clayey sedimentation with abundant and diversified ammonite faunas, free of detectable hiatuses. The Callovian–Oxfordian boundary is biostratigraphically located between the Lamberti and the Mariae zones or, more precisely, between the Lamberti Subzone (paucicostatum horizon) and the Scarburgense Subzone (thuouxensis horizon). The mixing of Boreal–Sub-Boreal Cardioceratinae and Sub-Mediterranean–Tethyan Hecticoceratinae, Peltoceratinae, and Perisphinctinae in this basin allows reliable worldwide correlations that enhance the choice of the Thuoux and Saint-Pierre d’Argencon sections as a Callovian–Oxfordian GSSP candidate.

Carbon and oxygen isotope signals from the Callovian-Oxfordian in French sedimentary basins.

High-resolution carbon and oxygen isotope data from the Paris Basin and the Subalpine Basin (France) are available in a precise biostratigraphic framework for the Callovian–Oxfordian stages. A biostratigraphically well-constrained δ13C curve, derived from bulk carbonates in the Paris Basin and the Subalpine Basin, is provided in order to document carbon-cycle evolution and to serve as a chemostratigraphic reference for the Callovian–Oxfordian in the Tethyan domain. Sea-temperature reconstructions, using diagenetically screened belemnite and oyster data, reveal major climate perturbations at the Middle–Late Jurassic transition.