Abstract: Late Jurassic Transgressive-Regressive Facies Cycle on the South European Tethyan Margin at the Start of the Thermal Subsidence

Dardeau Gerard, Yves Bodeur, Pierre Charles De Graciansky, Danielle Fauconnier, Dominique Fortwengler, Thierry Jacquin, Didier Marchand, Jacques Thierry, Peter R. Vail

The onset of the thermal subsidence of the south Western European margin of the Tethys is recorded by a second-order transgressive/regressive facies cycle ranging from middle Bathonian to middle Oxfordian. Lithologies in the deep marine setting of the Dauphine Basin are dominated by terrigenous black shales (Terres Noires). Abundant and well preserved ammonites provide dating at the horizon level. The onset of the transgression (Retrocostatum Z) coincides with three Bathonian and five Callovian third-order sequences. Detailed field mapping of the systems tracts shows the overall retrogradation of hemipelagic shales onto the adjacent platforms. The peak transgression is dated lowermost Oxfordian (Scarburgense Sz) and is surrounded by third-order sequences that are starved both in the b sin and on the platforms. The regressive part comprises seven early to middle Oxfordian third-order sequences. They record the overall progradation of calcareous mudstones onto the basinal shales. The maximum regression is dated late Oxfordian (Bimammatum Z) with emersion of most of the surrounding platforms. This is related to a regional tectonic event within the European craton. Several third-order sequences show a particularly big shaley lowstand, both during transgressive and regressive phases. These lowstands have been deposited on the hanging wall of synsedimentary extensional faults.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994