New data from the J/K boundary time interval (Clue de Taulanne section, SE France): implications for western Tethys palaeoclimatic and paleoceanographic scenarios

In the western Tethyan realm, the Jurassic/Cretaceous (J/K) boundary interval is marked by considerable palaeoclimatic and paleoceanocgraphic changes. It is also characterized by a calcareous nannofossil speciation event and by the first occurrence of calpionellids. The Clue de Taulanne section (SE France) exposes Upper Jurassic to Lower Cretaceous carbonate rocks that were deposited in a deep shelf setting on the north-western margin of the Alpine Tethys. A multidisciplinary approach, comprising lithostratigraphy, carbonate sedimentology, sequence stratigraphy, biostratigraphy (ammonites, calpionellids, nannofossils and pelagic microfossils), clay mineral analysis, magnetic susceptibility, and carbon-isotope stratigraphy is presented. The studied rocks cover a time interval from the Late Kimmerigian to the Late Berriasian. Preliminary clay-mineral and magnetic susceptibility data support a postulated dry phase during the Tithonian and a return to more humid conditions during the Berriasian (Rameil, 2005; Schnyder, 2003). Carbon-isotope analysis reveals a negative stratigraphic trend that correlates well with established curves. On the basis of a robust bio- and chemostratigraphy, correlations with various sections in platform and basinal settings on the northern and southern margins of the western Tethys (Rameil, 2005; Schnyder, 2003) are proposed. Within this stratigraphic framework changes in palaeoclimate, palaeoceanography, sedimentation patterns, plankton radiation and calcification events, and their potential interconnections are discussed.