SEQUENCE-STRATIGRAPHIC INTERPRETATION OF UPPER TITHONIAN-BERRIASIAN REFERENCE SECTIONS IN SOUTH-EAST FRANCE - A MULTIDISCIPLINARY APPROACH

Field observations (stacking pattern of carbonate and marlstone beds) and facies analysis allow the sequences-stratigraphic interpretation of three Upper Tithonian-Berriasian reference sections of the Vocontian trough (SE France): Broyon, Berrias (stratotype) and Angles. A succession of ten third-order depositional sequences (sensu VAIL) is defined: three in the Upper Tithonian (Ti 4 to Ti 6) and seven in the Berriasian (Be 1 to Be 7). The Upper Tithonian and basal Berriasian sequence consist mainly of stacked lowstand systems tracts which are essentially composed of slope fans and of biograding wedges Berriasian sequences show more complete successions including Lowstand. Trangressive and Highstand systems tracts. These third-order sequences are precisely calibrated by biostratigraphy, principally by the Calpionellid and Ammonite reference scales. At Berrias, they are also integrated into the paleomagnetic data. Samples have been selected by specialists in diverse disciplines such as geochemistry, clay mineralogy, palynofacies, and by biostratigraphers (palynology and calcareous nannoplankton) with two main objectives: to test the abilities and limitations of each of these specialities in sequence-stratigraphic interpretation by integrating their results into the pre-established sequence-stratigraphic framework For each discipline trends characterizing each of the systems tracts (mass-flow, lowstand wedge, transgressive, highstand) are observed and discussed: to improve the biostratigraphic resolution of the interval by adding Dinoflagellate and calcareous nanofossil zonations. These results are discussed in each of the specialist papers published in this volume (STROHMENGER & SIHASSER, DECONINCK, EMMANUEL & RENARD, STOIFEN & GOHIN, MONTEIL, GARDIN & MANIYIT). Some differences appear between the pre-established sequence-stratigraphic interpretation and the models proposed by some specialities (geochemistry and Dinoflagellates), essentially in the Upper Berriasian (EMMANUEL & RENARD, MONTEIL). New correlations and subdivisions are proposed by these authors. They still have to be checked by additional analysis in the outcrops studied and in other field or subsurface sections A synthesis of the most important results is submitted in this paper; it is co-signed by all the working group members.