THE HOLOCENE SEDIMENTATION ON THE GULF OF LIONS MARGIN - A QUANTITATIVE APPROACH

The volume of Holocene sediments deposited on the various physiographic zones of the margin is evaluated on the basis of structure, thickness, extension and nature of the deposits. These data are derived from high resolution seismic profiles and core analyses. Seventy percent of sediments are estimated to have been trapped on the shelf, with 30% on the slope and basin during the last high sea-level rise. These values take into account the Holocene progressive immersion of the shelf. They are compared to data on present-day sedimentation, at a stable high stand of sea level. Moreover, the study of recent sedimentation provides information on particle transfer processes which can be integrated into a deposition "model" for high sea-level stages. Starting from this model, it will be possible to reconstitute the Quaternary evolution of the Gulf of Lions margin, by using residual deposition marks left during the other stages of the glacioeustatic cycle and computing the successive cycles.