HR: 08:15h
AN: OS11D-02    [Abstracts]
TI: Paleosealevels and strata formation in the Gulf of Lion during the Plioquaternary : from field evidence to stratigraphic numerical modeling : what has been done, what will be done.
AU: * Rabineau, M
EM: mrabinea@univ-brest.fr
AF: CNRS, UMR6538 Domaines oceaniques, 1 place N. Copernic, Plouzane, 29280 France
AB: Observation and analysis of sedimentary strata, identification of sequences within the series enable the reconstruction of paleoenvironments and paleogeographies that describe the spatio-temporal evolution of sediment deposition. Eustasy, tectonic and sediment flux are the three main factors that control variations in accommodation and therefore geometries of sequences. However deciphering between the factors is not an easy task and stratigraphic simulation can be a tool to test different geological scenario and try reproduce numerically the observed geometries in a sedimentary basin. The Gulf of Lion is particularly well suited to undertake such an approach with field observation and numerical modelling. In particular, the Gulf of Lion offers a perfect natural laboratory for sea level calibration of glacial maxima for Plioquaternary climatic cycles because : (a) the Mediterranean Sea has been connected to the global ocean throughout Plio-Quaternary time, so that sea level variations are directly linked to Arctic and Antarctic ice caps fluctuations. (b) The Gulf of Lions is a young margin with subsidence still underway at present that continually creates a large amount of accommodation to be filled by sediments. (c) During the Last Glacial Maximum, mountain glaciers covered a large part of the Alps, and smaller parts of the Pyrenees and the Massif Central. However, neither the drainage basins nor the shelf were covered by ice. Moreover, the Gulf of Lions is situated sufficiently far from former ice sheets for significant glacio-isostasy of the margin to be excluded. (d) The presence of mountain glaciers led to important erosion and scouring providing an important source of sediments to be deposited in the Gulf of Lions. This approach applied for the late Quaternary already showed that the last five sequences recorded on the outer shelf were related to 100,000 years climatic cycles (MIS12 to MIS2). Preliminary results from the recent and successful PROMESS project (see the presentation by S. Berne) confirmed this general chronotratigraphic framework. Further work (G. Jouet) will enable to go a step further for the last 430, 000 years of sedimentation as the detailed chronostratigraphic framework, sedimentation rates, lithologies. will be measured and used as an input parameter in the 3D numerical simulation. On a broader time scale (Plioquaternary), both backstripping of sequences (see the presentation by Steckler) and numerical stratigraphic simulation are planned. This study is part of the national French GDR Marges ("Golfe du Lion") project, the european PROMESS project (S. Berne) and the US-Eurostrataform project (C. Nittrouer/ P. Weaver) which has been and will be a cooperation among CNRS Brest, IFREMER, IFP (Dionisos), INSTAAR (Sedflux), Lamont (Sequence), Minessota University and Utrecht. Participants in alphabetical order : Aslanian, Baztan, Berne, Granjeon, Gorini, Graindorge, Hutton, Jouet, Joseph, Kettner, Olivet, Overeem, Rabineau, Steckler, Storms, Swenson, Syvitsky.
DE: 4211 Benthic boundary layers
DE: 4267 Paleoceanography
DE: 3000 MARINE GEOLOGY AND GEOPHYSICS
DE: 1719 Hydrology
DE: 1724 Ocean sciences
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting