| Summary: | International audience Sediment instabilities commonly occur on carbonate slopes and constitutethe major processes involved in their geometry and presentdaymorphology. The Bahamian archipelago represents an outstandingexample of re-sedimented carbonate margin which enables to preciselybuil-up a detailed stratigraphic and geometric architecture. Coreand logging data from ODP Leg 166 and newly acquired 2D High-Resolution multichannel seismic reflection from the first Leg of the CARAMBARCruise allowed a re-evaluation of the Neogene seismic stratigraphyand architecture of the windward slope of the western GreatBahama Bank (GBB).The slope-to-basin Neogene deposits are controlled by two types of sedimentation: (1) the downslope gravity-driven carbonate deposits progradingwestward and (2) bottom currents deposits progressively migratingnorthward along the margin. These two sedimentary systems are simultaneouslyactive during Pliocene and interfinger at the toe-of-slopewhilst the slope sedimentation, typified by turbidite aprons and slumps,prevails during the Miocene and the Pleistocene.This work is centered on high-resolution seismic data and the refinementof carbonate depositional sequences. The seismic observations allowto highlight a broad variety of facies for each sequence which rangefrom gravity-flow slope carbonates, pelagic ooze to contourite deposits.Seismic facies display rapid lateral along strike and downdip transitionsranging between 1 and 10 km. The depositional cycles are interpretedas resulting from the global sea-level variations whilst the drift currentscome from a geodynamic re-organisation affecting the Central AmericanSeaway. Indeed, the Panama Isthmus occuring during the Neogenewhich significantly modified the north Atlantic thermohaline circulationand amplified the Florida Current intensity and pathway.
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