Neogene stratigraphic architecture anddynamic evolution of the great Bahamasbank slope : role of resedimented carbonatedeposits and bottom currents

• Main Authors: Principaud, Mélanie, Ponte, Jean-Pierre, Mulder, Thierry, Robin, Cecile, Gillet, Hervé, Borgomano, Jean
• Other Authors: Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2014
• Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; The Toe; North Atlantic
• Online Access: https://insu.hal.science/insu-01080748

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.