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Sedimentary Dynamics and High-Frequency Sequence Stratigraphy on the Slope of Great Bahama Bank


The interplay of depositional and erosional processes and their evolution in time are unraveled by the correlation of new high-resolution hydroacoustic data with sediment- and isotope data from ODP Leg 166 cores on the slope of Great Bahama Bank, providing new insights into sedimentation patterns of carbonate platform slopes through time. In result, a high-frequency sequence stratigraphic scheme encompassing the Marine Isotope Stages (MIS) 1 to 11 (the last 400 ka) is presented. High-frequency sequences consist of sea level highstand sediments bound by well-lithified lowstand intervals. The sequences display, however, considerable variations in morphology along strike and through time. In the northern part, all sequences contain mass transport complexes and channels accompanied by a lateral variable sediment thickness. In the southern part, by contrast, sediment thickness along the slope is controlled by off-bank transport and bottom currents. Large mass transport complexes leveled the slope morphology during MIS 11 to 9, whereas younger sequences (MIS 7 to 1) show a uniform along-strike thickness of the sequences without evidence of large gravity mass movements. A geological model was developed, based on the sedimentological data of two ODP cores and the hydroacoustic reflection patterns. This model evaluates how the changes in slope morphology influence the lateral facies distribution. Sequences of MIS 11 to 9 show a downslope and along strike facies variability, whereas younger sequences (MIS 7 to 1) are characterized by downslope variations only. The encountered changes in slope morphology and sediment distribution along the slope of Great Bahama Bank provide implications on established slope models and allow improved prediction of sediment heterogeneities in such sedimentary successions.