--> ABSTRACT: Seismic Sedimentologic Interpretation of a Carbonate Slope, North Margin of Little Bahama Bank, by Gill M. Harwood and Philip A. Towers; #91030 (2010)

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Seismic Sedimentologic Interpretation of a Carbonate Slope, North Margin of Little Bahama Bank

Gill M. Harwood, Philip A. Towers

Analysis of seismic profiles plus core descriptions of sediments from ODP Leg 101 have been combined to investigate the evolution of the northern margin of Little Bahama Bank, which has been prograding northward since the early Miocene. Modern depositional systems on the mid-slope and lower slope are found not to be characteristic of interpreted ancient sedimentary environments. Large slump masses covered much of the lower slope during the middle Miocene, possibly triggered by a regional tectonic event. Through the late Miocene and most of the Pliocene, a channel and levee system meandered across the sediment apron of the lower slope. The modern lower slope contains no meandering channels, although gullies incised in the mid-slope funnel sediments to the base of the slope apron, actively promoting sediment bypass on an accretionary margin. These changes in sedimentation pattern on the lower slope indicate increasing strength of ocean-bottom contour-following currents from the Pliocene. Pliocene to Holocene gravitational creep has produced large-scale rotational movement of unlithified sediments, with a major detachment surface along the base of the middle Miocene slump masses. These creep lobes extend far into the lower slope, where sediments are contorted by the propagation of, and movement along, multiple minor detachment surfaces.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.