--> Abstract: Deep-Water Coral Mound Growth and Burial from the Lower Slope of Great Bahama Bank, by Thiago B. Correa, Gregor P. Eberli, Mark Grasmueck, and John K. Reed; #90078 (2008)

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Deep-Water Coral Mound Growth and Burial from the Lower Slope of Great Bahama Bank

Thiago B. Correa1, Gregor P. Eberli1, Mark Grasmueck1, and John K. Reed2
1Comparative Sedimentology Laboratory, University of Miami - RSMAS, Miami, FL
2Harbor Branch Oceanographic Institution, Fort Pierce, FL

High-resolution multibeam bathymetry maps that were acquired with an Autonomous Underwater Vehicle across five deep-water coral mound fields in the Straits of Florida reveal an unexpected abundance and variability of mound structures. Simultaneously acquired sub-bottom profiles reveal additional mounds that are buried by Holocene sediment.

At the channelized toe-of-slope of western Great Bahama Bank, mounds preferentially align on the highs that run perpendicular to the platform margin. Currents are dominated by diurnal tides with a predominant north-south direction. Sub-bottom profiles depict mounds in the channels that are buried by sediment. In another area of the toe-of-slope, two slump scars of approximately 100 m high form a 3km long submarine plateau. The plateau is covered with 25m-high deep-water coral mounds, and a mound field is situated basinward of the slump. In both areas, sub-bottom profiles reveal numerous buried mounds. In contrast, no buried mounds are visible under a mound field on the lower slope of the Miami Terrace. Here the antecedent topography is undulating in some places and flat in others but the modern deep-water coral mounds do not follow this antecedent topography.

The onlapping sediment is mostly Holocene, while the underlying topography is probably Pleistocene. Thus, we postulate that during times of low sedimentation rates, deep-water corals colonize much of the lower slopes. Low sedimentation occurs during times when the platform is exposed (i.e. sea level lowstands). The recent burial of some of the mounds is attributed to higher sedimentation rates after the bank top is re-flooded and offbank transported sediment reaches the lower slope and basin.

 

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas