Evaluating Water-Depth Variation and Mapping Depositional Facies on Great Bahama Bank – a “Flat-Topped” Isolated Carbonate Platform
Paul M. (Mitch) Harris, Sam J. Purkis, James Ellis, 2014. "Evaluating Water-Depth Variation and Mapping Depositional Facies on Great Bahama Bank – a “Flat-Topped” Isolated Carbonate Platform", Evaluating Water-Depth Variation and Mapping Depositional Facies on the Great Bahama Bank – a “Flat-Topped” Isolated Carbonate Platform, Paul M. (Mitch) Harris, Sam J. Purkis, James Ellis
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Great Bahama Bank (GBB) stands behind many of the models used to illustrate depositional facies variation across flat-topped, isolated carbonate platforms. Such models have long served as subsurface analogs at a variety of scales. We have used Landsat TM and ETM+ imagery, and an extensive set of water depth measurements, to critically evaluate the magnitude and patterns of bathymetry across GBB. The refined bathymetric digital elevation model (DEM) and seafloor sample data were analyzed with eCognition to develop a map of depositional facies that is more robust than previous versions.
60%, or 61,400 km2, of GBB lies in 5 m or less of water. This includes carbonate sand accumulations where accommodation space is nearly filled, e.g., Tongue of the Ocean, Schooners, Exumas, Joulters, and the Cat Cay sand bodies, and also includes vast portions of the northern portion of GBB surrounding Andros Island and the New Providence Platform to the west of the Exuma Islands. The 40% of GBB lying in greater than 5 m of water occurs mainly in an east-west trending portion of the southern platform. These bathymetric patterns are important as a potential primary control over flooding history, filling (accommodation) history, and the resultant depositional facies patterns.