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Alternate Title

High-Resolution Multibeam Bathymetry and Acoustic Backscatter of Selected Northwestern Gulf of Mexico Outer Shelf Banks

Abstract

After the successful mapping of Stetson and the Flower Garden Banks, NW Gulf of Mexico, with a high-resolution multibeam echo sounder in the late 1990s, 14 additional banks located on the outer continental shelf and upper slope were mapped in 2001 using a similar system. Fourteen areas were chosen by benthic biologists to meet their needs for accurate base maps from which to conduct their various studies. The 14 banks display a wide variety of morphologies and associated surficial-sediment facies. The physiographies of some of the individual banks can be directly related to a salt dome that has either erupted through the seafloor or is in the near subsurface, whereas any association with salt tectonics at other banks is equivocal. Several of the banks clearly related to salt domes have basins that may represent dissolution features as has been previously documented on banks in other areas of the NW Gulf of Mexico. Simultaneously collected acoustic backscatter values suggest the sediment facies for each of the banks, which range from gravelly sand to mud. The spatial distributions of various features are often puzzling. Pockmarks are common around some banks but are absent from others. Pinnacles are abundant in the vicinity of some banks but are absent from others. However, west-to-east changes in some bank characteristics were found. Banks in the western sector of the mapped area have higher relief, have shallower tops, and are capped by coral reefs. Banks in the eastern sector are associated with abundant pinnacles, display a wide range of relief, and generally have smooth tops.

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