Abstract

Six continuous seismic reflection profiles traverse the Florida continental terrace (shelf plus slope), and four additional profiles extend nearly across the Florida Straits between 26° N. lat. and 25° N. lat. The terrace at 26° N. comprises a shelf of high-reflectivity material with scarplike relief, probably limestone, and a dip slope of low-reflectivity sediment. At 25° N, the terrace is formed by a prograded tongue of low-reflectivity sediment of problematic origin. A replacement series exists between the two end members in which the sedimentary tongue progrades the limestone shelf, last tentatively identified beneath about 270 m of sediment (about 470 m below sea level). The mean shelf depth is maintained at 300 ± 75 m throughout the change in terrace composition and structure. The gradient along the limestone-shelf surface at about 2.5 m/km to the south appears fairly consistent with regional subsidence combined with local isostatic response to sediment load.

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