Print this pageAAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
The Origin and Development of the Tampa Embayment and Its Role in the Tectonic Evolution of the Eastern Gulf of Mexico
(1) Geological Sciences, University of Alabama, Tuscaloosa, AL.
(2) Strectrum Geo Inc., Houston, TX.
In the Gulf of Mexico (GoM), current kinematic analyses, basement maps and paleogeographic reconstructions are a source of ongoing scientific debate. Issues such as the initial geometry of the basement rocks, the style of initial breakup and rifting, and how spreading occurred are contentious subjects. These issues are particularly unclear in the Eastern GoM where few new wells have been drilled since the early 1980’s. As a result of the sparse data, hypotheses for the evolution of the Eastern GoM have been primarily based on plate kinematic reconstructions and inferred deep basement faults.
Along the Florida shelf edge, alternating basement highs and lows have been identified through seismic mapping of the top basement surface. In this study, the origin and development of one of these basement lows, the Tampa Embayment, is analyzed through seven regional 2-D seismic lines that run along the continental shelf west of Tampa and into the deepwater west of the Florida Escarpment. Restored cross-sections from the seismic data help to understand the development of the embayment, as well as produce new ideas as to the tectonic evolution of the Eastern GoM.
Within the Tampa Embayment salt deposits are relatively thin (< 0.5 km) and have been mobilized into salt rollers, anticlines, and small domes, and some short allochthonous sheets. Rotational salt welds and other salt related features help identify the base of salt horizon, which is one of the last syn-rift horizons. This seismic horizon is continuous across the Florida Escarpment, implying that the Tampa Embayment and the West Florida Basin are, in fact, one continuous basin. Analysis of the horizons beneath the base of salt reveals that during Triassic time crustal attenuation led to the development of a graben beneath, and to the west of, the Tampa Embayment, reaching a sediment thickness of approximately 2 km. Seaward dipping basement reflectors beneath the embayment begin to flatten at approximately the same location as the point in which the salt pinches out, indicating a basement hinge zone. This tectonic hinge zone possibly represents a crustal attenuation boundary, and may be the controlling element on the location of the Cretaceous carbonate margin. Basinward thickening of the shelf sediments can be identified along strike within the Tampa Embayment and is persistent through most of the Cretaceous, indicating continued subsidence of the embayment through this time.