AMERICAN ASSOCIATION OF PETROLEUM GEOLOGISTS
Distinguished Lecture Tour

Abstract: Depositional Anticlines of Deep Environments-Past Success and Future Exploration

By

Mark E. Hennes

As the energy quest probes deeper into the oceanic environment, enormous depositional anticlines formed by deep current action am being documented, and certain of these with favorable rock properties beckon to the explorationist.

Wind-driven surface currents, such as the Gulf Stream, can shape these anticlines at the outer edges of detrital sedimentation where such high-velocity currents sweep the bases of continental slopes. Similarly, the "bottom" currents which are moving at slower velocities deeper on the continental rises will form varied anticlines profiles characteristic of particular bottom conditions. Redistributed terrigenous materials which in great part compose these anticlines are carried into both current systems by intermittent gravity sliding and turbidity currents.

A striking example of wind-driven current deposition occurs in the Florida Strait where calcareous sands from the Florida reef vicinity are swept along a trough by the Gulf Stream, then onto a broad anticlinal rise. Examples typifying "bottom" current anticlines are numerous in the North Atlantic, and deep-water coring programs have partly revealed their sedimentary sequences.

A wind-driven current origin can plausibly explain the Poza Rica trend in Mexico. As the Golden Lane Reef contributed its Tamabra talus downslope into swift currents of the Chicontepec foredeep, anticlines were shaped at the base of the slope. Similar origins are suggested for other examples in the geologic record.

Significant reserves in anticlines formed by current action will be found beyond the reefs and laterally away from the deltas in the deep environment where the subtle character of these features must come to be recognized. Reservoirs such as Poza Rica at test to the excellent rock properties and trap conditions which can be realized in an inspired search for such targets.

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