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Lower Cretaceous Shelf Edge, Offshore Louisiana, Main Pass Area, Line “B”

J. M. Reed
J. M. Reed
Texaco Incorporated
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January 01, 1983


Line B was recorded offshore Mississippi/Louisiana to define the position of the Lower Cretaceous shelf edge. The shelf edge arcs across the southern part of the North American plate from offshore West Florida, through the southern states and into Mexico. At its eastern position the shelf edge is coincident with the West Florida escarpment where two cores from the exposed carbonate bank complex were recovered by the Oceanographic Department of Texas A & M University and indicated to be Lower Cretaceous (Albian) in age.

Although increasingly buried by the younger section of the Gulf Coast geosyncline, the seismic signature of the Lower Cretaceous shelf edge is well defined from offshore Florida to the offshore Louisiana Main Pass area. This definition deteriorates to the west becoming nonexistent or of reduced dimensions in some parts of western Louisiana.

Exploratory tests in the vicinity of this seismic section have drilled into the shelf edge feature, revealing it to be the same age (Lower Cretaceous-Albian) as indicated by the offshore Florida cores. This extensive shelf edge or shelf bank complex remains an elusive petroleum target.

The trend effectively defines the separation between Interior and Gulf Coast salt basins and provides the focal position for extensive seaward thickening of the younger section. Classical fault patterns with expanded downthrown section are displayed. The "rollover" anomaly displayed on the fault just forward of the shelf edge is not productive here, but is typical of many producing structures in both younger and older sections. in South Louisiana and to the west of this line of section, the now-famous Tuscaloosa gas-trend of lower Upper Cretaceous age is positioned just seaward of this carbonate bank. Production is derived from an expanded sand section and rollover fault structures.

This section provides a view of a major structural and stratigraphic element of Gulf Coast geology along which significant petroleum reserves remain to be found.

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AAPG Studies in Geology

Seismic Expression of Structural Styles: A Picture and Work Atlas. Volume 1–The Layered Earth, Volume 2–Tectonics Of Extensional Provinces, & Volume 3–Tectonics Of Compressional Provinces

A. W. Bally
A. W. Bally
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American Association of Petroleum Geologists
ISBN electronic:
Publication date:
January 01, 1983




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