Abstract: Seismic Stratigraphy, Sedimentary History, and Petroleum Potential of Blake Plateau, U.S. Atlantic Continental Margin

Richard T. Buffler, Thomas H. Shipley, Joel S. Watkins

A 300-km UTMSI CDP seismic section extending northeast-southwest across the central Blake Plateau provides the basis for a detailed interpretation of the geologic history of the area. A 7 to 10 km-thick sedimentary section overlying a tilted basement of presumed Triassic age is subdivided into nine depositional sequences. The geometries of seismic reflectors and other evidence suggest a Jurassic through Late Cretaceous period of shallow-water carbonate sedimentation followed by Late Cretaceous through Tertiary deeper water carbonate sedimentation. Apparently the carbonate-shelf margin remained relatively stationary along the outer edge of the plateau throughout Jurassic and most of Cretaceous time. During the Late Cretaceous, relative sea level rose more rapidly, submergi g the plateau to water depths similar to today's and shifting the shelf margin landward to about its present location. Carbonate sedimentation during the Tertiary continued to build the shelf margin seaward, but deposition on the plateau was greatly abbreviated, probably because of continued erosion by currents similar to the present Gulf Stream.

Comparison of the geologic model inferred here for the Blake Plateau with petroleum-producing carbonate provinces elsewhere suggests that carbonate reservoirs as well as structural and stratigraphic traps may be expected. For example, reflectorless moundlike features on the seismic section interpreted to represent reefs are present along a regional structural high at the outer edge of the plateau. If adequate source beds are present, this area offers an excellent geologic setting in which to explore for petroleum.

AAPG Search and Discovery Article #90968©1977 AAPG-SEPM Annual Convention and Exhibition, Washington, DC