Multifold Seismic Data Across Outer Bering Sea Continental Margin: ABSTRACT

Abstract

Recent U.S. Geological Survey multifold seismic reflection records from the outer edge of the Bering Sea shelf show that a thick sedimentary section underlies the continental slope and rise. The subject segment of the Bering Sea margin extends from Cape Navarin in Siberia south to Pribilof Canyon, a distance of 700 km. This part of the margin is covered by 200 to 3,400 m of water, is incised by several large submarine canyons, and is underlain by up to 10 km of strata. The strata are thickest (7 to 10 km thick) at the base of the slope near Cape Navarin and near Zhemchug Canyon. A maximum thickness of 10 km (5.9 s two-way time) occurs in uplifted rise and slope deposits that lie in 800 m of water near the mouth of Zhemchug Canyon. Rocks dredged from the continental slope indicate that upper Eocene or lower Oligocene rocks rest unconformably on Mesozoic (Upper Jurassic and Lower and Upper Cretaceous) rocks that form the acoustic basement. The reflection profiles and dredge data obtained from the sediment-draped areas of the margin suggest that the upper half of the thick sedimentary section at the base of the slope is younger than early Oligocene age. The age of deeper rocks may be as old as Mesozoic. Several aspects of sediment wedges along the Bering Sea margin make them favorable targets for future hydrocarbon exploration: (1) the large total thickness of Cenozoic rocks; (2) the presence of structural and stratigraphic features such as diapirs, faults, crustal warps, onlaps, and pinch-outs; and (3) the possibility that Cenozoic sediment source areas may be rich in organic and coarse-grained detrital debris. End_of_Article - Last_Page 694------------