Abstract: Geology of Bering Shelf

Sankey L. Blanton

The Bering Shelf is a large shallow-water area which contains four large to very large Tertiary basins. The geology of the Navarin and St. George basins is related directly to the neutralization of the northern tip of the Kula plate (old North Pacific oceanic plate). Neutralization is a process in which a plate is divided by intraplate subduction, and the disassociated segment loses independent motion and moves in accord with the movement of the adjoining plate. That is, after the Kula plate was fragmented by a subduction zone, that part of the plate between the subduction zone and the North American plate was, in a sense, captured by the North American plate. The presence of large shelf-edge extensional basins (Navarin and St. George) along the edge of the old Bering Cre aceous shelf indicates that the processes of fragmentation and capture are accompanied by long-term tension where compression previously was present.

The Navarin and St. George basins have a complex system of sills on their shelf-edge side and are bounded by large growth faults on their shoreward edges. Together the basins are approximately 750 mi (1,200 km) long, average over 100 mi (160 km) in width, and are in excess of 30,000 ft (9,144 m) deep.

The obvious analog is the Gulf Coast Interior Salt basins. Although much older, the Gulf Coast basins et al appear to be products of plate neutralization. It is to be hoped that the Bering Shelf basins will have a similar or superior production history.

AAPG Search and Discovery Article #90966©1977 Alaska Geological Society 1977 Symposium, Anchorage, Alaska