Structure of Bowers Ridge, Bering Sea

Abstract

Bowers ridge is a totally submerged projection of the central Aleutian Islands ridge that extends counterclockwise into the Bering Sea, separating Bowers basin from the main Bering Sea (or Aleutian) basin. Three crustal sections of the ridge and adjacent basins based on two-ship seismic refraction measurements and closely spaced airgun-sonobuoy stations are presented. Bowers ridge is a thickened and raised welt of high velocity crustal material bordered on its convex side by a sediment filled trough (filled trench). The Bering Sea basin has normal oceanic crust covered by approximately 4 km of sediment; the M discontinuity is deeper than normal by about 2 to 3 km. Bowers basin seems to have a somewhat different velocity structure from that of the Bering Sea basin, although the total thickness of the layers is about the same. Bowers basin contains a 6.1-km/sec layer underlain by a 7.3-km/sec transitional layer between it and the upper mantle.