The deep-water basins of the Bering Sea, including the Aleutian, Bowers, and Komandorsky Basins, lie in water depths of 2,000 to 3,800 meters and are separated from one another by the submerged, high-relief (2,500 meters) Bowers and Shirshov Ridges. The basins are flanked on the north and west by Mesozoic and Tertiary rocks that overlie the continental crust of the Kamchatka-Koryak fold belt, on the east by the Mesozoic framework of the Beringian margin, and on the south by Cenozoic island-arc rocks of the Aleutian Ridge. A 2- to 10-kilometer-thick flat-lying section of Mesozoic(?) and Cenozoic sedimentary rocks overlies the igneous oceanic crust of these basins.

Although the basins are physiographically similar, their geophysical signatures and geologic histories differ. The Komandorsky Basin, which is characterized by thin sediment, irregular basement relief, high heat flow, and thickened igneous oceanic crust, is structurally separated from the Aleutian Basin by Shirshov Ridge. In the Aleutian Basin, thick sediment, normal heat flow, and typical oceanic crustal thickness are present. A similar structural discontinuity occurs across the arcuate and asymmetric Bowers Ridge. On the Aleutian Basin side of Bowers Ridge, a 10-kilometer-thick sediment wedge is associated with a −100-milligal gravity anomaly, whereas on the Bowers Basin side of the ridge, a 3- to 5-kilometer-thick sediment blanket laps onto the ridge and has no gravity expression.

The geophysical contrasts between the basins may in part reflect differing tectonic settings and corresponding origins. The Aleutian and Bowers Basins presently lie behind the obliquely underthrust section of the Aleutian arc and are thought to be underlain by Mesozoic oceanic crust, which was entrapped by the development of the Aleutian arc during late Mesozoic to early Tertiary time. In contrast, the Komandorsky Basin lies behind the strike-slip section of the arc and is underlain by young (Cenozoic?) or rejuvenated crust that probably formed there either by seafloor-spreading or by basaltic flooding of older oceanic crust.

The hydrocarbon potential of these deep-water basins varies and is generally greatest in areas of thick sediment and high heat flow. The thick sediment body that lies beneath the Bering Sea continental slope and continental rise between the Aleutian Ridge and Cape Navarin may be a favorable habitat for hydrocarbon accumulations because (1) the Paleogene(?) through Holocene sedimentary section is as much as 5 to 10 kilometers thick; (2) temperature gradients range from 40° to 60°C per kilometer; (3) organic carbon contents are 0.5 to 1.0 percent; (4) structural and stratigraphic traps may be associated with diapirs, faults, and crustal warps, on-laps, and pinchouts; (5) gas hydrates are present; (6) diatomaceous sedimantary rock with a porosity of 58 to 85 percent and a permeability of 10 to 35 millidarcies occur in the uppermost kilometer of the sedimentary section.

Areas of higher than average heat flow and 2- to 8-kilometer-thick sedimentary sections also occur in the southern and western parts of the Komandorsky Basin, in the central and southwestern parts of the Aleutian Basin, and beneath Umnak Plateau. In the central Aleutian Basin, the sedimentary section contains numerous acoustic features, or VAMPS, which are 1- to 2-kilometer-wide pockets of gas and possibly other hydrocarbons. These features are found in late Miocene to Pliocene diatomaceous sediment that is capped by Pleistocene turbidites and underlain by mid-Miocene and older mudstone. Large basement relief (greater than 1 kilometer) and slightly higher heat flow in this area suggest that a thermal event, possibly important to hydrocarbon generation, may have heated the central basin in Cenozoic time.

Although the extreme water depths over the deep-water basins of the Bering Sea presently preclude commercial development, there is evidence of hydrocarbon accumulations in the basins. Further exploration in these vast frontier areas is required to adequately evaluate the basins’ hydrocarbon potential.