The Gulf of Anadyr is adjacent to eastern Siberia in the northern Bering Sea. The gulf and adjacent onshore area are floored by Anadyr Basin, a large sediment-filled structural depression that encompasses a total area of more than 100,000 sq km. Navarin Basin lies southeast of Anadyr Basin and encompasses more than 45,000 sq km of the northern Bering Sea shelf, an area tentatively scheduled for leasing for hydrocarbon exploration in 1984. The two basins are separated by a northwest-trending structural high.

During 1980, the U.S. Geological Survey collected 3,000 km of 24-channel seismic reflection gravity, magnetic, and high-resolution seismic reflection data from 22 sonobuoy-refraction stations in the Gulf of Anadyr and the northern part of the Navarin Basin. These data reveal that the offshore area of Anadyr Basin contains 2,000 to 4,000 m or more of strata. Near Cape Navarin, these beds have been broadly folded into large antiforms tens of kilometers across that may be possible traps for hydrocarbons. Onshore in Anadyr Basin, Soviet exploration has located 50 northeast-trending anticlinal structures.

Magentic and seismic refraction data indicate that the Okhotsk-Chukotsk volcanic belt of eastern Siberia extends offshore southeastward along the inner Bering shelf and flanks the northern side of Anadyr Basin.

On the basis of onshore drilling results in Anadyr Basin, we suspect that the offshore section consists of Cretaceous and early Cenozoic rocks that were folded, uplifted, and eroded during late Mesozoic and again during late Miocene to Pliocene time, when the adjacent Koryak range was deformed. Onshore shows of oil in early Tertiary rocks, and gas shows in Miocene sandstone suggest the presence of adequate source beds in the onshore area of Anadyr Basin. These beds may extend to the offshore basin and into nearby Navarin Basin. Numerous shallow acoustic anomalies, which were detected from records in the Gulf of Anadyr, are probably due to shallow gas accumulations.

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