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Hess, G.R., 1985

Quaternary stratigraphy and sedimentation: northern Bering Sea, Alaska

Bibliographic Reference

Hess, G.R., 1985, Quaternary stratigraphy and sedimentation: northern Bering Sea, Alaska: Palo Alto, California, Stanford University, Ph.D. dissertation, 89 p., illust., maps.

Abstract

The Quaternary sedimentation history of the Northern Bering Sea can be interpreted from study of single-channel seismic-reflection profiles. Nine acoustic facies are recognized; (1) organized channel fill, (2) unorganized channel fill, (3) chaotic, (4) deltaic, (5) parallel, flat, continuous (marine), (6) transparent (ice contact or glacial), (7) opaque reflective (gravel- or boulder-lag covered seafloor), (8) opaque absorptive (modern Yukon fine sand), and (9) broken-scattered-penetrative (gas-charged sediment). Total thickness of the Quaternary section can be determined over Chirikov basin and western Norton Sound. The section thickens to the west, reaching 60+ m with up to 80 m in filled channels. Transparent or glacial sediments make up the Pleistocene section in western Chirikov basin. They are bordered on the east by extensive chaotic facies of outwash-fan and stream deposits. Chaotic facies grade eastward into channel facies with both organized and unorganized channel fill. These channel deposits define a large drainage system trending northwest across central Chirikov basin toward the Bering Strait. To the east in Norton Sound, the dominant facies are flat-lying marine sediments comprising two distinct sequences. The lower of the two, although showing parallel and continuous reflectors, is extensively folded, faulted, and eroded and is clearly much older than the overlying sequence, which shows no folding or major faulting. In the upper sequence, a large delta has built northward into a depression on the north side of Norton Sound. Large areas around the modern Yukon delta are opaque to or allow only scattered windows of penetration of the seismic-reflection system. The fine sand being deposited by the modern Yukon delta system prevents penetration completely, and gas present in the upper few meters of section yield only scattered windows of penetration depending on gas concentration. Throughout much of the Quaternary the northern Bering shelf has been bypassed by sediment. Multiple episodes of regressions and transgression during the Pleistocene, sometimes accompanied by glaciations, have left behind varied but sparse deposits of sediment compared to Quaternary sections on other similar passive margins around the world.

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