Age and tectonic significance of volcanic rocks on St. Matthew Island, Bering Sea, Alaska

Journal of Research of the U.S. Geological Survey
By: , and 

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Abstract

Reconnaissance investigations of the heretofore little known volcanic assemblage on St Matthew Island provide significant information on the tectonic history of the Bering Sea shelf. St. Matthew Island is made up of approximately 500 m of subaerial calc-alkaline volcanic rocks ranging in composition from high-alumina basalt to rhyolite. Four K-Ar analyses of samples from this volcanic sequence give Late Cretaceous ages of 65-77 m.y., and intercalated carbonaceous tuff layers yield Cretaceous pollen assemblages. Along the northeast coast of St. Matthew Island, the volcanic rocks are intruded by granodiorite that gives an early Tertiary K-Ar age of 61 m.y. Correlations with on-land geology in northeast Siberia and marine geophysical data from the western Bering Sea strongly suggest that St. Matthew Island represents a southeastward extension of the Okhotsk-Chukotsk belt, a Cretaceous and early Tertiary volcanic arc that borders the Pacific margin of Siberia for nearly 3,000 km. The apparent continuation of this volcanic arc along the margin of the Bering shelf at least as far east as St. Matthew Island supports suggestions by Burk and by Scholl and others that in late Mesozoic time the Pacific plate margin coincided with the present Bering shelf margin and did not shift to the Aleutian trench until the end of Cretaceous or the beginning of Tertiary time.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Age and tectonic significance of volcanic rocks on St. Matthew Island, Bering Sea, Alaska
Series title Journal of Research of the U.S. Geological Survey
Volume 4
Issue 1
Year Published 1976
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Description 7 p.
First page 67
Last page 73
Country United States
State Alaska
Other Geospatial Bering Sea, St. Matthew Island
Online Only (Y/N) N
Additional Online Files (Y/N) N