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Cook, D.B., 1988

Seismology and tectonics of the North American plate in the Arctic: northeast Siberia and Alaska

Bibliographic Reference

Cook, D.B., 1988, Seismology and tectonics of the North American plate in the Arctic: northeast Siberia and Alaska: East Lansing, Michigan, Michigan State University, Ph.D. dissertation, 250 p., illust., maps.


Through the use of geological and geophysical methods, new conclusions have been reached regarding the tectonic setting and history of three regions of the North American plate within the Arctic. The settings of these regions, the western Bering Sea margin, interior Alaska, and the North American plate boundary in northeast Siberia, are independently examined using seismological methods or tectonostratigraphic terrane analysis. The results of each investigation are summarized as follows. The western Bering Sea margin is composed of five terranes of oceanic affinity that were accreted during a period of Cretaceous to Miocene convergence. Presently, extension is taking place in the western Bering Sea, consistent with results from the remainder of the Bering Sea region. In northern and western Alaska, however, intraplate earthquake focal mechanism solutions indicate three distinct regions of stress orientation. A northwest-southeast horizontal stress in much of interior Alaska is created by Pacific plate subduction at the Aleutian trench. Stresses in northern and eastern Alaska are northeast-southwest, similar to the mid-continent region of North American. The Yukon-Koyukuk province and the Bering Sea are currently undergoing extension. Interplate earthquake focal mechanism solutions in northeast Siberia and its adjacent seas are used to delineate the position and character of the North American plate boundary in Siberia. The onshore continuation of the Arctic mid-ocean ridge does not represent a continental rift, and is instead expressed as a compressional zone within the Cherskii Mountains. This transition is caused by the uniqueness of this boundary where the pole of rotation lies very close to the plate boundary, causing an abrupt transition in faulting style. A complete dataset extends the Arctic mid-ocean ridge to the Aleutian-Kuril arc. Arc-arc junction best fits a three-plate system, with an independent Sea of Okhotsk plate.

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