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Book Chapter

Kodiak Shelf, Gulf of Alaska

J.G. Wiston
J.G. Wiston
Mobil Oil Corporation
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January 01, 1983


The Kodiak Shelf basin is part of an extensive forearc region formed by the convergence of the Pacific and North American plates. This convergence and subsequent subduction of the Pacific plate began in earliest Mesozoic time with the development of a volcanic arc (Aleutian Peninsula) and associated nearshore trench along the entire extent of today's Aleutian Peninsula. During the Mesozoic and earliest Tertiary the trench received thousands of feet of melange, turbidites, and hemipelagic sediments. Uplift of the first forearc basin shelf-edge high (non-volcanic arc) probably occurred during late Eocene or earliest Oligocene forming today's Kenai Peninsula together with Kodiak and the surrounding islands.

After this regional uplift, the present-day Kodiak forearc basin began to form. Subsidence and subsequent deposition of a transgressing shallow-marine sequence of Oligocene-Miocene clastics probably occurred over much of the shelf. Deposition was interrupted by a second regional uplift at the end of the Miocene which removed much of the Oligo-Miocene sequence. This uplift also formed a shelf-edge high about 48 to 56 km (30 to 35 mi) seaward of Kodiak Island, especially in the southern part of the shelf where, in all likelihood, a small northeast to southwest trending island chain was formed. Deposition resumed in the Pliocene and, except for a few localized unconformities, has continued uninterrupted since than.The relation of the Kodiak Shelf basin to the tectonic setting of the Aleutian margin is illustrated in the generalized cross section. The seismic line, shot from northwest to southeast, is situated offshore southeast of Kodiak Island (see index map). The seismic line is displayed in three separate and overlapping segments, labeled (from northwest to southeast) KS 1, KS 2, and KS 3, respectively. The Kodiak Shelf basin shown here is elongate in a northeast to southwest direction and extends for over 483 km (300 mi) from just off Chirikof Island (southwest of Kodiak) to near Montague Island off the Kenai Peninsula.

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AAPG Studies in Geology

Seismic Expression of Structural Styles: A Picture and Work Atlas. Volume 1–The Layered Earth, Volume 2–Tectonics Of Extensional Provinces, & Volume 3–Tectonics Of Compressional Provinces

A. W. Bally
A. W. Bally
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American Association of Petroleum Geologists
ISBN electronic:
Publication date:
January 01, 1983




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