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Circum-Pacific and Caribbean Orogens |
United States Geological Survey, Alaskan Mineral Resources Branch, 345 Middlefield Road, Menlo Park, California 94025, U.S.A.
Alaska occupies a strategic location in the circum-Pacific orogen. It is the northern extremity of the western American cordilleras, embraces the intersection of the Innuitian and Cordilleran foldbelts of King (1969)—probably representatives of circum-Arctic and circum-Pacific foldbelts of differing ages (Churkin 1969, 1970; Lathram 1970, in press)—and is the transition zone between these foldbelts and those of eastern Asia. Mesozoic and later deformations of the Cordilleran regime have affected most of Alaska, largely concealing evidence of the varied and continuing mobility that has characterized the State throughout its geologic history—mobility that is still in evidence along its southern margin where high volcanic and earthquake activity continue to the present day. In addition, the recent and continuing discovery of major economic mineral deposits, and the very size of the State—l,500,000 km2—impress the importance of Alaskan geologic knowledge.
Segment: because of the differing nature of Mesozoic and Cenozoic earth movements in various parts of the North American Cordillera in Alaska, the entire State, excluding the Aleutian Arc, is included in the segment. The northern margin lies in the south of the Arctic Coastal Plain, at the northern limit of folds and thin-skinned thrust tectonic features resulting from Mesozoic and Cenozoic orogeny. The southern margin is placed at the southern foot of the Pacific continental slope, i.e. the north wall of the Aleutian Trench. Between these margins, the Cordillera has a width of 1200 km in eastern Alaska, and widens to 1700 km in western Alaska.
Zones: the Cordillera is here described
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This 250-word extract was created in the absence of an abstract.
