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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 58 (1974)

Issue: 7. (July)

First Page: 1441

Last Page: 1441

Title: Evolution of Porphyry Copper Province of Northern Cordilleran Orogen: ABSTRACT

Author(s): V. F. Hollister

Article Type: Meeting abstract

Abstract:

In the area from the Columbia Plateau to the Wrangel Mountains of Alaska, porphyry copper deposits formed as adjuncts to differing magmatic and tectonic environments. The most important early event related to development of porphyry copper appears to have been the rifting of the Alexander terrain in Alaska away from the North American craton beginning in the late Paleozoic and continuing into the Jurassic. Introduced during this period of distensional tectonism were the "diorite" porphyry copper deposits and the composite zoned batholiths carrying porphyry copper deposits (the granitic-pluton type). Most deposits of these types are Triassic in age. Porphyry copper deposits are not present in the Upper Jurassic and Lower and middle Cretaceous rocks. The Late Jurassic and E rly and middle Cretaceous appear to have contained periods of rapid sea-floor spreading and strong compression, as well as periods of intrusion of the large batholiths. This implies that magmas associated with porphyry copper deposits do not necessarily have an origin similar to that postulated for Sierra Nevada type batholiths.

Porphyry copper deposits also have been dated as Late Cretaceous and Tertiary. These deposits differ from their Triassic predecessors in that they tend to be smaller stocks or bosses, have some of the features of diapir or piercement, and mineralization associated with them tends to be associated with a quartz monzonite magma.

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