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Geochronology, geochemistry, and tectonic environment of porphyry mineralization in the central Alaska Peninsula

Open-File Report 83-783

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Abstract

Porphyry type sulfide systems on the central Alaska Peninsula occupy a transition zone between the Aleutian island magmatic arc and the continental magmatic arc of southern Alaska. Mineralization occurs associated with early and late Tertiary magmatic centers emplaced through a thick section of Mesozoic continental margin clastic sedimentary rocks. The systems are of the molybdenum-rich as opposed to gold-rich type and have anomalous tungsten, bismuth, and tin, attributes of continental-margin deposits, yet gravity data suggest that at least part of the study area is underlain by oceanic or transitional crust. Potassium-argon age determinations indicate a variable time span of up to 2 million years between emplacement and mineralization in a sulfide system with mineralization usually followed by postmineral intrusive events. Finally, mineralization in the study area occurred at many times during the time span of igneous activity and should be an expected stage in the history of a subduction related magmatic center.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Geochronology, geochemistry, and tectonic environment of porphyry mineralization in the central Alaska Peninsula
Series title:
Open-File Report
Series number:
83-783
Edition:
-
Year Published:
1983
Language:
ENGLISH
Publisher:
U.S. Geological Survey,
Description:
25 p. ill., maps ;28 cm.