Hard rock uranium potential in Alaska

Open-File Report 76-246
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Abstract

Discussing the potential of "hardrock" (i.e., non-sedimentary type) uranium deposits in a 586,000 mi2 portion of the North America Cordillera is a difficult task compounded by the fact that the remoteness of much of the region and the logistical difficulties have resulted in only reconnaissance geologic information being available for large parts of the state.

Cobb (1970) has listed known occurrences of uranium and thorium minerals in the state and a somewhat modified version of his compilation showing chiefly hardrock occurrences is given in figure 1; it should be emphasized that these are occurrences only and not necessarily deposits of possible economic significance. The distribution pattern shows a concentration of occurrences in southeastern Alaska and particularly in the interior.

The only production of uranium in Alaska from any type of deposit has been from a hardrock deposit, that being the roughly 120,000 tons of ore averaging about one percent U308 from the Ross-Adams mine near Bokan Mountain on Prince of Wales Island close to the southern tip of southeastern Alaska.

The Bokan Mountain uranium-thorium area includes about 71 mi2 and is largely underlain by plutonic rocks (MacKevett, 1963). The plutonic rocks range from pyroxenite to peralkaline granite and syenite, but they consist chiefly of diorite, quartz diorite, granodiorite, and quartz monzonite. The peralkaline granite, a small pluton about 3 mi2 in area, is Late Triassic or Early Jurassic in age while the other plutonic rocks are early Paleozoic.

Study Area

Publication type Report
Publication Subtype USGS Numbered Series
Title Hard rock uranium potential in Alaska
Series title Open-File Report
Series number 76-246
DOI 10.3133/ofr76246
Year Published 1976
Language English
Publisher U.S. Geological Survey
Description 6 p.
Country United States
State Alaska
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