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Unnamed (outlet of Salmon Lake)

Occurrence, Inactive

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Commodities and mineralogy

Main commodities Cu; Pb; W
Ore minerals chalcopyrite; galena; scheelite; pyrite; pyrrhotite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale CR
Quadrangle map, 1:63,360-scale C-2
Latitude 55.57458
Longitude -132.64232
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is at the mouth of Salmon Lake. It is near the northeast corner of section 4, T. 73 S., R. 84 E. The location is accurate.

Geologic setting

Geologic description

This occurrence is at or near the contact of a large granodiorite-quartz diorite stock (Sainsbury, 1961; Eberlein and others, 1983; Brew, 1996). Early workers considered the stock to be Mesozoic or Cretaceous, but recent radiometric dating indicates that it is Devonian (S.M. Karl, oral communication, 2003). The pluton is in contact with hornfelsed chert, argillite, graywacke, and tuff of the Silurian and Ordovician Descon Formation. The rocks near the contact contain disseminated sulfides and quartz-sulfide veins with a few grains of scheelite (Sainsbury, 1961). The sulfides are mainly pyrite and pyrrhotite with minor chalcopyrite and galena.
Geologic map unit (-132.643974478635, 55.5742162727232)
Mineral deposit model Contact metamorphic Cu-Pb-W deposit.
Age of mineralization The mineralization is in the contact zone of a Devonian granitic pluton and is probably related to its emplacement.
Alteration of deposit The mineralized sedimentary rocks near the contact are hornfelsed.

Production and reserves

Workings or exploration Only surface sampling by a government geologist.
Indication of production None

Additional comments

This occurrence is in the Karta River Wilderness Area, which is closed to exploration and mining.

References

MRDS Number A010028

References

Brew, D.A., 1996, Geologic map of the Craig, Dixon Entrance, and parts of the Ketchikan and Prince Rupert quadrangles, southeastern Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-2319, 53 p., 1 sheet, scale 1:250,000.
Cobb, E. H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Craig quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-869, 262 p.
Eberlein, G.D., Churkin, Michael, Jr., Carter, Claire, Berg, H.C., and Ovenshine, A. T., 1983, Geology of the Craig quadrangle, Alaska: U.S. Geological Survey Open-File Report 83-91, 52 p.
Sainsbury, C.L., 1961, Geology of part of the Craig C-2 quadrangle and adjoining area, Prince of Wales Island, southeastern Alaska: U.S. Geological Survey Bulletin 1058-H, p. H299-H362.
Reporters D.J. Grybeck (Applied Geology)
Last report date 5/1/2004