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Unnamed (east of lower Kuskulana Glacier)

Occurrence, Inactive

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Commodities and mineralogy

Main commodities Cu
Ore minerals native copper; tenorite
Gangue minerals epidote; quartz

Geographic location

Quadrangle map, 1:250,000-scale MC
Quadrangle map, 1:63,360-scale C-8
Latitude 61.6312
Longitude -143.634
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is on the east valley wall of lower Kuskulana Glacier. It is at an elevation of about 3,900 feet, 5,400 feet north-northwest of elevation 6610, and 2,000 feet south-southwest of the center of section 5, T. 3 S., R. 10 E. of the Copper River Meridian. This is locality 128 of MacKevett (1976) and locality 23 of MacKevett and others (1978). The location is accurate to within about 100 feet.

Geologic setting

Geologic description

This occurrence consists of amygdules in Triassic Nikolai Greenstone that are filled with epidote, quartz , and smaller amounts of native copper and tenorite (MacKevett, 1976). A sample of the mineralization contained 3,000 parts per million copper. The widespread deposition of copper in Triassic greenstone and limestone of the area is thought to have accompanied regional deformation and low-grade metamorphism in the Late Jurassic or Early Cretaceous (MacKevett and others, 1997). Copper-bearing minerals were deposited in the underlying Nikolai Greenstone at about 112 Ma (Silberman and others, 1980).
Geologic map unit (-143.636087674073, 61.6307461038273)
Mineral deposit model Basaltic Cu (Cox and Singer, 1986; model 23)
Mineral deposit model number 23
Age of mineralization Cretaceous? The widespread deposition of copper in Triassic greenstone and limestone of the area is thought to have accompanied regional deformation and low-grade metamorphism in the Late Jurassic or Early Cretaceous (MacKevett and others, 1997). Copper-bearing minerals were deposited in the underlying Nikolai Greenstone at about 112 Ma (Silberman and others, 1980).
Alteration of deposit Oxidation.

Production and reserves

Indication of production None

Additional comments

The locality is in the Wrangell-Saint Elias National Park and Preserve.

References

MRDS Number W000011

References

MacKevett, E.M., Jr., 1976, Mineral deposits and occurrences in the McCarthy quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-773-B, 2 sheets, scale 1:250,000.
MacKevett, E.M., Jr., Cox, D.P., Potter, R.W., III, and Silberman, M.L., 1997, Kennecott-type deposits in the Wrangell Mountains, Alaska--High-grade copper ores near a basalt-limestone contact, in Goldfarb, R.J., and Miller, L.D., eds., Mineral deposits of Alaska: Economic Geology Monograph 9, p. 66-89.
MacKevett, E.M., Jr., Smith, J.G., Jones, D.L., and Winkler, G.R., 1978, Geologic map of the McCarthy C-8 quadrangle, Alaska: U.S. Geological Survey Geologic Quadrangle Map GQ-1418, 1 sheet, scale 1:63,360.
Silberman, M.L., MacKevett, E.M., Jr., Connor, C.L., and Mathews, A., 1980, Metallogenic and tectonic significance of oxygen isotope data and whole-rock potassium-argon ages of Nikolai Greenstone, McCarthy quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-2019, 31 p.
Reporters Travis L. Hudson (Applied Geology, Inc.)
Last report date 1/12/2003