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Unnamed (east of head of Dry Creek)

Occurrences, Inactive

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Commodities and mineralogy

Main commodities Cu
Ore minerals bornite; malachite; native copper

Geographic location

Quadrangle map, 1:250,000-scale MC
Quadrangle map, 1:63,360-scale C-8
Latitude 61.5784
Longitude -143.9069
Nearby scientific data Find additional scientific data near this location
Location and accuracy These occurrences are on the ridge east of the head of Dry Creek. The coordinates for this record is based on is locality 29 of MacKevett and others (1978). This occurrence is at an elevation of about 5,050 feet, 700 feet north of the center of section 26, T. 3 S., R. 8 E. of the Copper River Meridian. This record includes localities 141 and 142 of MacKevett (1976).

Geologic setting

Geologic description

At least two occurrences of copper-bearing minerals in Triassic Nikolai Greenstone have been identified in this area (localities 141 and 142 of MacKevett, 1976). At locality 141, a sample of amygdaloidal greenstone contained 1,500 parts per million copper and may contain some native copper. At locality 142, bornite and malachite occur in several subparallel thin veins and veinlets cutting greenstone. 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 (-143.908987735313, 61.5779355916444)
Mineral deposit model Basaltic Cu (Cox and Singer, 1980; 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

Workings or exploration Only limited surface sampling.
Indication of production None

Additional comments

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

References

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