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Unnamed (east of lower Lime Creek)

Prospect, Inactive

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Commodities and mineralogy

Main commodities Cu
Ore minerals bornite; chalcopyrite
Gangue minerals calcite; epidote; quartz

Geographic location

Quadrangle map, 1:250,000-scale MC
Quadrangle map, 1:63,360-scale C-8
Latitude 61.693
Longitude -143.9312
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is on the east valley wall of lower Lime Creek. it is at an elevation of about 3,700 feet, 4,500 feet southwest of elevation 6830, and 1,200 feet southeast of the center of section 15, T. 2 S., R. 8 E. of the Copper River Meridian. This is locality 167 of MacKevett (1976) and locality 13 of MacKevett and others (1978). The location is accurate to within about 100 feet. Cobb and MacKevett (1980) included this prospect under the name 'Lime Cr., tributary to Rock Cr.'.

Geologic setting

Geologic description

The deposit at this prospect consists of bornite and minor chalcopyrite in small lenses, as disseminations, and in veins in Triassic Nikolai Greenstone (Moffit and Mertie, 1923; MacKevett, 1976). The copper-bearing minerals are partly associated with quartz and epidote and with quartz-calcite veins (Moffit and Maddren, 1909; Moffit and Mertie, 1923). The deposits were explored by two adits and open cuts. 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 (-143.933293099939, 61.6925370494559)
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

Workings or exploration The prospects were explored by two adits and open cuts.
Indication of production None

Additional comments

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

References

MRDS Number A011754

References

Cobb, E.H., and MacKevett, E.M., Jr., 1980, Summaries of data on and lists of references to metallic and selected nonmetallic mineral deposits in the McCarthy quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-885, 156 p.
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.
Moffit, F.H., and Maddren, A.G., 1909, Mineral resources of the Kotsina-Chitina region, Alaska: U.S. Geological Survey Bulletin 374, 103 p.
Moffit, F.H., and Mertie, J.B., Jr., 1923, The Kotsina-Kuskulana district, Alaska: U.S. Geological Survey Bulletin 745, 149 p.
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