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Unnamed (west of lower Nabesna Glacier)

Occurrence, Inactive

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Commodities and mineralogy

Main commodities Cu
Ore minerals chalcopyrite; pyrite

Geographic location

Quadrangle map, 1:250,000-scale NB
Quadrangle map, 1:63,360-scale A-4
Latitude 62.1283
Longitude -142.9363
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is on the east nose of a low ridge along the north side of a west tributary stream to lower Nabesna Glacier. It is at an elevation of about 3,800 feet, 2,500 feet west of the glacier and about 1.6 miles east-southeast of elevation 5370. The site is in the NE1/4 of section 13, T. 4 N., R. 13 E. of the Copper River Meridian. This is locality 11 of Richter (1973), locality 21 of Richter and others (1975), and National Park Service locality WRST-29 (unpublished data). Cobb and Richter (1980) included this locality as an 'Unnamed occurrence'. It is located to within a few hundred feet.

Geologic setting

Geologic description

Small irregular masses of pyrite and minor chalcopyrite occur in contact-metamorphosed Triassic, Nikolai Greenstone. A chip sample of pyrite-bearing greenstone contained 500 parts per million (ppm) copper, more than 100 ppm scandium, 200 ppm nickel, and 300 ppm chromium (Richter and Matson, 1970 [OFR 70-276]). This occurrence is in the contact zone of a diorite stock that is inferred to be a border phase of the mid-Cretaceous Nabesna pluton (Richter, 1973).
Geologic map unit (-142.938423608594, 62.1279033852809)
Mineral deposit model Contact metamorphic copper deposit
Age of mineralization Mid-Cretaceous? The nearby diorite stock is inferred to be a border phase of the mid-Cretaceous Nabesna pluton (Richter, 1973).
Alteration of deposit Tactite development in contact metamorphosed greenstone.

Production and reserves

Indication of production None

Additional comments

The occurrence is in the Wrangell-St. Elias National Preserve.

References

MRDS Number A011394

References

Cobb, E.H., and Richter, D.H., 1980, Summaries of data on and list of references to metallic and selected nonmetallic mineral deposits in the Nabesna quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-927, 117 p.
Richter, D.H., and Matson, N.A., Jr., 1970, Geochemical data from the Nabesna A-4 quadrangle, Alaska: U.S. Geological Survey Open-File Report 70-276, 14 p., 1 sheet, scale 1:63,360.
Richter, D.H., Singer, D.A., and Cox, D.P., 1975, Mineral resources map of the Nabesna quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-655-K, 1 sheet, scale 1:250,000.
Reporters Travis L. Hudson (Applied Geology)
Last report date 11/24/2002