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  3. Alaska Resource Data File (ARDF)

Unnamed (near Toby Creek)

Occurrence, Inactive

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Commodities and mineralogy

Main commodities Cu
Ore minerals chalcocite; malachite

Geographic location

Quadrangle map, 1:250,000-scale MC
Quadrangle map, 1:63,360-scale B-4
Latitude 61.493
Longitude -142.28
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is low on the south valley wall of the Chitistone River. It is at an elevation of about 2,900 feet, 6,000 feet northeast of the mouth of Toby Creek and 6,500 feet northwest of elevation 6930. The site is in the NE1/4 of section 26, T. 4 S., R. 17 E. of the Copper River Meridian. This is locality 83 of MacKevett (1976); the location is accurate to within a few hundred feet.

Geologic setting

Geologic description

This occurrence consists of chalcocite- and malachite-bearing veinlets and copper-stained amygdules in the lower part of Triassic Nikolai Greenstone (MacKevett and Smith, 1972; MacKevett, 1976). Copper mineralization is common in Nikolai Greenstone and is thought to have accompanied regional deformation and low-grade metamorphism in the Late Jurassic to Early Cretaceous (MacKevett and others, 1997).
Geologic map unit (-142.282065192512, 61.4925859942076)
Mineral deposit model Basaltic Cu (Cox and Singer, 1986; model 23)
Mineral deposit model number 23
Age of mineralization Cretaceous? Copper mineralization is common in Nikolai Greenstone and is thought to have accompanied regional deformation and low-grade metamorphism in the Late Jurassic to Early Cretaceous (MacKevett and others, 1997).
Alteration of deposit Oxidation.

Production and reserves

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

Additional comments

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

References

MRDS Number A011716

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., and Smith, J.G., 1972, Geologic map of the McCarthy B-4 quadrangle, Alaska: U.S. Geological Survey Geologic Quadrangle Map GQ-943, 1 sheet, scale 1:63,360.
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.
Reporters Travis L. Hudson (Applied Geology, Inc.)
Last report date 1/12/2003