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Copper Lode

Prospect, Inactive

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Commodities and mineralogy

Main commodities Cu
Other commodities Au
Ore minerals chalcopyrite; limonite; malachite; pyrrhotite

Geographic location

Quadrangle map, 1:250,000-scale MM
Quadrangle map, 1:63,360-scale B-2
Latitude 63.2687
Longitude -150.8642
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Copper Lode prospect (Cobb, 1980, p. 20 [OFR 80-363]) is in the upper west fork of Carlson Creek at an elevation of about 3600 feet (Moffit, 1933, p. 322). The approximate location is about on the section line between sections 17 and 18, T. 19 S., R. 17 W., Fairbanks Meridian. The location appears to match Moffit's description of a prospect on the north bank of this part of the creek. It is probably accurate within 1/2 mile. The prospect is number 33 of Cobb (1972 [MF 366]) and number 42 of MacKevett and Holloway (1977).

Geologic setting

Geologic description

The country rocks at the Copper Lode prospect in upper Carlson Creek are strata of Paleozoic (Devonian?) age. The Paleozoic rocks form a thin wedge north of the mid-Tertiary McGonagall batholith, and south of sedimentary rocks of the Cretaceous or Tertiary Cantwell Formation. The contact between Paleozoic rocks and Cantwell Formation is a fault that strikes NE and is roughly parallel to the Denali fault, which is about 5 1/2 miles to the southeast (Reed, 1961).
The Copper Lode deposit consists of irregular masses of pyrrhotite and minor chalcopyrite up to several feet across in mainly dark-colored, fine-grained rock provisionally called altered limy shale (Moffit, 1933, p. 322). The mineralized hostrock strikes NE; it is about 25 feet thick and has been traced for about 250 feet. The mineralized outcrop is pervasively iron stained and locally copper stained (malachite?). Rocks northwest of the mineralized outcrop are bluish-gray limestone locally interbedded with conglomerate. The mineralization is probably middle Tertiary, roughly contemporaneous with the emplacement of the McGonagall pluton (Reed and Lanphere, 1974).
Geologic map unit (-150.866448698493, 63.2681889422777)
Mineral deposit model Fault-controlled, polymetallic replacement lode.
Age of mineralization The deposit is probably Oligocene, roughly contemporaneous with the emplacement of the McGonagall batholith (Reed and Lanphere, 1974).
Alteration of deposit Oxidation of iron and copper minerals.

Production and reserves

Workings or exploration Some surface cuts. The prospect was staked in about 1930 and probably has been inactive since about 1940.
Indication of production None

Additional comments

The occurrence is in Denali National Park and Preserve.

References

MRDS Number A011208

References

Cobb, E. H., 1972, Metallic mineral resources map of the Mount McKinley quadrangle, Alaska: U. S. Geological Survey Miscellaneous Field Studies Map MF-366, 1 sheet, scale 1:250,000.
Cobb, E.H., 1980, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Mount McKinley quadrangle, Alaska: U. S. Geological Survey Open-File Report 80-363, 150 p.
MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous and selected non-metalliferous mineral deposits in the eastern part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-A, 99 p., 1 sheet, scale 1:1,000,000.
Moffit, F.H., 1933, The Kantishna district, in Smith, P.S. and others, Mineral resources of Alaska: report on investigations in 1930, U. S. Geological Survey Bulletin 836, p. 301-338.
Reed, B. L., and Lanphere, M. A., 1974, Offset plutons and history of movement along the McKinley segment of the Denali fault system, Alaska: Geological Society of America Bulletin, v. 85, p. 1883-1892.
Reed, J. C., Jr., 1961, Geology of the Mt. McKinley quadrangle, Alaska: U. S. Geological Survey Bulletin 1108-A, p. A1-A36.
Reporters C.C. Hawley
Last report date 12/13/2000