Unnamed (east side of the West Fork Maclaren River) (ARDF #MH063) Cu

Unnamed (east side of the West Fork Maclaren River)

Prospect, Inactive

Commodities and mineralogy

Main commodities	Cu
Other commodities	Ag
Ore minerals	chalcocite; malachite
Gangue minerals	epidote; quartz

Geographic location

Quadrangle map, 1:250,000-scale	MH
Quadrangle map, 1:63,360-scale	A-6
Latitude	63.2371
Longitude	-146.7373
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	This prospect is approximately located on the east side of the West Fork Maclaren River at an elevation of about 3,500 feet, in the NE1/4SW1/4 section 26, T. 19 S., R. 5 E., Fairbanks Meridian. The site corresponds to locality 16 in figure 4 of Cobb (1979 [OFR 79-238]) and to locality 22 in table 2 of Nokleberg and others (1991).

Geologic setting

Geologic description The rock at the prospect is propylitized metabasalt of the Nikolai Greenstone of Late Triassic age (Nokleberg and others, 1991). The deposit consists of malachite or chalcocite in quartz-epidote veinlets, in vesicles, or on fracture or joint surfaces in the metabasalt (Saunders, 1961 [report for the year]). No assay data are available; small amounts of silver typically occur with the copper deposits of the Nikolai Greenstone.
Geologic map unit	(-146.73956695998, 63.2366629523443)
Mineral deposit model	Basaltic Cu (Cox and Singer, 1986; model 23).
Mineral deposit model number	23
Age of mineralization	Probably Cretaceous (Nokleberg and others, 1986) or early Tertiary (Stout, 1976); see MH060 and MH100.
Alteration of deposit	Propylitic alteration of metabasalt; oxidation of iron- and copper-bearing minerals.

Production and reserves

Workings or exploration	Copper occurrences were found during geologic investigations in about 1960; there are no known workings.
Indication of production	None

References

References Cobb, E.H., 1979, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Mount Hayes quadrangle, Alaska: U.S. Geological Survey Open-File Report 79-238, 140 p. Nokleberg, W.J., Aleinikoff, J.N., and Lange, I.M., 1986, Cretaceous deformation and metamorphism in the northeastern Mount Hayes quadrangle, eastern Alaska Range, in Bartsch-Winkler, Susan, and Reed, K. M., eds., Geologic studies in Alaska by the U.S. Geological Survey during 1985: U.S. Geological Survey Circular 978, p. 64-69 Nokleberg, W.J., Lange, I.M., Roback, R.C., Yeend, Warren, and Silva, S.R., 1991, Map showing locations of metalliferous lode and placer mineral occurrences, mineral deposits, prospects, and mines, Mount Hayes quadrangle, eastern Alaska Range, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1996-C, 42 p., 1 sheet, scale 1:250,000. Saunders, R.H., 1961, Susitna-MacClaren area in Williams, J.A., 1961, Report of the Division of Mines and Minerals for the year 1961: Alaska Division of Mines and Minerals Annual Report 1961, pp. 37-40. Stout, J.H., 1976, Geology of the Eureka Creek area, east-central Alaska Range: Alaska Division of Geological and Geophysical Surveys Geologic Report 46, 32 p., 1 plate, scale 1:63,360.
Reporters	W.T. Ellis (Alaska Earth Science), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS)
Last report date	8/4/2001