Unnamed (east of lower Nabesna Glacier) (ARDF #NB045) Au, Cu

Unnamed (east of lower Nabesna Glacier)

Prospect, Inactive

Commodities and mineralogy

Main commodities	Au; Cu
Ore minerals	chalcopyrite; gold; pyrite
Gangue minerals	quartz; sericite

Geographic location

Quadrangle map, 1:250,000-scale	NB
Quadrangle map, 1:63,360-scale	A-4
Latitude	62.1548
Longitude	-142.8302
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	This prospect is on the lower-west flank of the large ridge east of Nabesna Glacier. It is at an elevation of about 3,500 feet in a small drainage about 5,000 feet west of peak 6045 and 1,500 feet east of the glacier. The site is in the SW1/4 of section 3, T. 4 N., R. 14 E. of the Copper River Meridian. This is locality 7 of Richter (1973), locality 24 of Richter and others (1975), and National Park Service locality WRST-42 (unpublished data). Cobb and Richter (1980 [OFR 80-927]) include this locality as an 'Unnamed prospect'. It is located to within a few hundred feet.

Geologic setting

Geologic description Hydrothermally altered porphyry dikes and small masses of quartz diorite contain disseminated pyrite and chalcopyrite; local stockworks of quartz veins with pyrite and chalcopyrite also cut volcanic country rocks (Richter and Matson, 1970 [OFR 70-276]; Richter and others, 1975). Assays of 3 rock samples from this area contained 0.2 to 0.4 ounce gold per ton. One is a 200-foot composite chip sample of pyrite-bearing sericitized porphyry that contained 0.04 ounce of gold per ton and 2,000 parts per million copper (Richter and Matson, 1970 [OFR 70-276]). The altered intrusive rocks are Tertiary in age (Richter, 1973). They cut volcanic rocks and argillite of the upper Paleozoic Tetelna Volcanics (Richter, 1973; 1976).
Geologic map unit	(-142.832326088903, 62.1544069529768)
Mineral deposit model	Disseminated and stockwork veins with copper and gold
Age of mineralization	The altered and mineralized intrusive rocks are considered to be Tertiary (Richter, 1973).
Alteration of deposit	Quartz-sericite-pyrite replacement and veining.

Production and reserves

Workings or exploration	Surface prospecting has occurred in this area.
Indication of production	None
Additional comments The prospect is in the Wrangell-St. Elias National Preserve.

References

MRDS Number	A011397
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., 1976, Geologic map of the Nabesna quadrangle, Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map I-932, 1 sheet, scale 1:250,000. 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