Unnamed (east tributary of Wortmanns Glacier) (ARDF #CV038) Cu, Zn

Unnamed (east tributary of Wortmanns Glacier)

Occurrence, Inactive

Commodities and mineralogy

Main commodities	Cu; Zn
Other commodities	Ag
Ore minerals	chalcopyrite; pyrite; sphalerite

Geographic location

Quadrangle map, 1:250,000-scale	CV
Quadrangle map, 1:63,360-scale	D-5
Latitude	60.95
Longitude	-145.65
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	This occurrence is at an elevation of 4000 feet above an east tributary to Wortmanns Glacier and 1.4 miles due south of peak 6145. It is in the NW1/4 sec. 6, T. 11 S., R. 2 W., of the Copper River Meridian. The location of the site is accurate to within 2000 ft. The occurrence is shown as site C-97 in Jansons and others (1984).

Geologic setting

Geologic description The country rocks at this occurrence are metavolcanic rocks (greenstone) and metasedimentary rocks of the Upper Cretaceous Valdez Group. These rocks are part of a 65-mile-long belt of volcanic rocks having potential for volcanogenic massive sulfide deposits, extending to the Copper River (Nelson and others, 1984; 1985). The ore minerals at this site presumably are chalcopyrite, pyrite, and sphalerite, but their mode of occurrence has not been made public. One grab sample contained 1.0% Zn, 0.1 to 0.5% Cu, and 0.5 ppm to 3 ppm Ag (Jansons and others, 1984).
Geologic map unit	(-145.651982411856, 60.9494726466304)
Mineral deposit model	Cyprus massive sulfide (Cox and Singer, 1986; model 24a)
Mineral deposit model number	24a
Age of mineralization	Late Cretaceous based on the age of the host rocks.

Production and reserves

Workings or exploration	Site was sampled as part of a U.S. Bureau of Mines and USGS mineral resource assessment of the Chugach National Forest (Jansons and others, 1984; Nelson and others, 1984). One grab sample contained 1.0% Zn, 0.1 to 0.5% Cu, and 0.5 ppm to 3 ppm Ag (Jansons and others, 1984).
Indication of production	None
Additional comments Crowe and others (1992; 1993) and Sainsbury (1993) discuss the genesis of the volcanogenic massive sulfide deposits in this area.

References

MRDS Number	10307371
References Crowe, D.E., Nelson, S.W., Brown, P.E., Valley, J.W., and Shanks, W.C., III, 1992, Geology and geochemistry of volcanogenic massive sulfide deposits and related igneous rocks, Prince William Sound region, south-central Alaska: Economic Geology, v. 87, no. 7, p. 1722-1746. Crowe, D.E., Nelson, S.W., Brown, P.E., Valley, J.W., and Shanks, W.C., III, 1993, Geology and geochemistry of volcanogenic massive sulfide deposits and related igneous rocks, Prince William Sound, south-central Alaska--Reply: Economic Geology, v. 88, p. 1285-1288. Jansons, Uldis, Hoekzema, R.B., Kurtak, J.M., and Fechner, S.A., 1984, Mineral occurrences in the Chugach National Forest, southcentral Alaska: U.S. Bureau of Mines Mineral Land Assessment 5-84, 218 p., 2 sheets, scale 1:250,000. Nelson, S.W., Dumoulin, J. A., and Miller, M.L., 1985, Geologic map of the Chugach National Forest, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1645-B, 16 p., 1 sheet, scale 1:250,000. Nelson, S.W., Miller, M.L., Barnes, D.F., Dumoulin, J.A., Goldfarb, R.J., Koski, R.A., Mull, C.G., Pickthorn, W.J., Jansons, Uldis, Hoekzema, R.B., Kurtak, J.M., and Fechner, S.A., 1984, Mineral resource potential of the Chugach National Forest, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1645-A, 24 p., 1 plate, scale 1:250,000. Sainsbury, C.L., 1993, Geology and geochemistry of volcanogenic massive sulfide deposits and related igneous rocks, Prince William Sound, south-central Alaska, A discussion: Economic Geology, v. 88, p. 1284-1285.
Reporters	S.W. Nelson, Anchorage, AK
Last report date	6/10/2000