Unnamed (northeast of upper Cross Creek) (ARDF #NB055) Ag, Au, Cu, Pb, Zn

Unnamed (northeast of upper Cross Creek)

Prospect, Inactive

Commodities and mineralogy

Main commodities	Ag; Au; Cu; Pb; Zn
Ore minerals	chalcopyrite; galena; pyrite; sphalerite
Gangue minerals	quartz

Geographic location

Quadrangle map, 1:250,000-scale	NB
Quadrangle map, 1:63,360-scale	A-4
Latitude	62.0844
Longitude	-142.5969
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	This prospect is on the north side of a glacial valley that is an unnamed north tributary to Cross Creek. It is at an elevation of about 6,600 feet, 6,000 feet southwest of peak 8233, and 4,400 feet northwest of peak 7115. The prospect is near the center of the NW1/4 of section 36, T. 4 N., R. 15 E. of the Copper River Meridian. It is locality 16 of Richter (1973), locality 34 of Richter and others (1975), and National Park Service locality WRST-49 (unpublished data). Cobb and Richter (1980) included this prospect under the name 'Cross Cr.'. It is located to within a few hundred feet.

Geologic setting

Geologic description This prospect was known as early as 1909 (Moffit and Knopf, 1909). It is a zone of intense hydrothermal alteration in upper Paleozoic volcanic rocks of the Tetelna Volcanics that contains fragments of volcanic rock cemented by quartz with minor pyrite, galena, sphalerite and chalcopyrite (Richter, 1973; Richter and others, 1975). A sample of a galena- and sphalerite-bearing, quartz vein from a strongly limonite-stained area contained 0.06 parts per million (ppm) gold, 50 ppm silver, 100 ppm copper, more than 10,000 ppm lead, and more than 10,000 ppm zinc (Richter and Matson, 1970 [OFR 70-276]). The limonite-stained alteration zone is 2,000 feet across and appears to be localized in the contact zone of a Tertiary porphyry complex that intrudes rocks of the upper Paleozoic Tetelna Volcanics (Richter, 1973, Richter, 1976).
Geologic map unit	(-142.599028728613, 62.0840077175449)
Mineral deposit model	Polymetallic veins (Cox and Singer, 1986; model 22c)
Mineral deposit model number	22c
Age of mineralization	Tertiary. The alteration zone appears to be localized in the contact zone of a Tertiary porphyry complex with rocks of the upper Paleozoic Tetelna Volcanics (Richter, 1973; Richter, 1976).
Alteration of deposit	The host rocks to this deposit are highly altered but the type and extent of alteration have not been reported. The area is iron-stained.

Production and reserves

Workings or exploration	This prospect was known as early as 1909 (Moffit and Knopf, 1909). There has been surface prospecting.
Indication of production	None
Additional comments The prospect is in the Wrangell-St. Elias National Preserve.

References

MRDS Number	A011407
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. Moffit, F.H., and Knopf, Adolph, 1909, Mineral resources of the Nabesna-White River district: U.S. Geological Survey Bulletin 379-D, p. 161-180. 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