Unnamed (upper Chilligan River) (ARDF #LH029) Ag, Cu, Pb, Sn, Zn

Unnamed (upper Chilligan River)

Occurrence, Inactive

Commodities and mineralogy

Main commodities	Ag; Cu; Pb; Sn; Zn
Ore minerals	galena; pyrite; sphalerite
Gangue minerals	quartz; sericite

Geographic location

Quadrangle map, 1:250,000-scale	LH
Quadrangle map, 1:63,360-scale	B-1
Latitude	61.4451
Longitude	-153.2218
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	This occurrence is on the north side of the upper Chilligan River within a small glacier-filled valley. It is at the toe of a south-flowing glacier, at an elevation of about 4,600 feet, and 1.5 miles north of Chilligan River. The map site is in the SE1/4 section 28, T 16 N, R 22 W, of the Seward Meridian. This is locality 15 of Cobb (1972 [MF 412]; 1976 [OF 76-485]) and location 30 of Gamble and others (1989). The location is probably accurate to within one-half mile.

Geologic setting

Geologic description Reed and Elliott (1970) reported that float in a medial moraine at this locality consists of silicified and sericitized quartz monzonite that contains 5 to 10 percent galena, sphalerite, and pyrite. The sulfide minerals are in clots as much as 2 cm in diameter and in thin veinlets up to 5 mm wide. Shear zones in nearby metasedimentary rocks contain galena and sphalerite. Sulfide-bearing samples contain up to greater than 20,000 ppm lead, greater than 10,000 ppm zinc, greater than 1,000 ppm tin, 2,000 ppm copper, and 150 ppm silver. The mineralization is near the contact between a Tertiary granitic pluton and Mesozoic metamorphic rocks.
Geologic map unit	(-153.224013667409, 61.4444715627727)
Mineral deposit model	Polymetallic veins (Cox and Singer, 1986, model 22c)
Mineral deposit model number	22c
Age of mineralization	Tertiary. Mineralization occurs in Tertiary intrusive rocks and in shear zones in nearby metasedimentary rocks.
Alteration of deposit	Silicification? and sericite-pyrite replacement?

Production and reserves

Workings or exploration	Reconnaissance sampling has been completed in this area (Reed and Elliott, 1970).
Indication of production	None
Additional comments This occurrence is within Lake Clark National Park.

References

MRDS Number	A013072
References Cobb, E.H., 1972, Metallic mineral resources map of the Lime Hills quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-412, 1 sheet, scale 1:250,000. Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Iliamna, Lake Clark, Lime Hills, and McGrath quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-485, 101 p. Cobb, E.H., and Reed, B.L., 1981, Summaries of data on and lists of references to metallic and selected nonmetallic mineral occurrences in the Iliamna, Lake Clark, Lime Hills, and McGrath quadrangles, Alaska; Supplement to Open-File Report 76-485; Part A, Summaries to January 1, 1981: U.S. Geological Survey Open-File Report 81-1343-A, 25 p. Gamble, B.M., Bailey, E.A., and Reed, B.L., 1989, Gold occurrences near Snowcap Mountain, Lime Hills B-2 quadrangle, Alaska: U.S. Geological Survey Open-File Report 89-0646, 8 p. Reed, B.L., and Elliott, R.L., 1970, Reconnaissance geologic map, analyses of bedrock and stream sediment samples, and an aeromagnetic map of parts of the southern Alaska Range: U.S. Geological Survey Open-file Report 70-271, 24 p., 4 sheets, scale 1:250,000.
Reporters	Travis L. Hudson and Madelyn A. Millholland
Last report date	6/10/2001