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West Chilligan

Occurrence, Inactive

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Commodities and mineralogy

Main commodities Ag; Cu; Mo; Pb; Zn
Ore minerals chalcopyrite; galena; molybdenite; pyrite; sphalerite
Gangue minerals clay; chlorite; quartz; sericite

Geographic location

Quadrangle map, 1:250,000-scale LH
Quadrangle map, 1:63,360-scale B-1
Latitude 61.4668
Longitude -153.2472
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is on the east side of an unnamed north tributary valley to the upper Chilligan River. It is near the toe of a small glacier at an elevation of about 5,000 feet, 0.9 mile north-northwest of peak 6237. The map site is in the NE1/4 section 20, T 16 N, R 22 W, of the Seward Meridian. This occurrence is included under the name West Chilligan by Cobb and Reed (1981); it is location 31 of Gamble and others (1989). It is approximately located, perhaps within one-half mile.

Geologic setting

Geologic description

This occurrence consists mainly of pyrite-filled fractures and of quartz-chlorite veins containing traces of chalcopyrite, galena, and sphalerite in argillized granitic rocks. Disseminated sulfides are present locally, and molybdenite occurs as coarse flakes in some quartz veins. Rock samples contained from 0.1 to 1.6 percent copper (Resource Associates of Alaska, 1976). Geochemical anomalies trend northwest and may be controlled by splays of a regional northwest-southeast fault in Chilligan River valley. The granitic host rocks are small stocks of Tertiary granodiorite that intrude locally mineralized quartz diorite (Cobb and Reed, 1981). The granitic rocks are overlain by barren volcanic rocks.
Geologic map unit (-153.24941703712, 61.4661705109859)
Mineral deposit model Porphyry Cu-Mo (Cox and Singer, 1986, model 21a)
Mineral deposit model number 21a
Age of mineralization Tertiary. Sulfide-bearing quartz veins crosscut Tertiary granitic rocks.
Alteration of deposit Argillization and quartz-chlorite veining.

Production and reserves

Workings or exploration Reconnaissance surface observation and sampling has been completed in this area.
Indication of production None

Additional comments

This occurrence is within Lake Clark National Park.

References

MRDS Number A013077

References

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.
Resource Associates of Alaska, Inc., 1976, Geology and geochemistry of certain land within the Lake Clark National Park: Contract report for U.S. Bureau of Mines, Contract JO166108, 7 v.
Reporters Travis L. Hudson and Madelyn A. Millholland
Last report date 6/10/2001