Clearwater Mountain claims; 'Joy Creek' block Prospect, Valdez Creek Mining District, Matanuska-Susitna Borough, Alaska, USAi

Regional Level Types
Clearwater Mountain claims; 'Joy Creek' block Prospect	Prospect
Valdez Creek Mining District	Mining District
Matanuska-Susitna Borough	Borough
Alaska	State
USA	Country

Location: A cluster of mineral deposits at elevations of 4,200 to 4,600 feet occurs near the center of section 29, T. 19 S., R. 5 E., Fairbanks Meridian. The location for this record is about at the center of the section. The mineralized area includes locality 4 of Clautice and others (1989), which lies west-northwest of the center of section 29, and several mineral locations of R.A. Blakestad (written communication, 1980), which lie east of the center of section 29. The location is accurate as the approximate center of a group of mineral deposits. This site was called the Joy Creek area by Blakestad and G.A. Moerlein (written communications, 1980), who mapped the area in detail in about 1980.
Geology: The mineral deposits of the locally named Joy Creek area are in complexly faulted rocks in the footwall of a major thrust (Clautice and others, 1989, plate 1). Mineralized rocks in the footwall zone include greenstone of probable Late Triassic age, skarn in limestone, also believed to be Triassic, and argillite and andesitic volcanic rocks of uncertain age. Mineral deposits are of diverse types. A mineral deposit about 400 feet west-northwest of the center of section 29 consists of gray-green epidote-silica rock that contains disseminated pyrite and chalcopyrite; it is locally stained with malachite. A sample assayed 295 parts per billion (ppb) gold, 1,775 parts per million (ppm) copper, and 400 ppm tungsten (Clautice and others, 1989, locality 4). Several deposits are clustered about 500 feet east-southeast of the center of section 29. A gold-bearing copper skarn occurs south of, and parallel to, a quartz porphyry dike; gold also occurs in slightly altered sedimentary rocks east of a fault that appears to cut off the skarn body. The copper-bearing skarn contains as much as 5.5 ppm gold; the metasedimentary rocks contain as much as 7.6 ppm gold (R.A. Blakestad, written communication, 1980). Anomalous values in stream-sediment and pan-concentrate samples seem to indicate widespread mineralization. Pan-concentrate samples collected by Blakestad from the small creeks below the mineral occurrences contained gold and scheelite and had anomalous values of silver. A pan-concentrate sample collected in the main drainage about one mile west of the tributary creeks contained anomalous amounts of gold, silver, tungsten, and molybdenum (O'Leary and others, 1982).
Workings: The area was mapped and sampled in detail in 1980 by Rodney A. Blakestad for Mankomen Exploration and by George A. Moerlein for Occidental Minerals Co. (written communications, 1980). Regional geologic work and sampling was done on behalf of the U.S. Bureau of Mines by the Alaska Division of Geological and Geophysical Surveys (Clautice and others, 1988, 1989).
Age: Possibly Cretaceous, synchronous with regional metamorphism and emplacement of quartz porphyry dikes.
Alteration: Silicification; formation of skarn in limy rocks.

Commodities (Major) - Au, Cu; (Minor) - Ag, Mo, W
Development Status: Undetermined.
Deposit Model: Complex epigenetic mineralization, including skarn and replacement deposits in

Other Databases

Link to USGS - Alaska:	MH055

Other Regions, Features and Areas containing this locality

References