Sheep Creek-West Prospect, Yukon-Koyukuk Census Area, Alaska, USAi

Regional Level Types
Sheep Creek-West Prospect	Prospect
Yukon-Koyukuk Census Area	Census Area
Alaska	State
USA	Country

Location: The Sheep Creek-West prospect is located on the west side of Sheep Creek Valley just below the intersection of the Rat Fork and the South Fork of Sheep Creek at an elevation of 3,400 feet (1,036 m) in the SW1/4 sec. 13, T. 26 N., R. 24 W., of the Seward Meridian. The location is accurate; the reporter visited the site in 1981.
Geology: The Sheep Creek-West prospect contains oxidized, sulfide mineralization in a steeply dipping, northeast-striking fault (?) zone, 2 to 3 meters wide that juxtaposes silty limestone against tan arkosic sandstone; both lithologies belong to the Lower to Upper Silurian Terra Cotta Mountains Sandstone, a formation within the Dillinger subterrane (Bundtzen, Harris, and Gilbert, 1997). The zone strikes northeast for a minimum distance of 135 meters and is marked by a distinctive notch along the steep sidehill. Sphalerite, galena, chalcopyrite and pyrrhotite that are accompanied by a gangue of epidote, johannsenite, and garnet replace limestone in vug fillings and shear zones (Bundtzen, Kline, and Clough, 1982). Abundant malachite stain and replacements is locally abundant and a locally conspicuous feature along the fault zone. Two chip samples collected across about 3 meters of the zone contain up to 0.85 percent copper, 1.01 percent lead, 0.58 percent zinc, 30 ppm cadmium, 86 grams/tonne silver, and 0.60 grams/tonne gold (Bundtzen, Kline, and Clough, 1982). The vein appears to be spatially related to nearby polymetallic veins at the Dahl (MG053), and the Sheep Creek-South (MG057) prospects, within the Farewell Mineral Belt. The structurally controlled vein mineralization at the Sheep Creek-West prospect may be distally related to skarn mineralization observed throughout the Farewell Mineral Belt.
Workings: Surface sampling was conducted by the reporter in 1981. Two chip-channel samples collected across a 3 meter width of the vein contained 0.85 percent copper, 1.01 percent lead, 0.58 percent zinc, 30 ppm cadmium, 86 grams/tonne silver, and 0.60 grams/tonne gold (Bundtzen, Kline, and Clough, 1982).
Alteration: Sulfides are highly oxidized with conspicuous cerrusite, iron oxides, and malachite replacements.
Reserves: None.

Commodities (Major) - Ag, Cu, Pb, Zn; (Minor) - Au, Cd
Development Status: No
Deposit Model: Polymetallic vein (Cox and Singer, 1986; model 22c).

Other Databases

Link to USGS - Alaska:	MG052

Other Regions, Features and Areas containing this locality

References