Unnamed Occurrence (ARDF - GO007; west of Kemuk River), Bristol Bay Region District, Dillingham Census Area, Alaska, USAi

Regional Level Types
Unnamed Occurrence (ARDF - GO007; west of Kemuk River)	- not defined -
Bristol Bay Region District	- not defined -
Dillingham Census Area	Census Area
Alaska	State
USA	Country

Location: This occurrence is on the west side of Kemuk River, 2 miles southeast of Atshichlut Mountain. It is area 4 of Kilburn and others (1993) and also includes areas of copper-bearing mineralization noted by Hoare and Cobb (1977) along a north-trending fault west of Kemuk River (Hoare and Coonrad, 1978). The map site is at an elevation of about 1,300 feet, just east of the center of section 34, T 5 S, R 62 W, of the Seward Meridian. It is approximately located, perhaps within a mile.
Geology: The upland between Togiak Lake and Kemuk River is cored by a large, Cretaceous(?) granitic pluton with a well-developed hornfels aureole (Hoare and Coonrad, 1978). Many stream-sediment samples in this area contain anomalous amounts of copper and manganese (Cieutat and others, 1988; Hessin and others, 1978 [OF 78-9-M]). A large north-trending, high-angle fault transects the area just to the west of Kemuk River. Hoare and Cobb (1977) reported copper-bearing minerals in volcaniclastic rocks along this fault. Large debris fans on the west side of Kemuk River contain blocks of volcanic sandstone, bleached and iron-stained argillite, and highly silicified argillite that contain milky quartz veins, disseminated pyrite, and thin pyrite veinlets (Kilburn and others, 1992). Float samples of altered argillite contain up to 27 ppm Ag, 150 ppm As, 0.4 ppm Au, greater than 5,000 ppm Ba, 1.8 ppm Hg, 52 ppm Mo, 310 ppm Pb, and 570 ppm Zn (Kilburn and others, 1992, Table 1).
Workings: Reconnaissance stream-sediment sampling has been completed in the area.
Age: Probably Late Cretaceous. Mineralization is probably related to the granitic pluton in the area, which is part of a regionally extensive Upper Cretaceous and Lower Tertiary plutonic suite. K/Ar ages for granitic samples from the nearby pluton to the east are 63.7 +/- 2 Ma on biotite and 67.5 +/-3 Ma on hornblende (Hoare and Coonrad, 1978).
Alteration: Silicification and oxidation.

Commodities (Major) - Ag, Au, Cu; (Minor) - Hg, Mo, Pb, Zn
Development Status: None
Deposit Model: Polymetallic veins (Cox and Singer, 1986; model 22c)

Other Databases

Link to USGS - Alaska:	GO007

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References