Unnamed Prospect (ARDF - SW002; on western Nakchamik Island), Alaska Peninsula District, Lake and Peninsula Borough, Alaska, USA
Latitude & Longitude (WGS84): | 56° 20' 24'' North , 157° 52' 47'' West |
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Latitude & Longitude (decimal): | 56.34000,-157.87972 |
This site is on land selected by the Koniag Native Corporation.
Location: This site is on the western part of Nakchamik Island which is located approximately 10 miles south of Cape Kumliun in Chignik Bay (MacKevett and Holloway, 1977, locality 8; Cox and others, 1981, locality 5). Site location is at an elevation of about 700 feet and is accurate to within 1/2 mile.
Geology: On Nakchamik Island, dacite plug domes intrude Oligocene and Eocene volcanic rocks of the Meshik Formation (Detterman and others, 1981). The prospect is marked by a large color anomaly. Closely-spaced quartz(?) veinlets containing abundant pyrite and chalcopyrite have been noted. Stream-sediment samples contain anomalous values in copper, lead, silver, and zinc and many contain barite. Cox and others (1981) report the grade of surface samples at <0.2 percent copper. Sixteen rock samples were collected in the 1970's by the U.S. Geological Survey (Yount and others, 1978). The highest values obtained were 1600 ppm copper, 130 ppm lead, and 260 ppm zinc.
Workings: Remnants of old mining equipment have been found at this prospect, indicating early exploration. The U.S. Geological Survey collected 16 rock samples in the 1970's (Yount and others, 1978). The highest metal values obtained were 1600 ppm copper, 130 ppm lead, and 260 ppm zinc. Cox and others (1981) report surface copper values at <0.2 percent.
Age: Tertiary.
Alteration: Country rocks are propylitically and sericitically altered. The area is marked by a large color anomaly.
Commodities (Major) - Cu; (Minor) - Pb, Zn
Development Status: None
Deposit Model: Porphyry copper (Cox and Singer, 1986, model 17)
Mineral List
6 valid minerals.
Regional Geology
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
Tertiary 2.588 - 66 Ma | Hypabyssal intrusions Age: Cenozoic (2.588 - 66 Ma) Description: Fine to coarse crystalline, light- to dark-gray dacite. Numerous small hypabyssal plug domes and associated dikes. Lithology: Igneous Reference: Wilson, F.H., Hults, C.P., Mull, C.G, and Karl, S.M. (compilers). Geologic map of Alaska. doi: 10.3133/sim3340. U.S. Geological Survey Scientific Investigations Map 3340, pamphlet 196. [21] |
Data and map coding provided by Macrostrat.org, used under Creative Commons Attribution 4.0 License