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West Ospook

Occurrence, Inactive

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Commodities and mineralogy

Main commodities Cu
Other commodities Mo; Pb
Ore minerals chalcopyrite; magnetite; pyrite

Geographic location

Quadrangle map, 1:250,000-scale LC
Quadrangle map, 1:63,360-scale A-3
Latitude 60.14
Longitude -153.92
Nearby scientific data Find additional scientific data near this location
Location and accuracy Locality is approximately 2.4 km west of the mouth of Ospook Creek, along an unnamed northward flowing stream which drains into Kontrashibuna Lake. This is locality 35 of Nelson and others (1985) and locality 34 of MacKevett and Holloway (1977). Sec. 35, T. 1 N., R. 27 W., of the Seward Meridian. Location is accurate to about 1.6 km.

Geologic setting

Geologic description

Occurrence is associated with sulfide mineralization near contact between Tertiary granodiorite and Tertiary andesite porphyry. Sulfide mineralization is disseminated but mineralization is strongest along fracture zones at the contact of the granodiorite and andesite. Undefined Mo and Pb sulfide minerals occur at this locality. Andesite locally contains 2 to 4 percent disseminated pyrite, magnetite, and trace chalcopyrite. In the vicinity of the site andesite porphyry, tuffs, agglomerates, and other intermediate volcanic rocks are intruded by small gabbro and granodiorite bodies. Soil and stream sediment samples yielded values of up to 1,800 ppm Cu, 183 ppm Mo, and 230 ppm Pb (Resource Associates of Alaska, 1976).
Geologic map unit (-153.922193572476, 60.1393409927285)
Mineral deposit model Porphyry Cu-Mo? (Cox and Singer, 1986; model 21a?).
Mineral deposit model number 21a?
Age of mineralization Tertiary or younger.

Production and reserves

Workings or exploration Soil and stream sediment samples yielded values of up to 1,800 ppm Cu, 183 ppm Mo, and 230 ppm Pb (Resource Associates of Alaska, 1976).
Indication of production None
Reserve estimates No reserves
Production notes No production

Additional comments

Possibility for hydrothermal vein or replacement deposit in the andesite near the granodiorite or along strongly fractured fault zones. Site is in Lake Clark National Park and Preserve.

References

MRDS Number A013013

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.
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 B, Lists of references to Januray 1, 1981: U.S. Geological Survey Open-File Report 81-1343-B, 20 p.
MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous mineral deposits in the western part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-F, 38 p., 1 sheet, scale 1:1,000,000.
Nelson, W.H., King, H.D., Case, J.E., Tripp, R.B., Crim, W.D., and Cooley, E.F., 1985, Mineral resource map of the Lake Clark quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1114-B, 1 sheet, scale 1:250,000.
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 M.L. Miller (USGS); D.P. Bickerstaff (USGS)
Last report date 6/15/1998