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Unnamed (head of Ohio Creek)

Prospect, Inactive

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Commodities and mineralogy

Main commodities Ag; Sn
Other commodities Au; Cu; Nb; Ta; W; Zn
Ore minerals arsenopyrite; cassiterite; gold; wodginite
Gangue minerals feldspar; muscovite; quartz; tourmaline

Geographic location

Quadrangle map, 1:250,000-scale HE
Quadrangle map, 1:63,360-scale A-6
Latitude 63.19
Longitude -149.93
Nearby scientific data Find additional scientific data near this location
Location and accuracy The prospect is at an elevation of about 3,500 feet at the northwest edge of the glacial moraine at the head of Ohio Creek. The site is on the boundary of secs. 7 and 18, T. 20 S., R. 12 W., of the Fairbanks Meridian. The accuracy of the location is within 0.5 mile. This is locality 18 of Cobb (1978, OFR 78-1062).

Geologic setting

Geologic description

The host rock at this prospect is Upper Cretaceous to Upper Jurassic, intensely deformed and locally highly metamorphosed flysch which is several thousand meters thick (Wilson and others, 1998). The strata have been intruded by a granitic stock 1 mile long by 0.5 mile wide. The deposit consists of tourmaline and muscovite greisen and quartz-arsenopyrite veins. The greisen is up to 10 feet thick. It adjoins a biotite-rich inclusion at least 150 feet long, and locally contains 0.1% Sn (Hawley and others, 1969). The upper 3 to 10 feet of the granitic body contains pegmatitic quartz-arsenopyrite veins that parallel the contact with country rock (Hawley and Clark, 1974). The veins also contain wodginite, a manganese-tin-niobium oxide, and 1.25% tungsten, 147 ounces of silver per ton and traces of tin, lead, and copper (Hawley and others, 1978).
Geologic map unit (-149.932292050627, 63.1895204944576)
Mineral deposit model Sn greisen (Cox and Singer, 1986; model 15c)
Mineral deposit model number 15c
Age of mineralization Late Cretaceous or younger.
Alteration of deposit Greisenization.

Production and reserves

Workings or exploration There has been minor surface exploration. Veins contain wodginite, a manganese-tin-niobium oxide, and 1.25% tungsten, 147 ounces of silver per ton and traces of tin, lead, and copper (Hawley and others, 1978).
Indication of production None

Additional comments

Stream sediment samples taken from area adjacent to granitic stock suggest undiscovered vein deposits in country rock.

References

MRDS Number A011329

References

Balen, M.D., 1990, Geochemical sampling results from Bureau of Mines investigations in the Valdez Creek mining district, Alaska: U.S. Bureau of Mines Open-File Report 34-90, 218 p., 2 sheets, scale 1:63,360.
Capps, S.R., 1919, Mineral resources of the upper Chulitna region: U.S. Geological Survey Bulletin 692-D, p. 207-232.
Capps, S.R., 1924, Geology and mineral resources of the region traversed by the Alaska Railroad: U.S. Geological Survey Bulletin 755-C, p. 73-150.
Clark, A.L., and Cobb, E.H., 1972, Metallic mineral resources map of the Healy quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-394, 1 sheet, scale 1:250,000.
Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Healy quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-1062, 113 p.
Hawley, C.C., and Clark, A.L., 1974 (1975), Geology and mineral deposits of the upper Chulitna district, Alaska: U.S. Geological Survey Professional Paper 758-B, p. B1-B47, 2 plates, scale 1:12,000 and 1:48,000.
Hawley, C.C., and others, 1978, Mineral appraisal of lands adjacent to Mt. McKinley National Park, Alaska. Contract No. JO166107: U.S. Bureau of Mines Open-File Report 24-78, 274 p., 12 sheets.
Hawley, C.C., Clark, A.L., Herdrick, M.A., and Clark, S.H.B., 1969, Results of geological and geochemical investigations in an area northwest of the Chulitna River, central Alaska Range: U.S. Geological Survey Circular 617, 19 p.
Nokleberg, W.J., and (seven) others, 1994, Metallogeny and major mineral deposits of Alaska and Metallogenic map of significant metalliferous lode deposits and placer districts of Alaska, in Plafker, G. and Berg, H.C., eds., The Geology of Alaska: Geological Society of America, DNAG, The Geology of North America, Vol.. G1, p. 855-904, Plate 11, scale 1:2,500,000.
Ross, C.P., 1933, The Valdez Creek mining district, Alaska: U.S. Geological Survey Bulletin 849-H, p.425-468.
Wilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of central (interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 76 p., 3 sheets, scale 1:500,000.
Reporters N. Van Wyck (Stevens Exploration Management Corporation)
Last report date 4/7/2000