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Unnamed (south of Flat Creek)

Prospects, Inactive

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Commodities and mineralogy

Main commodities Cu
Other commodities Au; Pb; W
Ore minerals chalcopyrite
Gangue minerals carbonate; quartz; tourmaline

Geographic location

Quadrangle map, 1:250,000-scale GU
Quadrangle map, 1:63,360-scale C-1
Latitude 62.73
Longitude -144.13
Nearby scientific data Find additional scientific data near this location
Location and accuracy The site consists of several occurrences near an unnamed prospect (Cobb, 1979 [OFR 79-1247, p. 30] on the north side of the center part of the broad ridge between Cobb Lakes and Flat Creek. The broad ridge was called the Grizzly Hills by Kirk Stanley (written communication, 2000). The prospects are about 0.4 miles, south-southwest of a prospect mapped by Richter (1966, fig. 5). It is within a broad lead-zinc geochemical anomaly defined by Richter (1966) and a nearly coincident, gold geochemical anomaly defined by WGM Inc. (WGM Inc., 1980; anomaly 3a). The locality is approximately the same as number 11 of Richter and Matson (1972), and number 27 of MacKevett and Holloway (1977). The occurrences are in the NE1/4SE1/4, section 17, T. 11 N,. R. 7 E., Copper River Meridian.

Geologic setting

Geologic description

The area consists mainly of the Grubstake, medium-grained quartz monzonite phase of the Pennsylvanian to Permian, Ahtell pluton and its quartz-rich border phase (Richter, 1966). The area has widespread mineralization. Richter (1966 fig. 5) mapped a prospect with a sulfide-bearing quartz-carbonate vein at an elevation of about 3,400 feet in the drainage north of the ridge. Rocks nearby contain disseminated chalcopyrite. WGM Inc. (WGM Inc., 1980) mapped a half-mile-long altered area containing sulfide veins centered on this location. Stream sediments in the drainage below Richter's prospect contained 700 ppb gold and the south-draining stream from the ridge contained 300 ppm tungsten. Kirk Stanley (written communication, 2000) reported the existence of tourmaline and silver-lead veins on the Grizzly Hills but without specifying an exact location.
Geologic map unit (-144.132184265299, 62.7296061824606)
Mineral deposit model Polymetallic vein (Cox and Singer, 1986; model 22c)
Mineral deposit model number 22c
Age of mineralization Emplaced subseqent to or is related to the border phase of the Pennsylvanian to Permian, Ahtell pluton.
Alteration of deposit Tourmaline.

Production and reserves

Workings or exploration The area has been explored intermittently by reconnaissance mapping, sampling, and minor bulldozer trenching since about 1963.
Indication of production None

Additional comments

Additional information can be obtained from Ahtna Minerals in Anchorage, Alaska.

References

MRDS Number A011849

References

Cobb, E.H., 1979, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Gulkana quadrangle, Alaska: U.S. Geological Survey Open-File Report 79-1247, 36 p.
MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous and selected non-metalliferous mineral deposits in the eastern part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-A, 99 p., 1 sheet, scale 1:1,000,000.
Richter, D.H., 1966, Geology of the Slana district, southcentral Alaska: Alaska Division of Geological and Geophysical Surveys Geological Report 2l, 54 p., 3 sheets, scale 1:63,360.
Richter, D.H., and Matson, N.A., Jr., 1972, Metallic mineral resources map of the Gulkana quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-419, 1 sheet, scale 1:250,000.
WGM Inc., 1980, 1979 Summary report of gold potential, Slana District, Ahtna project: WGM Inc., 10 p., map, scale 1:63,360. (Report held by Ahtna Mineral Co., Anchorage, Alaska).
Reporters W.T. Ellis (Alaska Earth Sciences), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (U.S. Geological Survey)
Last report date 12/5/2000