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Unnamed (near headwaters of Takahula River)

Occurrence, Inactive

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Commodities and mineralogy

Main commodities F; Sn; Zn
Other commodities As; Be; Bi; Sn
Ore minerals fluorite; sphalerite
Gangue minerals calc-silicate minerals

Geographic location

Quadrangle map, 1:250,000-scale SP
Quadrangle map, 1:63,360-scale B-2
Latitude 67.32
Longitude -153.99
Nearby scientific data Find additional scientific data near this location
Location and accuracy This site is at an elevation of about 3500 feet near the headwaters of the Takahula River. It is in the N1/2 of sec. 9, T. 22 N., R. 22 E., of the Kateel River Meridian. The location is accurate to within 2000ft. The site corresponds to locality 52 of Grybeck and Nelson (1981).

Geologic setting

Geologic description

This occurrence consists of a skarn deposit in an approximately 1000 x 500 ft. area at the contact of Devonian granite with Paleozoic calcareous rocks (Nelson and Grybeck, 1980). Epidote-garnet, magnetite-quartz-hornblende, and magnetite-hornblende skarns contain erratically distributed sphalerite and fluorite. Analyses of numerous grab samples show as much as 7000 ppm As, and most show 700 to 1000 ppm Be, 100 to 200 ppm Bi, and 500 to 1000 ppm Zn. Sn values range from 500 to more than 1000 ppm Sn, but petrographic examination indicates that the Sn is not present as an oxide or sulfide. This occurrence is one of many skarn deposits adjacent to the Devonian granite and is similar to others elsewhere in the Brooks Range (Newberry and others, 1986).
Geologic map unit (-153.992799783306, 67.3195048501538)
Mineral deposit model Skarn (Cox and Singer, 1986; model 14b)
Mineral deposit model number 14b
Age of mineralization Devonian; related to the intrusion of Devonian pluton.
Alteration of deposit Contact metamorphic.

Production and reserves

Indication of production None

Additional comments

Located within Gates of the Arctic National Park.

References

MRDS Number A011918

References

Grybeck, D.J., and Nelson, S.W., 1981, Mineral deposit map of the Survey Pass quadrangle, Brooks Range, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1176-F, 1 sheet, scale 1:250,000.
Nelson, S.W., and Grybeck, D.J., 1980, Geologic map of the Survey Pass quadrangle, Brooks Range, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1176-A, 2 sheets, scale 1:250,000.
Newberry, R.J., Dillon, J.T., and Adams, D.D., 1986, Regionally metamorphosed calc-silicate-hosted deposits of the Brooks Range, northern Alaska: Economic Geology, v. 81, p. 1728-1752.
Reporters S.W. Nelson (Anchorage, Alaska)
Last report date 9/21/1999