Unnamed (headwaters of Kobuk River)

Occurrences, Inactive

Commodities and mineralogy

Main commodities Sn
Other commodities As; Be; Bi; Sb
Gangue minerals calc-silicates

Geographic location

Quadrangle map, 1:250,000-scale SP
Quadrangle map, 1:63,360-scale B-3
Latitude 67.31
Longitude -154.39
Nearby scientific data Find additional scientific data near this location
Location and accuracy This site represents two occurrences in an east-trending mile-long area near the headwaters of the Kobuk River. The map site is at the center of the area, sec. 15, T. 22 N., R. 20 E., of the Kateel River Meridian. Location is accurate to within 2000 ft. The site corresponds to localities 47 and 48 of Grybeck and Nelson (1981).

Geologic setting

Geologic description

The occurrences consist of sparse float of vein or segregation quartz in foliated porphyritic granite of Devonian age (Nelson and Grybeck, 1980) and
of abundant skarn near the contact of the granite with Paleozoic carbonates (Nelson and Grybeck, 1981). Selected samples of float contain 5000 ppm As, 200 ppm Be, 30 to 100 Bi ppm, 200 ppm Sb, and 500 to 1000 ppm Sn. These occurrences are similar to other contact-metamorphic deposits elsewhere in the Brooks Range (Newberry and others, 1986).
Geologic map unit (-154.392772313483, 67.309501625378)
Mineral deposit model Skarn (Cox and Singer, 1986; model 14b)
Mineral deposit model number 14b
Age of mineralization Devonian; related to the intrusion of the Devonian pluton.
Alteration of deposit Skarn.

Production and reserves

Indication of production None

Additional comments

Located within Gates of the Arctic National Park.

References

MRDS Number 10308334

References

Reporters S.W. Nelson (Anchorage, Alaska)
Last report date 9/21/1999