Unnamed (southwestern Buckstock Mountains)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; As
Other commodities Au; Sb
Ore minerals unspecified gray sulfide
Gangue minerals axinite; quartz; tourmaline

Geographic location

Quadrangle map, 1:250,000-scale SM
Quadrangle map, 1:63,360-scale A-8
Latitude 61.14126
Longitude -158.76578
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is a 0.6-mile-long area on a northeast-trending ridge overlooking an unnamed tributary of the Buckstock River. The coordinates are for the center of the area which is at elevation of about 1,900 feet in the SE1/4 sec. 12, T. 12 N., R. 53 W., of the Seward Meridian. The location is accurate.

Geologic setting

Geologic description

This occurrence consists of a large swarm of hydrothermally altered of dikes of granite porphyry to alaskite that intrudes sedimentary rocks of the Mesozoic Gemuk Group (Cady and others, 1955; T.K. Bundtzen, unpublished field field data, 1999). The altered area includes numerous quartz-tourmaline-axinite-bearing veins that are associated with highly altered felsic dikes that, based on rubble-crop, strike northeast and dip steeply. The zone of alteration can be traced N70E about 0.6 mile and has a width of from 50 to 300 feet. The quartz veins contains blades of an unidentified gray sulfide mineral in small hairline fractures. In some areas the alteration zone contains tourmaline and axinite-bearing breccias that replace alaskite dikes. Grab samples of tourmaline-quartz veins contain up to 437 parts per million (ppm) arsenic, 700 parts per billion (ppm) silver, 18 ppb gold, and 29 ppm antimony (T.K. Bundtzen, unpublished analytical data, 1999).
Geologic map unit (-158.768105750629, 61.140546157517)
Mineral deposit model Silver-polymetallic veins? (Cox and Singer, 1986; model 20b).
Mineral deposit model number 20b?
Age of mineralization Unknown. Miller and others (2002) give a U-Pb age of 59.2 Ma for the Buckstock pluton.
Alteration of deposit Development of tourmaline-axinite-quartz greisen.

Production and reserves

Workings or exploration Surface sampling and mapping was completed by the U.S. Geological Survey in 1999.
Indication of production None

References

References

Reporters T.K. Bundtzen (Pacific Rim Geological Consulting, Inc.) and M.L. Miller (U.S. Geological Survey)
Last report date 5/8/2003