Unnamed (near head of east fork of Broxson Gulch)

Occurrence, Undetermined

Commodities and mineralogy

Main commodities Ag; Au; Cu; Zn
Ore minerals chalcopyrite; magnetite; pyrite; pyrrhotite

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale B-5
Latitude 63.3346
Longitude -146.0087
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is at an elevation of about 4,900 feet about a mile south of the head of the east fork of Broxson Gulch. It is about 0.7 mile northwest of peak 6346, about 0.4 mile northeast of peak 5995, and about 0.6 mile southwest of the center of section 22, T. 18 S., R. 9 E.

Geologic setting

Geologic description

The rocks in the area are limestone and calcareous sedimentary rocks of the Pennsylvanian and Permian, Slana Spur Formation that are intruded by Triassic gabbro dikes (Rose, 1965; Nokleberg and others, 1992 [MF]; 1992 [Open-File]). Bittenbender and others (2007) identified an area about 5 feet by 20 feet in outcrop of iron-stained clinopyroxene-garnet-magnetite skarn with a small amount of chalcopyrite, pyrrhotite, and pyrite. A sample contained more than 15 percent iron, but only 177 parts per million (ppm) copper and no gold. A sample collected by Nokleberg and others (1991) contained 1.2 ppm gold, 300 ppm silver, and 720 ppm zinc. The source of the mineralization at this occurrence may be the gabbro dikes.
Geologic map unit (-146.010963716935, 63.3341817881719)
Mineral deposit model Skarn related to gabbro dikes.
Age of mineralization Possibly related to nearby Triassic gabbro dikes.
Alteration of deposit Silver-gold-copper mineralization in skarn near gabbro dikes.

Production and reserves

Workings or exploration Examined and sampled only by state and federal agencies.
Indication of production None
Reserve estimates None.
Production notes None.

References

MRDS Number A011822

References

Reporters W.T. Ellis (Alaska Earth Sciences), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS); D.J. Grybeck (Contractor, USGS)
Last report date 5/13/2012