West Fork

Prospect, Active

Commodities and mineralogy

Main commodities Ag; Pb; Zn
Other commodities Cu
Ore minerals galena; pyrite; sphalerite
Gangue minerals quartz; sericite

Geographic location

Quadrangle map, 1:250,000-scale HE
Quadrangle map, 1:63,360-scale D-1
Latitude 63.81
Longitude -147.49
Nearby scientific data Find additional scientific data near this location
Location and accuracy The West Fork prospect is at an elevation of about 4,500 feet, in the south wall of an east-flowing branch of West Fork Little Delta River. The map site is about 4 miles southwest of the junction of Forgotten Creek, in the NW1/4 of sec. 11, T. 13 S., R. 1 E., of the Fairbanks Meridian. The location is accurate to within 0.5 mile.

Geologic setting

Geologic description

The country rocks at the West Fork prospect are Upper Devonian(?) felsic metavolcanic rocks consisting of schist and phyllite, locally containing relict phenocrysts of quartz, orthoclase, and plagioclase (Wilson and others, 1998). The deposit consists of stratiform layers of massive pyrite, galena, and sphalerite, accompanied by quartz and sericite. Samples of a 20-30-centimeter-wide massive-sulfide horizon contained 3.68% lead, 4.05% zinc, 131 grams of silver per tonne and 0.38 grams of gold per tonne (www.grayd.com, 1999).
Geologic map unit (-147.49230647899, 63.8095699015989)
Mineral deposit model Kuroko massive sulfide (Cox and Singer, 1986; model 28a)
Mineral deposit model number 28a
Age of mineralization Mineralization was probably syngenetic with the Upper Devonian(?) host rocks.
Alteration of deposit Quartz and sericite.

Production and reserves

Workings or exploration The prospect has been explored by surface sampling, geophysical work, and one drill hole (Inmet Mining, personal communication, 1999). Samples of a 20-30-centimeter-wide massive-sulfide horizon contained 3.68% lead, 4.05% zinc, 131 grams of silver per tonne and 0.38 grams of gold per tonne (www.grayd.com, 1999).
Indication of production None

References