Lower Canwell Prospect, Delta River Mining District, Southeast Fairbanks Census Area, Alaska, USAi

Regional Level Types
Lower Canwell Prospect	Prospect
Delta River Mining District	Mining District
Southeast Fairbanks Census Area	Census Area
Alaska	State
USA	Country

Location: The prospect is at an elevation of 4,600 feet on the southwest valley wall of lower Canwell Glacier, just south of MH227. It is in the SE1/4NW1/4 section 26, T. 18 S., R. 11 E., Fairbanks Meridian. Access to the property is by a 3-mile-long trail from the end of a dirt road (not shown on the 1984 topographic map) on the east side of the Richardson Highway at mile 213.5, approximately 1 mile south of Millers Roadhouse. The site described by Barker (1988) corresponds to American Copper and Nickel Company's Lower Canwell prospect (W.T. Ellis, oral communication, 1998).
Geology: At this prospect, disseminations and massive segregations of pyrrhotite, chalcopyrite, and pentlandite, with associated cobalt, platinum group element (PGE) minerals, and gold, are in serpentinite, gabbronorite dikes and sills, and contact-related deposits (Foley and others, 1989). The sulfides are also disseminated in mafic gabbro at the base of the mafic and ultramafic rocks of the Canwell complex of Late Triassic age, a 2.5-mile-long by 0.5-mile-wide southwest-dipping sill that is intruded by a Cretaceous or Tertiary quartz diorite to quartz monzonite stock (W.T. Ellis, oral communication, 1998). Locally, the chalcopyrite is oxidized to malachite, and the serpentine is altered to chrysotile. The complex consists of a dunite core that grades outward into wehrlite, feldspathic peridotite, and mafic gabbro (W.T. Ellis, oral communication, 1998). Fort Knox Gold Resources, Inc. has reported that a mineralized mafic gabbro grab sample contained 0.42 percent nickel, 0.87 percent copper, 332 parts per billion (ppb) gold, 790 ppb palladium, and 825 ppb platinum (A.T. MacGibbon, written communications, 1997-2001). A U.S. Bureau of Mines total PGE analysis of a grab sample of quartz diorite or mafic gabbro containing disseminated sulfides assayed 1.55 percent copper, 2.65 percent nickel, 368 ppb gold, 400 ppb platinum, 600 ppb palladium, 100 ppb osmium, 45 ppb rhodium, and 40 ppb ruthenium (Barker, 1988). A U.S. Bureau of Mines gabbronorite sample contained 0.6 percent copper, 0.37 percent nickel, 137 ppb gold, 200 ppb platinum, and 370 ppb palladium (Barker, 1988).
Workings: Exploration in this area has been by American Copper and Nickel Company (ACNC) working with Fort Knox Gold Resources, Inc. Exploration from 1994 through 2001 included rock sampling, hand trenching, airborne and ground geophysical surveys, and completion of five diamond drill holes. Fort Knox Gold Resources has reported that a mineralized mafic gabbro grab sample contained 0.42 percent nickel, 0.87 percent copper, 332 parts per billion (ppb) gold, 790 ppb palladium, and 825 ppb platinum (A.T. MacGibbon, written communications, 1997-2001). A U.S. Bureau of Mines total platinum group element (PGE) analysis of a grab sample of quartz diorite or mafic gabbro containing disseminated sulfides that assayed 1.55 percent copper, 2.65 percent nickel, 368 ppb gold, 400 ppb platinum, 600 ppb palladium, 100 ppb osmium, 45 ppb rhodium, and 40 ppb ruthenium (Barker, 1988). A U.S. Bureau of Mines gabbronorite sample contained 0.6 percent copper, 0.37 percent nickel, 137 ppb gold, 200 ppb platinum, and 370 ppb palladium (Barker, 1988). The prospect is on active claims of Fort Knox Gold Resources.
Age: Late Triassic.
Alteration: Local oxidation of chalcopyrite to malachite, and alteration of the serpentine to chrysotile.

Commodities (Major) - Au, Co, Cu, Ni, Pd, Pt; (Minor) - Os, Rh, Ru
Development Status: None
Deposit Model: Ni-Cu-PGE in differentiated mafic-ultramafic sill.

Other Databases

Link to USGS - Alaska:	MH228

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References