Occurrence, Active

Commodities and mineralogy

Main commodities Cu; Ni
Other commodities Pd; Pt
Ore minerals chalcopyrite; pyrrhotite
Gangue minerals serpentine

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale A-4
Latitude 63.2102
Longitude -145.9144
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is at an elevation of 3,800 feet on the south flank of peak 3924 about 2.5 miles southeast of Fish Lake. It is in the NW1/4SW1/4 section 6, T. 20 S., R. 10 E., Fairbanks Meridian.

Geologic setting

Geologic description

The Antler occurrence is near the east end of the Fish Lake mafic-ultramafic intrusive complex of Late Triassic age. The occurrence was discovered by American Copper and Nickel Corporation (ACNC) geologists in 1995 and consists of disseminated pyrrhotite and chalcopyrite in wehrlite and in adjacent gabbro dikes that strike N45E and dip 75 SE. ACNC grab samples contain 0.14 percent nickel, 0.17 percent copper, 90 parts per billion (ppb) palladium, and 45 ppb platinum.
The Fish Lake complex is a south-dipping layered intrusion of dunite, peridotite, and gabbro that varies from less than 3,000 feet thick to more than 7,000 feet thick and extends for more than 24 miles in length (W.T. Ellis, oral communication, 2001). It may be a lopolithic feeder of the Nikolai basalt flows of the Wrangellia Terrane (W.T. Ellis, oral communication, 2001). The complex intrudes the Tangle Formation of Permian age (Nokleberg and others, 1991). It may connect with the Tangle complex at depth below the Amphitheater synform. Magmatic mineralization is synchronous with emplacement of the Fish Lake complex, which is part of a 120-mile-long belt of mafic-ultramafic and associated rocks in the east-central Alaska Range.
Geologic map unit (-145.916649154765, 63.2097795903811)
Mineral deposit model Ni-Cu-PGE in differentiated mafic-ultramafic sill.
Age of mineralization Late Triassic.
Alteration of deposit The peridotite is moderately serpentinized.

Production and reserves

Workings or exploration
Exploration on the Fish Lake property has been by American Copper and Nickel Company working with Fort Knox Gold Resources Inc. Exploration through 2001 included rock sampling, hand trenching, airborne and ground geophysical surveys, and completion of eight diamond drill holes (W.T. Ellis, oral communication, 2001).
The occurrence is on active claims of Fort Knox Gold Resources.
Indication of production None


Reporters W.T. Ellis (Alaska Earth Science), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS)
Last report date 6/17/2002