Unnamed Occurrence (ARDF - MH178; Fish Lake), Delta River Mining District, Southeast Fairbanks Census Area, Alaska, USAi

Regional Level Types
Unnamed Occurrence (ARDF - MH178; Fish Lake)	- not defined -
Delta River Mining District	Mining District
Southeast Fairbanks Census Area	Census Area
Alaska	State
USA	Country

Location: This occurrence is located on the hill southeast of Fish Lake at an elevation of 3,900 feet. It is in the NW1/4NE1/4 section 1, T. 20 S., R. 9 E., Fairbanks Meridian. The site corresponds to locality S72 in table 2 of Nokleberg and others (1991) and represents localities S73 and S74, which were similar occurrences within a mile of this one.
Geology: The rocks in the area of this occurrence are part of the Fish Lake mafic-ultramafic intrusive complex of Late Triassic age, which may be a lopolithic feeder of the Nikolai basalt flows of the Wrangellia terrane (W.T. Ellis, oral communication, 1998). Serpentinized olivine-pyroxene cumulate in the complex contains sparsely disseminated chromite. Grab samples contain 5,000 (or more) parts per million chromium (Nokleberg and others, 1991, see sample 9ZN022A). The Fish Lake ultramafic-mafic 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). 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.
Workings: 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 area is on active claims of Fort Knox Gold Resources.
Age: Late Triassic.
Alteration: The olivine-pyroxene cumulate inclusion is serpentinized.

Commodities (Major) - Cr
Development Status: None
Deposit Model: Disseminated chromite in a layered mafic-ultramafic complex.

Other Databases

Link to USGS - Alaska:	MH178

Other Regions, Features and Areas containing this locality

References