Unnamed Occurrence (ARDF - MH244; south side of the West Fork Robertson River valley), Tok Mining District, Southeast Fairbanks Census Area, Alaska, USAi

Regional Level Types
Unnamed Occurrence (ARDF - MH244; south side of the West Fork Robertson River valley)	- not defined -
Tok Mining District	Mining District
Southeast Fairbanks Census Area	Census Area
Alaska	State
USA	Country

Unpublished data cited is available for viewing by contacting Grayd Resources Inc. in Vancouver, B. C., Canada (www.grayd.com), or Northern Associates Inc. in Fairbanks, Alaska.
Location: This unnamed occurrence is about 1.8 miles southwest of the mouth of Rock Candy Creek. It is at an elevation of about 4,000 feet in the SE1/4 section 31, T. 18 S., R. 16 E., Fairbanks Meridian. The occurrence is on the moraine of the glacier at the head of the West Fork Robertson River near the junction with a smaller tributary glacier. The location is accurate.
Geology: Two types of massive sulfide mineralization were found on glacial moraine here during geological reconnaissance in 1975. These occurrences contain sparse base metal concentrations. Banded pyrrhotite with approximately 1 percent combined copper, lead, and zinc is in carbonate breccia with siliceous fragments. Pyrrhotite and calcite occur in bands that wrap around the breccia fragments. Farther up the glacier, banded pyrite and quartz-sericite schist with disseminated pyrite are abundant on the moraine on the ice. The rocks contains blueish-white quartz crystals and porphyroblasts as much as one-quarter inch in diameter; the protolith is probably a rhyolitic lapilli tuff. Along the southern side of the glacier, meta-andesite (?) with black chlorite and white tourmaline crystals developed in open spaces (R.A. Blakestad and others, unpublished Resource Associates of Alaska, Inc. report, 1976). This occurrence is in the Jarvis Creek Glacier subterrane of Devonian age (Nokleberg and others, 1992). This subterrane consists of a complex sequence of volcaniclastic metasedimentary rocks, predominantly of intermediate composition. The unit includes felsic and mafic metavolcanic units and metasedimentary rocks, including calcareous schist, dolomite, limestone, siltstone, quartzite, and black carbonaceous schist. The rock units are typically thin bedded, strike northwest, and dip moderately southwest. The schistosity and folds are generally parallel to the regional strike but with local exceptions (R.A. Blakestad and others, unpublished Resource Associates of Alaska, Inc. report, 1976). The metamorphosed volcanic and sedimentary rocks have been intruded by several gabbro and mafic sills and dikes and plutons of felsic to intermediate composition
Workings: This occurrence has only had limited surface sampling.
Age: Devonian or younger, on the basis of the age of the host rock, which is in the Jarvis Creek Glacier subterrane (Nokleberg and others, 1992).

Commodities (Major) - Cu, Pb, Zn
Development Status: None
Deposit Model: Kuroko massive sulfide (Cox and Singer, 1986; model 28a).

Other Databases

Link to USGS - Alaska:	MH244

Other Regions, Features and Areas containing this locality

References