Unnamed Occurrence (ARDF - EA074; near mouth of Columbia Creek), Fortymile District, Southeast Fairbanks Borough, Alaska, USA

Location: This occurrence is located in an outcrop on the east side of the Taylor Highway near the mouth of Columbia Creek. The occurrence is in section 35, T. 5 S., R. 32 E., of the Fairbanks Meridian. The location is accurate within 1,000 feet.
Geology: The rocks in the vicinity of this occurrence are predominantly Paleozoic greenschist-facies black carbonaceous quartzite (Dusel-Bacon and others, 1998). Approximately 1.5 miles to the south, these rocks are in fault contact with Paleozoic amphibolite-facies metamorphic rocks (Foster, 1976). Sulfides occur in a carbon-free or carbon-poor quartzite that is interpreted to be metachert or possibly a metamorphosed exhalite(?). This occurrence is interpreted to be a sedimentary-exhalative massive sulfide occurrence by Dusel-Bacon and others (1998), but the presence of possible felsic metavolcanic rocks indicates that it could be a Kuroko-type volcanogenic massive sulfide deposit. The host rock is a tan to pale-gray quartzite with minor muscovite. The quartzite is interlayered with more muscovite-rich quartzite and muscovite schist, which may have originally been felsic tuff. Sulfides occur as discontinuous lenses, 1 to 2 centimeters thick, that contain sphalerite, and lesser galena and chalcopyrite (Dusel-Bacon and others, 1998). A sample of this material contains 8.1 percent zinc, 100 ppm cadmium, 38 ppb gold, and 132 ppm mercury.
Age: Paleozoic or younger.

Commodities (Major) - Cu, Pb, Zn; (Minor) - Au, Cd, Hg
Development Status: None
Deposit Model: Sedimentary exhalative massive sulfide or Kuroko-type volcanogenic massive sulf

Mineral List

5 entries listed. 5 valid minerals.

References