Unnamed Occurrence (ARDF - MH299; near peak 5850 south of Chisna Pass), Chistochina Mining District, Southeast Fairbanks Census Area, Alaska, USAi

Regional Level Types
Unnamed Occurrence (ARDF - MH299; near peak 5850 south of Chisna Pass)	- not defined -
Chistochina Mining District	Mining District
Southeast Fairbanks Census Area	Census Area
Alaska	State
USA	Country

Location: The occurrence is 0.3 mile southwest of peak 5850 one mile south of Chisna Pass. The occurrence is plotted at an outcrop of massive chalcopyrite and pyrite on the ridge crest within an area of mineralization; it is near the northeast corner of sec. 35, T. 20 S., R. 15 E., Fairbanks Meridian. The location is accurate within 0.1 mile. The site is near locality 140 in table 2 of Nokleberg and others (1991).
Geology: Disseminated sulfides with local occurrences of massive to semimassive sulfides are found in a Permian (?) meta-andesite to metadacite porphyry (Lange and others, 1981; Nokleberg and others, 1987; Nokleberg and others, 1991). A prominent zone of sulfidized rock that strikes northwest crops out in a gully in the NE1/4NE1/4, sec 35, T. 20 S., R. 15 E., Fairbanks Meridian (Randy Moore and C. C. Hawley, written communication, 1996). One sample of semimassive pyrite, chalcopyrite, and possibly bornite assayed 0.488 ounce of gold per ton and more than 1 percent copper. Other samples from the mineralized area collected in the 1996 examination generally contain less than 500 parts per million (ppm) copper. Altered rocks with disseminated galena and sphalerite occur in the vicinity; they contain as much as 28.4 ppm silver, 1,235 ppm arsenic, 2,690 ppm lead, and 1,560 ppm zinc (Moore and Hawley, as above). A sample, probably from the massive sulfide zone, collected by the U.S. Geological Survey assayed 2 ppm gold, 70 ppm silver, 2 percent copper, 1,500 ppm arsenic, 30 ppm tin, and 530 ppm zinc (Nokleberg and others, 1991). The occurrence may be a distal porphyry copper deposit of possible Permian age.
Workings: Only a few surface samples.
Age: The volcanic host rocks probably are early Permian, and the mineralization is related to a Permian(?) metadacite intrusive.

Commodities (Major) - Cu; (Minor) - Ag, Au, Pb, Sn, Zn
Development Status: None
Deposit Model: Porphyry Cu, distal (Cox and Singer, 1986; model 20c).

Other Databases

Link to USGS - Alaska:	MH299

Other Regions, Features and Areas containing this locality

References