Unnamed Prospect (ARDF - MH137; east side of upper Specimen Creek), Delta River Mining District, Southeast Fairbanks Census Area, Alaska, USAi

Regional Level Types
Unnamed Prospect (ARDF - MH137; east side of upper Specimen Creek)	- not defined -
Delta River Mining District	Mining District
Southeast Fairbanks Census Area	Census Area
Alaska	State
USA	Country

Location: This prospect is at an elevation of about 5,050 feet on the south flank of a ridge at the head of an unnamed east fork of Specimen Creek. The prospect is about 2,000 feet south of the center of section 28, T. 18 S., R. 9 E., Fairbanks Meridian. The location corresponds to locality 15 on figure 2 of Rose (1965), locality 21 of MacKevett and Holloway (1977), locality 41 of Cobb (1979 [OFR 79-238]), and locality 57 in table 2 of Nokleberg and others (1991).
Geology: The rock at this prospect has been described either as amphibole 'serpentinite' by Rose (1965) or as metabasalt of the Nikolai Greenstone of Late Triassic age by Nokleberg and others (1991, locality 57). A thin section examined by Rose was composed mainly of olivine and amphibole with minor amounts of epidote, pyrite, and chalcopyrite. He also identified actinolite and glaucophane. The deposit consists of a copper-bearing shear zone that trends about N35 E. Rose (1965) noted that irregular pods of dark- and light-colored rock were present along this zone and that quartz was present in the lighter colored rock. W.T. Ellis (unpublished data, 1996) interpreted the mineralized zone to be magnetite-bearing skarn associated with the contact of the lighter colored felsic intrusive rock . A 4-foot sample collected by Rose (1965) assayed 0.09 ounce of gold per ton, 1.18 ounces of silver per ton, 0.75 percent copper, and a trace of nickel. Nokleberg and others (1991, table 2) collected samples that assayed as much as 0.75 percent copper 1.05 ounces of silver per ton, and 0.8 ounce of gold per ton.
Workings: The deposit was discovered by Rose (1965 ). The area is on active claims of MAN Resources.
Age: Epigenetic mineralization in a shear zone in the Upper Triassic host rock is possibly Cretaceous, the age of faulting and regional metamorphism. If the mineralization is skarn related to the felsic intrusion, it could be of Late Cretaceous to Early Tertiary age.
Alteration: Silicification, along with magnetite-amphiobole alteration of the host rock.

Commodities (Major) - Ag, Au, Cu
Development Status: None
Deposit Model: Uncertain, possible copper skarn (Cox and Singer, 1986; model 18b).

Other Databases

Link to USGS - Alaska:	MH137

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References