Unnamed Occurrence (ARDF - MH121; ridge between middle and east forks in Broxson Gulch), Delta River Mining District, Southeast Fairbanks Census Area, Alaska, USAi

Regional Level Types
Unnamed Occurrence (ARDF - MH121; ridge between middle and east forks in Broxson Gulch)	- not defined -
Delta River Mining District	Mining District
Southeast Fairbanks Census Area	Census Area
Alaska	State
USA	Country

Rose (1965) recommended more prospecting at this locality, a suggestion supported by the higher metal values reported by Foley (1992).
Location: This occurrence is at an elevation of 4,900 feet on the north side of the ridge between the locally named middle and east forks of the stream(s) in Broxson Gulch (see figure 2 of Rose, 1965). It is in the NE1/4NE1/4 section 19, T. 18 S., R. 9 E., Fairbanks Meridian. The occurrence corresponds to locality 19 on figure 2 of Rose (1965), to locality 18 of MacKevett and Holloway (1977), and to locality 47 in table 2 of Nokleberg and others (1991).
Geology: This occurrence is in amphibolitized 'serpentinite' inferred to be in the hanging wall of a major thrust fault (Rose, 1965, figure 2, locality 19). Boulders of massive sulfide material were found along a 20-foot-wide zone on the north side of the ridge. Mineralized material assayed 0.9 percent copper, a trace of zinc, and less than 0.1 percent nickel (Rose, 1965). Fifty feet south of this zone a layer of pyrrhotite a few inches thick crops out for several feet. The amphibole 'serpentinite' in this area is considerably pyritized and sheared. Sample 79IL029A of float that contained pyrite, pyrrhotite, pentlandite, and chalcopyrite assayed 500 parts per million (ppm) cobalt (Nokleberg and others, 1991, locality 47). Later sampling determined higher metal values and a wider suite of metals (Foley, 1992). The massive sulfide lenses in the Broxson Gulch area sampled by Foley assayed as much as 2.4 percent copper, 0.66 percent nickel, 0.1 percent cobalt, 13 ppm silver, 416 ppm gold, and 137 parts per billion each platinum and palladium.
Workings: This occurrence was discovered by Rose (1965). It subsequently was examined by Nokleberg and others (1991) and Foley (1992). The area is currently claimed by MAN Resources.
Age: Late Triassic, the age of the host rock.
Alteration: The amphibole 'serpentinite' is considerably pyritized and sheared (Rose 1965).

Commodities (Major) - Cu; (Minor) - Ag, Au, Co, Ni, Pd, Pt, Zn
Development Status: None
Deposit Model: Ni-Cu-PGE in differentiated mafic-ultramafic sill.

Other Databases

Link to USGS - Alaska:	MH121

Other Regions, Features and Areas containing this locality

References