|Quadrangle map, 1:250,000-scale||MH|
|Quadrangle map, 1:63,360-scale||B-5|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This location represents several prospects at about 4,800 feet in elevation on the east side of the ridge between the locally named middle and east forks of the stream(s) in Broxson Gulch (Rose, 1965, figure 2). It is at the southeast corner of section 17, T. 18 S., R. 9 E., Fairbanks Meridian. The site corresponds to locality 18 on figure 2 of Rose (1965), locality 19 of MacKevett and Holloway (1977), and locality 50 in table 2 of Nokleberg and others (1991).|
This deposit consists of sulfide lenses along the contact between peridotite and sheared serpentinized olivine cumulate, layered units of an Upper Triassic ultramafic intrusive complex (Rose, 1965, figure 2; Nokleberg and others, 1991). The deposit was discovered by Rose (1965), who described six lenses of massive sulfide in an area having a radius of 100 feet. The largest lens was 3 feet thick by 6 feet long. The massive sulfides are mainly marcasite, but chalcopyrite, pyrrhotite, pentlandite, and probably magnetite are also present. The marcasite is probably a retrograde product of pyrrhotite.The occurrence was also sampled by Nokleberg and others (1991). Their samples 79IL030A-D of massive pyrrhotite containing disseminated chalcopyrite and pyrite assayed as much as 2 percent copper, 1,000 parts per million (ppm) cobalt, and 2,000 ppm nickel (locality 50, table 2). Foley (1992) collected massive sulfide samples assaying as much as 13 ppm silver, 416 parts per billion (ppb) gold, 137 ppb palladium, 2.4 percent copper, 0.66 percent nickel, and 0.08 percent cobalt.
|Geologic map unit||(-146.050365509892, 63.3480815866485)|
|Mineral deposit model||Ni-Cu-PGE in differentiated mafic-ultramafic sill.|
|Age of mineralization||Late Triassic, the age of the host rock.|
|Alteration of deposit||Some of the peridotite and olivine cumulate is serpentinized, mainly near their contacts, but it mostly is relatively unaltered (Rose, 1965).|
|Workings or exploration||
The massive sulfide lenses in the Broxson Gulch area assay as much as 13 parts per million silver, 416 parts per billion (ppb) gold, 137 ppb palladium, 137 ppb platinum, 2.4 percent copper, 0.66 percent nickel, and 0.08 percent copper (Foley, 1992).The occurrence is on active MAN Resources claims.
|Indication of production||None|
Foley, J.Y., 1992, Ophiolite and other ultramafic metallogenic provinces in Alaska (west of the 141th meridian): U.S. Geological Survey Open-File Report 92-20-B, 55 p.
MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous and selected non-metalliferous mineral deposits in the eastern part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-A, 99 p., 1 sheet, scale 1:1,000,000.
Nokleberg, W.J., Lange, I.M., Roback, R.C., Yeend, Warren, and Silva, S.R., 1991, Map showing locations of metalliferous lode and placer mineral occurrences, mineral deposits, prospects, and mines, Mount Hayes quadrangle, eastern Alaska Range, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1996-C, 42 p., 1 sheet, scale 1:250,000.
|Reporters||W.T. Ellis (Alaska Earth Science), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS)|
|Last report date||6/19/2001|