|Quadrangle map, 1:250,000-scale||MH|
|Quadrangle map, 1:63,360-scale||A-5|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The BM-75 occurrence is at an elevation of about 4,300 feet in the headwaters of a north-flowing tributary of upper Eureka Creek and is in the SE1/4SE1/4 section 21, T. 19 S., R. 8 E., Fairbanks Meridian.|
Geologic descriptionThe BM-75 occurrence is hosted by the Fish Lake mafic-ultramafic intrusive complex, which is of Late Triassic age and believed to be a lopolithic feeder of the Nikolai basalt flows (Nokleberg and others, 1991). The occurrence is in a pod of serpentinized peridotite in a gabbroic unit of the third magmatic cycle of the Fish Lake complex. The pod of serpentinized peridotite contains a few percent disseminated pyrrhotite, chalcopyrite, pentlandite, and magnetite (Foley, 1992; Foley and others, 1989) A grab sample contained 70 parts per billion (ppb) palladium and 70 ppb platinum (U.S. Bureau of Mines, unpublished data, 1985).
|Geologic map unit||(-146.210258482266, 63.2472754733795)|
|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||The peridotite is serpentinized.|
|Workings or exploration||The occurrence is on active Fort Knox Gold Resource 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.
Foley, J.Y., Burns, L.E., Schneider, C.L., and Forbes, R.B., 1989, Preliminary report of platinum group element occurrences in Alaska: Alaska Division of Geological and Geophysical Surveys Public Data File 89-20, 32 p., 1 map sheet, scale 1:2,500,000.
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||6/18/2001|