|Quadrangle map, 1:250,000-scale||MG|
|Quadrangle map, 1:63,360-scale||B-2|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Sheep Creek-West prospect is on the west side of Sheep Creek Valley just downstream from the intersection of the Rat Fork and the South Fork of Sheep Creek; it is at an elevation of 3,400 feet in the SW1/4 section 13, T. 26 N., R. 24 W., of the Seward Meridian. The location is accurate.|
The Sheep Creek-West prospect contains oxidized, sulfide mineralization. It is along a steeply dipping, northeast-striking fault(?) zone, 2 to 3 meters wide that juxtaposes silty limestone against tan arkosic sandstone. Both units belong to the Lower to Upper Silurian, Terra Cotta Mountains Sandstone, a formation within the Dillinger sub-terrane (Bundtzen, Harris, and Gilbert, 1997). The fault zone strikes northeast for at least 135 meters and is marked by a distinctive notch along the steep side hill. Sphalerite, galena, chalcopyrite and pyrrhotite in epidote, johannsenite, and garnet skarn replace limestone as vug fillings and stringers along the shear zone (Bundtzen, Kline, and Clough, 1982). Abundant malachite staining is a conspicuous feature locally along the fault zone.
Two chip samples collected across about 3 meters of the zone contain up to 0.85 percent copper, 1.01 percent lead, 0.58 percent zinc, 30 parts per million cadmium, 86 grams of silver per tonne and 0.60 grams of gold per tonne. (Bundtzen, Kline, and Clough, 1982).
The vein is probably related to nearby polymetallic veins at the Dahl (MG053), and the Sheep Creek-South (MG057) prospects that are part of the Farewell Mineral Belt. The structurally controlled, vein-type mineralization may be related to skarn mineralization observed throughout the Farewell Mineral Belt.In 2008, this prospect was one of several in a block of claims that covered more than 70 square miles, known collectively as the BMP project (International Tower Hill Mines, Ltd., 2008).
|Geologic map unit||(-153.813721447378, 62.3291868444464)|
|Mineral deposit model||Polymetallic vein (Cox and Singer, 1986; model 22c).|
|Mineral deposit model number||22c|
|Alteration of deposit||Sulfides are highly oxidized with the development of conspicuous cerussite, iron oxides, and malachite.|
|Workings or exploration||Surface sampling by Bundtzen and others in 1981 and 1982 was done on behalf of the Alaska Division of Geological and Geophysical Survey. As of 2008, the prospect was within a large block of claims called the BMP project by International Tower Hill MIne, Ltd. (2008).|
|Indication of production||None|
Bundtzen, T.K., Harris, E.E., and Gilbert, W.G., 1997, Geologic Map of the eastern McGrath quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 97-14, 34 p., 1 sheet, scale 1:125,000.
Bundtzen, T.K., Kline, J.T., and Clough, J.G., 1982, Preliminary geology of the McGrath B-2 quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Open-File report 149, 22 p., 1 sheet, scale 1:40,000.
Cobb, E.H., 1972, Metallic mineral resources map of the McGrath quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-379, 1 sheet, 1:250,000 scale.
Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Iliamna, Lake Clark, Lime Hills, and McGrath quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-485, 101 p.
International Tower Hills Mines, Ltd., 2008, BMP: http://www.ithmines.com/s/BMP.asp (as of April 30, 2008).
|Reporters||T.K. Bundtzen (Pacific Rim Geological Consulting); D.J. Grybeck (Port Ludlow, WA)|
|Last report date||6/5/2008|