Unnamed (south of upper Caribou Creek) (ARDF #ID056) Bi, Sn

Unnamed (south of upper Caribou Creek)

Occurrence, Inactive

Commodities and mineralogy

Main commodities	Bi; Sn
Other commodities	Ag; As; Pb; Sb; Zn
Gangue minerals	calcite; chlorite; tourmaline

Geographic location

Quadrangle map, 1:250,000-scale	ID
Quadrangle map, 1:63,360-scale	C-4
Latitude	62.50971
Longitude	-157.86091
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	This occurrence is 0.2 mile southeast of hill 1,850 on a north-facing knob in the headwaters of Caribou Creek. The occurrence at an elevation of about 1,600 feet in the SW1/4 SW1/4 section 18, T. 28 N., R. 46 W., of the Seward Meridian. The location is accurate.

Geologic setting

Geologic description This occurrence is a zone of extensive tourmaline-calcite-chlorite alteration in intermediate dikes that intrude shale and sandstone of the Upper Cretaceous, Kuskokwim Group (Miller and Bundtzen, 1994; Miller, Bundtzen, and Gray, 2005). The occurrence is of uncertain size and orientation. Grab samples contain up to 200 parts per million (ppm) tin, 500 ppm zinc, 500 ppm antimony, 480 ppm arsenic, 200 ppm lead, 46 ppm bismuth, and 1,000 parts per billion (ppb) silver (McGimsey and others, 1988).
Geologic map unit	(-157.863308135968, 62.5090271768207)
Mineral deposit model	Sn-polymetallic deposit or Polymetallic vein (Cox and Singer, 1986; model 20b or 22c).
Mineral deposit model number	20b or 22c
Age of mineralization	Unknown; the dikes that intrude the Upper Cretaceous Kuskokwim Group in the area are undated.
Alteration of deposit	Development of tourmaline-chlorite-calcite greisen.

Production and reserves

Workings or exploration	The occurrence was sampled by the U.S. Geological Survey in the 1980s (McGimsey and others, 1988).
Indication of production	None

References

References McGimsey, R.G., Miller, M.L., and Arbogast, B.F., 1988, Paper version of analytical results, and sample locality map for rock samples from the Iditarod quadrangle, Alaska: U.S. Geological Survey Open-File Report 88-421-A, 110 p., 1 sheet, scale 1:250,000. Miller, M.L., and Bundtzen, T.K., 1994, Generalized geologic map of the Iditarod quadrangle, Alaska showing potassium-argon, major oxide, trace element, fossil, paleocurrent, and archeological sample localities: U.S. Geological Survey Miscellaneous Field Studies Map MF-2219-A, 48 pages; 1 sheet, scale 1:250,000. Miller, M.L., Bundtzen, T.K., and Gray, J.E., 2005, Mineral resource assessment of the Iditarod quadrangle, west-central Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-2219-B, scale 1:250,000, pamphlet.
Reporters	T.K. Bundtzen (Pacific Rim Geological Consulting, Inc.), M.L. Miller (U.S. Geological Survey); and C.C. Hawley (Hawley Resource Group)
Last report date	5/19/2003