Unnamed (Upper Kogoyuk Creek) (ARDF #SM050) Au, Bi, Te

Unnamed (Upper Kogoyuk Creek)

Occurrence, Inactive

Commodities and mineralogy

Main commodities	Au; Bi; Te
Other commodities	Ag; As
Ore minerals	unspecified sulfides
Gangue minerals	quartz

Geographic location

Quadrangle map, 1:250,000-scale	SM
Quadrangle map, 1:63,360-scale	B-7
Latitude	61.33459
Longitude	-158.5076
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	This occurrence is on a steep northwest-facing knob overlooking upper Kogoyuk Creek in the northeast Buckstock Mountains. The occurrence is on hill 2147 in the NE1/4 sec. 1, T. 14 N., R. 52 W., of the Seward Meridian. The location is accurate.

Geologic setting

Geologic description This occurrence consists of quartz-sulfide veins in a sericitized porphyry dike or sill that is part of the Cretaceous Buckstock Mountains plutonic complex. The Buckstock Mountains pluton has a U-Pb age of 59.2 Ma (Miller and others, 2002). The dike or sill is one of many near the occurrence that cut hornfels of the Upper Cretaceous Kuskokwim Group (Cady and others, 1955). No other information is available. One grab sample of the quartz-sulfide mineralization contained 150 parts per billion (ppb) gold, 400 parts per million (ppm) bismuth, 1,000 ppb silver, 190 ppm arsenic, and 8.8 ppm tellurium (M.L. Miller, unpub. assay data, 1993). The occurrence is in the northeast corner of area of anomalous stream-sediment and panned-concentrate samples (Gray, Motooka, and Theodorako, 1997). Stream sediments contained up to 1.3 parts per million (ppm) gold, 150 ppm arsenic, 14 ppm bismuth, and elevated antimony and tungsten. Panned concentrates contained up to 200 ppm gold, 100 ppm silver, 500 ppm antimony, 3,000 ppm tungsten, and more than 2,000 ppm bismuth.
Geologic map unit	(-158.509950701201, 61.3338775702125)
Mineral deposit model	Polymetallic vein? (Cox and Singer, 1986; model 22c).
Mineral deposit model number	22c?
Age of mineralization	Unknown. Miller and others (2002) report a U-Pb age of 59.2 Ma for the Buckstock pluton that makes up much of the area.
Alteration of deposit	Strong sericite alteration of dike or sill.

Production and reserves

Workings or exploration	This occurrence was found in 1993 during a cooperative study by the Alaska Division of Geological and Geophysical Surveys and the U.S. Geological Survey in the Buckstock Mountains.
Indication of production	None

References

References Cady, W.M., Wallace, R.E., Hoare, J.M., and Webber, E.J., 1955, The central Kuskokwim region, Alaska: U.S. Geological Survey Professional Paper 268, 132 p. Gray, J.E., Motooka, Jerry, and Theodorakos, P.M., 1997, Areas favorable for metallic resources and newly discovered mineral occurrences in the Buckstock Mountains area, southwestern Alaska, in Dumoulin, J.A., and Gray, J.E., eds, Geologic Studies in Alaska by the U.S. Geological Survey in 1995: U.S. Geological Survey Professional Paper 1574, p. 111- 124. Miller, M.L., Bradley, D.C., Bundtzen, T.K., and McClelland, William, 2002, Late Cretaceous through Cenozoic strike-slip tectonics of southwestern Alaska: Journal of Geology, vol.110, p. 247-270.
Reporters	T.K. Bundtzen (Pacific Rim Geological Consulting, Inc.) and M.L. Miller (U.S. Geological Survey)
Last report date	5/9/2003