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



Reporters T.K. Bundtzen (Pacific Rim Geological Consulting, Inc.) and M.L. Miller (U.S. Geological Survey)
Last report date 5/9/2003