Unnamed (tributary to Trail Creek) (ARDF #GO010) Au

Unnamed (tributary to Trail Creek)

Occurrence, Inactive

Commodities and mineralogy

Main commodities	Au
Other commodities	Ag; As; B; Bi; Sb; Zn
Ore minerals	arsenopyrite; pyrite
Gangue minerals	clay; quartz; tourmaline

Geographic location

Quadrangle map, 1:250,000-scale	GO
Quadrangle map, 1:63,360-scale	D-3
Latitude	59.94
Longitude	-159.89
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	This occurrence is in an unnamed west tributary to Trail Creek, about 7 miles northeast of Kagati Lake and 2 miles north of the Kagati Lake prospect (GO011). The map site is at an elevation of about 1,800 feet in the SW1/4 of section 2, T 3 S, R 62 W, of the Seward Meridian. It is area 3 of Kilburn and others (1992), and is approximately located, perhaps within 1 mile.

Geologic setting

Geologic description This occurrence is in hornfels near the contact of an Upper Cretaceous granitic stock (Hoare and Coonrad, 1978). Reconnaissance stream-sediment and pan concentrate samples from the area contain anomalous levels of several elements (Kilburn and Jones, 1992; Jones and Kilburn, 1992). Silicified hornfels contains disseminated pyrite and pyrite-, arsenopyrite-, and tourmaline-bearing quartz veins. Clay alteration and weakly disseminated pyrite characterize some iron-stained outcrops. Rock samples of altered and mineralized hornfels contain up to 0.28 ppm Ag, greater than 3,800 ppm As, 0.15 ppm Au, greater than 2,000 ppm B, 11 ppm Bi, greater than 5,000 ppm Mn, 5.4 ppm Sb, and 230 ppm Zn (Kilburn and others, 1992).
Geologic map unit	(-159.892238314547, 59.9392517197488)
Mineral deposit model	Polymetallic veins (Cox and Singer, 1986; model 22c)
Mineral deposit model number	22c
Age of mineralization	Late Cretaceous. The mineralization is assumed to be related to the Upper Cretaceous granitic stock, which yielded a K/Ar age of 71.1 +/- 2.1 Ma on biotite (Hoare and Coonrad, 1978).
Alteration of deposit	Silicification, clay alteration, and oxidation.

Production and reserves

Workings or exploration	Only reconnaissance surface observations and sampling have been completed in the area.
Indication of production	None

References

MRDS Number	DE00938
References Hoare, J.M., and Coonrad, W.L., 1978, Geologic map of the Goodnews and Hagemeister Island quadrangles region, southwestern Alaska: U.S. Geological Survey Open-File Report 78-9-B, 2 sheets, scale 1:250,000. Jones, J.L., and Kilburn, J.E., 1992, Geochemical map showing the distribution of selected elements in heavy-mineral-concentrate samples from the Goodnews Bay, Hagemeister Island, and Nushagak Bay quadrangles, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-2186, 2 sheets, scale 1:250,000. Kilburn, J., Box, S.E., Goldfarb, R.J., and Gray, J.E., 1992, Geochemically anomalous areas in the eastern Goodnews Bay 1 degre x 3 degree quadrangle, southwest Alaska, in Bradley, D.C., and Ford, A.B., eds., Geologic studies by the U.S. Geological Survey in 1990: U.S. Geological Survey Bulletin 1999, p. 156-162. Kilburn, J.E., and Jones, J.L., 1992, Geochemical map showing the distribution of selected elements determined in stream-sediment samples from the Goodnews Bay, Hagemeister Island, and Nushagak Bay quadrangles, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-2355, 2 sheets, scale 1:250,000.
Reporters	Travis L. Hudson
Last report date	3/20/2001