|Quadrangle map, 1:250,000-scale||HU|
|Quadrangle map, 1:63,360-scale||A-2|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This occurrence is located on Black Creek, upstream from the placered area (HU022). The occurrence is at an elevation of about 2,000 feet on the west side of Black Creek, about 0.3 mile south of the center of section 20, T. 8 N., R. 24 E., of the Kateel River Meridian. The location is accurate.|
This occurrence consists of disseminated pyrite and traces of chalcopyrite in Cretaceous metavolcanic rocks and late-stage aplite near the margin of a Cretaceous, granodiorite-quartz monzonite pluton (Miller and Ferrians, 1968). The occurrence is upstream from the placer gold area on Black Creek (HU022). Grab samples collected by Miller and Ferrians, described as pyritiferous hornfels and pyritiferous, felsic-intrusive rock, contain disseminated sulfides, 1,000 copper and up to 0.05 ppm gold.
Kurtak and others (1999) describe the geology as interbedded graywacke and mudstone that have been metamorphosed to resistant , brown hornfels along the contact of the granodiorite/quartz monzonite. They also observed quartz cemented breccia zones, quartz veinlets, felsic dikes, and lesser porphyritic andesite(?) cutting the sediments and hornfels. The graywacke and hornfels contain 1-2% pyrrhotite and minor arsenopyrite that occur as disseminations and stringers. Quartz veinlets contain a little chalcopyrite. The sulfides appear to be more prevalent near the felsic dikes. Samples contain up to 611 ppb gold, 3,912 ppm copper, 2,676 ppm arsenic, and 473 ppm, bismuth.Nokleberg and others (1996) describe, without a specific location, the general Indian Mountain area as a porphyry Cu-Au system. This system, which likely includes all the individual lode occurrences within the area, consists predominately of chalcopyrite- and tourmaline-bearing intrusive breccias that are surrounded by concentric phyllic-argillic-propylitic alteration halos. A pyrite zone surrounds the intrusive rocks.
|Geologic map unit||(-153.865731902329, 66.0758622583072)|
|Mineral deposit model||Porphyry Cu-Au? (Cox and Singer, 1986; model 20c?).|
|Mineral deposit model number||20c?|
|Alteration of deposit||Fine-grained, pyritiferous intrusive rocks in the area are reported to be highly altered but there is no detailed description of the alteration.|
|Workings or exploration||Only surface sampling.|
|Indication of production||None|
Bottge, R.G., 1988, Maps summarizing land availability for mineral exploration and development in western Alaska, 1986: U.S. Bureau of Mines Open-File Report 14-88, 38 quadrangle overlays.
Cobb, E.H., 1972, Metallic mineral resources map of the Hughes quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-458, 1 sheet, scale 1:250,000.
Cobb, E.H., 1975, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in five quadrangles in west central Alaska (Hughes, Kotzebue, Melozitna, Selawik, Shungnak): U.S. Geological Survey Open-File Report 75-627, 58 p.
Eberlein, G.D., Chapman, R.M., Foster, H.L., and Gassaway, J.S., 1977, Map and table describing known metalliferous and selected nonmetalliferous mineral deposits in central Alaska: U.S. Geological Survey Open-File Report 77-168-D, 132 p., 1 sheet, scale 1:1,000,000.
Kurtak, J.M., Klieforth, R.F., Clark, J.M., and Williams, E.M., 1999, Mineral investigations in the Koyukuk mining district, northern Alaska--Progress Report: U.S. Bureau of Land Management Open-File Report 74, 158 p.
Miller, T.P., and Ferrians, O.J., Jr., 1968, Suggested areas for prospecting in the central Koyukuk River region, Alaska: U.S. Geological Survey Circular 570, 12 p.
Nokleberg, W.J., Bundtzen, T.K., Dawson, K.M., Eremin, R.A., Goryachev, N.A., Koch, R.D., Ratkin, V.V, Rozenblum, I.S., Shpikerman, V.I., Frolov, Y.F., Gorodinsky, M.E., Melnikov, V.D., Diggles, M.F., Ognyanov, N.V., Petrachenko, E.D., Petrochenko, R.I., Pozdeev, A.I., Ross, K.V., Wood, D.H., Grybeck, D., Khanchuck, A.I., Kovbas, L.I., Nekrasov, I.Y., and Sidorov, A.A., 1996, Significant metalliferous and selected non-metalliferous lode mineral deposits and placer districts, and for metallogenesis of the Russian Far East, Alaska, and the Canadian Cordillera: U.S. Geological Survey Open-File Report 96-513-B, 385 p.; U.S. Geological Survey Open-File Report 96-513-B, 385 p. (CD-ROM format).
|Reporters||J.M. Britton (Anchorage)|
|Last report date||8/1/2002|