|Quadrangle map, 1:250,000-scale||SP|
|Quadrangle map, 1:63,360-scale||D-5|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This site represents roughly circular area of about 30 square miles centered at about the midpoint of the Weyahok River, a headwater tributary to the Alatna River. The coordinates are for the approximate center of the area, which is mostly in sec. 4, T. 28 N., R. 16 E., of the Kateel River Meridian. Includes localities 1-4 of Grybeck and Nelson (1981) and is accurate to within 2000 ft.|
The site consists of a sprinkling of small occurrences of epigenetic quartz veins, lenses, and breccia zones less than 3 feet thick that contain various combinations of galena, sphalerite, chalcopyrite, and pyrite. The occurrences are in an area of about 30 square miles in an otherwise monotonous sequence of feldspathic sandstone of the Hunt Fork Shale (Nelson and Grybeck, 1980; Grybeck and Nelson, 1981). Assays of the sulfide-bearing samples show up to 100 ppm Ag and 200 ppm Sb. Fieldwork (S.W. Nelson and D. Grybeck, unpublished data, 1977-1980), and geochemical sampling (Cathrall and others, 1981) suggest that many additional such deposits may occur in this area. All the occurrences found to date are small and discontinuous and there is no obvious sign of any large deposit within the area.There are two theories about the origin of the deposits: (1) Grybeck and others, 1985) cite geochemical evidence that they may be related to a buried felsic intrusion; (2) Schmidt and Werdon (1993) and Schmidt (1997) believe that they are related to post-depositional dewatering of the sedimentary rock section and are similar in origin to other sedimentary-rock hosted mineral occurrences in the Brooks Range.
|Geologic map unit||(-155.282826760497, 67.8595038466441)|
|Mineral deposit model||Polymetallic vein (Cox and Singer, 1986; model 22c). (See also Schmidt and Werdon, 1993, p. 143.).|
|Mineral deposit model number||22c|
|Workings or exploration||The site is defined by a few short traverses and spot stations by USGS in late 1970s, and since closed to exploration.|
|Indication of production||None|
Additional commentsThe area is within the Gates of the Arctic National Park and Wilderness and has been closed to prospecting since 1981.
|MRDS Number||AO11931; AO11932|
Cathrall, J.B., Billings, T.M., Cooley, E.F., and O'Leary, R.M., 1981, Map showing anomalous drainage areas of selected elements in the Survey Pass quadrangle, Brooks Range, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1176-D, 1 sheet, scale 1:250,000.
Grybeck, D.J., and Nelson, S.W., 1981, Mineral deposit map of the Survey Pass quadrangle, Brooks Range, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1176-F, 1 sheet, scale 1:250,000.
Grybeck, D.J., Cathrall, J.B., LeCompte, J.R., and Cady, J.W., 1985, Buried felsic plutons in upper Devonian redbeds, central Brooks Range, in Bartsch-Winkler, Susan, and Reed, K.M., eds., The United States Geological Survey in Alaska--Accomplishments during 1983: U.S. Geological Survey Circular 945, p. 8-10.
Nelson, S.W., and Grybeck, D.J., 1980, Geologic map of the Survey Pass quadrangle, Brooks Range, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1176-A, 2 sheets, scale 1:250,000.
Schmidt, J.M., 1997, Shale-hosted Zn-Pb-Ag and barite deposits of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral deposits of Alaska, 1997: Economic Geology Monograph 9, p. 35-65.
Schmidt, J.M., and Werdon, M.B., 1993, Clastic-hosted stratiform, vein/breccia and disseminated Zn-Pb-Ag deposits of the northwestern Brooks Range, Alaska; Are they different expersions of dewatering of the same source basin? [abs.]: Geological Society of America, Abstracts with Programs, v. 25, no. 5, p. 143.
|Reporters||S.W. Nelson (Anchorage, Alaska)|
|Last report date||9/16/1999|