|Quadrangle map, 1:250,000-scale||KC|
|Quadrangle map, 1:63,360-scale||D-3|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This occurrence is at an elevation of about 2900 feet, approximately 3.5 miles southeast of the confluence of the Chickamin River and the South Fork of the Chickamin. The site is in section 34, T. 69 S., R. 96 E., of the Copper River Meridian. It corresponds to area M-6 in Berg and others (1977), and to loc. 20 in Elliott and others (1978). The location is accurate within 0.1 mile.|
The country rocks in the area of this occurrence consist chiefly of Tertiary or Cretaceous foliated granodiorite of the Coast Range batholith, and of rusty-weathering pelitic paragneiss that forms roof pendants, screens, and inclusions in the batholith (Berg and others, 1977, p. 129-132; Berg and others, 1977). The paragneiss probably represents marine argillaceous and clastic strata that underwent high-grade regional metamorphism in Cretaceous or Tertiary time. The premetamorphic age of the strata is uncertain, but they probably are mainly Paleozoic and may be as old as Precambrian (Berg and others, 1988, p. 26; Gehrels and others, 1990; Crawford and others, 2000).The occurrence consists of a conspicuous band of rusty-weathering pyritic gneiss about 1000 feet wide that strikes northwest and dips northeast, and can be traced in outcrop for about 3 miles (Berg and others, p. 129-132 and pl. 2). The rocks include quartzofeldspathic gneiss, which is gradational with the foliated plutonic rocks of the Coast Range batholith, and subordinate pelitic schist and paragneiss. The rocks contain pyrite in amounts up to several volume percent, and sparse grains of chalcopyrite. Thirty-six chip samples collected at three locations along the outcrop of the band assayed up to 700 ppm Cu, 150 ppm Pb, 200 ppm Zn, 70 ppm Mo, and 5 ppm Ag (Berg and others, 1977, table 13). A rock grab sample from the band contained up to 450 ppm Pb and 0.05 ppm Ag, and a stream-sediment sample from a creek draining the band was anomalous in Cu, Pb, Zn, Mo, Au, and Ag (Berg and others, 1977, fig. 9 and table 13).
|Geologic map unit||(-130.676705173041, 55.8386593733882)|
|Mineral deposit model||Disseminated base-metal sulfides in rusty-weathering paragneiss|
|Alteration of deposit||Conspicuous iron-staining.|
|Workings or exploration||Thirty-six chip samples collected at three locations along the outcrop of this 3-mile-long, 1000-foot-wide band of rusty-weathering gneiss assayed up to 700 ppm Cu, 150 ppm Pb, 200 ppm Zn, 70 ppm Mo, and 5 ppm Ag (Berg and others, 1977, table 13). A rock grab sample from the band contained up to 450 ppm Pb and 0.05 ppm Ag, and a stream-sediment sample from a creek draining the band was anomalous in Cu, Pb, Zn, Mo, Au, and Ag (Berg and others, 1977, fig. 9 and table 13).|
|Indication of production||None|
Additional commentsSite is in Misty Fiords National Monument Wilderness.
Berg, H.C., Elliott, R.L., and Koch, R.D., 1988, Geologic map of the Ketchikan and Prince Rupert quadrangles, southeastern Alaska: U.S. Geological Survey Mineral Investigations Series Map I-1807, 27 p., scale 1:250,000.
Berg, H.C., Elliott, R.L., Smith, J.G., Pittman, T.L., and Kimball, A. L., 1977, Mineral resources of the Granite Fiords Wilderness Study Area, Alaska, with a section on aeromagnetic data by Andrew Griscom: U.S. Geological Survey Bulletin 1403, 151 p.
Crawford, M.L., Crawford, W.A., and Gehrels, G.E., 2000, Terrane assembly and structural relationships in the eastern Prince Rupert quadrangle, British Columbia, in H.H. Stowell and W.C.McClelland, eds., Tectonics of the Coast Mountains, southeastern Alaska and British Columbia: Geological Society of America Special Paper 343, p. 1-21.
Elliott, R.L., Berg, H.C., and Karl, S.M., 1978, map and table describing metalliferous and selected non-metalliferous mineral deposits, Ketchikan and Prince Rupert quadrangles, Alaska: U.S. Geological Survey Open-File Report 78-73-B, 17 p., 1 sheet, scale 1:250,000.
Gehrels, G.E., McClelland, W.C., Samson, S.D., Patchett, P.J., and Jackson, J.L., 1990, Ancient continental margin assemblage in the northern Coast Mountains, southeast Alaska and northwest Canada: Geology, v. 18, no. 3, p. 208-211.
|Reporters||H.C. Berg, USGS|
|Last report date||6/29/1999|