1. Mineral Resources
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  3. Alaska Resource Data File (ARDF)

Unnamed (along Summit Creek)

Occurrences, Probably inactive

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Commodities and mineralogy

Main commodities Ag; Au; Ba; Zn
Other commodities Bi
Ore minerals chalcopyrite; galena; pyrite; pyrrhotite; sphalerite
Gangue minerals calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale SK
Quadrangle map, 1:63,360-scale B-3
Latitude 59.33
Longitude -136.12
Nearby scientific data Find additional scientific data near this location
Location and accuracy This site consists of several locations along the length of Summit Creek. The center of these occurrences is somewhat arbitrarily placed near the southern edge of the SE1/4, section 22, T. 29 S., R. 55 E. of the Copper River Meridian. The site is shown as number 23 by Still and others (1991).

Geologic setting

Geologic description

According to Still and others (1991), 'Bedrock in the area consists predominately of slate and phyllite, limy slate, and minor limestone.' Stream sediment samples from the mouth of Summit Creek and from small springs near the head of Summit Creek contained up to 0.020 ppm gold, 1.2 ppm silver, 1,620 ppm zinc, 1,950 ppm barium, and 660 ppm bismuth (sheet 1, numbers 209 to 217 and F83 to F90 of Gilbert and others, 1991).
Still and others (1991) also report that bedrock and float samples were collected at scattered locations along Summit Creek . Quartz-calcite-sulfide float samples from talus slopes and moraine contained up to 0.686 ppm gold, 380.9 ppm silver, 2.5% zinc, 700 ppm copper, and 4.1% lead. A stream sediment sample from below a spring surrounded by iron-stained gossan contained 1.9% zinc, and a sample of iron-stained calcite-cemented slate collected several hundred feet below this stream-sediment sample contained 1.2 % zinc. The calcite cement precipitated from the spring water contains sphalerite.
Virtually the entire drainage of Summit Creek consists of slate (MacKevett and others, 1974). The Triassic or Devonian age of this unit, the Porcupine Slate (Redman and others, 1985; Gilbert and others, 1987), establishes a maximum age for the mineralization. Mineralization contained in cemented scree, ferricrete, and spring water precipitates is very young if not Recent but descriptions of float samples (Still and others, 1991) also suggest that the quartz-sulfide veins are probably of Tertiary age based on the 29.3 + 1 to 33.0 + 1 m.y. age of nearby intrusive bodies (Gilbert and others, 1987).
Geologic map unit (-136.121862062479, 59.3296580107331)
Age of mineralization The Devonian or Triassic age of the Porcupine Slate (Redman and others, 1984; Gilbert and others, 1987) establishes a maximum age for the mineralization. The veins are of probable Tertiary based on the 29.3 + 1 to 33.0 + 1 m.y. age of nearby intrusive bodies (Gilbert and others, 1987). Mineralization in ferricrete, scree cement , and spring- water precipitates is very young to Recent (Still and others, 1991).

Production and reserves

Indication of production None

References

MRDS Number 10308247

References

Gilbert, W.G., Burns, L.E., Redman, E.C., and Forbes, R.B., 1987, Preliminary bedrock geology and geochemistry of the Skagway B-3 quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 87-2, 2 sheets, scale 1:36,200.
Gilbert, W.G., Still, J.C., Burns, L.E., Wier, K.R., and Redman, E.C., 1991, Geochemistry of Haines-Klukwan-Porcupine area, southeastern Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 91-5, 75 p., 2 sheets, scale 1:63,360,
MacKevett, E.M., Jr., Robertson, E.C., and Winkler, G.R., 1974, Geology of the Skagway B-3 and B-4 quadrangles, southern Alaska: U.S. Geological Survey Professional Paper 832, 33 p., 1 plate.
Redman, E.C., Retherford, R.M., and Hickok, B.D., 1984, Geology and geochemistry of the Skagway B-2 Quadrangle, southeastern Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 84-31, 34 p., 4 sheets, scale 1:40,000.
Still, J.C., Hoekzema, R.B., Bundtzen, T.K., Gilbert, W.G., Wier, K.R., Burns, L.E., and Fechner, S.A., 1991, Economic geology of Haines-Klukwan-Porcupine area, southeastern Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 91-4, 156 p., 5 sheets, scale 1:63,360.
Reporters T.C. Crafford (T. Crafford & Associates, Anchorage)
Last report date 2/4/2001