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Unnamed (near Battery Point on the Chilkat Peninsula)

Occurrence, Probably inactive

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Commodities and mineralogy

Main commodities Cu
Other commodities Au
Ore minerals chalcopyrite; malachite
Gangue minerals epidote

Geographic location

Quadrangle map, 1:250,000-scale SK
Quadrangle map, 1:63,360-scale A-1
Latitude 59.2
Longitude -135.37
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is at an elevation of approximately 300 feet on the east side of the the Chilkat Peninsula about 0.5 miles south of Battery Point. It corresponds to location 19 of Cobb (1972 [MF 424]); sample site BD473 of Winkler and MacKevett, (1970); and number 38 of Still and others (1991).

Geologic setting

Geologic description

Winkler and MacKevett (1970) describe a sample from this occurrence as a, 'Chalcopyrite-epidote-rich greenstone/amphibolite (?),' which contains 300 ppm Cu. Still (1988) says this occurrence is, 'where a 100-foot-high metabasalt cliff has a few patches of malachite stain.' Samples contained up to 0.51 ppm gold and 2,650 ppm copper. Plafker, Hudson, and Silberling (1979) and Plafker and Hudson (1980) note that metabasalts on the Chilkat Peninsula are vesicular and/or amygdaloidal and that well-developed pillow textures are locally present. Based in part on fossil evidence that supports a Late Triassic (Karnian) age, they suggest that the metavolcanics and carbonates may correlate with similar rocks of the Wrangellia terrane. This site is located near an ultramafic body which is probably 108-109 m.y. old based on potassium-argon ages reported by MacKevett and others (1974) for pyroxenite at Battery Point . The age of the mineralization is not well established, but can be no older than the Late Triassic age of the host rocks. It may be related to the ultramafic body whose age is 108-109 m.y.
Geologic map unit (-135.371826215913, 59.1996746064875)
Mineral deposit model There is little information for assigning a deposit model. The mineralization may be related to elevated copper levels in the metabasalts or to the nearby ultramafic body.
Age of mineralization The age of the mineralization is not well established. It can be no older than the Late Triassic age of the host rocks and may be related to the 108-109 m.y. old ultramafic body nearby.
Alteration of deposit Epidotization.

Production and reserves

Indication of production None

Additional comments

This occurrence is within the Chilkat State Park.

References

MRDS Number A013108

References

Cobb, E.H., 1972, Metallic mineral resources map of the Skagway quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-424, 1 sheet, scale 1:250,000.
Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Mt. Fairweather and Skagway quadrangles, Alaska: U.S. Geological Survey Open-File Report 78-316, 123 p.
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.
Plafker, George, and Hudson, T., 1980, Regional implications of Upper Triassic metavolcanic and metasedimentary rocks on the Chilkat Peninsula, southeastern Alaska: Canadian Journal of Earth Sciences, v. 17, p. 681-689.
Plafker, George, Hudson, T.L., and Silberling, N.J., 1979, Late Triassic fossils from a sequence of volcanic and sedimentary rocks on the Chilkat Peninsula, southeastern Alaska, in Johnson, K.M., and Williams, J.R., eds., The United States Geological Survey in Alaska--Accomplishments during 1978: U.S. Geological Survey Circular 804-B, p. B107-B110.
Still, J.C., 1988, Gold-copper Mineralization of the Chilkat Peninsula and Islands: U.S. Bureau of Mines Open-File Report 49-88, 39 p., 11 sheets.
Still, J.C., 1991, Section A: Haines - Klukwan - Porcupine subarea, in U.S. Bureau of Mines, Mineral investigations in the Juneau Mining District, Alaska, 1984-1988: Volume 2 - Detailed mine, prospect, and mineral occurrence descriptions: U.S. Bureau of Mines Special Publication VOL. 2A, 214 p., 9 sheets.
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.
Winkler, G.R., and MacKevett, E.M., Jr., 1970, Analyses of bedrock and stream-sediment samples from the Haines-Porcupine region, southeastern Alaska: U.S. Geological Survey Open-File Report 369, 91 p., 1 sheet, scale 1:125,000.
Reporters T.C. Crafford (T. Crafford & Associates, Anchorage)
Last report date 2/4/2001