|Quadrangle map, 1:250,000-scale||SK|
|Quadrangle map, 1:63,360-scale||B-4|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The location of this occurrence, in the center of section 1, T. 29 S., R. 54 E. of the Copper River Meridian, is somewhat arbitrary and applies to a broad northwest trending band of mineralization. It is taken from Eakin (1919) who describes a northwest trending band of quartz-sulfide veinlets in slate that is 1,200 feet thick and cuts across Cahoon Creek near its mouth. This band is contained within a larger zone of sporadic quartz-sulfide veins and stringers that Eakin describes as extending in a northwesterly direction from the Salmon (Tsirku) River, through Porcupine, Glacier, and Jarvis Creeks to the mountain mass north of the Jarvis Glacier.|
Eakin (1918 and 1919) describes a nearly 1,200-foot-wide band of abundant quartz-sulfide veining in slate that cuts across Cahoon Creek near its mouth. He further notes that this zone of abundant veining occurs within a northwest-trending larger area of sediment hosted, discontinuous lode mineralization that consist of quartz, iron sulfides, and calcite veins, veinlets, and lenses that extends from south of the Salmon (Tsirku) River across the basins of Porcupine, Glacier, and Jarvis Creeks and into the mountain mass north of the Jarvis Glacier. Eakin infers that this larger zone of veining is the source of the placer gold in the Klehini and Salmon (Tsirku) River basins.
Wright (1904 [B 225 and B 236]) noted that this zone of mineralization occurs in sedimentary rocks in the Porcupine area that are all more or less mineralized by veins of quartz and calcite. Iron sulfides that occur as films and conformable lenticular masses up to a few inches thick form an interrupted zone of mineralization in the southern portion of the sedimentary series. Quartz veins are not abundant and are often stringers parallel to the cleavage of the slate. The few crosscutting quartz veins carry galena, sphalerite, and minor chalcopyrite. Although these quartz-sulfide veins are quite narrow, they often persist for considerable distances. Light-brown-weathering calcite veins are more numerous than quartz veins, are often more than a foot thick; they may include pyrite cubes up to an inch across. Gold has been reported from veins of this nature up McKinley Creek ; see (SK046) and (SK047).MacKevett and others (1974) observed that, 'Lode occurrences are localized mainly in or near the slate in the central part of the B-4 quadrangle, and the placers are mainly along streams that drain the slate terrane.'
|Geologic map unit||(-136.24185755968, 59.389670813014)|
|Mineral deposit model||Auriferous quartz-sulfide veins in slate and in silica-carbonate-altered mafic dikes (Cox and Singer, 1986; model 22c).|
|Mineral deposit model number||22c|
|Age of mineralization||Unknown, but probably Cretaceous or younger based on the age of intrusives in the area (MacKevett and others, 1974).|
|Alteration of deposit||Some of the larger auriferous quartz-sulfide veins in the vicinity are associated with mafic dikes that have been altered to silica-carbonate rocks (see Golden Eagle (SK047)).|
|Indication of production||None|
Beatty, W.B., 1937, Geology of the placer deposits of Porcupine, Alaska: Seattle, University of Washington, B.Sci. thesis, 97 p.
Berg, H.C., 1984, Regional geologic summary, metallogenesis, and mineral resources of southeastern Alaska: U.S. Geological Survey Open-file Report 84-572, 298 p., 1 plate, scale 1:600,000.
Bundtzen, T.K., 1986, Placer geology of the Porcupine Mining District, Skagway B-4 Quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Public-Data File 86-27, 26 p., 1 sheet, scale 1:40,000.
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.
Eakin, H.M., 1918, Gold placer mining in the Porcupine district: U.S. Geological Survey Bulletin 662-B, p. 93-100.
Eakin, H.M., 1919, The Porcupine gold placer district, Alaska: U.S. Geological Survey Bulletin 699, 29 p.
Hoekzema, R.B., Fechner, S.A., and Bundtzen, T.K., 1986, Distribution, analysis, and recovery of placer gold from the Porcupine mining area, southeast Alaska: U.S. Bureau of Mines Open-File Report 89-86, 49 p., 4 sheets.
Koschmann, A.H., and Bergendahl, M.H., 1968, Principal gold producing districts of the United States: U.S. Geological Survey Professional Paper 610, 283 p.
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.
Roppel, Patricia, 1975, Porcupine: Alaska Journal, v. 5, no. 1, pp. 2-10.
Smith, P.S., 1933, Past placer gold production from Alaska: U.S. Geological Survey Bulletin 857-B, 19 p.
Smith, P.S., 1941, Fineness of gold from Alaska placers: U.S. Geological Survey Bulletin 910-C, p. 147-269.
Stewart, B.D., 1926, Notes on placer operations in Porcupine District: Alaska Territorial Department of Mines Miscellaneous Report 109-1, 5 p.
Still, J.C., Gilbert, W.G., and Forbes, R.B., 1987, Final report of stream sediment, float, and bedrock sampling in the Porcupine mining area, southeast Alaska, 1983-1985: U.S. Bureau of Mines Open-File Report 36-87, 35 p., 8 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.
Still, J.C., Weir, K.R., Gilbert, W.G., and Redman, Earl, 1984, Stream sediment, float, and bedrock sampling in the Porcupine mining area, southeast Alaska: U.S. Bureau of Mines Open-File Report 173-84, 6 p., 1 sheet, scale 1:250,000.
Williams, J.A., 1960, Report of the Division of Mines and Minerals for the year 1959: Alaska Division of Mines and Minerals Annual Report 1959, 80 p.
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.
Wright, C.W., 1904, The Porcupine placer district, Alaska: U.S. Geological Survey Bulletin 236, 35 p.
|Reporters||T.C. Crafford (T. Crafford & Associates, Anchorage)|
|Last report date||2/4/2001|