|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 is plotted where Cottonwood Creek flattens and forms an alluvial fan on the northern side of the Tsirku River, about 1 mile northeast of the terminus of the Le Blondeau Glacier. It is shown as location 29 by Cobb (1974 [MF 424]).|
Placer gold was discovered on Cottonwood Creek in 1899. Although encouraging amounts of gold have been found, none has been produced in significant amounts. Gravel resources in the creek channel are limited due to the steep gradient and narrow bedrock canyon. The average gradient is 750 feet per mile. A significant but untested identified resource exists in the alluvial fan at the mouth of the creek which coalesces with the fan at the mouth of Nugget Creek to the east. Abandoned channels, which may host placer gold have been identified in the fan between Cottonwood and Nugget Creeks. Reconnaissance samples contained up to 0.0005 ounces of gold per cubic yard and pan concentrates contained 10-20% magnetite, up to 10% pyrite, and minor amounts of garnet, zircon, and scheelite. (Hoekzema and others, 1986).The Cottonwood Creek placer lies within a northwest-trending zone of quartz-sulfide veining in sediments and slates in the Skagway B-4 quadrangle described by Wright (1904 [B 225 and B 236]), Eakin (1918 and 1919), and MacKevett and others (1974) and considered to be the source of placer gold in this area.
|Geologic map unit||(-136.211869954135, 59.2896488733493)|
|Mineral deposit model||Placer in alluvial fans and paleo-channels (Cox and Singer, 1986; model 39a).|
|Mineral deposit model number||39a|
|Age of mineralization||Quaternary placer.|
|Workings or exploration||Hoekzema and others (1986) report that placer gold was discovered on Cottonwood Creek in 1899 but gold was never produced in significant amounts. The alluvial fan extending along the northern edge of the Tsirku River from Cottonwood Creek to below Nugget Creek was prospected with encouraging results prior to 1912 and a company was formed to dredge the alluvial gravels. Fifty claims were staked to cover the fan but the ground was abandoned in 1916. Portions of the Cottonwood-Nugget Creek fan were patented in 1934.|
|Indication of production||None|
|Production notes||No significant amount of gold produced.|
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.
Brooks, A.H., 1913, Mineral resources of Alaska, report on progress of investigations in 1912: U.S. Geological Survey Bulletin 542, 308 p.
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.
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.
Gilbert and Redman, 1989;
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.
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.
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.
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|