|Quadrangle map, 1:250,000-scale||OP|
|Quadrangle map, 1:63,360-scale||A-2|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||Anvil Creek is a 2.5-mile-long, northeast-flowing tributary to the Innoko River; the junction of Anvil Creek and the Innoko River is approximately 1 mile southeast of the town of Ophir. The coordinates are for the mine marked on the U.S. Geological Survey Ophir A-2 topographic map (1954, minor revisions 1965), in the SE 1/4SE 1/4 sec. 23, T. 27 S., R. 12 E., Kateel River Meridian. Anvil Creek is locality 15 of Cobb (1972 [MF 367]). The location is accurate within 500 feet.|
The rocks in the vicinity of Anvil Creek are sandstone, shale, and siltstone (Chapman and others, 1985). The creek probably also drains a small, Cretaceous or Tertiary intrusive body.
The gold in Anvil Creek occurs in a narrow pay streak in stream gravels and in less-rich bench deposits. The gold was found on bedrock surfaces and in crevices within the upper 6 inches of bedrock. The largest nugget reported from Anvil Creek was 6 ounces. The nuggets have a fineness of 878 parts gold and 117 parts silver (Mertie, 1936). Mertie (1936) also reports considerable cinnabar in concentrates.
Gold was discovered along Anvil Creek in 1917. Production occurred intermittently in Anvil Creek until 1950, and intermittently from the 1970s until at least 1986 (Brooks and Capps, 1924; Smith, 1932; Smith, 1936; Smith, 1938; Mertie, 1936; Roehm, 1937; Fowler, 1950).
An unnamed 'pup' tributary of Anvil Creek runs parallel to Anvil Creek and then enters an old oxbow on the south side of the Innoko River. This tributary was staked in 1980 and reportedly contains about 4 feet of gravel under 6 feet of mud. Although no coarse gold has been found, many grains of fine gold were recovered (Dick Forsgren, written communication, 2001).Bundtzen and Miller (1997) used radioactive-isotope dating techniques to demonstrate that the age of hydrothermal sericite from the Ophir-Little Creek prospect area is 70 Ma, contemporaneous with primary igneous white mica in dikes near Ophir. Lode gold mineralization in this area probably is related to magmatic fluids from these Upper Cretaceous or Tertiary dikes (or other, coeval plutons), which probably are the source of at least some of the placer gold in Anvil Creek (Bundtzen and Miller, 1997).
|Geologic map unit||(-156.504864126053, 63.1271709026989)|
|Mineral deposit model||Placer Au (Cox and Singer, 1986; model 39a)|
|Mineral deposit model number||39a|
|Age of mineralization||Quaternary. Bundtzen and Miller (1997) used radioactive-isotope dating techniques to demonstrate that the age of hydrothermal sericite from the Ophir-Little Creek prospect area is 70 Ma, contemporaneous with primary igneous white mica in dikes near Ophir. Lode gold mineralization in this area probably is related to magmatic fluids from these Upper Cretaceous or Tertiary dikes (or other, coeval plutons), which probably are the source of at least some of the placer gold in Anvil Creek (Bundtzen and Miller, 1997).|
|Workings or exploration||A narrow paystreak beneath the channel of Anvil Creek was worked by drift mining; less-rich bench deposits were worked by open cuts (Mertie, 1936). Mining occurred along Anvil Creek from 1917 to 1950 and also from the 1970s until at least 1986 (Bundtzen and others, 1987).|
|Indication of production||Yes; small|
|Production notes||Between 1917 and 1950, an estimated 3,394 ounces of gold and 12 ounces of silver were produced from Anvil Creek. Anvil Creek was also mined from the 1970s until at least 1986 (Bundtzen and others, 1987).|
Brooks, A.H., and Capps, S.R., 1924, The Alaska mining industry in 1922: U.S. Geological Survey Bulletin 755-A, p. 1-56.
Bundtzen, T.K., and Miller, M.L., 1997, Precious metals associated with Late Cretaceous-early Tertiary igneous rocks of southwestern Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 242-286.
Bundtzen, T.K., Cox, B.C., and Veach, N.C., 1987, Heavy mineral provenance studies in the Iditarod and Innoko districts, western Alaska: Alaska Division of Geological and Geophysical Surveys Public-Data File 87-16, 25 p.
Chapman, R.M., Patton, W.W., and Moll, E.J., 1985, Reconnaissance geologic map of the Ophir quadrangle, Alaska: U.S. Geological Survey Open-File Report 85-203, 19 p., 1 sheet, scale 1:250,000.
Cobb, E.H., 1972, Metallic mineral resources map of the Ophir quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-367, 1 sheet, scale 1:250,000.
Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction material) in the Iditarod and Ophir quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-576, 101 p.
Fowler, H.M., 1950, Report of investigations in the Innoko, Nulato, Bethel, Goodnews Bay, Wasilla, Chisana, and Ketchikan mining districts: Alaska Territorial Department of Mines Itinerary Report 195-7, 13 p.
Mertie, J.B., Jr., 1936, Mineral deposits of the Ruby-Kuskokwim region, Alaska: U.S. Geological Survey Bulletin 864-C, p. 115-245.
Roehm, J.C., 1937, Summary report of mining investigations in the Innoko, Mt. McKinley, Knik, and Talkeetna precincts: Alaska Territorial Department of Mines Itinerary Report 195-17, 16 p.
Smith, P.S., 1932, Mineral industry of Alaska in 1929, in Smith, P.S., and others Mineral resources of Alaska, report on progress of investigations in 1929: U.S. Geological Survey Bulletin 824-A, p. 1-81.
Smith, P.S., 1936, Mineral industry of Alaska in 1934: U.S. Geological Survey Bulletin 868-A, p. 1-91.
|Last report date||8/7/2001|