|Quadrangle map, 1:250,000-scale||ID|
|Quadrangle map, 1:63,360-scale||D-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Yankee Creek placer extends for 6 miles in the upper part of Yankee Creek. The coordinates are for a point about halfway in the mined portion of the creek in the Iditarod quadrangle, the center is in the SE1/4 SW1/4 of section 1, T. 33 N., R. 38 W., of the Seward Meridian. The location is accurate. Yankee Creek is locality 44 of Cobb (1972 [MF 363]); also described in Cobb (1976 [OFR 76-576]).|
Yankee Creek is one of the larger producers of placer gold mine in the Innoko mining district. Production from 1909 to 1995 has been at least 58,120 ounces of gold and 7,505 ounces of silver (Miller, Bundtzen, and Gray, 2005). About 20,000 ounces of placer gold has been mined in the Ophir-quadrangle part of the Yankee Creek drainage (Bundtzen and Laird, 1980).
Yankee Creek occupies a broad, 1,600-foot-wide valley. The auriferous gravel deposits were thawed and shallow, and covered by 6 to 15 feet of overburden. The pay gravel varies from about 5 to 12 feet thick and most of the gold occurred within 3 feet of bedrock.
Minor gold that was aggregated with the production from Yankee Creek came from its tributary creeks or gulches including Marten and Skookum Gulches. Although not important as producers themselves they are important as the sources of the gold in Yankee Creek as much of its production came from near the mouths of these tributaries. More than 90 percent of the gold-bearing gravels in Yankee Creek basin were in a single, fluvial, distributary channel about 7 miles long and 50 to about 250 feet wide. The remaining gold was produced from an ancestral terrace deposit on the east bank of Yankee Creek downstream from Yankee Creek placer camp. The placer gold in the Yankee Creek basin is downslope and downstream from the Ganes-Yankee Creek fault zone and its associated gold-bearing intrusions and country rocks (Bundtzen, 1980; Bundtzen and Miller, 1997; Miller, Bundtzen, and Gray, 2005).The gold from Yankee Creek varied from 850 to 886 fine and averages about 870 fine (Smith, 1941 [B 910-C]; Bundtzen, Cox, and Veach, 1987). Considerable placer scheelite was found near the head of the creek, just downstream from the Telephone Hill prospect (ID035). Other heavy minerals found in concentrates include arsenopyrite, magnesiochromite, ilmenite, anatase, akermanite, and a trace of hidalgoite (Bundtzen, Cox, and Veach, 1987). Nuggets up to 32 ounces in weight have been mined from Yankee Creek (Babe Anderson, oral communication, 2003). Although no large mafic or ultramafic rock bodies are known in the area, chromite and magnesiochromite are abundant in heavy mineral concentrates from Yankee Creek and also from Ganes Creek. Easily eroded, altered mafic-ultramafic dikes and sills near the Ganes-Yankee fault might be the source of the chromite and magnesiochromite.
|Geologic map unit||(-156.406992115509, 62.9726874815516)|
|Mineral deposit model||Placer Au deposit (Cox and Singer, 1986; model 39a).|
|Mineral deposit model number||39a|
|Age of mineralization||The Yankee Creek placer is probably Late Tertiary to Quaternary in age (Hopkins and others, 1971).|
|Alteration of deposit||Weathering at bedrock surface.|
|Workings or exploration||Yankee Creek was prospected in the winter of 1908-09 (Maddren, 1910) and mining probably began later in 1909. Most of the creek was explored with churn drills in 1918 and 1919 (Toivo Rosander, oral communication, 1979). Because the placer deposit was shallow and thawed, most prospecting and exploration since World War II has been in bulldozer cuts and test pits.|
|Indication of production||Yes|
|Reserve estimates||None documented. Placer gold resources probably exist in tributary creeks and in low-grade terrace deposits in the lower part of the Yankee Creek basin.|
Yankee Creek has been a significant producer of placer gold in the Innoko mining district. Production from 1909 to 1995 has been at least 58,120 ounces of gold and 7,505 ounces of silver (Miller, Bundtzen, and Gray, 2005). About 20,000 ounces of placer gold has been mined in the Ophir-quadrangle part of the Yankee Creek drainage (Bundtzen and Laird, 1980).
The creek was first mined in open cuts with scrapers and draglines and later by dredging. The Discovery claim is near the Rosander mine camp in section 1, T. 33 N., R. 38 W, of the Seward Meridian. The creek has been worked from 14 Above to 11 Below Discovery, almost all of which is in the Iditarod quadrangle. A diesel-powered flume dredge, the Felder, Gale, and Higgins dredge, operated from 1921 to about World War II (Smith, 1942). The dredge burned; remnants of the dredge are on No. 6 Above Discovery in the SE1/4 section 21, T. 33 N., R. 38 W (Eakin, 1914; Mertie, 1936; T.K. Bundtzen, unpublished data, 1978, 1979, 2002).Mining was renewed in 1946, when the Toivo Rosander and Larry Reed began mining Yankee Creek and recovered the gold with a large elevated-sluice box fed by bulldozers and draglines (Stewart, 1947). This operation, which accounts for about 65 percent of the recorded production on Yankee Creek, continued until 1968 (unpublished U.S. Mint records; Tovio Rosander oral communication, 1980). From 1986-1994, Anderson and Sons, Inc. mined in open cuts with bulldozers on Yankee Creek and two Yankee Creek has produced gold nuggets up to 32 ounces in weight (Babe Anderson, oral communication., 2003).
Bundtzen, T.K., 1980, Geological guides to heavy mineral placers, in Second annual conference on Alaskan Placer Mining-Focus on Gold: University of Alaska Mineral Industry Research Laboratory, p. 21-44.
Bundtzen, T.K., and Laird, G.M., 1983, Geologic map of the Iditarod D-1 quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Professional Report 78, scale 1:63,360.
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: Process Mineralogy VII, The Metallurgical Society, p. 221-246.
Bundtzen, T.K., Swainbank, R.C., Clough, A.H., Henning, M.W., and Charlie, K.M., 1996, Alaska's mineral industry, 1995: Alaska Division of Geological and Geophysical Surveys Special Report 50, 72 p.
Cobb, E.H., 1972, Metallic mineral resources map of the Iditarod quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-363, 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.
Hopkins, D.M., Matthews, J.V., Wolfe, J.A., and Silberman, M.L., 1971, A Pliocene flora and insect fauna from the Bering Sea region: Paleoecology, vol. 9, p. 211-231.
Maddren, A.G., 1910, The Innoko gold-placer district, Alaska, with accounts of the central Kuskokwim valley and the Ruby Creek and Gold Hill placers: U.S. Geological Survey Bulletin 410, 87 p.
Mertie, J.B., Jr., 1936, Mineral deposits of the Ruby-Kuskokwim region, Alaska: U.S. Geological Survey Bulletin 864-C, p. 115-245.
Miller, M.L., and Bundtzen, T.K., 1994, Generalized geologic map of the Iditarod quadrangle, Alaska showing potassium-argon, major oxide, trace element, fossil, paleocurrent, and archeological sample localities: U.S. Geological Survey Miscellaneous Field Studies Map MF-2219-A, 48 pages; 1 sheet, scale 1:250,000.
Miller, M.L., Bundtzen, T.K., and Gray, J.E., 2005, Mineral resource assessment of the Iditarod quadrangle, west-central Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-2219-B, scale 1:250,000, pamphlet.
Smith, P.S., 1941, Fineness of gold from Alaska placers: U.S. Geological Survey Bulletin 910-C, p. 147-269.
Smith, P.S., 1942, Mineral industry of Alaska in 1940: U.S. Geological Survey Bulletin 933-A, p. 1-102.
|Reporters||T.K. Bundtzen (Pacific Rim Geological Consulting, Inc.), M.L. Miller (U.S. Geological Survey); and C.C. Hawley (Hawley Resource Group)|
|Last report date||5/16/2003|