Yankee Creek Mine, Iditarod District, Yukon-Koyukuk Borough, Alaska, USA
|Latitude & Longitude (WGS84):||62° 58' 23'' North , 156° 24' 18'' West|
|Latitude & Longitude (decimal):||62.97306,-156.40500|
|Köppen climate type:||Dfc : Subarctic climate|
Location: 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]).
Geology: 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, eckermanite, 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 magneisochromite 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.
Workings: 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 commun., 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.
Age: The Yankee Creek placer is probably Late Tertiary to Quaternary in age (Hopkins and others, 1971).
Alteration: Weathering at bedrock surface.
Production: 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).
Reserves: 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.
Commodities (Major) - Au; (Minor) - Ag, Cr, Sb, W
Development Status: Yes
Deposit Model: Placer Au deposit (Cox and Singer, 1986; model 39a).
Commodity ListThis is a list of exploitable or exploited mineral commodities recorded at this locality.
11 valid minerals.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
0 - 2.588 Ma
|Unconsolidated surficial deposits, undivided|
Age: Pleistocene (0 - 2.588 Ma)
Reference: Wilson, F.H., Hults, C.P., Mull, C.G, and Karl, S.M. (compilers). Geologic map of Alaska. doi: 10.3133/sim3340. U.S. Geological Survey Scientific Investigations Map 3340, pamphlet 196. 
66 - 100.5 Ma
|Sedimentary; Slope and deep water|
Age: Late Cretaceous (66 - 100.5 Ma)
Description: Interior western Alaska, Southwest Basin
Comments: Sedimentary basin; Wilson & Hults, unpublished compilation, 2007-08
Reference: J.C. Harrison, M.R. St-Onge, O.V. Petrov, S.I. Strelnikov, B.G. Lopatin, F.H. Wilson, S. Tella, D. Paul, T. Lynds, S.P. Shokalsky, C.K. Hults, S. Bergman, H.F. Jepsen, and A. Solli. Geological map of the Arctic. doi:10.4095/287868. Geological Survey of Canada Map 2159A.