|Quadrangle map, 1:250,000-scale||BD|
|Quadrangle map, 1:63,360-scale||B-5|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||Tenderfoot Creek parallels the Richardson Highway from near its headwaters to its mouth on the Tanana River about 5 miles east-southeast of the the town of Richardson. About 4 miles of the creek above its mouth has been mined and the coordinates are at about the center of the mining in the southeast quarter of section 30, , T. 8 S., R. 8 E., of the Fairbanks Meridian.|
The Richardson District is characterized by gentle slopes and broad, alluvium-filled valleys (Prindle and Katz, 1913). The area is unglaciated and largely overlain by windblown silt, sand, and loess, locally up to 50 meters thick (Foster and others, 1979). The rocks consist of three structure-bounded units (Weber and others, 1978; Swainbank and others, 1984; Noyes and others, 2006; Freeman, 2011). There is a core that consists mainly of biotite-hornblende-feldspar-quartz gneiss and lesser amphibolite, quartzite, marble and calc-silicate hornfels. The core is bounded on the north and south by amphibolite-grade pelitic schist. The contacts between the units are probably low-angle faults; north-trending vertical faults occur widely. Weber and others (1978) assign the pre-metamorphic age of the rocks to the Precambrian or Paleozoic. They were metamorphosed in the Middle to Late Devonian and recrystallized in the Early Cretaceous (Dusel-Bacon and others, 2004; Freeman, 2011). The metamorphic rocks are intruded by 90 Ma, felsic to intermediate dikes and plugs, notable the mineralized quartz-feldspar porphyry dike at the nearby Democrat Mine (BD014).
Tenderfoot Creek has been the largest gold producer in the Richardson district. Placer gold was discovered in the Richardson District on Tenderfoot Creek in 1905 and mining has continued intermittently to 2010. The depth to bedrock along most of the creek that was mined before WWII varied from 30 feet to 155 feet near its mouth and the early mining was largely by underground drifting (Ellsworth and Parker, 1911). The peak year of early mining was 1908. Mining then declined until a bench on the north side of the creek was discovered that led to a resurgence of mining until 1916 (Olson and others, 1985). Mining probably continued now and then in subsequent years but documentation is sparse. Wedow and others (1954) reported that the only placer mine in operation on Tenderfoot Creek in 1946 was on 13 Below Discovery. In 2012, A large area of tailings barren of vegetation at the head of the creek can be easily seen on satellite imagery available on the internet; it probably represents fairly recent open-pit mining with earth-moving equipment. Szumigala and others (2011) reports that two miners produced gold from an open pits on Tenderfoot Creek in 2010.
There are several determinations of the fineness of the gold from Tenderfoot Creek. Bundtzen and Reger (1977) reported the gold to be 670 fine. Metz and Hawkins (1981) reported the gold to average 901 fine and Glover (1950) reported that the gold varies from 622 to 735 fine. Chapin (1914) reported that a piece of gold-bearing galena float was recovered during mining operations; the source has not been found.The Richardson District produced about 95, 000 ounces of gold and 24, 000 ounces of silver from 1905 to 1921 (Bundtzen and Reger, 1977). Much if not the great majority of that gold came from Tenderfoot Creek. No data is available for later production.
|Geologic map unit||(-146.232253299652, 64.2745945530884)|
|Mineral deposit model||Placer Au (Cox and Singer, 1986; model 39a).|
|Mineral deposit model number||39a|
|Age of mineralization||Quaternary.|
|Workings or exploration||Placer gold was discovered in the Richardson district in 1905. Mining initially occurred on Tenderfoot Creek and expanded to nearby Banner Creek (BD001) and associated tributaries. Because the depth to bedrock in the drainage is 30 to 155 feet, early mining on Tenderfoot Creek was largely by drifting methods (Ellsworth and Parker, 1911). In recent years, surface mining, utilizing earth moving equipment, has taken place at the head of Tenderfoot Creek.|
|Indication of production||Yes; medium|
|Production notes||From 1905 through 1921, the Richardson District produced about 95,000 ounces of gold and 24,000 ounces of silver (Bundtzen and Reger, 1977). Most of this was from placers on Tenderfoot Creek. Since 1980, the district has produced approximately 10,000 additional ounces of gold from intermittent mining; an unknown portion of this came from Tenderfoot Creek (Olson and others, 1985).|
Bundtzen, T.K., and Reger, R.D., 1977, The Richardson lineament--A structural control for gold deposits in the Richardson mining district, Alaska, in Short notes on Alaskan Geology, 1977: Alaska Division of Geological and Geophysical Surveys Geologic Report 55, p. 29-34.
Dusel-Bacon, C., Wooden, J.L., and Layer, P.W., 2004, A Cretaceous Ion-Microprobe U-Pb zircon Age for the West Point Orthogneiss: Evidence for another Gneiss Dome in the Yukon-Tanana Upland in Galloway, J.P., ed., 2004, Studies by the U.S. Geological Survey in Alaska, 2001: U.S. Geological Survey Professional Paper 1678, p. 41 - 60.
McCoy, D.T.; Newberry, R.J.; Layer, P., DiMarchi, J.; Bakke, A.; Masterman, J.S. and Minehane, D.L., 1997, Plutonic-related gold deposits of interior Alaska: in Economic Geology Monograph 9, p. 191-241.
|Reporters||Cameron S. Rombach (ADGGS); D.J. Grybeck (Contractor, USGS)|
|Last report date||4/1/2012|