|Quadrangle map, 1:250,000-scale||CY|
|Quadrangle map, 1:63,360-scale||B-5|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Woodchopper Creek basin and the area surrounding it cover approximately 55 square miles. Tributaries to Woodchopper Creek include Dome Creek (CY010), Mineral Creek (CY020), Moore Creek (CY016), and Iron Creek (CY019). The coordinates for the Woodchopper Creek mine are located in the center of the placer workings marked on the Charley River (B-5) quadrangle topographic map, in section 34, T. 6 N., R. 21 E., of the Fairbanks Meridian. The principal placer mining activity was about 1.25 miles upstream and downstream from this point. The location is accurate.|
The headwaters of Woodchopper Creek are underlain by Precambrian to Paleozoic metamorphic rocks that are intruded by Mesozoic(?) granitic plutons. The creek flows across a belt of Cretaceous to Tertiary conglomerate and other sedimentary rocks (Brabb and Churkin, 1969; Dover and Miyaoka, 1988). Gold placers are found in or immediately downstream from this belt. The proximal source of the gold is likely the conglomerate, but the ultimate source is probably the older metamorphic rocks upstream (Prindle and Mertie, 1912). Platinum metals are alloyed with the gold, and monazite is also present. In the 1912 workings, the depth to the conglomerate bedrock was about 22 feet; about 11 feet of this was gravel that contained many granite boulders (Prindle and Mertie, 1912). In 1942, the mean of 6 assays from the creek was 932 parts Au per thousand, and 62 parts Ag per thousand. One sample assayed 0.42 percent Pt with a trace of Ir (Mertie, 1942).Gold was discovered in 1902, or possibly earlier; mining and exploration continued intermittently in the area until 1964. In 1910, the gold output for the area was about $20,000 (1910 dollars) (Cobb, 1973; B 1374).
|Geologic map unit||(-143.291396698863, 65.3036648315207)|
|Mineral deposit model||Placer Au (Cox and Singer, 1986; model 39a).|
|Mineral deposit model number||39a|
|Age of mineralization||Quaternary.|
|Workings or exploration||Gold was discovered in 1902, or possibly earlier, and mining and exploration continued intermittently in the area until 1964, when the dredge that had been operating since 1937 shut down.|
|Indication of production||Yes; medium|
|Production notes||Gold output for 1910 was estimated to be about $19,000 (1910 dollars) for the Woodchopper Creek area. For 1909, gold production was estimated to be about $20,000 (1909 dollars) (Cobb, 1976 [OFR 76-632]).|
Additional commentsSee also Mineral Creek (CY020), Alice Gulch (CY002), Dome Creek (CY010), and Iron Creek (CY019). This site is within the Yukon-Charley Rivers National Preserve.
|MRDS Number||A010754; A015234; M045828|
Bates, R.G., and Wedow, Helmuth, Jr., 1953, Preliminary summary review of thorium-bearing mineral occurrences in Alaska: U.S. Geological Survey Circular 202, 13 p.
Brabb, E.E., and Churkin, M.J., 1969, Geologic map of the Charley River quadrangle, east-central Alaska: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-573, 1 sheet, scale 1:250,000.
Brooks, A.H., 1903, Placer gold mining in Alaska in 1902: U.S. Geological Survey Bulletin 213, p. 41-48.
Cobb, E.H., 1972, Metallic mineral resources map of the Charley River quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-390, 1 sheet, scale 1:250,000.
Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Charley River and Coleen quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-632, 45 p.
Dover, J.A., and Miyaoka, R.T., 1988, Reinterpreted geologic map and fossil data, Charley River quadrangle, east-central Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-2004, 2 sheets, scale 1:250,000.
Ellsworth, C.E., and Davenport, R.W., 1913, Placer mining in the Yukon-Tanana region: U.S. Geological Survey Bulletin 542-F, p. 203-222.
Mertie, J.B., Jr., 1938, Gold placers of the Fortymile, Eagle, and Circle districts, Alaska: U.S. Geological Survey Bulletin 897-C, p. 133-261.
Mertie, J.B., Jr., 1942, Tertiary deposits of the Eagle-Circle district, Alaska: U.S. Geological Survey Bulletin 917-D, p. 213-264.
Overstreet, W.C., 1967, The geologic occurrence of monazite: U.S. Geological Survey Professional Paper 530, 327 p.
Prindle, L.M., and Mertie, J.B., Jr., 1912, Gold placers between Woodchopper and Fourth of July Creeks, upper Yukon River: U.S. Geological Survey Bulletin 520-G, p. 201-210.
|Reporters||C.E. Cameron (ADGGS)|
|Last report date||4/7/2000|