|Quadrangle map, 1:250,000-scale||SO|
|Quadrangle map, 1:63,360-scale||D-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This occurrence is on the second north tributary to Clear Creek upstream from the confluence of Clear Creek and the Tubutuluk River. It is 1.2 miles upstream from the tributaries confluence with Clear Creek and at about 275 feet elevation. This is sample locality 2983 of West (1953, Plate 1) and locality 132 of Cobb (1972, MF 445; 1978, OF 78-181).|
Geologic descriptionHeavy-mineral concentrate (concentration ratio of 1,100:1) from stream gravels at this locality contain 0.086% equivalent uranium. Minerals identified in the heavy-mineral concentrates include hematite, ilmenite, garnet, topaz, allanite, sphene, an unidentified uraniferous titanium niobate, and trace cassiterite and scheelite. This is the farthest downstream sample in this drainage (West, 1953) and it is located near the eastern contact of the Darby pluton with metasedimentary rocks (Till and others, 1986). Clear Creek and its north tributaries have headwaters in the Darby pluton. Many of the heavy minerals in the concentrates from stream sediments in the area are known accessory minerals in the Darby pluton. The widespread elevated Nb values in stream sediments (Miller and Grybeck, 1973) and in heavy -mineral concentrates (West, 1953) of the Clear Creek-Vulcan Creek area may indicate specific mineralized zones of disseminations in late, felsic phases of the Darby pluton (Miller and Grybeck, 1973). The Darby pluton is a mid-Cretaceous granodiorite and granite that has elevated background levels of uranium and thorium (Miller and others, 1972; Miller and Bunker, 1976; Johnson and others, 1979). This pluton is considered the bedrock source of uranium that was mobilized and deposited in the Death Valley sandstone uranium deposit (in the Bendeleben quadrangle to the north) during the Eocene (Dickinson and others, 1987). K/Ar ages for the Darby pluton are 88.3 +/- 1.5 and 92.8 +/- 2.6 Ma (Berry and others, 1976).
|Geologic map unit||(-162.24559659574, 64.8812953208985)|
|Mineral deposit model||Disseminated; uranium- and rare-earth-bearing minerals are probably accessory phases in the Darby pluton. Other types of deposits could be present locally as suggested by the presence of cassiterite and scheelite.|
|Age of mineralization||The heavy mineral concentrates are from Holocene surficial materials but these have been primarily derived from the nearby bedrock of the Darby pluton. The Darby pluton is mid-Cretaceous; K/Ar ages for the Darby pluton are 88.3 +/- 1.5 and 92.8 +/- 2.6 Ma (Berry and others, 1976).|
|Workings or exploration||There are no known workings; exploration in the region may have included reconnaissance stream sediment sampling and radiometric surveys.|
|Indication of production||None|
|MRDS Number||A012616; D002608|
Berry, A.L., Dalrymple, G.B., Lamphere, M.A., and Von Essen, J.C., and others, 1976, Summary of miscellaneous potassium-argon age measurements, U.S. Geological Survey, Menlo Park, California, for the years 1972-1974: U.S. Geological Survey Circular 727, 13 p.
Cobb, E.H., 1972, Metallic mineral resources map of the Solomon quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-445, 1 sheet, scale 1:250,000.
Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Solomon quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-181, 185 p.
Johnson, B.R., Miller, T.P., and Karl, Susan, 1979, Uranium-thorium investigations of the Darby pluton, Seward Peninsula, Alaska: U.S. Geological Survey Circular 804-B, p. B68-B70.
Miller, T.P., and Bunker, C.M., 1976, A reconnaissance study of the uranium and thorium contents of plutonic rocks of the southeastern Seward Peninsula, Alaska: U.S. Geological Survey Journal of Research, v. 4, p. 367-377.
Miller, T.P., and Grybeck, D.J., 1973, Geochemical survey of the eastern Solomon and southeastern Bendeleben quadrangles, Seward Peninsula, Alaska: U.S. Geological Survey Open-File Report 73-189, 115 p.
Miller, T.P., Grybeck, D.J., Elliott, R.L., and Hudson, T.L., 1972, Preliminary geologic map of the southeastern Bendeleben and eastern Solomon quadrangles, eastern Seward Peninsula, Alaska: U.S. Geological Survey Open-File Report 72-256, 11 p., 1 sheet, scale 1:250,000.
Till, A.B., Dumoulin, J.A., Gamble, B. ., Kaufman, D.S., and Carroll, P.I., 1986, Preliminary geologic map and fossil data, Soloman, Bendeleben, and southern Kotzebue quadrangles, Seward Peninsula, Alaska: U.S. Geological Survey Open-File Report 86-276, 10 p., 3 plates, scale 1:250,000.
|Reporters||Travis L. Hudson (Applied Geology)|
|Last report date||8/19/1999|