Unnamed (tributary to Clear Creek)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Sn; U; W
Other commodities REE
Ore minerals allanite; cassiterite; scheelite; uraniferous titanium niobate
Gangue minerals garnet; hematite; ilmenite; sphene; topaz

Geographic location

Quadrangle map, 1:250,000-scale SO
Quadrangle map, 1:63,360-scale D-1
Latitude 64.882
Longitude -162.243
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 setting

Geologic description

Heavy-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).

Production and reserves

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


Reporters Travis L. Hudson (Applied Geology)
Last report date 8/19/1999