Unnamed (tributary to Clear Creek)

Occurrence, Inactive

Commodities and mineralogy

Main commodities U
Other commodities REE
Ore minerals allanite; uraniferous titanium niobate mineral
Gangue minerals anatase; hematite; hornblende; ilmenite; magnetite; sphene; topaz

Geographic location

Quadrangle map, 1:250,000-scale SO
Quadrangle map, 1:63,360-scale D-1
Latitude 64.895
Longitude -162.184
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is on the first north tributary to Clear Creek upstream from the confluence of Clear Creek and the Tubutuluk River. It is about 0.2 miles upstream from the confluence of the tributary and Clear Creek and at an elevation of about 125 feet. This is sample location 2974 of West (1953, Plate 1) and locality 131 of Cobb (1972, MF 445; 1978, OF 78-181).

Geologic setting

Geologic description

A heavy-mineral concentrate (concentration ratio of 600:1) from stream gravels at this locality contained 0.023% equivalent uranium (West, 1953). Minerals identified in this concentrate include pyrite, ilmenite, magnetite, anatase, hornblende, topaz, allanite, biotite, and sphene. This drainage crosses the eastern contact of the Darby pluton with metasedimentary rocks (Till and others, 1986). 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 to the north, may indicate specific mineralized zones or 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 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 (-162.186597005218, 64.8942966793615)
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 in metasedimentary rocks of this drainage.
Age of mineralization The heavy mineral concentrates are from Holocene surficial materials but some of these have been derived from 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

References

MRDS Number 10308267

References

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