Unnamed (on Rock Creek)

Occurrence, Inactive

Commodities and mineralogy

Main commodities U
Other commodities REE
Ore minerals allanite; uraniferous titanium niobate mineral
Gangue minerals anatase; epidote; garnet; hematite; ilmenite; kyanite; sphene; topaz

Geographic location

Quadrangle map, 1:250,000-scale SO
Quadrangle map, 1:63,360-scale D-1
Latitude 64.971
Longitude -162.338
Nearby scientific data Find additional scientific data near this location
Location and accuracy Rock Creek is a west tributary to the Tubutuluk River. This occurrence is at an elevation of about 900 feet along the main drainage; it is about 4.3 miles upstream from the north boundary of the Solomon D-1 quadrangle. It is sample location 3052 of West (1953, Plate 1) and locality 126 of Cobb (1972, MF 445; 1978, OF 78-181).

Geologic setting

Geologic description

A heavy-mineral concentrate (concentration ratio 2,250:1) from stream gravels at this locality contained 0.036 percent equivalent uranium (West, 1953). Minerals identified in the concentrate included allanite, hematite, ilmenite, magnetite, anatase, garnet, topaz, kyanite, epidote, and sphene. An unidentified uraniferous titanium niobate mineral is present in many heavy-mineral concentrates from the eastern part of the Darby pluton (West, 1953). The Rock Creek drainage is primarily within the Darby pluton but headwater areas cross the western contact of the pluton to areas of metasedimentary rocks (Till and others, 1986). 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 (-162.340605371357, 64.9702962585346)
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 much of these materials 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 A012619

References

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