Unnamed (on Rock Creek)

Site Name

Primary: Unnamed (on Rock Creek)

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Commodity

Primary: Uranium
Primary: REE

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Location

State: Alaska
District: Koyuk

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Land Status

Not available

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Holdings

Not available

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Workings

Not available

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Ownership

Not available

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Occurrence
Operation Type: Unknown
Years of Production:
Organization:
Significant:

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Physiography

Not available

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Mineral Deposit Model

Not available

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Orebody

Not available

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Structure

Not available

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Alterations

Not available

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Rocks

Role: Associated
Age Type: Associated Rock
Age in Years: 92.800000+-2.600000
Dating Method: K-Ar
Age Young: Late Cretaceous

Role: Associated
Age Type: Associated Rock
Age in Years: 88.300000+-1.500000
Dating Method: K-Ar
Age Young: Late Cretaceous

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Analytical Data

Not available

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Materials

Ore: Allanite
Gangue: Topaz
Gangue: Anatase
Gangue: Epidote
Gangue: Garnet
Gangue: Hematite
Gangue: Ilmenite
Gangue: Kyanite
Gangue: Sphene

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Comments

Comment (Geology): Age = Chron age is for the Darby pluton.

Comment (Exploration): Status = Inactive

Comment (Reference): Primary Reference = West, 1953

Comment (Workings): Workings / Exploration = There are no known workings; exploration in the region may have included reconnaissance stream sediment sampling and radiometric surveys.

Comment (Commodity): Ore Material = uraniferous titanium niobate mineral

Comment (Deposit): Model Name = 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.

Comment (Geology): Geologic Description = A heavy-mineral concentrate (concentration ratio 2,250:1) from stream gravels at this locality contained 0.036% equivalent uranium (West, 1953). Minerals identified in the concentrate included allanite, hematite, ilmenite, magnetite, anatase, garnet, topaz, kyanite, epidote, and sphene. An unidenitied 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).

Comment (Geology): Age = 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).

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References

Reference (Deposit): West, W.S., 1953, Reconnaissance for radioactive deposits in the Darby Mountains, Seward Peninsula, Alaska, 1948: U.S. Geological Survey Circular 300, 7 p.

Reference (Deposit): 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.

Reference (Deposit): 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.

Reference (Deposit): Berry, A.L., Dalrymple, G.B., Lamphere, M.A., and Von Essen, J.C., 1976, Summary of miscellaneous potassium-argon age determinations, U. S. Geological Survey, Menlo Park, California, for the years 1972-1974: U.S. Geological Survey Circular 727, 13 p.

Reference (Deposit): 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 553, 115 p.

Reference (Deposit): Cobb, E.H., 1972, Metallic resources map of the Solomon quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-445, scale 1:250,000.

Reference (Deposit): Miller, T.P., Grybeck, D.J., Elliott, R.L., and Hudson, T.L., 1972, Preliminary geologic map of the eastern Solomon and southeastern Bendeleben quadrangles, eastern Seward Peninsula, Alaska: U.S. Geological Survey Open-File Report 72-256, 11 p.

Reference (Deposit): Johnson, B.R., Miller, T.P., and Karl, S., 1979, Uranium-thorium investigations of the Darby pluton, Seward Peninsula, Alaska: U.S. Geological Survey Circular 804-B, p. 68-70.

Reference (Deposit): 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.

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