Unnamed (on Rock Creek)

Occurrence in Alaska, United States with commodities REE, Uranium

Geologic information

Identification information

Deposit ID 10001810
MRDS ID A012619
Record type Site
Current site name Unnamed (on Rock Creek)

Geographic coordinates

Geographic coordinates: -162.34134, 64.97047 (WGS84)
Relative position 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).
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
REE Primary
Uranium Primary

Comments on the commodity information

  • Ore Material = uraniferous titanium niobate mineral

Materials information

Materials Type of material
Allanite Ore
Anatase Gangue
Epidote Gangue
Garnet Gangue
Hematite Gangue
Ilmenite Gangue
Kyanite Gangue
Sphene Gangue
Topaz Gangue

Host and associated rocks

  • Host or associated Associated
    Chronological age 88.3
    Uncertainty 1.5
    Dating method K-Ar
    Stratigraphic age (youngest) Late Cretaceous
    Chronological age 92.8
    Uncertainty 2.6
    Dating method K-Ar
    Stratigraphic age (youngest) Late Cretaceous

Nearby scientific data

(1) -162.34134, 64.97047

Comments on the geologic information

  • 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).
  • 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).
  • Age = Chron age is for the Darby pluton.

Economic information

Economic information about the deposit and operations

Development status Occurrence
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Koyuk

Comments on the workings information

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

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A012619
USGS Alaska Resource Data File ARDF SO044

Bibliographic references

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

Comments on the references

  • Primary Reference = West, 1953

General comments

Subject category Comment text
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.

Reporter information

Type Date Name Affiliation Comment
Reporter 19-AUG-1999 Travis L. Hudson Applied Geology