Clifton

Prospect in Alaska, United States with commodity Molybdenum

Geologic information

Identification information

Deposit ID 10002210
MRDS ID A013111
Record type Site
Current site name Clifton
Related records 10258422

Geographic coordinates

Geographic coordinates: -135.22211, 59.52976 (WGS84)
Relative position This prospect is marked by a shallow shaft about 1,000 feet northeast of Clifton. It is just east of the White Pass and Yukon Railroad track at an elevation of about 900 feet in the SW 1/4, section 16, T. 27 S., R. 60 E. of the Copper River Meridian. Clifton is an old station on the White Pass and Yukon Railroad that is essentially coincident with Bench Mark 855 ('BM 855'). Smith (1942) refers to the location of a 30-foot tunnel about 80 feet south of the shaft on the west side of the railroad track. Herbert and Race (1965), however, mention a short tunnel on the west side of the railroad track west of their map location 2 , which is plotted about 2,500 feet southwest of Clifton. This prospect is location 21 of Cobb (1972 [MF 424]).
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Molybdenum Primary

Materials information

Materials Type of material
Molybdenite Ore
Quartz Gangue

Alteration

  • (Local) None is specifically referenced in the geologic descriptions in Smith (1942) but Herbert and Race (1965) suggest bleaching and possibly, silicification.

Host and associated rocks

  • Host or associated Host
    Chronological age 48.8
    Uncertainty 1
    Dating method U-Pb (zircon)
    Type of media Zircon
    Stratigraphic age (youngest) Middle Eocene
    Stratigraphic age (oldest) Early Eocene
    Chronological age 48
    Uncertainty 2
    Dating method U-Pb (zircon)
    Type of media Zircon
    Stratigraphic age (youngest) Middle Eocene
    Stratigraphic age (oldest) Early Eocene

Nearby scientific data

(1) -135.22211, 59.52976

Comments on the geologic information

  • Geologic Description = According to Herbert and Race (1965), sparse molybdenite occurs in an aplite dike at a shallow shaft northeast of Clifton. The aplite dike occurs within a quartz monzonite that contains strong horizontal sheeting, vertical joints, and generally horizontal silicified bands with very sparse molybdenite. The molybdenum mineralization may be associated with a N60E fracture zone. Five stream sediment samples collected over an interval of approximately 4,000 feet along the railway to the southwest of Clifton contained 13 to 120 ppm molybdenum. Smith (1942) summarizes the description of J.B. Mertie, Jr. who visited the site in 1917. According to Mertie, the molybdenite appears to occur in a rock that varies from alaskite to granite and contains no mafic minerals. The molybdenite is distributed in patches throughout the granitic rock and was estimated to constitute about 1% of the rock. The granite was described as being extensively sheeted horizontally and cut by prominent joint planes that strike N50W and dip 72 degrees to the southwest.? the Clifton prospect occurs within the Clifton granite of Gilbert and others (1990) who note the presence of widespread molybdenite mineralization in the granite and attribute it to the high level of emplacement and rapid cooling of the granite. Clough (1991 [BOM, v. 2, sec C]) observed that the Clifton granite contains miarolitic cavities and that it is the youngest granite in the region. U-Pb zircon age dates for the Clifton granite of 48.8 +/- 1.0 m.y. (Gehrels and others, 1991) and 48 +/- 2 m.y. (Barker and others, 1986) establish a likely age for the Clifton prospect.
  • Age = U-Pb zircon age dates for the Clifton pluton of 48.8 +/- 1.0 m.y. (Gehrels and others, 1991) and 48 +/- 2 m.y. (Barker and others, 1986) establish a likely age for the Clifton prospect.
  • Age = Chron age is for the Clifton pluton.

Economic information

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Juneau (Skagway subdistrict)

Comments on the workings information

  • Workings / Exploration = Brooks (1918) reported a 10-foot shaft and a 25-foot adit in 1916. In 1917, the prospect was examined by J.B. Mertie, Jr. who reported a 15-foot deep shaft on east side of railroad track about 1,000 north of Clifton. About 80 feet south of the shaft on the west side of the track, an approximately 30-foot tunnel was driven S55E along a prominent joint plane (Smith, 1942). Herbert and Race (1965) also refer to the shaft and short tunnel. They note that although scattered grains of molybdenum can be found over a large area on the well-exposed slopes in the vicinity of Clifton, there is no evidence of other underground workings or surface trenching.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A013111
USGS Alaska Resource Data File ARDF SK072

Bibliographic references

  • Deposit

    Barker, Fred, 1952, The coast range batholith between Haines, Alaska and Bennett Lake, British Columbia: Alaska Territorial Department of Mines Miscellaneous Report 109-3, 48 p., 2 sheets, scale 1:126,720.

  • Deposit

    Herbert, C.F., and Race, W.H., 1964, Geochemical investigations of selected areas in southeastern Alaska, 1964: Alaska Division of Mines and Minerals Geochemical Report 1, 75 p.

  • Deposit

    Herbert, C.F., and Race, W.H., 1965, Geochemical investigations of selected areas in southeastern Alaska, 1964 and 1965: Alaska Division of Mines and Minerals Geochemical Report 6, 75 p., 4 sheets, scale 1:63,360.

  • Deposit

    Berg, H.C., and Cobb, E.H., 1967, Metalliferous Lode Deposits of Alaska. U.S. Geological Survey Bulletin 1246, 254 p.

  • Deposit

    Cobb, E.H., 1972, Metallic mineral resources map of the Skagway quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-424, 1 sheet, scale 1:250,000.

  • Deposit

    Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Mt. Fairweather and Skagway quadrangles, Alaska: U.S. Geological Survey Open-File Report 78-316, 123 p.

  • Deposit

    Berg, H.C., 1984, Regional geologic summary, metallogenesis, and mineral resources of southeastern Alaska: U.S. Geological Survey Open-file Report 84-572, 298 p., 1 plate, scale approx. 1:600,000.

  • Deposit

    Barker, Fred, Arth, J.G., and Stern, T.W., 1986, Evolution of the Coast batholith along the Skagway traverse, Alaska and British Columbia: American Mineralogist, v. 71, p. 632-643.

  • Deposit

    Clough, A.H., 1991?, Bureau of Mines mineral investigations in the Juneau mining district, Alaska, 1984-1988, v. 2, Detailed mine, prospect, and mineral occurrence descriptions, section E, Coast Range subarea: U.S. Bureau of Mines of Mines Special Publication, 44 p.

  • Deposit

    Gehrels, G.E., McClelland, W.C., Samson, S.D., Patchett, P.J., and Jackson, J.L., 1990, Ancient continental margin assemblage in the northern Coast Mountains, southeast Alaska and northwest Canada: Geology, v. 18, p. 208-211.

  • Deposit

    Gehrels, G.E., McClelland, W.C., Samson, S.D., Patchett, P.J., and Brew. D.A., 1991, U-Pb geochronology and tectonic significance of Late Cretaceous-early Tertiary plutons in the northern Coast Mountains batholith: Canadian Journal of Earth Sciences, v. 28, p. 899-911.

  • Deposit

    Brew, D.A., and Ford, A.B., 1994, The coast mountains plutonic-metamorphic complex and related rocks between Haines, Alaska, and Fraser, British Columbia q tectonic and geologic sketches and Klondike Highway road log: U.S. Geological Survey Open-File Report 94-268, 25 p.

  • Deposit

    Smith, P.S., 1942, Occurrences of molybdenum in Alaska: U.S. Geological Survey Bulletin 926-C, p. 161-210.

Comments on the references

  • Primary Reference = Smith, 1942

General comments

Subject category Comment text
Deposit Model Name = Disseminated molybdenite in granitic rocks, possibly related to a fracture zone.

Reporter information

Type Date Name Affiliation Comment
Reporter 04-FEB-01 T.C. Crafford T. Crafford & Associates