Geroe Creek

Prospect in Alaska, United States with commodities Copper, Molybdenum

Geologic information

Identification information

Deposit ID 10001397
MRDS ID A012140
Record type Site
Current site name Geroe Creek
Alternate or previous names MAS claims

Geographic coordinates

Geographic coordinates: -148.81333, 67.67973 (WGS84)
Relative position The reference point is at an elevation of 5,500 feet, near the divide between Geroe Creek and Willow Creek (NW1/4 sec. 24, T. 33 N., R. 6 W., of the Fairbanks Meridian) and at the center of a large claim block (239 claims). A second large claim block northeast of of the Geroe property, and contiguous with its northeast corner (U.S. Bureau of Mines, 1973), may be part of this large property. The location is accurate within a 1-mile radius.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Copper Primary
Molybdenum Primary

Comments on the commodity information

  • Ore Material = Copper sulfides (chalcopyrite)

Materials information

Materials Type of material
Chalcopyrite Ore
Molybdenite Ore
Chlorite Gangue
Quartz Gangue
Sericite Gangue

Alteration

  • (Local) Seritization and propylitization of porphyritic host rocks; quartz-sericite-chlorite plus or minus epidote; calcite.

Mineral occurrence model information

Model code 79
USGS model code 21a
Deposit model name Porphyry Cu-Mo
Mark3 model number 2

Host and associated rocks

  • Host or associated Associated
    Rock type Plutonic Rock > Mafic Intrusive Rock > Diorite
    Stratigraphic age (youngest) Late Cretaceous
  • Host or associated Associated
    Rock type Plutonic Rock > Granitoid > Granite
    Rock unit name Geroe Creek Pluton
    Rock description Geroe Creek Pluton
  • Host or associated Host
    Rock type Plutonic Rock > Granitoid > Granite

Nearby scientific data

(1) -148.81333, 67.67973

Comments on the geologic information

  • Geologic Description = The Geroe Creek prospect is one of several quartz stockworks and altered zones in the northeast-trending belt of Devonian peraluminous biotite-muscovite granites of the Baby Creek batholith and the Devonian metaluminous biotite-hornblende granites and granodiorites of the Horace Mountain plutons (Newberry and others, 1986). Porphyritic phases are locally present in these plutons, and Young and others (1997) reported that the mineralizing intrusives are porphyritic meta-granodiorites and biotite meta-granites. The country rocks are mainly Paleozoic schists and marble along with peraluminous meta-granodiorite. Young and others (1997) also noted that there is no skarn development in the calcareous rocks. The veinlets in the stockworks on the Geroe prospect contain disseminated molybdenite, chalcopyrite, and pyrite along with intense quartz-sericite-chlorite plus or minus epidote alteration. Eakins and others (1983, p. 41) reported Mo grades as much as 0.1 percent, and Nokleberg and others (1987) report that zones in the plutons as much as several meters thick contain values of 0.6 percent Cu, 0.02 percent Mo, and 0.1 grams of gold per ton.
  • Age = Devonian based on reported Early Devonian Pb/Pb zircon ages from the associated Baby Creek batholith and Horace Mountain plutons (Dillon and others, 1996).

Economic information

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Chandalar and Koyukuk

Comments on the workings information

  • Workings / Exploration = 239 claims staked in 1975 and 1976.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A012140
USGS Alaska Resource Data File ARDF CH053

Bibliographic references

  • Deposit

    U.S. Bureau of Mines, 1973, Alaska 1:250,000-scale quadrangle map overlays showing mineral deposit locations, principal minerals, and number and type of claims: U.S. Bureau of Mines Open-File Report 20-73, 95 overlays (updated in 1986, 1987).

  • Deposit

    Grybeck, D.J., 1977, Known mineral deposits of the Brooks Range, Alaska: US Geological Survey Open-File Report 77-166C, 41 p., 1 sheet, scale 1:1,000,000.

  • Deposit

    DeYoung, J.H., Jr., 1978, Mineral resources map of the Chandalar quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-878-B, 2 sheets, scale 1:250,000.

  • Deposit

    Arctic Environmental Information and Data Center, 1982, Mineral terranes of Alaska: University of Alaska, Fairbanks, 7 sheets, scale 1:1,000,000.

  • Deposit

    Bundtzen, T.K., Eakins, G.R., and Conwell, C.N., 1982, Review of Alaska mineral resources 1981: Alaska Division of Geological and Geophysical Surveys Annual Report 1981, 48 p., 2 sheets, scale 1:3,000,000.

  • Deposit

    Bundtzen, T.K., Eakins, G.R., and Conwell, C.N., 1982, Alaska mineral resources 1981-82: Alaska Division of Geological and Geophysical Surveys Annual Report 1981-82, 153 p., 4 sheets, scale 1:2,500,000.

  • Deposit

    Eakins, G.R., Bundtzen, T.K., Robinson, M.S., Clough, J.G., Green, C.B., Clautice, K.H., and Albanese M.A., 1983, Alaska's mineral industry, 1982, Alaska Division of Geological and Geophysical Surveys Special Report 31, 63 p.

  • Deposit

    Newberry, R.J., Dillon, J.T., and Adams, D.D., 1986, Regionally metamorphosed calc-silicate-hosted deposits of the Brooks Range, northern Alaska: Economic Geology, v. 81, p. 1728-1752

  • Deposit

    Nokleberg, W.J., Bundtzen, T.K., Berg, H.C., Brew, D.A., Grybeck, D.J., Robinson, M.S., Smith, T.E., and Yeend, W., 1987, Significant metalliferous lode deposits and placer districts of Alaska: U.S. Geological Survey Bulletin 1786, 104 p.

  • Deposit

    Maas, K.M., 1987, Maps summarizing land availability for mineral exploration and development in northern Alaska, 1986: U.S. Bureau of Mines Open-File Report 10-87, 33 sheets.

  • Deposit

    Nokleberg, W.J., Bundtzen, T.K., Berg, H.C., Brew, D.A., Grybeck, Donald, Robinson, M.S., Smith, T.E., and Yeend, Warren, 1988, Metallogeny and major mineral deposits of Alaska: U.S. Geological Survey Open-File Report 88-73, 97 p., 2 plates, scale 1:5,000,000.

  • Deposit

    Nokleberg, W.J., Bundtzen, T.K., Grybeck, D.J., Koch, R.D., Eremin, R.A., Rozenblum, I. S., Sidorov, A.A., Byalobzhesky, S.G., Sosunov, G.M., Shpikerman, V.I., Gorodinsky, M.E., 1993, Metallogenesis of mainland Alaska and the Russian Northeast: U.S. Geological Survey Open-File Report 93-0339, 3 sheets, 230 p.

  • Deposit

    Young, L.E., St. George, P., and Bouley, B., 1997, Porphyry copper deposits in relation to the magmatic history and palinspastic restoration of Alaska, in Goldfarb, R.J., and Miller, L.D., (eds.), Mineral deposits of Alaska: Economic Geology Monograph 9, p. 306-333.

Comments on the references

  • Primary Reference = Newberry and others, 1986

General comments

Subject category Comment text
Deposit Model Name = Porphyry Cu-Mo (Cox and Singer, 1986; model 21a)
Deposit Other Comments = See also: Venus (CH065), Victor (CH064), Eva (CH063) and Evelyn Lee (CH059) prospects; Alaska Kardex No. 031-68 (Kardex is a card file mining claim information system located at the State of Alaska DNR Public Information Center in Fairbanks).

Reporter information

Type Date Name Affiliation Comment
Reporter 17-NOV-1999 J.M. Britton U.S. Geological Survey