Unnamed (northwest of Smith Lake)

Occurrence in Alaska, United States with commodities Copper, Cobalt, Lead, Zinc

Geologic information

Identification information

Deposit ID 10307857
Record type Site
Current site name Unnamed (northwest of Smith Lake)

Geographic coordinates

Geographic coordinates: -153.88184, 62.36048 (WGS84)
Relative position The unnamed occurrence is located at the divide between the West Fork and Main Fork of Sheep creek, 8 kilometers northwest of Smith Lake, at an elevation of 5,100 feet (1,555 m) in the NE1/4 sec. 10, T. 26 N., R. 25 W., of the Seward Meridian. The reporter investigated the site in 1981.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Copper Primary
Cobalt Secondary
Lead Secondary
Zinc Secondary

Materials information

Materials Type of material
Chalcopyrite Ore
Pyrrhotite Ore
Amphibole Gangue
Olivine Gangue
Clinopyroxene Gangue

Alteration

  • (Local) None.

Mineral occurrence model information

Model code 10
USGS model code 5b
Deposit model name Noril'sk Cu-Ni-PGE
Model code 85
USGS model code 22c
Deposit model name Polymetallic veins
Mark3 model number 46

Nearby scientific data

(1) -153.88184, 62.36048

Comments on the geologic information

  • Geologic Description = This unnamed occurrence consists of disseminated chalcopyrite and pyrrhotite in a medium grained, phaneritic, gabbro sill thought to be a feeding system for Triassic volcanism in the Tatina River Volcanics, a unit of the Mystic subterrane (Bundtzen, Kline, and Clough, 1982). An alternative hypothesis offered by Foley (1987) is that the mafic igneous rocks that host the occurrence are flows or feeders of the Paleocene to Eocene Sheep Creek Volcanic Field as defined by Bundtzen, Harris, and Gilbert (1997). Bundtzen, Harris, and Gilbert (1997) believe that unnamed and related occurrences constitute magmatic-disseminated sulfide Cu-Ni-Co-Fe mineralization similar to deposit model 5b of Cox and Singer (1986). Selected samples of the gabbro sills in the prospect area contain up to 540 ppm copper, 190 ppm nickel, 63 ppm cobalt, and 450 ppm zinc (Foley, 1987).
  • Age = Undated; inferred to be either Late Triassic or early Tertiary, based on isotopic age dates of Tatina River Volcanics and Sheep Creek Volcanic Field respectively (Bundtzen, Harris, and Gilbert, 1997).

Economic information

Economic information about the deposit and operations

Development status Occurrence

Comments on exploration

  • Status = Inactive

Mining district

District name McGrath

Comments on the workings information

  • Workings / Exploration = The gabbro feeders were mapped by the reporter in 1981 (Bundtzen, Kline, and Clough, 1982). Selected samples of the gabbro sills in the prospect area contain up to 540 ppm copper, 190 ppm nickel, and 450 ppm zinc (Foley, 1987).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF MG048

Bibliographic references

  • Deposit

    Bundtzen, T.K., Kline, J.T., and Clough, J.G., 1982, Preliminary geologic map of the McGrath B-2 quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Open-File report 149, 22 pages, one sheet, scale 1:63,360.

  • Deposit

    Foley, J.Y., 1987, Reconnaissance strategic and critical mineral investigations in the McGrath A-3 and B-2 quadrangles, southwest Alaska: U.S. Bureau of Mines Field Report, 26 pages.

  • Deposit

    Bundtzen, T.K., Harris, E.E., and Gilbert, W.G., 1997, Geologic Map of the eastern McGrath quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 97-14, 34 pages, one sheet, scale 1:125,000.

Comments on the references

  • Primary Reference = Foley, 1987

General comments

Subject category Comment text
Deposit Model Name = Magmatic sulfide Cu-Ni-Co or polymetallic replacement (Cox and Singer, 1986; models 5b or 22c).
Deposit Other Comments = See also Roberts PGM (MG030), Unnamed (MG045), and Chip-Loy (MG032) prospects and deposits.

Reporter information

Type Date Name Affiliation Comment
Reporter 08-DEC-98 T.K. Bundtzen Pacific Rim Geological Consulting