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Ketchem Dome

Prospect in Alaska, United States with commodity Tin
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Commodities
  6. Materials information
  7. Alteration
  8. Mineral occurrence model information
  9. Host and associated rocks
  10. Nearby scientific data
  11. Economic information about the deposit and operations
  12. Mining district
  13. Links to other databases
  14. Bibliographic references
  15. General comments
  16. Reporter information

Geologic information

Identification information

Deposit ID 10001519
MRDS ID A012266
Record type Site
Current site name Ketchem Dome
Related records 10111568

Geographic coordinates

Geographic coordinates: -144.78986, 65.46668 (WGS84)
Relative position The location is approximately 1500 ft NE of the Ketchem Dome summit at the site of the Ketchem Dome tin prospect trench reported in Dahlin and others (1987). The Ketchem Dome tin prospect is located approximately 5 miles southwest of Circle Hot Springs. The prospect lies 1 mile to the west of, and approximately 1300 ft above, a gravel road that leads north to the Steese Highway.

Site location context

Political divisions (FIPS codes)

Yukon-Koyukuk(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Circle B-2(quadrangle 1:63,360 scale)

Circle SE(quadrangle 1:100,000 scale)

Circle(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Alaska(hydrologic region)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Tin Critical Primary

Materials information

Materials Type of material
Cassiterite Ore
Feldspar Gangue
Muscovite Gangue
Quartz Gangue
Tourmaline Gangue

Alteration

  • (Local) Chloritic, quartz-white mica, topaz, fluorite.

Mineral occurrence model information

Model code 49
USGS model code 15c
Deposit model name Sn greisen

Host and associated rocks

  • Host or associated Host
    Rock type
    Stratigraphic age (youngest) Middle Paleocene
    Chronological age 60.5
    Dating method K-Ar

Nearby scientific data

(1) -144.78986, 65.46668
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = The following information is taken from a Bureau of Mines report by Dahlin and others (1987). The tin mineralization on Ketchem Dome consists of cassiterite which occurs as grains disseminated in a greisen matrix. A bulk sample from the largest and best-developed greisen vein exposed at Ketchem Dome contained 0.51 percent Sn. Concentration of the cassiterite by gravity table methods resulted in a product that contained 56 percent cassiterite at a grade of 41.4 percent Sn. The tin-bearing greisen vein mineralization near Ketchem Dome cuts a leucocratic, seriate phase of the Circle Hot Springs biotite granite pluton near its contact with hornfelsed sedimentary rocks. The pluton has been K-Ar dated at 60.5 +/- 1.8 m.a. (Wilson and Shew, 1981). Four hand-excavated trenches expose the greisen near Ketchem Dome. The greisen is mineralogically zoned, with a selvage of muscovite-altered granite that grades into a core of dense, black, chlorite- and sericite-altered granite with traces of limonite after pyrite and veinlets of quartz. Purple fluorite occurs on fractures, and topaz is locally associated with more pervasive alteration. The mineralization exposed at Ketchem Dome is typical of greisen found elsewhere in the area. One sample assayed greater than 1,000 ppm Sn (Dave Menzie, USGS, field notes, 1984).
  • Age = The tin-bearing greisen vein mineralization near Ketchem Dome cuts a biotite granite pluton near its contact with hornfelsed sedimentary rocks. The pluton has been K-Ar dated at 60.5 +/- 1.8 m.a. (Wilson and Shew, 1981).
  • Age = Chron age is for the biotite granite pluton into which the tin-bearing greisen vein cuts.

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Circle

Comments on the workings information

  • Workings / Exploration = Five pits in area, excavated by Resource Associates of Alaska in 1983.

Reference information

Bibliographic references

  • Deposit

    Wilson, F.H., and Shew, N., 1981, Map and tables showing preliminary results of potassium-argon age studies in the Circle Quadrangle, Alaska, with a compilation of earlier dating work: U.S. Geological Survey Open-File Report 81-889, 1 sheet, scale 1:250,000.

  • Deposit

    Foster, H.L., Laird J., Keith T.E.C., Cushing, G.W., and Menzie, W.D., 1983, Preliminary geologic map of the Circle quadrangle, Alaska: U.S. Geological Survey Open-File Report 83-170-A, 1 sheet, scale 1:250,000.

  • Deposit

    Menzie, W.D., Foster, H.L., Tripp, R.B., and Yeend, W.E., 1983, Mineral resource assessment of the Circle quadrangle, Alaska: U.S. Geological Survey Open-File Report 83-170-B, 61 p., 1 sheet, 1:250,000.

  • Deposit

    Dahlin, D.C., Brown, L.L., and Warner J.D., 1987, Characterization of Ketchem Dome tin prospect, east-central Alaska: U.S. Bureau of Mines Report of Investigation 9145, 11 p.

  • 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

    Wilkinson, K., 1987, Geology of a subarctic, tin-bearing batholith, Circle Hot Springs, Alaska: Fairbanks, Alaska, University of Alaska, Mineral Industry Research Laboratory Report 74, 70 p.

Comments on the references

  • Primary Reference = Dahlin and others, 1987.

General comments

Subject category Comment text
Deposit Model Name = Sn greisen deposit (Cox and Singer, 1986; model 15c)

Reporter information

Type Date Name Affiliation Comment
Reporter 09-SEP-98 C.J. Freeman Avalon Development Corporation
Reporter 09-SEP-98 J.R. Guidetti Schaefer Avalon Development Corporation
Reporter 09-SEP-98 Clements, A.S. Avalon Development Corporation

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

Maps centered on this site

Authoritative Alaska resources

These are landing pages for further research — the state agencies don't currently expose per-mine deep links.