Unnamed (near the north end of Shikosi Island)

Occurrence in Alaska, United States with commodities Silver, Copper, Zinc, Gold

Geologic information

Identification information

Deposit ID 10308234
Record type Site
Current site name Unnamed (near the north end of Shikosi Island)

Geographic coordinates

Geographic coordinates: -135.27208, 59.03975 (WGS84)
Relative position This occurrence is about 0.15 miles south of the narrow northern tip of Shikosi Island.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Copper Primary
Zinc Primary
Gold Secondary

Materials information

Materials Type of material
Chalcopyrite Ore
Epidote Gangue
Quartz Gangue

Alteration

  • (Local) Epidotization, silicification.

Host and associated rocks

  • Host or associated Host
    Stratigraphic age (youngest) Late Triassic

Nearby scientific data

(1) -135.27208, 59.03975

Comments on the geologic information

  • Geologic Description = Still and others (1991) describe this occurrence as, 'A narrow epidotized and silicified shear zone that contains chalcopyrite and chalcopyrite hosted in metabasalt.' Samples contained up to 0.05 ppm gold, 6.7 ppm silver, 3,000 ppm zinc, and 2.74% copper. This zone is similar to the unnamed occurrence (SK001) to the south on Kataguni Island. Plafker, Hudson, and Silberling (1979) and Plafker and Hudson (1980) note that on the Chilkat Peninsula the same metabasalts are vesicular and/or amygdaloidal and that well-developed pillow textures are locally present. Based in part on fossil evidence that supports a Late Triassic (Karnian) age, they suggest that the metavolcanics and carbonates may correlate with similar rocks of the Wrangellia terrane. The age of the mineralization is not well established, but can be no older than the Late Triassic age of the host rocks. If the structure that localizes the mineralization is related to the Chilkat Fault, then the age of the mineralization is probably Tertiary or younger as most movement on the Chilkat Fault has been post-Mesozoic (Lanphere, 1978).
  • Age = the age of this occurrence is not well established, but can be no older than the Late Triassic age of the host rocks (Plafker, Hudson and Silberling, 1979; Plafker and Hudson, 1980). If the structure that localizes the mineralization is related to the Chatham Strait Fault, then the age of the mineralization is probably Tertiary or younger as most movement on the Chilkat Fault has been post-Mesozoic (Lanphere, 1978).

Economic information

Economic information about the deposit and operations

Development status Occurrence

Comments on exploration

  • Status = Inactive

Mining district

District name Juneau (Skagway subdistrict)

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF SK002

Bibliographic references

  • Deposit

    Lanphere, M.A., 1978, Displacement history of the Denali fault system, Alaska and Canada: Canadian Journal of Earth Sciences, v. 115, p. 817-822

  • Deposit

    Plafker George, Hudson, T.L., and Silberling, N.J., 1979, Upper Triassic fossils from a sequence of volcanic and sedimentary rocks on the Chilkat Peninsula, southeastern Alaska, in Johnson, K.M., and Williams, J.R., eds., The United States Geological Survey in Alaska: Accomplishments during 1978: U.S. Geological Survey Circular 804-B, p. B107-B110.

  • Deposit

    Plafker, George, and Hudson, T., 1980, Regional implications of Upper Triassic metavolcanic and metasedimentary rocks on the Chilkat Peninsula, southeastern Alaska: Canadian Journal of Earth Sciences, v. 17, p. 681-689.

  • Deposit

    Still, J.C., 1991, Bureau of Mines mineral investigations in the Juneau mining district, Alaska, 1984 - 1988, v. 2, Detailed mine, prospect, and mineral occurrence descriptions, section A, Haines-Klukwan-Porcupine subarea: U.S. Bureau of Mines of Mines Special Publication, 214 p.

  • Deposit

    Still, J.C., Hoekzema, R.B., Bundtzen, T.K., Gilbert, W.G., Wier, K.R., Burns, L.E., and Fechner, S.A., 1991, Economic geology of Haines-Klukwan-Porcupine area, southeastern Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 91-4, 156 p., 5 sheets, scale 1:63,360.

Comments on the references

  • Primary Reference = Still and others, 1991 (BOM, v. 2, sec. A)

General comments

Subject category Comment text
Deposit Model Name = Very little information. Base and precious metal mineralization localized along a shear zone in metabasalt.
Deposit Other Comments = This occurrence is within the Chilkat Islands, State Marine Park.

Reporter information

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