Unnamed (north of confluence of Chickamin River and South Fork)

Occurrence in Alaska, United States with commodities Copper, Silver

Geologic information

Identification information

Deposit ID 10001548
MRDS ID A012295
Record type Site
Current site name Unnamed (north of confluence of Chickamin River and South Fork)

Geographic coordinates

Geographic coordinates: -130.72566, 55.90865 (WGS84)
Relative position This occurrence is at an elevation of about 1300 feet in the walls of a steep avalanche gully west of the Chickamin River, approximately 2.5 miles north of its confluence with the South Fork. The site is in section 5, T. 69 S., R. 96 E., of the Copper River Meridian. It corresponds to area M-3 in Berg and others (1977), and to loc. 18 in Elliott and others (1978). The location is accurate within 0.1 mile.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Copper Primary
Silver Secondary

Materials information

Materials Type of material
Chalcopyrite Ore

Alteration

  • (Local) Conspicuous iron-staining.

Host and associated rocks

  • Host or associated Host
    Rock type Metamorphic Rock > Gneiss

Nearby scientific data

(1) -130.72566, 55.90865

Comments on the geologic information

  • Geologic Description = The country rocks in the area of this occurrence consist chiefly of rusty-weathering pelitic paragneiss that forms roof pendants, screens, and inclusions in Tertiary or Cretaceous foliated granodiorite and quartz diorite of the Coast Range batholith (Berg and others, 1977, p. 126; Berg and others, 1988). The paragneiss probably represents marine argillaceous and clastic strata that underwent high-grade regional metamorphism in Cretaceous or Tertiary time. The premetamorphic age of the strata is uncertain, but they probably are mainly Paleozoic and may be as old as Precambrian (Berg and others, 1988, p. 26; Gehrels and others, 1990; Crawford and others, in press).? the occurrence consists of a 150-foot-thick zone of rusty-weathering paragneiss that strikes about N10W and can be traced in outcrop for about a mile northwest of Chickamin River (Berg, 1977, p. 126 and pl. 2). The zone probably is the northwest extension of a similar rusty zone on the other side of the river (KC019). the paragneiss locally contains a little pyrrhotite and a trace of chalcopyrite. Eight chip samples across about 125 feet of section perpendicular to the foliation assayed as much as 340 ppm Cu and 2 ppm Ag (Berg and others, 1977, p. 126 and fig. 35).

Economic information

Economic information about the deposit and operations

Development status Occurrence
Commodity type Metallic

Mining district

District name Ketchikan

Comments on the workings information

  • Workings / Exploration = Eight chip samples across about 125 feet of section perpendicular to the foliation assayed as much as 340 ppm Cu and 2 ppm Ag (Berg and others, 1977, p. 126 and fig. 35).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A012295
USGS Alaska Resource Data File ARDF KC018

Bibliographic references

  • Deposit

    Berg, H.C., Elliott, R.L., Smith, J.G., Pittman, T.L., and Kimball, A. L., 1977, Mineral resources of the Granite Fiords wilderness study area, Alaska, with a section on aeromagnetic data by Andrew Griscom: U.S. Geological Survey Bulletin 1403, 151 p.

  • Deposit

    Elliott, R.L., Berg, H.C., and Karl, Susan, 1978, map and table describing metalliferous and selected nonmetalliferous mineral deposits, Ketchikan and Prince Rupert quadrangles, Alaska: U.S. Geological Survey Open-file Report, 78-73-B,17 p., scale 1:250,000.

  • Deposit

    Berg, H.C., Elliott, R.L., and Koch, R.D., 1988, Geologic map of the Ketchikan and Prince Rupert quadrangles, southeastern Alaska: U.S. Geological Survey Mineral Investigations Series Map MF-1807,27 p., scale 1:250,000.

  • 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

    Crawford, M.L., Crawford, W.A., and Gehrels, G.E., 2000, Terrane assembly and structural relationships in the eastern Prince Rupert quadrangle, British Columbia, in H.H. Stowell and W.C.McClelland, eds., Tectonics of the Coast Mountains, southeastern Alaska and British Columbia: Boulder, Colorado, Geological Society of America Special Paper 343, p. 1-21.?

Comments on the references

  • Primary Reference = Berg and others, 1977

General comments

Subject category Comment text
Deposit Model Name = Disseminated base-metal sulfides in rusty-weathering paragneiss
Deposit Other Comments = Site is in Misty Fiords National Monument Wilderness.

Reporter information

Type Date Name Affiliation Comment
Reporter 29-JUN-1999 H.C. Berg U.S. Geological Survey