1. Mineral Resources
  2. Online Spatial Data
  3. Mineral Resource Data System (MRDS)

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

Occurrence in Alaska, United States with commodity Copper
Map
XML
JSON
KML
C

Geologic information

Identification information

Deposit ID 10001550
MRDS ID A012297
Record type Site
Current site name Unnamed (southeast of confluence of Chickamin River and South Fork)

Geographic coordinates

Geographic coordinates: -130.67676, 55.83865 (WGS84)
Relative position This occurrence is at an elevation of about 2900 feet, approximately 3.5 miles southeast of the confluence of the Chickamin River and the South Fork of the Chickamin. The site is in section 34, T. 69 S., R. 96 E., of the Copper River Meridian. It corresponds to area M-6 in Berg and others (1977), and to loc. 20 in Elliott and others (1978). The location is accurate within 0.1 mile.
(click for info)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Copper Primary

Materials information

Materials Type of material
Chalcopyrite Ore
Magnetite Ore
Pyrite Ore

Alteration

  • (Local) Conspicuous iron-staining.

Host and associated rocks

  • Host or associated Host
    Rock type Metamorphic Rock > Gneiss

Nearby scientific data

(1) -130.67676, 55.83865
ListMap

Comments on the geologic information

  • Geologic Description = The country rocks in the area of this occurrence consist chiefly of Tertiary or Cretaceous foliated granodiorite of the Coast Range batholith, and of rusty-weathering pelitic paragneiss that forms roof pendants, screens, and inclusions in the batholith (Berg and others, 1977, p. 129-132; Berg and others, 1977). 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 conspicuous band of rusty-weathering pyritic gneiss about 1000 feet wide that strikes northwest and dips northeast, and can be traced in outcrop for about 3 miles (Berg and others, p. 129-132 and pl. 2). The rocks include quartzofeldspathic gneiss, which is gradational with the foliated plutonic rocks of the Coast Range batholith, and subordinate pelitic schist and paragneiss. The rocks contain pyrite in amounts up to several volume percent, and sparse grains of chalcopyrite. Thirty-six chip samples collected at three locations along the outcrop of the band assayed up to 700 ppm Cu, 150 ppm Pb, 200 ppm Zn, 70 ppm Mo, and 5 ppm Ag (Berg and others, 1977, table 13). A rock grab sample from the band contained up to 450 ppm Pb and 0.05 ppm Ag, and a stream-sediment sample from a creek draining the band was anomalous in Cu, Pb, Zn, Mo, Au, and Ag (Berg and others, 1977, fig. 9 and table 13).

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 = Thirty-six chip samples collected at three locations along the outcrop of this 3-mile-long, 1000-foot-wide band of rusty-weathering gneiss assayed up to 700 ppm Cu, 150 ppm Pb, 200 ppm Zn, 70 ppm Mo, and 5 ppm Ag (Berg and others, 1977, table 13). A rock grab sample from the band contained up to 450 ppm Pb and 0.05 ppm Ag, and a stream-sediment sample from a creek draining the band was anomalous in Cu, Pb, Zn, Mo, Au, and Ag (Berg and others, 1977, fig. 9 and table 13).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A012297
USGS Alaska Resource Data File ARDF KC020

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