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  3. Mineral Resource Data System (MRDS)

Bearskin Gulch

Occurrence in Alaska, United States with commodities Silver, Gold, Copper, Molybdenum
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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 10001669
MRDS ID A012447
Record type Site
Current site name Bearskin Gulch

Geographic coordinates

Geographic coordinates: -158.95246, 56.24927 (WGS84)
Relative position This site represents an area of approximately 8 square miles in T. 45 S., R. 62 W., of the Seward Meridian, covering the headwaters of both the east and west forks of Bearskin Creek (Cox and others, 1981, locality 6). The map site is plotted at an elevation of 1200 feet at the head of the east branch of Bearskin Gulch, which is at the head of Bearskin Creek. The location is accurate to within 2 miles.

Site location context

Political divisions (FIPS codes)

Lake and Peninsula(Borough)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Chignik A-3(quadrangle 1:63,360 scale)

Chignik SE(quadrangle 1:100,000 scale)

Chignik(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Port Heiden(hydrologic unit)

Kvichak-Port Heiden(hydrologic accounting unit)

Southwest(hydrologic subregion)

Alaska(hydrologic region)

Federal lands

Alaska Peninsula National Wildlife Refuge(National Wildlife Refuge)

National Wildlife Refuge FWS(Type of land area)

FWS(Federal land areas administered by FWS)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Gold Primary
Copper Primary
Molybdenum Primary

Materials information

Materials Type of material
Chalcopyrite Ore
Gold Ore
Molybdenite Ore
Pyrite Ore

Alteration

  • (Local) Secondary biotite is present within the copper-bearing areas and beyond. Chlorite is present throughout the area in all rock types. Sericite is present as veinlet selvages and within the higher sulfide areas on the periphery of the system. Other periphery alteration minerals include epidote, kaolinite, montmorillonite, and pyrophyllite.

Mineral occurrence model information

Model code 53
USGS model code 17
Deposit model name Porphyry Cu
Mark3 model number 4
Model code 78
USGS model code 20c
Deposit model name Porphyry Cu-Au
Mark3 model number 34
Model code 79
USGS model code 21a
Deposit model name Porphyry Cu-Mo
Mark3 model number 2

Host and associated rocks

  • Host or associated Associated
    Rock type Plutonic Rock > Mafic Intrusive Rock > Diorite
    Rock unit name Naknek Formation;Naknek Formation;Naknek Formation
    Rock description Naknek Formation;Naknek Formation;Naknek Formation
  • Host or associated Host
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Siltstone
    Rock unit name Naknek Formation;Naknek Formation;Naknek Formation
    Rock description Naknek Formation;Naknek Formation;Naknek Formation

Nearby scientific data

(1) -158.95246, 56.24927
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = The Jurassic Naknek Formation is the main rock unit exposed at the site (Detterman and others, 1981). It consists of graywacke, siliceous siltstone, hornfels, quartzite, and minor grit. The strata strike N 20 to 45 E, and dip 28 to 40 southeast. A small (1000 feet diameter) weakly-mineralized diorite porphyry stock crops out within the western fork of Bearskin Creek.? the sulfide system as exposed is approximately 2 by 4 miles (Fields, 1977). Pyrite and chalcopyrite occur in highly shattered and fractured rocks throughout the area as fracture fillings, veinlets, and disseminations. Some of the better copper mineralization appears to occur within the sandstone and grit units of the Naknek Formation. The sulfide content of the sedimentary rocks varies from 3 to 10 percent with a high pyrite to chalcopyrite ratio. Within the diorite sulfide content is 1 to 2 percent.? Secondary biotite is present within the copper-bearing areas and beyond. Chlorite is ubiquituous throughout the area in all rock types. Sericite occurs as veinlet selvages and within the higher sulfide areas on the periphery of the system. Other peripheral alteration minerals include epidote, kaolinite, montmorillonite, and pyrophyllite.? In the eastern fork of Bearskin Creek metal values ranged from 235 to 1500 ppm copper, 0.01 to 0.13 ppm gold, 4 to 30 ppm molybdenum, 0 to 4.1 ppm silver (Fields, 1977). These values outlined an area of 1500 by 3000 feet. In the diorite located in the western fork maximum values of 800 to 900 ppm copper, 0.02 to 0.62 ppm gold, and 2 to 26 ppm molybdenum were obtained from an area of 1000 feet by 2000 feet.
  • Age = Tertiary

Economic information about the deposit and operations

Development status Occurrence
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Alaska Peninsula

Comments on the workings information

  • Workings / Exploration = Bear Creek mapped and sampled this site during the period 1975 to 1976 (Fields,1977). Maximum metal values obtained were 1500 ppm copper, 30 ppm molybdenum, and small amounts of precious metals.

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Fields, 1977

General comments

Subject category Comment text
Deposit Model Name = Porphyry copper; porphyry copper-gold; porphyry copper-molybdenum (Cox and Singer, 1986; models 17, 20c, 21a)
Deposit Model Number = 17, 20c, 21a
Deposit Other Comments = This site is on lands selected by the Bristol Bay Native Corporation.

Reporter information

Type Date Name Affiliation Comment
Reporter 08-FEB-2000 S.H. Pilcher U.S. Geological Survey

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.