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Unnamed (on tributary to Tin Creek)

Occurrence in Alaska, United States with commodities Silver, Copper, Lead, Zinc, Bismuth, Cadmium, Cobalt
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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 10307852
Record type Site
Current site name Unnamed (on tributary to Tin Creek)

Geographic coordinates

Geographic coordinates: -153.67485, 62.43348 (WGS84)
Relative position This unnamed occurrence is located at an outcrop on the south side of an unnamed, east-flowing tributary of Tin Creek at an elevation of 2,850 feet (868 m) in the NW1/4 sec. 14, T. 27 N., R. 24 W., of the Seward Meridian. The reporter investigated the occurrence in 1981 at station nos. 81BT428-429.

Site location context

Political divisions (FIPS codes)

Yukon-Koyukuk(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

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

McGrath SE(quadrangle 1:100,000 scale)

McGrath(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Upper Kuskokwim River(hydrologic accounting unit)

Southwest(hydrologic subregion)

Alaska(hydrologic region)

Federal lands

Cook Inlet Region, Incorporated(ANCSA Region)

ANCSA Region NTVPIC(Type of land area)

NTVPIC(Federal land areas administered by NTVPIC)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Copper Primary
Lead Primary
Zinc Critical Primary
Bismuth Critical Secondary
Cadmium Secondary
Cobalt Critical Secondary

Materials information

Materials Type of material
Arsenopyrite Ore
Chalcopyrite Ore
Galena Ore
Malachite Ore
Pyrite Ore
Sphalerite Ore
Marmatite Ore
Diopside Gangue
Epidote Gangue
Garnet Gangue
Magnetite Gangue

Alteration

  • (Local) Extensive diopside(?) replacement.

Mineral occurrence model information

Model code 60
USGS model code 18c
Deposit model name Skarn Zn-Pb
Mark3 model number 22

Host and associated rocks

  • Host or associated Associated
    Rock type
    Stratigraphic age (youngest) Oligocene
    Chronological age 27.5

Nearby scientific data

(1) -153.67485, 62.43348
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = The unnamed occurrence is a well exposed sulfide skarn typical of many silver-base metal-bearing skarns in the Farewell Mineral Belt (Bundtzen, Harris, and Gilbert, 1997; Newberry and others, 1997). Host lithologies are mainly a highly folded and sheared, mid-Silurian, argillaceous limestone of the Terra Cotta Mountains Sandstone, a unit of the Dillinger subterrane (Bundtzen, Harris, and Gilbert, 1997). The metasedimentary rocks are intruded by a N10W-trending, vertically dipping, 20 meter thick, granodiorite dike. Thinner, anastomosing dikes, which occur throughout the limestone, do not appear to alter the limestone (Smith and Albanese, 1985). . Mineralization consists of a 2 meter by 6 meter zone containing disseminated to semi-massive arsenopyrite, chalcopyrite, pyrite, iron-rich sphalerite (marmatite), galena, and pyrite encased in diopside(?)-garnet gangue minerals. The sulfide mineralization is encrusted with a thin but conspicuous malachite rind. The mineralization is parallel to bedding in host limestone, and begins at the contact of a hornblende granodiorite dike. Although mineralization is spatially related to the dike, no thermal alteration of the limestone was identified. Gangue minerals that accompany the sulfides include magnetite, diopside, and garnet. Bundtzen, Kline, and Clough (1982) reported that chip-channel samples contained up to 2.30 percent copper, 0.30 percent lead, 6.20 percent zinc, 110 grams/tonne silver, 500 ppm cadmium, 100 ppm bismuth, and 100 ppm cobalt. Smith and Albanese (1985) reported that one sample from the mineral zone contained 5,890 ppm copper, 229 ppm lead, 6,690 ppm zinc, 74 ppm cadmium, and 37.5 grams/tonne silver.
  • Age = Unknown; thought to be related to the 25 to 30 Ma granodiorite dike swarm in area (Solie and others, 1991; Szumigala, 1987).
  • Age = Chronological age is for granodiorite dike swarm in area .

Economic information about the deposit and operations

Development status Occurrence

Comments on exploration

  • Status = Inactive

Mining district

District name McGrath

Comments on the workings information

  • Workings / Exploration = The Tin Creek Occurrence was first described by Bundtzen, Kline, and Clough (1982) and later by Smith and Albanese (1985). The former reference reported that chip-channel samples contained up to 2.30 percent copper, 0.30 percent lead, 6.20 percent zinc, 110 grams/tonne silver, 500 ppm cadmium, 100 ppm bismuth, and 100 ppm cobalt. Smith and Albanese (1985) reported that a single grab sample contained 5,890 ppm copper, 229 ppm lead, 6,690 ppm zinc, 74 ppm cadmium, and 37.5 grams/tonne silver.

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Bundtzen and others, 1982

General comments

Subject category Comment text
Deposit Model Name = Low-temperature lead-zinc skarn (Cox and Singer, 1986; model 18c).
Deposit Other Comments = See Tin Creek-Midway deposit (MG043).

Reporter information

Type Date Name Affiliation Comment
Reporter 05-DEC-98 T.K. Bundtzen Pacific Rim Geological Consulting

Beyond USGS

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

Maps centered on this site

Authoritative Alaska resources

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