Unnamed (on a tributary to Windy Fork)

Occurrence in Alaska, United States with commodities Silver, Zinc, Molybdenum

Geologic information

Identification information

Deposit ID 10307869
Record type Site
Current site name Unnamed (on a tributary to Windy Fork)

Geographic coordinates

Geographic coordinates: -153.92882, 62.12947 (WGS84)
Relative position Occurrence is located in a bedrock outcrop on the north side of an unnamed west-flowing tributary stream to Windy Fork; it is at an elevation of 3,900 feet (1,189 m) in the NE1/4 sec. 31, T. 24 N., R. 25 W., of the Seward Meridian. The reporter investigated the site in 1983 and in 1997. Note that the occurrence is properly located in Bundtzen and others (1988; #8), but mislocated in Bundtzen, Harris, and Gilbert, (1997; #23).
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Zinc Primary
Molybdenum Secondary

Materials information

Materials Type of material
Galena Ore
Pyrite Ore
Sphalerite Ore

Mineral occurrence model information

Model code 208
USGS model code 31a
BC deposit profile E14
Deposit model name Sedimentary exhalative Zn-Pb
Mark3 model number 13

Nearby scientific data

(1) -153.92882, 62.12947

Comments on the geologic information

  • Geologic Description = This unnamed occurrence consists of three thin, stratiform sulfide layers in black shale of the Lower Ordovician to Lower Silurian Post, River Formation a unit of the Dillinger subterrane (Bundtzen, Harris, and Gilbert, 1997). The sulfide beds are isoclinally folded along with host strata and are believed to be syngenetic in origin. The occurrence is just below the contact between the Post River Formation and the mid-Silurian Terra Cotta Mountains Sandstone, and hence has an inferred age of Early Silurian. . Three 6 centimeter thick sulfide layers mainly contain pyrite, with minor to trace disseminated sphalerite and galena (Bundtzen and others, 1988; Bundtzen Harris, and Gilbert, 1997). Grab samples of one sulfide bearing horizon contained 700 ppm zinc, 1.2 grams/tonne silver, and 31 ppm molybdenum.
  • Age = Undated, inferred to be Early Silurian, based on stratigraphic evidence.

Economic information

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 reporter first found the occurrence in 1983 (Bundtzen and others, 1988). Grab samples of one sulfide bearing horizon contained 700 ppm zinc, 1.2 grams/tonne silver, and 31 ppm molybdenum.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF MG071

Bibliographic references

  • Deposit

    Bundtzen, T.K., Harris, E.E., and Gilbert, W.G., 1997, Geologic Map of the eastern McGrath quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 97-14, 34 pages, one sheet, scale 1:125,000.

  • Deposit

    Bundtzen, T.K., Kline, J.T., Smith, T.E., and Albanese, M.D., 1988, Geology of the McGrath A-2 quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Professional Report 91, 18 p., 1sheet, scale 1:63,360.

Comments on the references

  • Primary Reference = Bundtzen and others, 1988

General comments

Subject category Comment text
Deposit Model Name = Sedimentary exhalitive lead-zinc (?) (Cox and Singer, 1986; model 31a).

Reporter information

Type Date Name Affiliation Comment
Reporter 08-DEC-98 T.K. Bundtzen Pacific Rim Geological Consulting