Willow Branch of Tozer Creek

Prospect in Alaska, United States with commodities Zinc, Tin

Geologic information

Identification information

Deposit ID 10308439
Record type Site
Current site name Willow Branch of Tozer Creek

Geographic coordinates

Geographic coordinates: -166.7454, 65.50628 (WGS84)
Relative position This prospect is on the south side of the Willow Branch of Tozer Creek in the south-central Teller C-4 quadrangle. Willow Branch is a south tributary to Tozer Creek, a major east tributary to the Don River. Mineralization is along a fault that is about 500 feet south and parallel to Willow Branch at elevations between 440 and 600 feet. This is locality 12 of Cobb and Sainsbury (1972). Cobb (1975) summarized relevant references under the name 'Black Mtn.'.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Zinc Primary
Tin Secondary

Materials information

Materials Type of material
Cassiterite Ore
Sphalerite Ore
Arsenopyrite Gangue
Fluorite Gangue
Garnet Gangue
Pyrite Gangue
Quartz Gangue

Alteration

  • (Local) Garnet and sulfide-rich tactite replaces calc-silicate rock (hornfels); possibly some later quartz-fluorite veining.

Nearby scientific data

(1) -166.7454, 65.50628

Comments on the geologic information

  • Geologic Description = The Willow Branch of Tozer Creek is in the northwest part of the upland that includes Black Mountain. This upland is an area of hornfels, calc-silicate hornfels, and tactite intruded by a locally exposed biotite granite. The metasedimentary rocks, fine-grained metapelitic and metacarbonate rocks, are of unknown but probable Paleozoic age. The Late Cretaceous (79.1 +/- 2.9 my, Hudson and Arth, 1983, p. 769) biotite granite, medium-grained and equigranular, is exposed in a small area on the southern flanks of the upland and is interpreted to be part of an early precurser granite phase rather than an mineralyzing granite phase (Hudson and Arth, 1983, p. 784; Hudson and Reed, 1997, figure 3). The wide distribution of thermally metamorphosed rocks and the results of gravity and aeromagnetic surveys (McDermott, 1983) indicate that most of the Black Mountain area is underlain by granite at depth. The area is transected by many normal faults and related fractures. Sainsbury and Hamilton (1967) mapped a northwest-trending fault along the south side of Willow Branch that is noticeably mineralized over a distance of about 2,500 feet. This fault juxtaposes metapelitic rocks to the north against calc-silicate rocks to the south. Along the fault, calc-silicate rocks are variably replaced by garnet and sulfide-rich assemblages over widths of a few to 12 feet. The sulfide minerals include sphalerite, pyrite, arsenopyrite, and a sooty, black unidentified material. Fluorite and fine-grained silica are noted as gangue minerals in this assemblage (Sainsbury and Hamilton, 1969, p. B23). One sample of the sulfide-rich material has been analyzed (Sainsbury and Hamilton, 1967, p. B24). This sample contained 3% zinc, 700 ppm tin, 300 ppm copper, and 300 ppm lead.
  • Age = Late Cretaceous; the Black Mountain biotite granite, interpreted to be linked to alteration and mineralization in this area, has been determined to be 79.1 +/- 2.9 my old by the K/Ar method (Hudson and Arth, 1983, p. 769).

Economic information

Economic information about the deposit and operations

Development status Prospect

Comments on exploration

  • Status = Inactive

Mining district

District name Port Clarence

Comments on the workings information

  • Workings / Exploration = Surface reconnaissance mapping and an analysis of one random chip sample is all the information available for this prospect.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF TE089

Bibliographic references

  • Deposit

    Sainsbury, C.L., and Hamilton, J. C., 1967, Mineralized veins at Black Mountain, western Seward Peninsula, Alaska: U.S. Geological Survey Professional Paper 575-B, p. B21-B25.

  • Deposit

    Hudson, T.L., and Arth, J. G., 1983, Tin-granites of Seward Peninsula, Alaska: Geological Society of America Bulletin, v. 94, p. 768-790.

  • Deposit

    McDermott, M.M., 1983, Seward Peninsula reconnaissance 1982 geophysical report: Anchorage, Anaconda Minerals Company internal report. 29 p. (Report held by Cook Inlet Region, Inc., Anchorage, Alaska.)

  • Deposit

    McDermott, M.M., 1983, Investigation of the magnetic contact aureoles of the Khotol and Black Mountain granites, Alaska: Anchorage, Alaska, Anaconda Minerals Company internal report (Report held by Cook Inlet Region, Inc., Anchorage, Alaska).

  • Deposit

    McDermott, M.M., 1983, Seward Peninsula reconnaissance 1982 geophysical report: Anchorage, Anaconda Minerals Company internal report, 29 p. (Report held by Cook Inlet Region, Inc., Anchorage, Alaska.)

Comments on the references

  • Primary Reference = Sainsbury and Hamilton, 1967

General comments

Subject category Comment text
Deposit Model Name = Fault-controlled replacement and veining. Possibly tin skarn (14b) or tin vein (15b) model after Cox and Singer (1986).

Reporter information

Type Date Name Affiliation Comment
Reporter 10-MAY-98 Travis L. Hudson Applied Geology