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Blt

Prospect in Alaska, United States with commodities Silver, Gold, Copper, Lead, Zinc
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Geologic information

Identification information

Deposit ID 10307514
Record type Site
Current site name Blt

Geographic coordinates

Geographic coordinates: -149.65383, 63.21258 (WGS84)
Relative position The BLT prospect is at an elevation of about 3,650 feet on the west bank of the head of Bryn Mawr Creek, a northeast-flowing tributary of the West Fork Chulitna River. The map site is on the east edge of sec. 4, T. 20 S., R. 11 W., of the Fairbanks Meridian. Access is via dirt road from Colorado Station along the north side of the West Fork Chulitna River to the junction with Bryn Mawr Creek. The road crosses the West Fork Chulitna River and climbs southwesterly to the Golden Zone mine (HE043), which adjoins the BLT prospect on the north. The location is accurate to within 1,000 feet.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Gold Primary
Copper Secondary
Lead Secondary
Zinc Secondary

Materials information

Materials Type of material
Arsenopyrite Ore
Chalcopyrite Ore
Galena Ore
Sphalerite Ore
Tetrahedrite Ore
Ankerite Gangue
Calcite Gangue
Marcasite Gangue
Quartz Gangue
Sericite Gangue

Alteration

  • (Local) Clays, ankerite/calcite, and quartz are the dominant alteration assemblages in the mafic dikes.

Mineral occurrence model information

Model code 85
USGS model code 22c
Deposit model name Polymetallic veins
Mark3 model number 46

Nearby scientific data

(1) -149.65383, 63.21258
ListMap

Comments on the geologic information

  • Geologic Description = BLT is the name given to the prospect that includes the Blind, Little, and Tunnel veins near the Golden Zone mine (HE043) (C.C. Hawley, oral communication, 1999). The veins and a strongly altered mafic dike are in a shear zone that defines the southeast margin of the Golden Zone porphyry. The shear zone and mafic dike cut Triassic redbed sandstone, conglomerate, limestone, and volcanoclastic rocks. The shear zone-dike (BLT zone) also cuts the quartz-biotite porphyry associated with the Golden Zone breccia pipe. The BLT prospect consists of early, arsenopyrite-rich quartz veins, followed by quartz-carbonate-sulfide veins, stockwork zones, and massive sulfide lenses. The veins are colloform and banded, indicating an epithermal depositional environment. Sulfide phases in the BLT differ from those in the Golden Zone, in that they contain more pyrite and marcasite, more lead and zinc, and less copper. Only the younger, sulfide-quartz-carbonate veins that locally cut the arsenopyrite-rich veins contain free gold. The arsenopyrite-rich veins probably correlate with the Upper Cretaceous veins at the Golden Zone mine (unpublished report by Addwest Minerals International Ltd., 1997).
  • Age = Late Cretaceous and younger.

Economic information

Economic information about the deposit and operations

Development status Prospect

Comments on exploration

  • Status = Active

Mining district

District name Valdez Creek

Comments on the workings information

  • Workings / Exploration = Underground work encountered the Blind Vein in the 1970's. 19 drill holes (totalling over 6,000 feet) have been completed up to the present (1999), along with widespread trenching and soil geochemistry grids. Closely-spaced helicopter aeromagnetic and EM geophysical surveys have been flown over this prospect. The State of Alaska flew a more widely-spaced helicopter aeromagnetic survey in 1996 (Burns, 1997).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF HE044

Bibliographic references

  • Deposit

    Ross, C.P., 1933, The Valdez Creek mining district, Alaska: U.S. Geological Survey Bulletin 849, p. 289-467.

  • Deposit

    Wells, R.R., 1956, Laboratory concentration of various Alaska copper ores: U.S. Bureau of Mines Report of Investigations 5245, 9 p.

  • Deposit

    Berg, H.C., and Cobb, E.H., 1967, Metalliferous Lode Deposits of Alaska. U.S. Geological Survey Bulletin 1246, 254 p.

  • Deposit

    Mulligan, J.J., Warfield, R.S., and Wells, R.R., 1967, Sampling a gold-copper deposit, Golden Zone Mine, south-central Alaska: U.S. Bureau of Mines Open-File Report 9-67, 59 p.

  • Deposit

    Hawley, C.C., and Clark, A.L., 1974, Geology and mineral deposits of the upper Chulitna district, Alaska: U.S. Geological Survey Professional Paper 758-B, p. 1-47, 2 sheets, scale 1:12,000 and 1:48,000.

  • Deposit

    Hawley, C.C., and others, 1978, Mineral appraisal of lands adjacent to Mt. McKinley National Park, Alaska. Contract No. JO166107: U.S. Bureau of Mines Open-File Report 24-78, 274 p., 12 sheets.

Comments on the references

  • Primary Reference = Hawley and others, 1978

General comments

Subject category Comment text
Deposit Model Name = Polymetallic vein (Cox and Singer, 1986; model 22c)

Reporter information

Type Date Name Affiliation Comment
Reporter 07-APR-00 N. Van Wyck Stevens Exploration Management Corporation