Banner Dike Zone

Site Name

Primary: Banner Dike Zone

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Commodity

Primary: Gold
Secondary: Silver
Secondary: Arsenic
Secondary: Lead
Secondary: Antimony
Secondary: Zinc

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Location

State: Alaska
District: Fairbanks

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Land Status

Not available

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Holdings

Not available

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Workings

Not available

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Ownership

Not available

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Prospect
Operation Type: Unknown
Years of Production:
Organization:
Significant:

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Physiography

Not available

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Mineral Deposit Model

Not available

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Orebody

Not available

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Structure

Not available

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Alterations

Not available

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Rocks

Not available

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Analytical Data

Not available

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Materials

Ore: Stibnite
Ore: Pyrite
Ore: Gold
Ore: Galena
Ore: Arsenopyrite
Gangue: Limonite
Gangue: Quartz
Gangue: Sericite

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Comments

Comment (Production): Production Notes = There has been no gold production from the Banner Dike Zone prospect.

Comment (Reference): Primary Reference = Swainbank and others, 1984

Comment (Workings): Workings / Exploration = Placer gold was first discovered in the Richardson district in 1905. Mining initially occurred on the nearby Tenderfoot Creek (BD039) and expanded to Banner Creek and associated tributaries. After peak gold production in 1908, mining in the area declined (Olson and others, 1985). In 1998, an exploration program consisting of reconnaissance mapping, stream-sediment, heavy-mineral concentrate, and rock-chip sampling was conducted in the Richardson area. A total of 182 rock-chip samples were collected from 38 prospect pits and 109 pan concentrates from local streams. The Banner Dike Zone has been prospected within a 3,000- by 1,000-foot area (F.L. Blystone, press release, 1998).

Comment (Exploration): Status = Active

Comment (Deposit): Model Name = Plutonic-related mesothermal, shear-hosted deposit

Comment (Geology): Geologic Description = The Richardson area is characterized by gentle slopes and broad, alluvium-filled valleys (Prindle and Katz, 1913, p. 140). The area is unglaciated and largely overlain by windblown silt, sand, and loess, locally up to 50 meters thick (Foster and others, 1979). The bedrock in the region comprises greenschist to amphibolite facies schist, marble, and gneiss that have been intruded by various igneous bodies (Bundtzen and Reger, 1977, p. 29). The schist and marble are probably Paleozoic, and the gneiss has a probable protolith of Precambrian and Paleozoic sedimentary and igneous rocks (Weber and others, 1978). The intrusive bodies in the area range in composition from rhyolite to andesite. Fine-grained rhyolite containing quartz and feldspar phenocrysts is common throughout the area (Olson and others, 1985). At the nearby Democrat Lode (BD014), the rhyolite contains arsenopyrite, gold, and pyrite, and is albitic, clay, and sericite altered (R.J. Newberry, oral communication, 1998). Structurally, the Richardson region is cut by a northwest-trending fracture system termed the Richardson Lineament. The lineament appears to correspond to the distribution of the rhyolite and other intrusive bodies and placer gold deposits (Bundtzen and Reger, 1977, p. 29). Also, the lineament tends to separate gneissic rocks to the northeast from schistose rocks to the southwest (Swainbank and others, 1984). . The extent of the Banner Dike Zone is not well defined, but it appears to trend northwest-southeast and is subparallel to the nearby Democrat Lode (BD014). The zone is defined by mineralized areas of strongly-fractured, limonite-stained, altered quartz-sericite-pyrite gneiss that is cut by rhyodacite dikes. Gold mineralization in the Banner Dike Zone is characterized by quartz veinlets containing gold and silver, and arsenic, and quartz veinlets that contain silver, arsenic, antimony, lead, and zinc. The best assay results range between 0.026 to 0.05 ounces/ton Au and 2.3 to 5.0 ounces/ton Ag (F.L. Blystone, press release, 1998). Sulfide assemblages include variable combinations of arsenopyrite, galena, pyrite, stibnite, and Pb-Sb sulfosalts (K. Ausburn, oral communication, 1998). The zones of mineralization are open to the northwest and southeast along strike (F.L. Blystone, press release, 1998). Placer gold was first discovered in the Richardson district in 1905. Mining initially occurred on the nearby Tenderfoot Creek (BD039) and expanded to Banner Creek and associated tributaries. After peak gold production in 1908, mining in the area declined (Olson and others, 1985). In 1998, an exploration program consisting of reconnaissance mapping, stream-sediment, heavy-mineral concentrate, and rock-chip sampling was conducted in the Richardson area. A total of 182 rock-chip samples were collected from 38 prospect pits and 109 pan concentrates from local streams. The Banner Dike Zone has been prospected in a 3,000- by 1,000-foot area (F.L. Blystone, press release, 1998). There has been no gold production from the Banner Dike Zone prospect.

Comment (Geology): Ore Material = sulfosalts (Pb-Sb)

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References

Reference (Deposit): Weber, F.R., Foster, H.L., Keith, T.E.C., Dusel-Bacon, C., 1978, Preliminary geologic map of the Big Delta quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-529A, 1 sheet, scale 1:250,000.

Reference (Deposit): Prindle, L.M., and Katz, F.J., 1913, Detailed description of the Fairbanks district, in Prindle, L. M., A geologic reconnaissance of the Fairbanks quadrangle, Alaska: U.S. Geological Survey Bulletin 525, p. 59-152.

Reference (Deposit): Cobb, E.H., and Eberlein, G.D., 1980, Summaries of data on and lists of references to metallic and selected nonmetallic mineral deposits in the Big Delta and Tanacross quadrangles, Alaska: U.S. Geological Survey Open-File Report 80-1086, 77 p.

Reference (Deposit): Swainbank, R.C., Burton, J.P., and Metz, P.A., 1984, Bedrock geology of the Richardson mining district, Alaska: University of Alaska, Mineral Industry Research Laboratory Open-File Report 84-2, 60 p., 8 maps, scale 1:40,000.

Reference (Deposit): Menzie, W.D., and Foster, H.L., 1979, Metalliferous and selected nonmetalliferous mineral resource potential in the Big Delta quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-529D, 61 p., 1 sheet, scale 1:250,000.

Reference (Deposit): Eberlein, G.D., Chapman, R.M., Foster, H.L., and Gassaway, J.S., 1977, Map and table describing known metalliferous and selected nonmetalliferous mineral deposits in central Alaska: U.S. Geological Survey Open-File Report 77-168-D, 132 p., 1 map, scale 1:1,000,000.

Reference (Deposit): Olson, B.G., Burton, J., Wolff, E.N., and Swainbank, R.D., 1985, Mining and minerals in the golden heart of Alaska: Fairbanks North Star Borough Publication, 80 p.

Reference (Deposit): Metz, P.A., and Hawkins, D.B., 1981, A summary of gold fineness values from Alaska placer deposits: University of Alaska, Fairbanks, Mineral Industry Research Laboratory Report No. 45, 63 p.

Reference (Deposit): Bundtzen, T.K., and Reger, R.D., 1977, The Richardson lineament-a structural control for gold deposits in the Richardson mining district, Alaska: Alaska Division of Geological and Geophysical Surveys Geologic Report 55, 46 p.

Reference (Deposit): Chapin, Theodore, 1914, Placer mining in the Yukon-Tanana region: U.S. Geological Survey Bulletin 592-J, p. 357-362.

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