Banner Dike Zone Prospects, Fairbanks Mining District, Fairbanks North Star Borough, Alaska, USAi

Regional Level Types
Banner Dike Zone Prospects	Group of Prospects
Fairbanks Mining District	Mining District
Fairbanks North Star Borough	Borough
Alaska	State
USA	Country

Location: The Banner Dike Zone is situated in the Banner Creek (BD001) drainage approximately 2 miles north of the town of Richardson on the Richardson Highway. The full extent of the Banner Dike Zone is not well defined. It is situated approximately 3 miles west of the Buckeye Zone (BD048) and about 1.5 miles southeast of the Democrat Lode (BD014). The approximate center of the zone is in SW1/4SE1/4 section 10, T. 7 S., R. 7 E., of the Fairbanks Meridian. Numerous unimproved roads provide access to the Banner Creek drainage. It was not identified as a separate location by Cobb (1972) or by Cobb and Eberlein (1980).
Geology: 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.
Workings: 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).
Production: There has been no gold production from the Banner Dike Zone prospect.

Commodities (Major) - Au; (Minor) - Ag, As, Pb, Sb, Zn
Development Status: None
Deposit Model: Plutonic-related mesothermal, shear-hosted deposit

Other Databases

Link to USGS - Alaska:	BD046

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References