Baumeister Bench Mine, Innoko Mining District, Yukon-Koyukuk Census Area, Alaska, USAi

Regional Level Types
Baumeister Bench Mine	Mine
Innoko Mining District	Mining District
Yukon-Koyukuk Census Area	Census Area
Alaska	State
USA	Country

Location: The Baumeister Bench is on a dissected alluvial terrace about 100 feet higher than the modern flood plain of Ganes Creek. It is about 500 feet southeast of the Ganes Creek mining camp near the common corners of sections 4, 5, 8, and 9, T. 33 N., R. 38 W., of the Seward Meridian. The location is accurate.
Geology: The Baumeister Bench mine is on a relict strath terrace formed by ancestral Ganes Creek before headward erosion and stream piracy of upper Ganes Creek. In late Tertiary or early Pleistocene, upper Ganes Creek flowed into the Beaver Creek drainage (Eakin, 1914; Mertie, 1916; Bundtzen, 1980 (GR 63); Bundtzen and Miller, 1997). The bench is the part of ancestral Ganes Creek that is locally preserved on both flanks of modern Ganes Creek over a distance of more than 10 miles kilometers. The rocks at the base of the Baumeister Bench are altered, probably by surficial weathering processes; up to 10 feet of the Upper Cretaceous, Kuskokwim Group sedimentary rocks on bedrock are oxidized and dike rocks are altered to clay and gossan. Alluvium on the bench consists of rounded gravel and cobbles of sedimentary and igneous rocks. Placer gold, often with adhering quartz, occurs in the alluvium, as well as magnetite. Exceptionally large nuggets have been found in the bench deposit.
Workings: The Baumeister Bench probably was discovered with other bench deposits of the area before 1910 (Maddren, 1910). The Baumeister Bench was mined by hydraulic methods at intervals between discovery and World War II (Warren Magnuson, pers. communication, 1986). After World War II, bulldozers were used for exploration and ground preparation activities.
Age: Probably late Tertiary or early Pleistocene (Hopkins and others, 1971).
Alteration: Bedrock below the gold-bearing alluvium is altered to at least 3 meters of depth. Dike rocks have been gossanized and converted to clay.
Production: Production prior to 1960 was lumped with Ganes Creek (ID011). About 3,500 ounces of gold were recovered from the Baumeister Bench during mining between 1960 and 1966 (Warren Magnuson, oral communication,, 1990). About 1,500 ounces were recovered from alluvium and reworked tailings in the 1980s and 1990s (T.K. Bundtzen, unpublished records, 1999). Between 1964 and 1986, 60-ounce and a 122-ounce gold nuggets were mined on the Baumeister Bench (Warren Magnuson, oral communication, 1990); during the 1990s, gold-quartz nuggets weighing up to 55 ounces were mined on the bench (Doug Clark, oral communication, 2001).

Commodities (Major) - Au; (Minor) - Ag
Development Status: Yes
Deposit Model: Placer Au deposit (Cox and Singer, 1986; model 39a).

Other Databases

Link to USGS - Alaska:	ID027

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References