Utah Creek Prospect, Hot Springs Mining District, Yukon-Koyukuk Census Area, Alaska, USAi

Regional Level Types
Utah Creek Prospect	Prospect
Hot Springs Mining District	Mining District
Yukon-Koyukuk Census Area	Census Area
Alaska	State
USA	Country

Location: Mining claims were staked in the 1970's, followed by placer mining, on Utah Creek (Alaska Kardex files). Mining claim location notices show 3 claims along Utah Creek about 2 miles upstream from its junction with Baker Creek. The site is in the southeast quarter of section 33, T. 4 N., R. 15 W., of the Fairbanks Meridian. The location is accurate within about 1,000 feet. This site closely corresponds with the site for Utah Creek, U.S. Bureau of Land Management MAS number 0020480110.
Geology: The Utah Creek placer prospect is one of a group of cassiterite- and gold-bearing placer deposits known as the Tofty tin belt, a 12-mile-long area that trends east-northeast, between Roughtop Mountain to the north and Hot Springs Dome to the south (Thomas, 1957). Roughtop Mountain and Hot Springs Dome respectively are underlain by Cretaceous (K-Ar age date of 92 +/- 5 Ma) and Tertiary (K-Ar age date of 62 +/- 3 Ma) granitic plutons (Chapman and others, 1982). The plutons intrude and contact metamorphose Mesozoic marine sedimentary strata, which also are cut by diverse faults, including regional-scale, east-northeast-striking, thrust faults (Reifenstuhl and others, 1998). A carbonatite sill(?) is in the Triassic section of these strata and there are exposures of serpentinized, Cretaceous(?) mafic and ultramafic rock, mainly on Serpentine Ridge. The gold- and cassiterite-bearing creeks flow normal to the trend of the tin belt. They head in the plutonic, metamorphic, and mafic/ultramafic rocks of Roughtop Mountain and Serpentine Ridge, which probably are the source(s) of some of the metalliferous minerals in the placer deposits. Concentrations of gold diminish toward the south, probably due to dispersion (Thomas, 1957). Bedrock at the Utah Creek prospect is Triassic or Permian, phyllitic argillite, sandstone, and shale, and a steeply-dipping Jurassic carbonatite sill (Reifenstuhl and others, 1998). Three mining claims were staked along Utah Creek in the 1970's (Alaska Kardex files). Affidavits of annual labor from 1979 to 1982 list excavation, an adit 18 feet high and 15 feet deep, and drilling. There is no record of production from Utah Creek, but if placer gold has been recovered, the creek would be the easternmost placer gold producer in the Tofty tin belt.
Workings: Three mining claims were staked along Utah Creek in the 1970's (Alaska Kardex files). Affidavits of annual labor from 1979 to 1982 list excavation, an adit 18 feet high and 15 feet deep, and drilling.
Age: Quaternary.
Production: There is no record of production from Utah Creek, but if placer gold has been recovered, the creek would be the easternmost placer gold producer in the Tofty tin belt.

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

Other Databases

Link to USGS - Alaska:	TN116

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References