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

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

Location: Killarney Creek drains the southeastern side of Roughtop Mountain. The site of this placer prospect is at a sled road crossing on Killarney Creek, just east of the center of section 2, T. 3 N., R. 16 W., of the Fairbanks Meridian. The location is accurate within half a mile. The site corresponds to location 35 of Cobb (1972), and roughly to the site for Killarney Creek, U.S. Bureau of Land Management MAS number 0020480021.
Geology: The Killarney Creek 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(?) occurs in the Triassic section of these strata and there are exposures of serpentinized, Cretaceous(?) mafic and ultramafic rock in the area, mainly on Serpentine Ridge. Bedrock at the Killarney Creek prospect is Triassic or Permian siliciclastic rocks (argillite, sandstone, and shale), characterized by subphyllitic to phyllitic textures (Reifenstuhl and others, 1998). The gold- and tin-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). Killarney Creek delineates the northeastern boundary of the tin belt (Thomas, 1957). The creek gravels contain cobbles of a coarse-grained biotite granite probably from Roughtop Mountain (Wayland, 1961). Bedrock in Killarney Creek consists of Triassic sedimentary rocks (Reifenstuhl and others, 1998). Prospecting began on Killarney Creek in 1912 (Wayland, 1961). Potential gold-bearing gravel deposits were drilled the following years by Hanson and Bock, and by Howell and Bargery (Brooks, 1916). The cassiterite and gold occur on phyllite bedrock for approximately 1,000 feet along Killarney Creek, at a depth of 40 to 80 feet. Unlike the other deposits in the tin belt, the cassiterite is fine; the largest piece recovered from one drilling program was only one inch in diameter (Wayland, 1961). More recent work on Killarney Creek has included testing the gravels for gold and tin by Bruce Savage in 1989 (Bundtzen and others, 1990). In 1997, Bed Rock Enterprises conducted placer exploration on Killarney Creek, as well as on Roughtop Mountain (Swainbank and others, 1998).
Workings: Prospecting began on Killarney Creek in 1912 (Wayland, 1961). Potential gold-bearing gravel deposits were drilled the following years by Hanson and Bock, and by Howell and Bargery (Brooks, 1916). The cassiterite and gold occur on phyllite bedrock for approximately 1,000 feet along Killarney Creek, at a depth of 40 to 80 feet. Unlike the other deposits in the tin belt, the cassiterite is fine; the largest piece recovered from one drilling program was only one inch in diameter (Wayland, 1961). More recent work on Killarney Creek included testing the gravels for gold and tin by Bruce Savage in 1989 (Bundtzen and others, 1990). In 1997, Bed Rock Enterprises conducted placer exploration on Killarney Creek, as well as on Roughtop Mountain (Swainbank and others, 1998).
Age: Quaternary.

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

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Link to USGS - Alaska:	TN106

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References