Dalton Gulch Mine, Hot Springs Mining District, Yukon-Koyukuk Census Area, Alaska, USAi

Regional Level Types
Dalton Gulch Mine	Mine
Hot Springs Mining District	Mining District
Yukon-Koyukuk Census Area	Census Area
Alaska	State
USA	Country

Location: The site of the Dalton Gulch placer mine is at the approximate midpoint of the gulch, in the southeast quarter of section 8, T.3 N., R. 16 W., of the Fairbanks Meridian. The location is accurate within half a mile. The site corresponds to location 32 of Cobb (1972), and roughly to the site for Dalton Gulch, U.S. Bureau of Land Management MAS number 0020480019.
Geology: The Dalton Gulch mine 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. Bedrock in Dalton Gulch is Triassic sedimentary rocks. The gold- and cassiterite ('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). Mining began in Dalton Gulch in 1910 and continued until World War I (Wayland,1961). One pay streak was 60 feet wide, but most of the pay was discontinuous. The gravels are thin, averaging 2 to 4 feet thick, with approximately 60 feet of overburden. The stream gradient is about 200 feet per mile. The cassiterite occurs as well-rounded to subangular particles that range in size from microscopic to several inches across. The larger sizes are commonly accompanied by quartz and tourmaline, as well as by fragments of sedimentary country rock. The smaller sizes generally are free of impurities (Thomas,1957). Dalton Gulch also includes bench placers on bedrock terraces. The richest bench placers are on the steepest slopes. They averaged $0.50 in gold per square foot, with local areas as rich as $10 per square foot (gold at $20.67 per ounce). Thomas (1957) reported that the total production of Dalton Creek through 1956 was 466 ounces of gold and 3,000 pounds of cassiterite concentrate. There was less cassiterite in Dalton Gulch than in the surrounding creeks (Wayland, 1961). Moxham (1954) reported aeschynite, columbite, monazite, and zircon in pan concentrates from Dalton Gulch. These minerals are possibly related to the carbonatite near the headwaters of the creek.
Workings: Mining began in Dalton Gulch in 1910 and continued until World War I (Wayland,1961). One pay streak was 60 feet wide, but most of the pay was discontinuous. The gravels are thin, averaging between 2 and 4 feet thick, with approximately 60 feet of overburden. Dalton Gulch also includes bench placers on bedrock terraces. The richest bench placers are on the steepest slopes. They averaged $0.50 in gold per square foot, with local areas as rich as $10 per square foot (gold at $20.67 per ounce). Cassiterite is less abundant in Dalton Gulch than in the surrounding creeks (Wayland, 1961). The U.S. Bureau of Mines churn-drilled and channel sampled (tailings) at the Dalton Gulch mine in the 1950's. The average content of five samples was 3.90 pounds of tin and 0.014 ounce of gold per cubic yard (Thomas, 1957).
Age: Quaternary.
Production: Thomas (1957) reported that the total production of Dalton Gulch through 1956 was 466 ounces of gold and 3,000 pounds of cassiterite concentrate (at approximately 60% tin content).

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

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Link to USGS - Alaska:	TN096

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References