Unnamed Occurrences (ARDF - TN104; Bean Ridge), Hot Springs Mining District, Yukon-Koyukuk Census Area, Alaska, USAi

Regional Level Types
Unnamed Occurrences (ARDF - TN104; Bean Ridge)	- not defined -
Hot Springs Mining District	Mining District
Yukon-Koyukuk Census Area	Census Area
Alaska	State
USA	Country

Location: These occurrences are along a 4,000-foot-long northeast trend along the top of Bean Ridge. The northernmost occurrence is approximately 1,700 feet south of Manley Hot Springs Dome. The site is at the center of the area of occurrences, at Alaska Division of Geological and Geophysical Surveys (ADGGS) sample station 97RN147 (Liss and others, 1998), just north of the middle of the south boundary of section 2, T. 2 N., R. 16 W., of the Fairbanks Meridian. The location is accurate within 500 feet.
Geology: Bedrock at thse occurrences is locally brecciated, mainly Lower Cretaceous sandstone, shale, and siltstone that is hornfelsed by the Tertiary Hot Springs granite pluton (Reifenstuhl and others, 1998). The hornfels consists of black, dense rock that contains unoriented crystals or rosettes of muscovite, biotite, and, locally, andalusite. The northwestern contact of the Tertiary Hot Springs granite pluton is in the prospect area. The breccia probably is due to high-angle faulting at the pluton-hornfels contact. In 1997, ADGGS collected several samples (97RN145A, 97RN147, and 97RN150) of iron- and manganese-oxide-cemented breccia, and of quartz veins in hornfels, along Bean Ridge south and southwest of Manley Hot Springs Dome (Liss and others, 1998). The samples contained one or more of the following maximum geochemical values: 690 parts per billion (ppb) gold, 8.5 parts per million (ppm) cadmium, 280 ppm lead, 3,750 ppm zinc, and more than 15 percent iron and 10,000 ppm manganese (Liss and others, 1998). There is no record of exploration or mining at this site, but there has been extensive exploration by industry around Hot Springs Dome and at the Barrett prospect (TN103).
Workings: In 1997, ADGGS collected several samples (97RN145A, 97RN147, and 97RN150) of iron- and manganese-oxide-cemented breccia, and of quartz veins in hornfels, along Bean Ridge south and southwest of Manley Hot Springs Dome (Liss and others, 1998). The samples contained one or more of the following maximum geochemical values: 690 parts per billion (ppb) gold, 8.5 parts per million (ppm) cadmium, 280 ppm lead, 3,750 ppm zinc, and more than 15 percent iron and 10,000 ppm manganese (Liss and others, 1998). There is no record of exploration or mining at this site, but there has been extensive exploration by industry around Hot Springs Dome and at the Barrett prospect (TN103).
Age: Tertiary. The granite has a [whole-rock?] K-Ar age date of 62 +/- 3 Ma (Chapman and others, 1982), and a biotite 40Ar/39Ar age date of 59 +/- 0.8 Ma (Reifenstuhl and others, 1998).

Commodities (Major) - Au, Pb, Zn; (Minor) - Fe, Mn
Development Status: None
Deposit Model: Polymetallic veins (Cox and Singer, 1986; model 22c).

Other Databases

Link to USGS - Alaska:	TN104

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References