Unnamed (Bean Ridge)

Occurrences, Inactive

Commodities and mineralogy

Main commodities Au; Pb; Zn
Other commodities Fe; Mn
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale TN
Quadrangle map, 1:63,360-scale A-2
Latitude 65.02312
Longitude -150.74827
Nearby scientific data Find additional scientific data near this location
Location and accuracy 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.

Geologic setting

Geologic description

Bedrock at these 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).
Geologic map unit (-150.750737589923, 65.0226272811723)
Mineral deposit model Polymetallic veins (Cox and Singer, 1986; model 22c).
Mineral deposit model number 22c
Age of mineralization 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).

Production and reserves

Workings or exploration 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).
Indication of production None

References