Alaskan

Prospect, Probably inactive

Commodities and mineralogy

Main commodities Au
Other commodities Cu; Pb; Zn
Ore minerals arsenopyrite; chalcopyrite; galena; gold; limonite; pyrite; sphalerite
Gangue minerals carbonate minerals; chlorite; quartz; white mica

Geographic location

Quadrangle map, 1:250,000-scale VA
Quadrangle map, 1:63,360-scale A-7
Latitude 61.1805
Longitude -146.3127
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is one-quarter mile west of upper Wood Creek at an elevation of 2,500 feet. The location is shown of the USGS Valdez A-7 topographic map with a shaft symbol. It is in about the center of the N1/2 section 16, T. 8 S., R. 6 W., of the Copper River Meridian. It is locality 27 of Cobb and Matson (1972) and locality 22 of Winkler and others (1981 [OFR 80-892-B]).

Geologic setting

Geologic description

A gold-bearing quartz vein, 6 inches to 5 feet thick, that can be traced for 150 feet in outcrop cuts metaflysch of the Valdez Group (Johnson, 1916). The vein contains pyrite, galena, sphalerite, chalcopyrite and free gold. A short shaft and adit explored this deposit. Another vein 200 feet from the main vein may be another vein or a continuation of the main vein. These veins are probably similar to other gold-bearing quartz veins cutting metaflysch of the Valdez Group in the southern Valdez quadrangle. Data summarized by Goldfarb and others (1997) show that gold-bearing quartz veins in the Valdez Group commonly contain pyrite, arsenopyrite, carbonate minerals, chlorite, and white mica and formed from water-rich fluids with 5 to 15 mole percent CO2 and significant amounts of CH4, N2, and H2S. The vein-forming fluid salinities were less than 8 percent, vein formation temperatures ranged from 225 to 375 degrees centigrade, and emplacement depths varied from 3 to 10 kilometers. The vein-forming fluids were produced by metamorphic devolatilization reactions. Radiometric dating indicates that the veins formed from 57 to 49 Ma (Goldfarb and others, 1997, p. 171), when deep parts of the accreted Valdez Group flysch underwent high-grade metamorphism and partial melting (Hudson, 1994).
Geologic map unit (-146.314743528059, 61.179980704312)
Mineral deposit model Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a)
Mineral deposit model number 36a
Age of mineralization Radiometric dating indicates that the gold-bearing quartz veins in the Valdez Group formed from 57 to 49 Ma (Goldfarb and others, 1997, p. 171), when deep parts of the accreted Valdez Group flysch underwent high-grade metamorphism and partial melting (Hudson, 1994).
Alteration of deposit Country rocks to gold-bearing quartz veins in Valdez Group metaflysch can be variably silicified, carbonitized, and sericitized (Goldfarb and others, 1997).

Production and reserves

Workings or exploration A short shaft and adit explored this deposit.
Indication of production Undetermined

References