Guthrie and Belloli Prospect, Prince William Sound Mining District, Valdez-Cordova Census Area, Alaska, USAi

Regional Level Types
Guthrie and Belloli Prospect	Prospect
Prince William Sound Mining District	Mining District
Valdez-Cordova Census Area	Census Area
Alaska	State
USA	Country

Location: This prospect is on the southwest side of Uno Basin, about seven-tenths of a mile northwest of peak 2733; it is at an elevation of about 1,800 feet in the NW1/4 section 30, T. 8 S., R. 7 W., of the Copper River Meridian. This prospect is probably located to within one-quarter mile. It is locality 16 of Cobb and Matson (1972) and locality 13 of Winkler and others (1981 [OFR 80-892-B]).
Geology: A gold-bearing quartz vein from 1 to 10 feet thick cuts sheared metaflysch of the Valdez Group (Johnson, 1915). The quartz vein contains calcite, chlorite, pyrite, chalcopyrite, arsenopyrite, sphalerite, and galena. The vein was traced on the surface for about 100 feet and explored by a 140-foot-long adit, a 90-foot-long crosscut, and 50 feet of drifts (Johnson, 1915; Jansons and others, 1984). Four U.S. Bureau of Mines grab samples from this area contained as much as 1.5 ppm gold and 19 ppm silver (Jansons and others, 1984). This vein is 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 devolatization 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).
Workings: The vein was traced on the surface for about 100 feet and explored by a 140-foot-long adit, a 90-foot-long crosscut, and 50 feet of drifts (Johnson, 1915; Jansons and others, 1984).
Age: 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: Country rocks to gold-bearing quartz veins in Valdez Group metaflysch can be variably silicified, carbonitized, and sericitized (Goldfarb and others, 1997).
Production: Production has not been reported from this deposit (Jansons and others, 1984).

Commodities (Major) - Au; (Minor) - Cu, Pb, Zn
Development Status: Undetermined.
Deposit Model: Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a)

Other Databases

Link to USGS - Alaska:	VA115

Other Regions, Features and Areas containing this locality

References