Ross

Prospect, Probably inactive

Commodities and mineralogy

Main commodities Au
Other commodities Pb
Ore minerals arsenopyrite; galena; gold; pyrite
Gangue minerals carbonate minerals; chlorite; quartz; white mica

Geographic location

Quadrangle map, 1:250,000-scale VA
Quadrangle map, 1:63,360-scale B-4
Latitude 61.319
Longitude -145.3516
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is one mile north of Mount Tiekel on the ridge between the south fork of Boulder Creek and the Tiekel River. It is at an elvation of about 4,850 feet in the SE1/4 section 26, T. 6 S., R. 1 W., of the Copper River Meridian. This prospect is probably located to within one-half mile. It is locality 45 of Cobb and Matson (1972) and locality 37 of Winkler and others (1981 [OFR 80-892-B]).

Geologic setting

Geologic description

Gold-bearing quartz veins with arsenopyrite and galena cut metaflysch of the Valdez Group at this prospect; the metaflysch is locally cut by felsic dikes (Moffit, 1918). These veins are probably similar to others that are widespread 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 (-145.353672655827, 61.3185022429888)
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 200-foot adit was driven on this prospect (Moffit, 1918).
Indication of production Undetermined
Production notes It is not known if gold was produced from this deposit. It is possible that a small amount of gold was recovered because some small high-grade zones were reported (Moffit, 1918).

References