Townsend and Holland

Prospect, Probably inactive

Commodities and mineralogy

Main commodities Au
Ore minerals arsenopyrite; 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 A-4
Latitude 61.2084
Longitude -145.4349
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is immediately below the Richardson Highway, about one-half mile west of mile 40. It is at benchmark Elbow (elevation of 1,656 feet) in the NW1/4 section 4, T. 8 S., R.1 W., of the Copper River Meridian. It is locality 42 of Cobb and Matson (1972) and locality 34 of Winkler and others (1981 [OFR 80-892-B]).

Geologic setting

Geologic description

Gold-bearing quartz veins from 3 to 5 feet thick cut metaflysch of the Valdez Group at this prospect (Moffit, 1935). One vein strikes N 40 E and was followed in an adit for 300 feet. Open cuts and a 150-foot long adit were also used to explore the veins. 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 (-145.436949821356, 61.2078987235808)
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 One vein strikes N 40 E and was followed in an adit for 300 feet. Open cuts and a 150-foot long adit were also used to explore the veins (Moffit, 1935).
Indication of production None

References