Palmer

Prospect, Probably inactive

Commodities and mineralogy

Main commodities Au
Ore minerals arsenopyrite; gold; pyrite
Gangue minerals carbonate minerals; chlorite; quartz; sericite

Geographic location

Quadrangle map, 1:250,000-scale VA
Quadrangle map, 1:63,360-scale A-8
Latitude 61.141
Longitude -146.6384
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is in the headwaters of Palmer Creek, 1,000 feet south of Shoup Glacier; it is at an elevation of about 900 feet near the center of the south side of section 27, T. 8 S., R. 8 W., of the Copper River Meridian. This prospect is probably located to within one-quarter mile. It is locality 10 of Cobb and Matson (1972) and locality 7 of Winkler and others (1981 [OFR 80-892-B]).

Geologic setting

Geologic description

A shear zone, 2.5 to 4.5 feet wide, cuts metaflysch of the Valdez Group and contains pyritiferous quartz stringers with free gold (Brooks, 1912). The shear zone that strikes northwest and is approximately vertical is marked by crushed country rock and a slickensided and gouge-lined hanging wall. At least one 100-foot-long adit explored this deposit, which is thought to be a continuation of the I.X.L. shear zone (VA113).
This deposit 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 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 (-146.640440138941, 61.1404759067552)
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 At least one 100-foot-long adit explored this deposit, which is thought to be a continuation of the I.X.L. shear zone (VA113).
Indication of production Undetermined

References