PG Southeast

Occurrence, Inactive

Commodities and mineralogy

Main commodities Fe
Other commodities Cu
Ore minerals chalcopyrite; pyrite; pyrrhotite
Gangue minerals calcite; chlorite; quartz; sericite

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale B-1
Latitude 63.331
Longitude -144.3303
Nearby scientific data Find additional scientific data near this location
Location and accuracy The PG Southeast occurrence is 0.7 mile south-southeast of peak 7523 at an elevation of about 6,000 feet. The occurrence is in the NW1/4NE1/4 section 19, T. 18 N., R. 6 E., Copper River Meridian. The location is accurate.

Geologic setting

Geologic description

The PG Southeast occurrence is a low-grade sulfide horizon within the Tushtena Pass unit and is part of a 2-mile-long zone of intermittently exposed semimassive and massive sulfides that include the PG East prospect (MH262). The sulfides are predominantly pyrite and pyrrhotite with minor chalcopyrite. The massive sulfides are as much as 2 feet thick and the semimassive sulfides are as much as 25 feet thick. Base metal grades are very low. Copper is typically below 0.1 percent; lead, zinc, and silver values do not exceed background; and gold values are about 30 parts per billion (E. Hunter, unpublished data, 1998).
The Tushtena Pass unit that hosts the PG East occurrence consists of medium- to coarse-grained, calcareous, quartz-sericite-chlorite-schist with local carbonate interbeds. The unit is is typically green to gray, foliated, schistose to blocky, laminated to medium-bedded, quartz-eye bearing, quartz-rich rocks with subordinate muscovite, sericite, and chlorite. In many places, sheared zones are the loci of pervasive iron-carbonate alteration that weathers to a distinct reddish hue. Discontinuous bands of siliceous limestone, dolomite, marble, and black, weakly pyritic metasiltstones are common (Dashevsky and others, 2003).
Geologic map unit (-144.332551102582, 63.3306239760347)
Mineral deposit model Kuroko massive sulfide (Cox and Singer, 1986; model 28a).
Mineral deposit model number 28a
Age of mineralization The Drum unit, which is part of the metamorphic sequence that includes the rocks at this deposit, has been dated at the Devonian-Mississippian boundary on the basis of one SHRIMP U-Pb zircon age of 359 +/- 6 Ma at the nearby DD South prospect (MH325) (Dashevsky and others, 2003).

Production and reserves

Workings or exploration Only preliminary surface examination of this sulfide occurrence; there are no significantly elevated base or precious metals reported with the iron sulfides (E. Hunter, unpublished data, 1998).
Indication of production None

Additional comments

Unpublished data cited is available for viewing by contacting Grayd Resources Inc. in Vancouver, B. C., Canada (www.grayd.com), or Northern Associates Inc. in Fairbanks, Alaska.

References