PG Northeast

Occurrence, Inactive

Commodities and mineralogy

Main commodities Zn
Other commodities Ag; Cu; Pb
Ore minerals chalcopyrite; galena; pyrite; pyrrhotite; sphalerite
Gangue minerals chlorite; quartz; sericite

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale B-1
Latitude 63.3492
Longitude -144.4023
Nearby scientific data Find additional scientific data near this location
Location and accuracy The PG Northeast occurrence is a mile north-northwest of peak 7886 at an elevation of about 4,900 feet. It is about one-half mile south of the center of section 11, T. 18 N., R. 5 E., Copper River Meridian. The location is accurate.

Geologic setting

Geologic description

The PG Northeast occurrence was found in 1995 during follow-up of airborne electromagnetic anomalies that coincided with a graphitic black schist horizon 600 feet to the west. It is a 1-foot-thick massive sulfide layer or unit that occurs in the lower Lagoon unit. Outcrop samples contained 0.28 percent copper, 0.28 percent lead, 5.5 percent zinc, 14 parts per million (ppm) silver, and 10 parts per billion (ppb) gold. A piece of float assayed 0.12 percent copper, 3.44 percent lead, 6.45 percent zinc, 38 ppm silver, and 90 ppb gold. Additional prospecting in this area failed to find other mineralization (E. Hunter, unpublished data, 1998).
The rocks surrounding this occurrence are part of the Tushtena Pass unit; however, the massive sulfide mineralization is in the Lagoon unit. The Lagoon unit consists of a basal section of banded, medium- to coarse-grained, quartz-sericite(-chlorite) schist and carbonaceous schist; the upper part of the section consists of finer grained schist and phyllite. The protoliths of the basal section are immature sediments or wackes, mudstone, quartz arenite, and lesser calcareous arenite and carbonate units. Thin, gray to white and pale-green interbedded metavolcanic members of the lower Lagoon unit are typically rhyolite and rhyodacite, but there is rare andesite and basalt (Dashevsky and others, 2003).
Geologic map unit (-144.404551181606, 63.3488236255026)
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 Work is limited to preliminary surface sampling and mapping in conjunction with its initial discovery. The PG Northeast occurrence was found in 1995 during follow-up of airborne electromagnetic anomalies that coincide with a graphitic black schist unit exposed 600 feet to the west.
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