Occurrence, Inactive

Commodities and mineralogy

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

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale A-1
Latitude 63.1554
Longitude -144.0927
Nearby scientific data Find additional scientific data near this location
Location and accuracy The UPP occurrence is located on the southeast side of the upper Tok River valley at an elevation of about 4,400 feet in the NE1/4 section 21, T. 16 N., R. 7 E., Copper River Meridian. It is about 5,000 feet southeast of the Cascade occurrence (MH350). The location is accurate.

Geologic setting

Geologic description

The UPP massive sulfide occurrence is part of a series of massive sulfide occurrences (MH327-MH328, MH350-MH353) that are intermittently exposed for 7 miles along strike in a thrust-repeated section of the lower Lagoon unit (Dashevsky and others, 2003). Disseminated to massive sulfide bands and lenses are closely associated with marble within a pelitic metasedimentary sequence that consists of metasiltstone, quartzite, carbonaceous phyllite, and siliceous marble or calcareous schist. Thin bands of white to pale-gray quartz-sericite schist, rarely hematitic or chloritic, occur within the metasedimentary rocks. A sequence of medium- to deep-green chlorite schist, in part calcareous and siliceous, occurs northeast of this occurrence (R.A. Blakestad and others, unpublished Resource Associates of Alaska Inc. report, 1976). Local, high-grade lenses contain as much as 3.2 percent copper, 4.6 percent lead, 9.5 percent zinc, 47 parts per million (ppm) silver, and 90 parts per billion (ppb) gold. More typical assays from the mineralized zone average 0.3 percent copper, 0.1 percent lead, 0.1 percent zinc, 3 ppm silver, and 20 ppb gold (E. Hunter, unpublished data, 1998).
Geologic map unit (-144.094941875548, 63.1550207439319)
Mineral deposit model Kuroko massive sulfide (Cox and Singer, 1986; model 28a).
Mineral deposit model number 28a
Age of mineralization The lower Lagoon unit, which is part of the metamorphic sequence that includes the rocks at this deposit, has been dated as Devonian on the basis of one SHRIMP U-Pb zircon age of 372 +/- 6 Ma at the nearby LZ East prospect (MH328) (Dashevsky and others, 2003).

Production and reserves

Workings or exploration The UPP occurrence has been evaluated by surface prospecting and mapping.
Indication of production None

Additional comments

The unpublished data that is cited can be seen by contacting Grayd Resources Inc. in Vancouver, B.C., Canada (www.grayd.com), or Northern Associates Inc. in Fairbanks, Alaska.