Northeast Cliffs

Prospect, Undetermined

Commodities and mineralogy

Main commodities Cu; Pb; Sn; Zn
Ore minerals chalcopyrite; galena; sphalerite

Geographic location

Quadrangle map, 1:250,000-scale PE
Quadrangle map, 1:63,360-scale C-1
Latitude 56.5164
Longitude -132.0607
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect represents sampling by an unknown company and by Still and others (2002) on the steep north-trending cliff face east of the middle section of Groundhog Basin. The coordinates are at about the center of the work at an elevation of about 3,400 feet; it is about 0.5 mile south of the center of section 6, T. 62 S., R. 86 E. The general location is accurate but the location of the specific sampling by industry is uncertain.

Geologic setting

Geologic description

The rocks in the prospect area are part of a belt of Mesozoic or Paleozoic sedimentary and volcanic rocks that have been metamorphosed to schist and gneiss. The belt is about 1 1/2 mile wide and strikes northwest (Brew, 1997; George and Wyckoff, 1973). The metamorphic rocks are bounded on the east by a thick, regionally extensive, 60 to 70 Ma tonalite sill and on the west by a 90 Ma granodiorite pluton (Brew, 1997 Still and others, 2002). On the north side of Groundhog Basin just west of the cliff faces, the metamorphic rocks are intruded by a 16.3 Ma biotite 'tin' granite pluton about 1,000 by 2,0000 feet in size. The granite is probably the source of the numerous rhyolite dikes and sills that extend from it and the mineralization in the area (Newberry and Brew, 1989).
Still and others (2002) found fixed climbing ropes at several places along about 0.5 mile on the cliff faces east of Groundhog Basin that probably represent sampling and mapping by AMAX Exploration Inc. between 1976 and 1981. Still and others (2002) collected several samples at the north and south ends of the cliffs. The rocks along the cliffs are mainly silicified gneiss and rhyolite. The mineralization consists of disseminated chalcopyrite, galena, and sphalerite (probably similar in origin to the mineralization at the Groundhog Basin prospect in the valley below (PE040)). Four samples collected by Still and others (2002) contained 112 to 980 parts per million (ppm) copper, 1,569 to 9,559 ppm zinc, and 58 to 1,941 ppm tin.
Geologic map unit (-132.062381450338, 56.5160658581491)
Mineral deposit model Banded Ag-Cu-Sn-Pb-Zn tabular replacement bodies, veins, and stringers.
Age of mineralization 16.3 Ma based on a probable genetic tie to a nearby, zinnwaldite 'tin' granite (Newberry and Brew, 1989).
Alteration of deposit None specifically noted.

Production and reserves

Workings or exploration Still and others (2002) found fixed climbing ropes at several places along about 0.5 mile on the cliff faces east of Groundhog Basin that probably represent sampling and mapping by AMAX Exploration Inc. between 1976 and 1981. Still and others (2002) collected several samples at the north and south ends of the cliffs.
Indication of production None
Reserve estimates None.

References

References

Reporters D.J. Grybeck (Port Ludlow, WA)
Last report date 3/4/2008