Northeast Cliffs Prospect, Petersburg Mining District, Wrangell City and Bourough, Alaska, USAi

Regional Level Types
Northeast Cliffs Prospect	Prospect
Petersburg Mining District	Mining District
Wrangell City and Bourough	Borough
Alaska	State
USA	Country

Location: 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.
Geology: 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.
Workings: 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.
Age: 16.3 Ma based on a probable genetic tie to a nearby, zinnwaldite 'tin' granite (Newberry and Brew, 1989).
Alteration: None specifically noted.
Reserves: None.

Commodities (Major) - Cu, Pb, Sn, Zn
Development Status: None
Deposit Model: Banded Ag-Cu-Sn-Pb-Zn tabular replacement bodies, veins, and stringers.

Other Databases

Link to USGS - Alaska:	PE103

Other Regions, Features and Areas containing this locality

References