Date of Award

1980

Document Type

Thesis

Degree Name

Bachelor of Science (BS)

Department

Geology

Abstract

The Pine Portage gold prospect is located in Kirkup Township approximately 12 kilometers east of Kenora, Ontario. The mine site is within the Wabigoon Subprovince of the Superior Province of the Precambrian Shield. The area is characterized by belts of metavolcanics in the amphibolite metamorphic facies that have been intruded by granitic bodies.

Reconnaissance mapping indicates three rock types present in the study area: amphibolite, granodiorite, and vein material. The amphibolite is composed of amphibole, plagioclase, chlorite, and clinozoisite. The granodiorite is composed of plagioclase, alkali feldspar, quartz, biotite, and epidote. The vein material is predominantly quartz-carbonate and contains altered schist, pyrite, and minor amounts of galena, sphalerite, tellurium, silver, and gold.

The vein material occupies a sheared fissure and can be further divided into quartz-carbonate material regularly bounded by the headwall and a thin clay zone, quartz-carbonate material with sheared and altered schist, and brecciated amphibolite bounded by an irregular footwall. The quartz and pyrite of the vein show evidence of brecciation with calcite filling the resulting fractures. This is thought to indicate deformation and shear of an original fissure filled with quartz and pyrite. Calcite and possibly sulfide materials, tellurium, silver, and gold were emplaced following the deformation.

This epigenetic, sheared fissure vein is thought to be the result of wallrock alteration and lateral secretion. The vein is proposed to be a redistribution of the host rock chemistry with the introduced volatiles CO2, H2O, and S. Meteoric water may be the source of these volatiles.

Mafic bodies that lie to the southwest of Pine Portage could be a source of trace gold that is released by alteration. Elements released by alteration migrate to and along the shear zone and become concentrated in suitable host structures where they recombine with introduced elements in dilatent areas.

Exploration concentrated on the alteration zones, the dilatent structures, and near the mafic bodies could prove fruitful.

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