Gerald Allen Perry HBSc thesis abstract

A section of the Quetico Gneiss Belt north of Thunder Bay, referred to as The Keelor Lake Area, was investigated to ascertain whether there was a relationship between metamorphism and the magnetic expression by the rocks of the area.

Three rock units were distinguished:  1) pelitic schists,  2) basic amphibole bearing schists and  3) quartzofeldspathic rocks.  Petrographic studies revealed the presence of upper amphibolite to granulite facies rocks in the central portion of the Quetico belt bounded both to the North and South by amphibolite facies rocks.  Chemical analysis of the pelitic rocks revealed that their chemical composition was very homogeneous thus providing evidence that the appearance of certain minerals was not due to a change in chemical composition.  Cordierite, garnet and sillimanite assemblages predominate near the centre of the Quetico Gneiss Belt.  Since the chemical composition consistently is the same, the appearance of higher grade mineral assemblages is suggested to be a result of their deeper crustal origin.  The highest grade rocks of the central portion of the Keelor Lake Area are in close proximity to the area which exhibits highest magnetic values.