Colloque

Discussion on the origin of foliation and schistosity in the Portneuf gneisses

Stephen Melheresik

Membre a labase

Stephen Melheresik

Résumé du colloque

The discussion concerns a study of the origin of foliation and schistosity in the regionally metamorphosed rocks of the Portneuf area. The structures inherent in the gneisses are dealt with and their relationships are compared to similar structures found in metamorphosed rocks of a more certain origin. Recent views upon this subject are dealt with and the theories, insofar as applicable, are used to explain the phenomenon of segregation of like minerals into bands and lenticles. It is concluded that the gneisses are of several origins and it is pointed out that in the high grade zone, in which the effects of temperature predominate over stress, the foliation is the result of original heterogeneity of the parent rock.