A structural interpretation of the Russick Lake area, Manitoba

Abstract

This thesis is an attempt to interpret the rock structures in the vicinity of Russick Lake, northern Manitoba. Deformation is thought to be the result of plastic flow. Statistical structural plots of foliation data show single strong maxima that suggest isoclinal folds. These folds are tightly compressed, their axial planes dip north-east at approximately 30o, and their axes plunge 10o to 20o north to north-east. The pattern of folds presented by a foliation trend map suggests flow movement and flow folding. Field evidence of movement in the gneisses and ptygmatically-folded pegmatitic stringers support this concept of folding. The high grade of regional metamorphism presents indirect evidence of high temperatures and pressures which would favor deformation by plastic flow. Accompanying the structural interpretation is a brief, general description of the rock units and their relationship to one another. The Sherridon gneiss group is interpreted to be younger than the Nokomis gneiss group; this interpretation supports the work of D. S. Robertson (1953). The study of a granite body north of Russick Lake established the existence of three zones. These zones were identified on the basis of differences in structure, texture and composition.