Robert Nicholas Spark MSc thesis abstract

The Quetico metasedimentary subprovince and the volcanic-plutonic Shebandowan belt to the south meet along an east-west steeply dipping boundary that is believed to have been affected by dextral transpressional deformation.   It is also parallel to a steep metamorphic gradient from greenschist facies rocks to the north.

Macroscopic petrofabrics are difficult to observe along the belt to the west of Thunder Bay but magnetic susceptibility fabrics (low-field) are quite consistent.  These define a gently plunging extensional fabric parallel to the belt boundary.  Within the Kashabowie area, general field observations of subhorizontal stretching (and intersection) lineations, and cleavage directions are in agreement with magnetic susceptibility axis directions.  Mineral separation reveals that all samples have multiple sources of magnetic susceptibility, dominated by metamorphic phyllosilicates.  Consequently it is not possible to simply quantitatively relate the magnetic fabrics to strain magnitudes although the magnetic fabrics accurately monitor significant kinematic directions.  Analyses of strain of low-grade detrital quartz grains, magnetic fabrics and general field observations recognize flattened oblate fabrics.  Moreover oblique, subhorizontal lineations favour a transpressive kinematic model with compression normal to the belt boundary.  The obliquity between mineral and magnetic lineations seem to indicate dextral transpressive deformation.

A copy of the thesis can be downloaded here