Roman Tykajlo HBSc thesis abstract

Thesis Title: 
Analysis of Strain, Shape, and Orientation of a Deformed Greywacke and Conglomerate from the Shabaqua Corners Area, Ontario

The study area is located approximately 55 km west of the city of Thunder Bay, at the intersection of Highwasy 11 and 17.

Two outcrops were studied; one being a coarse lithic greywacke and the other a polymict conglomerate, both of Archean age.

Rf/φ analysis was used to determine the shape and orientation of five strain ellipsoids from oriented samples of greywacke, and one strain ellipsoid from the conglomerate.  An averaged strain ellipsoid was calculated using averaged strain components.

Analysis showed that original pebbles had cross-sections ranging from circular (Ro = 1.0) to elliptical (Ro = 6.0).  The strain ellipsoid is a flattened type ellipsoid with k = 0.19, and the XtYt plane lying parallel to the plane of bedding in the greywackes.

The close approximation of the averaged strain ellipsoid to a uniaxial pancake type ellipsoid allows discussion to be simplified to the XtZt plane (ie. the maximum strain ellipse) of the strain ellipsoid.  The plane of the maximum strain ellipse lies perpendicular to the plane of bedding and defines a maximum shear strain of 4.5, a maximum angular shear of 77° with 80% shortening in the Zt direction versus 83% lengthening in the Xt direction.

A simple model involving progressive deformation of an infinity long bed is proposed to explain the shape and orientation of the strain ellipsoid, as well as the closely spaced opposing facing directions which occur in the study area.