Deep seismic sounding in southern Manitoba and Saskatchewan

Abstract

A CO-CRUST seismic refraction survey was done in July 1977 in southern Manitoba and Saskatchewan to determine the structure of the Churchill-Superior boundary. Data from two reversed refraction profiles, one north/south in the Superior Province and one east/west across the boundary of the Superior and Churchill Provinces were obtained. Preliminary interpretation of the data by Green et al. (1980) suggested that the crust beneath the north/south profile is similar to previously published crustal models for the Superior Province, while that of the east/west is typical of Churchillian crust of eastern Alberta and Saskatchewan. In this thesis, with the aid of such data processing and interpretation methods as bandpass and polarisation filtering. Herglotz inversion, ray tracing and WKBJ synthetic seismograph modelling, a detailed analysis and interpretation of the data was performed. The results indicate that for the north-south profile, the crust is divided into four laterally homogeneous layers, with velocity gradients both within and between layers. The crust under the east-west profile contains fault structures, layers of decreasing velocity and lateral velocity changes. From this study, the boundary is a region of finite lateral extent, marked by upper crustal discontinuities and lower crustal velocity changes.