Geophysical studies of the Canadian Appalachian region have contributed primarily to an understanding of the structural features at depth through the application of gravity, magnetic, and seismic techniques supplemented to a lesser extent by geomagnetic depth sounding and magne- totelluric and heat flow studies. In addition, gravity and magnetic maps allow comparisons between geological and geophysical features of the region. These comparisons may be used to extend the geological features to regions of poor or no exposure, for example to the northern offshore and Gulf of St. Lawrence. Paleomagnetic results have gen- erated discussion regarding the relative horizontal dis- placements of large parts of the orogen. Offshore geophysical surveys provided the first evidence of the existence of the thick Tertiary and Mesozoic sedimentary sequence on the continental shelf and slope which are the target of extensive petroleum exploration and activity.
The geophysical data have been collected over the last 30 years but the most exciting interpretations are arising from the integration of the older data sets with the results from the new, deep, seismic reflection data. New aero- magnetic data are also adding immensely to our understanding of the nature of the crust in water-covered areas, particularly the critical area between Newfoundland and Nova Scotia where geophysics is the only method of tracing the geological features across the Cabot Strait. The inter- pretation of each data set as it was collected and published was undertaken in the context of contemporary geological models. Many such models are now obsolete. The present
Figures & Tables
This volume focuses on the highly populated Canadian Appalachian region. The chapter on the East Greenland Caledonides stands alone and there is no attempt to integrate the geological accounts of the two far removed regions. Rocks of the Canadian Appalachian region are described under four broad temporal divisions: lower Paleozoic and older, middle Paleozoic, upper Paleozoic, and Mesozoic. The rocks of these temporal divisions define geographic zones, belts, basins, and graben, respectively. The area is of special interest because so many modern concepts of mountain building are based on Appalachian rocks and structures.