About This Item
Share This Item
This study focused on the use of (1) regional structural analysis of basement and Precambrian rocks surrounding a sedimentary basin, and (2) tracing basement structures into the sedimentary basin.
A large-scale regional study (supported by the Geological Survey of Canada) was carried out in Ontario and parts of Manitoba and Quebec using Landsat imagery analysis as a geologic mapping tool.
One hundred Landsat images at a scale of 1:500,000 covering the greater parts of the Archean Superior-Proterozoic, Churchill, Grenville, and Keeweenawan plates and the Paleozoic Hudson's Bay and Williston platforms were analyzed for geologic structure and lithology with the following techniques: (1) Detailed lineament mapping using visual analysis of multiseasonal and multispectral imagery. In particular, low sun illumination and light snow covered scenes permit delineation of subtle structures in heavy forest cover, and burned and glaciated terrains. (2) Using published geologic maps as a base, the integration and correlation of the lineament data with aeromagnetic and gravity trends.
Within the complexly deformed and reworked Precambrian shield, such analysis permits reconstruction of the outcrop pattern and delineation of major fold, fault, dyke, and other intrusive structures.
The structural analysis of the Precambrian shield has a fundamental bearing on interpretation of overlying sedimentary cover rocks. This is expressed in the southern part of the Hudson's Bay basin and its southeastern arm, the Moose River basin. For instance, the rims of both basins are controlled by faults or graben structures. Approximately 13 major fault systems with strike lengths of 200-300 km (125-186 mi) or more can be traced from the exposed Precambrian shield into the basin in terms of lineament arrays and/or aeromagnetic and/or gravity signature. The data suggest reactivation of faults during basin sedimentation.
This type of basement structural analysis in areas adjacent to sedimentary basins can provide a valuable interpretation base for subsequent seismic surveys and basin evaluation.
End_of_Article - Last_Page 535------------