Abstract

Remote sensing imagery and geophysical data are well known as valuable tools for reconnaissance mapping in unknown areas, but they can also be used to reinterpret existing regional geological maps. A combination of airborne magnetic data and synthetic aperture radar images, at both a regional and a detailed scale, have been used to identify a wrench-fault system on the Canadian Shield north of the Sudbury structure. The 3–4 km wide deformation zone comprises a set of subparallel vertical faults bounding blocks of Archean granites, Archean metavolcanics of the Benny greenstone belt, and Paleoproterozoic metasediments of the Huronian supergroup. Using high-resolution airborne radar and magnetic data, the fault zone is found to extend for 40 km along the southern margin of the Benny greenstone belt. The wrench-fault system may have been tectonically active during several episodes throughout the Proterozoic. An interpretation of these data, supported by additional field mapping, indicates that the 1240 Ma Sudbury dyke swarm has been intruded through the deformation zone after its most active period of movement. Overprinting of Sudbary impact breccia at the southern edge of the deformation zone suggests that some movement occurred on the faults postdating the 1850 Ma meteorite impact. Lineaments that correlate spatially with the wrench-fault system can be traced across the southern Superior Province and the Cobalt Embayment on the regional images. However, more high-resolution studies are required to establish the same overprinting relationships along the length of the lineaments.

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