CHARACTERIZATION OF THE BENNY DEFORMATION ZONE, SUDBURY, ONTARIO

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 combinatio n of airborne magnetic data and synthetic aperture radar images, at bo th a regional and a detailed scale, have been used to identify a wrenc h-fault system on the Canadian Shield north of the Sudbury structure. The 3-4 km wide deformation zone comprises a set of subparallel vertic al faults bounding blocks of Archean granites, Archean metavolcanics o f the Benny greenstone bell, and Paleoproterozoic melasediments of the Huronian supergroup. Using high-resolution airborne radar and magneti c data, the Fault zone is found to extend for 40 km along the southern margin of the Benny greenstone bell. The wrench-fault system may have been tectonically active during several episodes throughout the Prote rozoic. An interpretation of these data, supported by additional field mapping, indicates that the 1240 Ma Sudbury dyke swarm has been intru ded through the deformation zone after its most active period of movem ent. Overprinting of Sudbury impact breccia at the southern edge of th e deformation zone suggests that same movement occurred on the faults postdating the 1850 Ma meteorite impact, Lineaments that correlate spa tially with the wrench-fault system can be traced across the southern Superior Province and the Cobalt Embayment on the regional Images. How ever, more high-resolution studies are required to establish the same overprinting relationships along the length of the lineaments.