Seismic images and three-dimensional architecture of a Proterozoic shear zone in the Sudbury Structure (Superior Province, Canada)

A broad zone of intense ductile to brittle deformation transects the Paleo- Proterozoic Sudbury Igneous Complex and likely formed during the final stag es of the Penokean orogeny on the southern margin of the Superior Province. Herein we present a three-dimensional image of this deformation zone, deri ved from four seismic reflection profiles. Additional information from rock property measurements, drill results, and published structural mapping sug gests that the seismic data define the three-dimensional disposition of lis tric shear zones. The seismic image of the deformation is best developed wi thin the Onaping Formation. However, the images of the deformation zone env elope are imperfect, being most clear where truncating known contacts withi n the Sudbury Igneous Complex and its contact with Huronian host rocks. The southern edge of the seismically imaged shear zones does not extend signif icantly beyond the exposed Sudbury Igneous Complex, suggesting limits to th e extent of deformation in the Sudbury Structure.