Crater floor topography and impact melt sheet geometry of the Sudbury impact structure, Canada

Based on high-resolution topography data and the geometry of geological contact traces at the surface, we determined the orientation of layer interfaces of the Sudbury Igneous Complex (SIC). Our analysis provides, for the first time, quantitative structural evidence for the thickness variation of its layers, which supports an impact melt origin of the SIC. The present crater floor topography varies up to 400 m over distances of hundreds of metres to a few kilometres, and up to 1500 m over a distance of about 25 km. Crater floor depressions are spatially associated with economically important sulphide mineral deposits, which points to a viable exploration strategy. Finally, observed variations in the width of the thermal aureole imparted by the SIC on its host rocks are due to primary thickness variations of the SIC rather than post-impact deformation.