Reflection seismic imaging across a greenstone belt, Abitibi (Ontario), Canada

Established 2D seismic data processing methods such as Kirchhoff pre-stack time migration and Kirchhoff pre-stack depth migration function relatively well for regular acquisition geometries and well-constrained velocity models. Recently developed focusing pre-stack depth migration methods have the potential to enhance image quality in the case of sparse and non-regular source-receiver distribution. We have tested the performance of the coherency migration method as one of these focusing migration approaches in comparison to standard dip-moveout and Kirchhoff pre-stack time migration techniques by applying them to the Swayze East seismic profile acquired in the Abitibi greenstone belt of Canada. This seismic profile represents a crooked-line survey that intersects several metal-bearing deformation zones, providing good target geometries to examine various pre-stack migration methods. Analysis of the seismic data indicates reflectivity associated with shallowly dipping reflections appears relatively well preserved over the entire 0-6 km offset range for the frequency range between 20 to 90 Hz. Although most reflections are visible already in either the dip-moveout or the Kirchhoff pre-stack time migration results, the coherency migration method delivers the most improved image showing all reflective structures inferred for this area. The comparisons suggest the coherency migration method can be considered as superior in terms of resulting seismic image quality compared with conventional approaches for this type of crooked-line seismic survey in such a complex geological setting.