Defining regolith and beyond from regional seismic reflection data: A case study from the Tanami

Abstract

Regional seismic reflection data in hard rock areas contains more shallow information than might first be supposed. Here I use a subset of the 2005 Tanami Seismic Survey data to show that near surface features can be defined, including paleochannels, Palaeozoic basins and structures within the Proterozoic basement. Successful imaging depends on correct determination of refraction statics, including identification of refractor branches, and use of a floating or intermediate datum during seismic reflection processing. Recognition of steep stacking velocity gradients associated with surface referenced processing aids velocity analysis and can further delineate areas of thicker regolith in palaeochannels. The first arrival refraction analysis can also be applied in more detail to estimating thickness of regolith and depth to economic basement in areas of sedimentary cover.