The effectiveness of Transient Electromagnetics and Ground Penetrating Radar for investigating regolith

Abstract

Regolith can be mapped at the surface using a variety of landform mapping methods. Subsurface regolith structures can be investigated by excavating costeans through the profile, but non-invasive geophysical methods, such as Ground Penetrating Radar (GPR) and shallow focussed Transient Electromagnetics (TEM), are much less destructive techniques that can be used to provide information on the physical properties of the subsurface. GPR offers exceptional resolution imagery of the subsurface, and TEM can be used to produce exceptional resistivity sections of the top several tens of metres. White Dam, Curnamona province, is a gold and copper prospect and is home to a regolith case study. The two geophysical methods were used here to investigate how well each performs in such an environment, and results were compared with the regolith landform map. Paleochannels in the Girilambone-Cobar area, New South Wales, were investigated using transient EM. Sets of non-magnetic and magnetic channels were selected, and TEM was undertaken in a single transect over each set, coincident with lines of drill holes. Both transects were approximately 2km in length, and passed 2 or 3 drill holes, allowing direct comparison of TEM resistivity plots with drill derived cross sections.