Seismic refraction inversion of a palaeochannel system in the Lachlan Fold Belt, Central New South Wales

Abstract

We assess a method for conducting seismic refraction inversion in a 3-D setting to image the shape and structure of a palaeochannel. The trial survey was conducted over a suspected Tertiary palaeochannel adjacent to the Wyalong goldfields (Lachlan Fold Belt) in central NSW. This work has implications for the control of groundwater migration and dryland salinity studies. The method was conducted using standard multichannel seismic recording equipment and an unconventional 3-D field geometry. Three-dimensional velocity-depth models show a 4-layer sub-horizontal system underlain by high-velocity metasedimentitic basement at a variable depth, ranging from 70 to 170 m. The interpreted palaeochannel is coincident with high magnetic intensity features identified from recent surveys of the region.