Interpretation of helicopter AEM data from the Riverland area, S.A.

Abstract

RESOLVE frequency domain helicopter electromagnetic (HEM) data have been used to map the distribution of near-surface clay-rich sediments in and around the Riverland irrigation districts of South Australia. The results of the inversion also allow us to reconstruct the strandline-dominated palaeo-topography left when the sea retreated from the Murray Basin in the Early-Mid Pliocene. The survey also revealed a hitherto unsuspected, deeper variability in conductivity following the Pliocene strand line pattern. The cause of this pattern is not clear, but could be due to variations in the porosity of Loxton Sands or to strandline-correlated variability in the elevation of the contact between the Bookpurnong Beds and the Lower Loxton sands.