3D Lithological Inversion of Geophysical Data

We have developed a deterministic method for directly inverting geophysical data to 3D lithological models. This method is based upon a lithology-based model transform of the model parameters and their sensitivities from their physical property basis to one of a lithology basis. This method is general, as it can be applied to both linear and nonlinear geophysical methods, and that the physical properties defining a lithology may have a statistical distribution. We demonstrate the method with a case study for the 3D inversion of airborne electromagnetic (AEM) data for bathymetry mapping in the Backstairs Passage in South Australia, where the 3D earth model is characterized as discrete lithologies of seawater, sediment, and basement. Our results are shown to be in very good agreement with LiDAR bathymetry from the same area.