Geological modelling from field data and geological knowledge: Part II. Modelling validation using gravity and magnetic data inversion

The analysis of multiple data sets is required to select a realistic 3D geological model among an infinite number of possibilities. An inverse method that aims at describing the 3D geometry of geological objects is presented. The method takes into account the geology and the physical properties of rocks, while respecting the topological properties of an a priori model. The a priori model is built from the geological data set and its geometry is largely dependent upon assumptions about inaccessible geology at depth. This method, referred to as “total litho-inversion” is a generalised 3D inversion that results in quantifying the lithology and the distribution of rock property in a probabilistic way. Its application is demonstrated through (i) a simple synthetic case and (ii) the relative distribution characterization of granites and diorites in an orogenic domain.