3D prospectivity modelling of orogenic gold in the Marymia Inlier, Western Australia

The Proterozoic Marymia Inlier is known for orogenic gold deposits along granite-mafic rock contacts within major bounding thrust planes, including the producing Plutonic mine. A 3D prospectivity model was built based largely on surface geology extended into the subsurface using geophysical data, confirmed by drill data when available. Because of the complexities of taking 2D data into 3D and the length of time to test spatial associations in 3D, a 2D weights of evidence prospectivity model was initially created to constrain the 3D predictive maps integrated into the 3D prospectivity model. The final 3D model used a ranked fuzzy logic technique, with the ranking adjusted from the 2D weights of evidence model that was used to constrain the development of 3D predictive maps. The study shows that 3D prospectivity modelling can be used to identify targets at significant depth and establish depths for drilling them.