Integration of Discrete Geomechanical Models into Prospectivity Analysis: Targeting IOCG Systems in NW Queensland, Australia

This contribution reviews some aspects of the Mount Isa Inlier considered important in forming IOCG-style (Iron Oxide Copper Gold) economic mineralisation. We also define a conceptual model based on this knowledge, a standard approach implemented in mineral prospectivity analysis. This phase is preliminary to the selection of suitable geological predictors used to target IOCG-style mineralisation. A weighted overlay, GIS method based on the Bayes' rule of combination was used in a second phase to generate a preliminary mineral prospectivity model of the Mount Isa Inlier. A GIS database was assembled producing 38 indicator maps based on 80 IOCG occurrences by using the Contrast analysis method (an initial stage of the Weights of Evidence analysis). In addition to conventional datasets (e.g. lithostratigraphy, fault distribution data, regional scale geophysical and geochemical surveys etc.), the prospectivity model incorporates discrete element, models for three sub-domains of the Mount Isa Inlier, interpreted as prospective for IOCG deposits. Contrast analysis confirms that prospective areas are localised along NE to NS crustal scale, structural corridors. Known occurrences are proximal to mafic intrusions and cluster along the Corella-Soldier Cap group boundary. Cu-Au mineralisation occurs in a wide range of differential stresses and fluid pressures required for failure (PFf) although failure in tension appears to be the dominant process.