Surficial uranium mineral systems in Western Australia: Geologically-permissive tracts and undiscovered endowment

Abstract

This contribution describes a novel, integrated approach to prospectivity analysis and quantitative resource assessment of surficial uranium deposits in Western Australia that may serve as a universal, best practice template for the estimation and the planning and managing of undiscovered uranium resources elsewhere. The key objectives of and principal steps taken in this study were: (I) development of a process-based, mineral systems-type targeting model for surficial uranium deposits; (2) delineation of areas where the geology is permissive for the existence of surficial uranium deposits (i.e., geologically­permissive tracts) using mineral prospectivity analysis and employing a combination of knowledge-driven fuzzy inference systems (FIS) and data-driven weights-of-evidence and artificial neural networks; and (3) estimation of the number of undiscovered surficial uranium deposits and total amount of undiscovered uranium endowment utilizing regression models of deposit density and endowment density, the USGS three-part assessment and Zipfs Law analysis. The approach described in this contribution is a world first in that it is the first published quantitative mineral resource assessment employing three different methods and building upon the results of a systematic, multi-pronged knowledge- and data-driven prospectivity analyses. The results of these analyses indicate that the study area (the -1,700,000 km2 deserts and xeric shrublands region of Western Australia) contains a total undiscovered endowment (i.e., speculative resources) of >180,000 t U, contained in identified and up to 145 additional, undiscovered deposits. Based on the prospectivity analysis, undiscovered surficial uranium deposits are most likely to be found within geologically-permissive tracts in the remote, commonly sand dune-covered northern and eastern parts of the study area, which to date have recorded little, if any, uranium exploration.