Hyperspectral remote sensing study of the structurally-controlled Zn mineralization in the Flinders Ranges, South Australia

In this study, we investigate Zn mineralization in the Flinders Ranges, South Australia, using hyperspectral data from the Environmental Mapping and Analysis Program (EnMAP) satellite instrument to explore the spatial relationships between ore zones, hydrothermal alteration zones, and fault systems. Zinc mineralization in this area is hosted in Lower Cambrian lithologies and contains significant willemite, fraipontite, and Zn-phosphates, associated with extensive hematite- and dolomite-bearing hydrothermal alteration. Alteration mineral maps, showing relative abundance and compositional variations, were generated by applying a multiple-feature extraction methodology based on polynomial fitting and band ratios. Ground-truthing was conducted through laboratory spectroscopy and mineralogical-petrographic methods. This approach enabled the mapping of Fe oxy-hydroxides (i.e., hematite and goethite), carbonate minerals (i.e., dolomite and calcite), and dioctahedral phyllosilicates (i.e., white micas and kaolinite). It also successfully identified and mapped the ore mineral fraipontite based on its absorption feature at ~ 2260 nm. Multivariate statistical analysis and machine learning of the EnMAP imagery highlighted the co-occurrence of hematite, dolomite, and fraipontite in mineralized zones, making this assemblage a potential indicator for regional exploration of similar deposits. The study also revealed the controlling effects of fault structures on mineralization and the associated alteration haloes, with mineralized zones confined to fault-bounded rock volumes, predominantly located at intersections between interacting faults or in the proximity of lateral fault terminations. Overall, this work provides new insights into the spectral behavior of Zn-bearing minerals and demonstrates the effectiveness of hyperspectral sensing for characterizing oxidized Zn mineralization during regional prospecting programs.