Mineralization-alteration footprints in the Olympic Dam IOCG district, South Australia: The Acropolis prospect

摘要: Abstract The Acropolis prospect, 20 km southwest from the Olympic Dam Cu-U-Au-Ag deposit, South Australia, is a vein-style magnetite (±apatite ±hematite) system. A whole-rock dataset comprising 4864 core samples 14 drillholes was analysed using multivariate statistical analyses to understand and identify geochemical signatures of mineralization, as well expressions extents hydrothermal alteration. Statistical analysis included unsupervised (principal component analysis, hierarchical k-means clustering) supervised (random forests) machine learning algorithms. geology prospect presented 3D geological model complemented by cross-sections. results are overlaid interpreted relative model, encompass projection sodic propylitic alteration PC3, mineralization signature PC1. Although footprint partially overlaps with Hiltaba Suite granite, it not centred on granite body. distinct ‘magnetite’ Fe-V-Ni-Co developed in southwestern part represents containing >60 wt% Fe. In contrast, ‘hematite’ displays an association REE, W, Sn, Sb, U, Th, Ca P, present throughout exception drillhole ACD5, which non-mineralized. Interpolated values Cu (> 200 ppm) indicate offset Fe-rich veins, thus supporting genetic Cu-bearing overprints Cu-Au-deficient magnetite-dominant veins. obtained provide insights into evolution hematite-dominant IOCG systems may proxy for exploration shallow economically significant deposits eastern Gawler Craton.