• Corpus ID: 208781575

The critical role of architecture in constraining fluid-flow and chemical gradients in Late Archean Gold Systems, eastern Yilgarn Craton

@inproceedings{Bath2019TheCR,
  title={The critical role of architecture in constraining fluid-flow and chemical gradients in Late Archean Gold Systems, eastern Yilgarn Craton},
  author={Adam Bath and John L. Walshe},
  year={2019}
}

• A. Bath, J. Walshe
• Published 2019
• Geology

Depositto camp-scale quantified mineral maps have been generated for numerous Archean gold systems within the Yilgarn Craton to delineate gold mineral systems. Zoning of minerals produced by hydrothermal alteration are traced using energydispersive x-ray spectral measurements from the scanning electron microscope (SEM; 1000s of samples), textural SEM phase maps, whole-rock multi-element geochemistry and trace elements of select mineral phases. We show that fluid pathways in Archean gold systems can be strongly controlled by the architecture (both structural and lithological). Impermeable or weakly permeable talc-rich ultramafic and thick coherent phenocryst-rich mafic volcanics occur in the hanging-wall of ore-zones. Footwall domains contain broad (>100m) alteration zones with minerals, such as anhydrite paragenetically linked to mineralisation. Footwall pyriteanhydrite domains transition into pyrrhotite-domains into mineralised zones, indicating chemical redox gradients. Other minerals (micas, chlorite, sulphides, amphibole, Tiphases and feldspars) also display complex spatial distributions that are controlled by fluid pathways as well as the precursor lithology. Textural relationships demonstrate syn-mineral stage alteration that extends significant distances from the main structures which host ore zones. These data reflect the chemical evolution of gold mineral systems, ultimately driven by changes in fluid chemistry, T and P.