Using regolith and spinifex chemistry to detect fault-controlled fluids in the Ngururrpa area of northeastern Western Australia, with implications for Pb-Zn mineralization

Regolith and vegetation (spinifex) chemistry from transects across the Stansmore Fault in the Ngururrpa area of northeastern Western Australia have been used to detect the presence of fault-controlled fluid, and whether the fluid has been in contact with concealed mineralization. On one transect, the fine fraction of the regolith on the fault trace has elevated concentrations of low field strength elements (LFSE), rare earth elements (REE) and some chalcophile elements (Zn and Tl). On the second transect, which is more structurally complex, elevated LFSE, REE and Zn concentrations are coincident with the position of one fault and indicate the location of a second. Both fault traces are indicated by spinifex REE, B, Zn, REE and high field strength element (HFSE) chemistry, and are independently verified by passive seismic data. The wide range in the ionic potentials of elements on or close to fault traces indicates a high fluid flux, whereas high Zn, Tl, Re, Cd, and B concentrations are indicative of sediment-hosted Pb-Zn mineralization. Basin-bounding faults, such as the Stansmore Fault, are spatially related to Mississippi Valley Type (MVT) mineralization elsewhere in the Canning Basin, and rocks hosting sedimentary exhalative (SEDEX)-style mineralization in the adjacent west Arunta Orogen have been reported from the southeastern part of the Ngururrpa area.