Hydrogeochemical interpretations of apparent anomalies in base metals and radium in groundwater near Lake Maurice in the Great Victoria Desert

Apparently anomalous levels of Cu, Pb, Zn (up to 6.1, 26.0 and 10.8 mg 1^-1 respectively) and Ra (2000 pg 1^-1) have been noted in groundwaters from 28 drill holes within a 20 km × 20 km zone centred about a 10 times background airborne radiometric anomaly near Lake Maurice in the Great Victoria Desert in South Australia. Within 6 km of the anomaly centre the water table depth is generally less than 10 m, increasing to approximately 30 m in the drill holes furthest from the anomaly centre. All waters are very acid (pH 3.6 to 5.8) and deficient in carbonate species (all <0.5 mg 1^-1) but saturated with respect to calcium sulphate minerals. XRD traces of drill hole cuttings show the presence of quartz and halite at every sample site, pyrite at 75% of sites, variable amounts of kaolinite and muscovite at all sites, and variable amounts of feldspar, jarosite, calcium sulphate minerals, hydrated iron oxides, siderite, chlorite and calcite at certain locations only. Salinity of waters is very high ranging from that approximating sea water (Ionic strength (I) = 0.93 and Cl^- = 19 g 1^-1) to approximately six times sea water salinity (I = 4.61 and Cl^- = 120 g 1^-1).