National Geochemical Survey of Australia: A Continental-Scale Pb Isotope Map of the Australian Regolith - Additional Dataset

The element Pb (lead) is a particularly useful tracer as it is both a toxin of environmental concern and often associated with mineralisation. Isotopic analyses as opposed to simple Pb concentration data provide an important advantage as they can allow discrimination between different sources of Pb. Lead isotope analyses have been conducted on catchment outlet sediment (similar to floodplain) samples obtained from Geoscience Australia’s National Geochemical Survey of Australia (NGSA; http://www.ga.gov.au/ngsa) regolith archive. The selected samples were Top Outlet Sediments (TOS) taken from 0 to 10 cm depth and sieved to <2 mm. Analyses were performed by Candan Desem as part of her PhD research at the University of Melbourne using a Nu Instruments Attom Sector Field-Inductively Coupled Plasma-Mass Spectrometer (SF-ICP-MS). Analyses were undertaken on sequentially extracted samples, first after an ammonium acetate (AmAc) leach and then after a subsequent aqua regia (AR) digestion on all samples from the Northern Territory and those within the Exploring for the Future (EFTF) focus area into western Queensland. For the remaining States of Australia, only the samples obtained after the AR digestion step were presented to the SF-ICP-MS (the dried AmAc leachates were preserved for future analyses). These data allow the construction of the first continental-scale Pb isotope regolith map of Australia and can be used to understand contributions of Pb from underlying bedrock (including Pb-rich mineralisation), wind-blown dust and possibly from anthropogenic sources (industrial, transport, agriculture, residential, waste handling).