Beetaloo Sub-basin cores and cuttings isotope data

Abstract

This dataset contains the chemical and strontium isotope data of a selection of cores and cuttings from the Beetaloo Sub-basin, which were assessed from the core library of the Northern Territory Geological Survey. A total of 5 bores (Amungee NW-1, Beetaloo W1, BH 1, 12BC001, 12LE001) were sampled for either cuttings or parts of the core. The data showed that the aquifer variability for strontium isotopes is much higher than the groundwater variability (as expected) but also that waters in the CLA have a strontium isotope range that differs from the one of the aquifer rock. Furthermore the analyses allowed estimating the in-situ production of helium from radioactive decay of U and Th in the host rock and demonstrated that the high helium concentrations found in groundwater could not be produced within the aquifer itself but are due to fluid admixture from other (likely deeper) formations.

Attribution

Geological and Bioregional Assessment Program

History

These were analysed at the CSIRO Analytical Support Unit at Waite Campus for their elemental content by cation and Sr isotope analysis after digestion with Aqua Regia – for carbonate samples – or HF digestion – for samples with higher silicate contents such as basalts and sandstones below the CLA. Further elemental analysis, especially uranium and thorium analysis was performed using XRF analysis at CSIRO Mineral Resources.