Beetaloo Sub-basin cores and cuttings isotope data

\n## **Abstract** \nThis 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.\n\n\n## **Attribution** \nGeological and Bioregional Assessment Program\n\n\n## **History** \nThese 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.

## **摘要**
本数据集涵盖采自比塔罗次盆地（Beetaloo Sub-basin）的部分岩心与岩屑样品的化学及锶同位素（strontium isotope）数据，所有样品均由北领地地质调查局（Northern Territory Geological Survey）的岩心库中选取并完成评估。本次共对5个勘探钻孔（Amungee NW-1、Beetaloo W1、BH 1、12BC001、12LE001）的岩屑或部分岩心进行了采样。分析结果显示，含水层的锶同位素变异性远高于地下水的锶同位素变异性（符合预期），同时CLA内水体的锶同位素范围与含水层围岩的锶同位素范围存在显著差异。此外，本次分析还实现了对宿主岩石中铀（Uranium, U）与钍（Thorium, Th）放射性衰变产生的氦气原位生成量的估算，并证实地下水中的高氦浓度并非在含水层内部生成，而是源于其他（大概率为更深部）地层的流体混合作用。

## **数据归属**
地质与生物区域评估计划（Geological and Bioregional Assessment Program）

## **分析历程**
本次样品的元素含量与锶同位素分析由澳大利亚联邦科学与工业研究组织（Commonwealth Scientific and Industrial Research Organisation, 简称CSIRO）韦特校区分析支持单元完成：针对碳酸盐样品采用王水（Aqua Regia）消解，针对硅酸盐含量较高的样品（如CLA之下的玄武岩与砂岩）则采用氢氟酸（Hydrofluoric Acid, 简称HF）消解，随后通过阳离子分析与锶同位素分析完成检测。额外的元素分析（尤其铀与钍元素分析）则由CSIRO矿产资源部采用X射线荧光光谱法（X-ray Fluorescence, 简称XRF）完成。