Origins of Helium and Hydrogen in South Australia

Releasing only heat and water vapour when burnt, demand for hydrogen (H₂) is expected to increase eight-fold by 2050, driven by growth sectors such as transportation and industrial energy. Natural or gold H₂ is produced in the lithosphere via water radiolysis in U- and Th-rich Precambrian basement (alongside helium (He)) or serpentinization in mafic-ultramafic rocks. Gas occurrences in South Australia have anomalously high H₂ concentrations of up to 95%. It is, therefore, an excellent geographical focus to further understand the principles of H₂ exploration (source, migration, accumulation, and preservation).
This study reports noble gas isotopes (He to Xe) of gases dissolved in groundwater samples collected from 19 locations across the Yorke Peninsula and Adelaide Superbasin, along with their respective ages from radiocarbon dating. Using helium as a proxy, we provide insights into the source and migration of H₂ in South Australia. Through the use of a novel gas diffusion model (Cheng et al. 2023), we also investigate whether an H₂/He gas phase can be produced, critical for their concentration and formation as accessible resources.