Poster Presentation NCGRT/IAH Australasian Groundwater Conference 2019

Toward a new paradigm for the Great Artesian Basin: hydrologic mixing, multi-scale flow systems, fault-partitioned sub-basins, and mantle influences on groundwater quality (475)

Andrew J. Love 1 , Stacey C. Priestley 2 , Daniel Wohling 3 , Mark Keppel 4 , Pauline Rousseau-Gueutin 5 , Tim Ransley 6 , Karl Karlstrom 7 , Laura Crossey 7 , Paul Shand 1
  1. College of Science and Engineering & National Centre for Groundwater Research and Training, Flinders University, Bedford Park, SA, Australia
  2. Australian Nuclear Science and Technology Organisation, Sydney, NSW, Australia
  3. Innovative Groundwater Solutions, Adelaide, SA, Australia
  4. Science and Innovation Group, Department of Environment and Water, Adelaide, SA, Australia
  5. EHESP, Rennes, France
  6. Geoscience Australia, Canberra , ACT, Australia
  7. Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico, USA

The Great Artesian Basin (GAB) underlies 22% of the Australian continent and is one of the largest groundwater basins in the world. Of great national and societal significance for Australia, the GAB is also an iconic example of a continental-scale artesian groundwater system and of international scientific importance as sustainable groundwater management is emerging as one of the great global scientific challenges of the new millennium. Existing models involve recharge in Eastern Australia, relatively simple regional flow paths, and discharge in springs and bores in the western GAB. New geochemical and hydrologic data suggest this model needs modifications: 1) Hydrochemical data indicate that the dominant discharge springs (Dalhousie and SA mound springs) are hydrochemically distinct from each other and from evolved recharge waters requiring multiple scales of flow systems. 2) 3He/4He data from mound springs (Ra up to 0.1 and CO2/3He= 9 x10-9) in the western GAB indicate mantle inputs of fluid up deep-seated faults. 3) 87Sr/86Sr of 0.73-0.76 indicate crustal contributions along the flow path. New understandings of the Great Artesian Basin will require holistic models that merge these hydrologic, geochemical, and tectonic perspectives.