Artesian springs of the Great Artesian Basin, Australia, are the natural outlets of the artesian groundwater, and are predominantly found near the Basin’s southern, south-western, western and northern marginal discharge areas. Artesian springs also occur near the eastern recharge areas. Artesian springs played an important role in the discovery of the Basin’s artesian groundwater and the first flowing artesian waterbores were dug and drilled near springs. The largest concentration of springs and their sedimentary deposits, mainly tufa carbonates, forming conical mounds and platforms, occur near the south-western margins. The Basin is a multi-layered confined aquifer system, with aquifers in Jurassic and Cretaceous continental sandstones and intervening confining beds of siltstone and mudstone of the constituent Eromanga, Surat and Carpentaria sedimentary basins.
The Basin underlies semi-arid and arid regions across 1.7 million km2, or one-fifth of Australia. Hydrogeological and hydrochemistry studies show that most artesian springs and waterbores derive their water from the main (tapped) Jurassic-Lower Cretaceous Cadna-owie-Hooray Sandstone aquifer and its equivalents. Age dating by isotope hydrology studies of the artesian groundwater in the Basin determined ages of up to 1 to 2 million years. Drilling of the spring carbonate deposits revealed thicknesses of up to 30 m. Several age dating studies, including thermoluminescence and uranium series dating of the carbonate mound shaped spring deposits southwest of Lake Eyre, show ages up to 740 000 ± 120 000 years. Spring deposits appear to show a range of episodic ages, and could indicate a relationship with wet periods in the recharge areas of the Basin.