GAB | Hydrogeological implications of active tectonics in the Great Artesian Basin

• Mike Sandiford
• Ken Lawrie
• Ross Brodie

Derangement of surface drainage systems across central and eastern Australia testify to subtle tectonic modification of the landscape on the million-year timescale that is relevant to groundwater residence in the Great Artesian Basin (GAB). In the central part of the overlying Lake Eyre Basin, spatial variations in drainage channel form, and lateral offsets in drainage channels, reflect an active north to northwest-trending fault system that correlates with a distinct potentiometric anomaly in the deeper GAB aquifers. There are correlations in both the distribution of seismic activity and drainage form with changes in lithospheric thickness. This suggests that active faulting reflects, in part, stress sourced from sublithospheric mantle flow beneath the GAB. These observations have implications for hydrogeological interpretations and the understanding of groundwater processes, while also providing constraints on water balance studies and studies on the distribution of pressure within GAB aquifers.