Thermal anomaly and water origin in Weebubbie Cave, Nullarbor Karst Plain, Australia

The Nullarbor is one of the largest contiguous karst plains in world. Despite absence surface relict features and arid climate, subterranean flooded cave systems are among waters usually brackish their temperatures vary over a large range (18.6–23.7 °C) suggesting potential input warm groundwater to some caves. studied Weebubbie Cave total length ∼500 m penetrates ∼140 below ground ∼40 sea level. Temperature loggers were deployed water at various depths distances from entry lake detect inputs three different years. stable hydrogen, oxygen, carbon isotope compositions have been analysed hydrochemical differences inflowing investigate origin water. thermal irregularity Air Dome with 0.9 °C higher than all other sections, confirms heat transfer or an inflow warmer results suggest originates partially evaporated (up <20 %) modern infrequent precipitation events. relatively high salinity (23.3 mS cm−1) water, hydrochemistry composition that direct ocean contribution unlikely.