Mount Toondina, Australia

Located on the Great Artesian Basin (GAB), South Australia, the Mount Toondina is an impact structure previously thought as a salt diapere. The crater shows a concentric series of uplifted deformed Palaeozoic and Mesozoic rocks capped by flat-lying Cainozoic deposits. The rocks at the centre of the uplift are highly deformed Mt. Toondina Formation (Permian) surrounded by a ring of less deformed Algebuckina Sandstone (Jurassic), and Cretaceous Cadna-owie Formation and Bulldog Shale. Its circular topographic feature rises out of this otherwise relatively flat desert area, and Mount Toondina represents the central uplift, clearly visible in the radar image, which is the only exposed part of the crater. Gravity and seismic data indicate a disturbed zone from 3 to 4 km wide with a deformation extending to a depth of approximately 1 km.