Murray Basin

This slab was subducted during latest Cretaceous and Early Cenozoic periods to the north of the Australian continent underneath New Guinea.

If this theory is correct, then the Murray basin will move south over the next tens of millions of years and disappear under the Southern Ocean.

[1] Modelling using the Underworld program by Moresi indicates that the slab would be sinking at 8.5 mm per year and cause a depression on the surface 200 m deep around 2500 km wide.

[7] The sea level rose again in Late Oligocene to mid Miocene, forming the Murray Group of sediments, with marl and limestone in the deeper locations, and the Geera Clay[8] in the shallow waters.

[12][13] When the sea level fell again in mid-Miocene, the deposited Geera clay and Olney Formation moved westward over the limestone.

Locally heavy minerals have been concentrated by wave action, including rutile zircon and ilmenite, forming economic mining opportunities.

The dam formed Lake Bungunnia, which reached 40,000 square kilometres (15,000 sq mi) and deposited the Blanchetown Clay therein.

The Pooraka Formation[20] formed in the north west due to increased erosion, resulting in colluvium depositing.