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Murray Basin
The Murray Basin is a Cenozoic sedimentary basin in south eastern Australia. The basin is only shallow, but extends into New South Wales, Victoria and South Australia. It takes its name from the Murray River which traverses the Basin from east to west.
==Formation==
One theory for the formation of the basin is that it is dynamic topography due to a sinking slab of oceanic crust. This slab was subducted during latest Cretaceous and Early Cenozoic periods to the north of the Australian continent underneath New Guinea. The slab broke off and was gradually overridden by the Australian plate moving north. The sinking slab has a trace in the P-wave velocity in the mantle which is higher from 800 to 1200 km deep below the Murray basin, and also the Lake Eyre Basin. The velocity anomaly is oriented northwest-southeast and extends from 135°E 26°S to 144°E35°S. The sinking has dragged down the rock above it to make a hollow which is the basin. This hollow has moved south over the last 50 million years. 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. 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. In the past the basin depression was narrower but deeper in this model.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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