Original paper

Origin and age of the Mantung High Plain, a karst surface in the western Murray Basin of South Australia

Twidale, C.R.

Abstract

The Mantung High Plain of the western Murray Basin is a karstic surface of low relief developed on the Early Miocene Mannum Limestone. Dissected by the River Murray in its Gorge section it is exposed for some tens of kilometres on either side of the River Murray and to the east persists in unconformity beneath a thin sedimentary cover. The Plain is attributed to corrosion planation, i.e. dissolution and collapse down to the Pliocene water table associated first with the ancestral allogenic and exoreic River Murray that then flowed in shallow valley graded to a relatively high regional baselevel, and in later Pliocene times to the estuary that inundated the valley. During the Quaternary the Plain was left high and dry (and converted to the High Plain) by the incision of the Murray and becoming graded to lower baselevels and water tables. Conservation was enhanced by the widespread formation of a calcrete duricrust.

Keywords

karstebenemantung high plainriver murray