Late Cainozoic environmental evolution of the western Murray Basin ? evidence from the sedimentary record

Abstract

A model for the environmental and climatic evolution of the western Murray Basin during the Late Cainozoic can be determined from analysis of the sedimentary record. Stratigraphic measurements of cliff-sections along the Murray River gorge tract suggest a complex interaction between coastal and estuarine environments during the Pliocene. Predominantly estuarine conditions were restricted to the north-western part of the Murray Basin, centred in the vicinity of Morgan. Further east, more open-marine, coastal environments prevailed leading to deposition of the vast Loxton-Parilla Sands strandplain succession. This interaction between active coastal sand/dune systems and more restricted estuarine conditions may be analogous to the modern setting of Lake Alexandrina and Lake Albert, at the mouth of the Murray River, and the barrier sands/dunes of the Sir Richard and Younghusband Peninsulas, on the Mt. Gambier coastal plain. Analysis of strontium isotope ratios suggest that estuarine conditions in the western Murray Basin originated in the Early Pliocene and continued until well into the Late Pliocene.