Foraminiferal biofacies of the Miocene warm to cool climatic transition in the Port Phillip Basin, southeastern Australia

Abstract

The Miocene marine sediments of the Torquay Group in the Port Phillip Basin of southeast Australia were deposited at a paleolatitude of at least 45°S. Nevertheless, the presence of subtropical larger foraminifers, plankton of the "Orbulina" bioseries and other biofacies signals testify to a time of global warmth and correspond to the "Miocene Climatic Optimum". Throughout the Early Miocene to early Middle Miocene, bioclastic calcarenite of the Batesford Limestone was deposited in warm, sub-tropical and oligotrophic marine conditions in a high-energy inner-shelf (<70 m depth) environment. During the early Middle Miocene, a distinct change in foraminiferal assemblage accompanied the transition..