The palaeogeographic and palaeoenvironmental evolution of a Palaeogene mixed carbonate-siliciclastic cool-water succession in the Otway Basin, Southeast Australia

Abstract

The Otway Basin in southeast Australia contains a thick sequence of Cenozoic shelfal carbonates and siliciclastics that preserve signals relating to the progressive opening of the Southern Ocean since the Palaeogene. This multidisciplinary study integrates outcrop and subsurface well data from over 100 wells and bores throughout the Otway Basin with micropalaeontological analyses to constrain the age and palaeoenvironments of the Nirranda Group (Late Eocene to Middle Oligocene) and the Heytesbury Group (Late Oligocene to mid Miocene). These data were used to deduce the Late Eocene to Late Oligocene palaeogeographical evolution of the area. During the Late Eocene paralic high energy silicicla..