New potassium-argon basalt date in relation to the Pliocene Bluff Downs Local Fauna, northern Australia

Abstract

A new radiometric date of 3.6 Ma for the basalt overlying fossiliferous units of the Allingham Formation, provides a minimum age for the Bluff Downs Local Fauna. Ground studies and interpretation of aerial photography has clarified the volcanic history of the area and a new basalt flow has been identified and named. Although the age of the capping basalt permits a younger age for the Bluff Downs Local Fauna than originally described, the stratigraphy,combined with the interpreted stage of evolution of the fauna, still supports an Early Pliocene age for the site.