The lower tertiary Eyre formation of the Southwestern great Artesian basin

Abstract

The term ‘Eyrian Series’, proposed by Woolnough and David in 1926, is here redefined in terms of the Australian Code of Stratigraphic Nomenclature. In conformity with the code the orignal term is changed to Eyre Formation. The Eyre Formation is defined as the sequence, consisting of mature conglomerate, quartz sandstone, carbonaceous siltstone, and lignite, which rests unconformably on late Cretaceous or older rocks. Highly polished clastic components are typical. The top of the Eyre Formation is identified either by its contact with a Miocene carbonate‐shale sequence or by a quartzitic palaeosol. Detailed descriptions of type and reference sections are given. Microfloras show that the formation is of Paleocene and Eocene age. The Eyre Formation was deposited under ftuviatile and to a lesser degree lacustrine conditions and formed an almost continuous sediment blanket from southwest Queensland to the western and southern margins of the Great Artesian Basin. The thickness of the formation was influenced by syndepositional epeirogenic movements. Climate was warm‐temperate with at least seasonally high precipitation. Probable source areas and transport paths are suggested and correlations with equivalent units outside the Great Artesian Basin are discussed.