Stratigraphy and sedimentology of the lower Neales River, West Lake Eyre, Central Australia: from Palaeocene to Holocene

Abstract

The stratigraphy of the lower Neales River to the west of Lake Eyre, Australia's largest internal drainage system, preserves a detailed record of fluvial, lacustrine and aeolian deposits of early Tertiary to Holocene age. This stratigraphic framework provides a summary of the region's Cainozoic sedimentary units. Three units have been identified: an early Tertiary fluvial unit; a mid-Tertiary lacustrine unit; and a Quaternary unit composed of interbedded fluvial, lacustrine, and aeolian facies. Dramatic changes in depositional styles within, and between, these three major groups of sediments reflect the basin's response to changes in climate and sediment supply. Fluvial facies include perennial multi-channel, single-channel, and ephemeral river sequences. Lacustrine and deltaic facies reflect continuous fine-grained sedimentation during periods of high water-tables. The aeolian facies are evidence of aridity and sediment deflation in the basin. The early Tertiary fluvial unit is the result of Late Palaeocene–Eocene epeirogenic movements. A dramatic shift in facies to the mid-Tertiary lacustrine unit reflects a significant change in the basins climatic controls. Quaternary sediments reflect major changes in fluvial discharge regimes which may reflect major climatic and associated hydrological changes during past interglacial and glacial cycles.