Pleistocene stratigraphy of the Boco Plain, western Tasmania

Publisher Website
Google Scholar
Abstract
Mapping of surficial glacigenic sediments and logging of drill cores from the Boco Plain has revealed a more complete sequence of glacial and interglacial sediments, and a more complex history of middle to late Pleistocene depositional events than anywhere else in Australia. Radiocarbon dating of the uppermost fluvial and organic‐rich lacustrine sediments indicates that a long record of non‐glacial deposition followed the Penultimate or Boco Glaciation. Prior to this, a sequence of sediments indicating multiple glacial advances is intercalated with lacustrine silts and fluvial sands and gravels. Radiocarbon dates for the uppermost unit of organic lacustrine sediments show that they extend far beyond the range of the radiocarbon technique. In addition, uranium‐thorium dated ferricretes from the older sedimentary sequence provide minimum ages for the glacial events, and suggest ice advances into the plain broadly correlative with marine Isotope Stages 6, 8 and ?10. Normal detrital remanent magnetization of the sediments confirms a middle Pleistocene age for all the glacial episodes recorded in the cores. The glacial sediments overlie Cambrian volcanic bedrock weathered to a depth of 9 m which indicates a long time gap between initial erosion of the valley and the commencement of middle Pleistocene glacial deposition.