Early pleistocene stratigraphy and timing of the Bulgobac Glaciation, Western Tasmania, Australia

The Pieman River drainage basin, northwest Tasmania, preserves the most complete record of Cenozoic glacial advances from Australia although precise age control is mostly lacking. At least four pre-last Interglacial glaciations can be recognised. Magnetostratigraphic evidence demonstrates that the minimum age of the glacial diamictons (Bulgobac Formation) deposited during the most extensive glacial event, the Bulgobac Glaciation, is early Pleistocene in age (>0.783 m.y.) based on reversed-polarity recorded in associated glaciolacustrine sediments. The maximum age of this glaciation is >0.89 m.y. to latest Pliocene, based on the palynology and magnetostratigraphy of silts (Marionoak Formation) underlying the Bulgobac Formation at a site on the Huskisson-Marionoak River divide. Plant macrofossils, spores and pollen suggest that climates at the time of deposition of the Marionoak Formation silts were drier than at present and cool, but not stadial or glacial in severity.