An Early to Middle Pleistocene palynological record from the volcanic crater of Pejark Marsh, Western Plains of Victoria, southeastern Australia

Abstract

A discontinuous 70 m sediment core was extracted from the volcanic crater of Pejark Marsh to temporally extend the existing Quaternary record of vegetation and environments from the Western Plains of Victoria. The sequence was fission track dated to the Early–Middle Pleistocene transition. Both the sediments and the aquatic pollen indicate a general lake shallowing and progressive increase in drying and peat deposition events. The major dry land pollen taxa are similar to those that dominate the late Quaternary records from the area and indicate the alternation of regionally dominant sclerophyll forest during wetter periods and steppe or open woodlands during drier periods. A major feature of the pollen record is the presence of a number of regionally extinct taxa in the basal half of the record. Some of these taxa, including Araucaria, Canthium and Microcachrys, represent major range extensions of previously considered regionally extinct taxa into the Pleistocene. Tentative correlation with the marine oxygen isotope record suggests that the sequence may extend from isotope stages 30 to 17 with major changes within the record relating to the transition from the higher frequency, lower amplitude, orbitally forced climatic cycles of the Early Pleistocene to the lower frequency, higher amplitude cycles of the Middle–Late Pleistocene.