Palynology of some tertiary deposits from New South Wales

Abstract

Microfloras from freshwater sediments from three localities in New South Wales - Nerriga, Kiandra, and Cadia, have been studied and compared with previously described Tertiary assemblages. Samples for palynological study were taken from sections with a K-Ar dated basalt to give independerit age control. For two localities, Kiandra and Cadia (dated as early and middle Miocene, respectively) there is good agreement betw2an the microfloral and radiometric ages. At Nerriga, this dating is less precise; the age indicated by the microflora is early Eocene, whereas the K-Ar age on the basalts indicate late Eocene. All three microfloral suites could be compared to those described from the Gippsland and Otway Basins, and could therefore be related to zones described from these sequences. Many characteristic species from these south coast assemblages (e.g. some species of Proteacidites) are absent, however. Suites from all three localities suggest a rainforest vegetation, and can be considered part of the widespread Tertiary Cinnamomum flora. This flora consists of Nothofagus of all three types (brassi, menziesii, and fusca), various gymnosperms, and a diversity of angiosperms and pteridophytes. Whether this was a pan-Australian flora remains to be assessed, as data become available from areas outside of southeastern Australia. Elements of this flora are also found in Tertiary deposits of other southern regions - New Zealand, Antarctica, Kerguelen, southern South America, and Ninetyeast Ridge. Most fossil taxa can be related to living groups with a temperate distribution, although some tropical elements are present. The assemblage indicates a higher rainfall in these areas in the Tertiary than at present. Indications of warmer temperatures are uncertain from the microfloras, although palaeotemperature data indicate warmer temperatures at least in the Paleogene.