OFR 151.pdf - CRC LEME

The diversity of Nothofagus spp. remained high in Capricorn-1A but data from Aquarius-1,
located further offshore, indicate regional Nothofagus and Myrtaceae populations collapsed
during late Early Miocene time (N8). Both taxa are represented by trace pollen values only
throughout the Middle Miocene (~N8-N14). The relative abundances of other commonly
occurring taxa were relatively unaffected, e.g. Podocarpaceae and Casuarinaceae, or appear to
increase, e.g. Agathis. Otherwise the Middle Miocene assemblages are characterised by
abundant fern spores, including a possible aquatic species of Polypodiaceae
(Polypodiisporites usmensis), associated with lesser numbers of Euphorbiaceae (Austrobuxustype).
Rare taxa include Nothofagus (Lophozonia) and three taxa that are now typical of
low/open and salt-influenced coastal communities in eastern Australia, e.g. Asteraceae,
Chenopodiaceae, Convolvulaceae (Wilsonia-type).
c. Brisbane district
Oligo-Miocene microfloras are preserved in the GSQ Sandy Cape 1-3R drill hole at the
northern tip of Fraser Island and several boreholes near Brisbane (Harris 1965d, Wood 1986).
Independent age control from indirect K/Ar evidence (Grimes 1982) indicates that the Sandy
Cape 1-3R sequence is no older than 30 Ma.
Sandy Cape 1-3R includes a lower (Late Oligocene-late Early Miocene) fluvio-deltaic section
in which the associated microfloras are dominated by Casuarinaceae (35%) and Nothofagus
(Brassospora) spp. (14%). Cryptogams are less common (11%), with Cyathea being the most
abundant type. The only frequent gymnosperms are Araucariaceae (3%) and Dacrydium
(5%). Cupanieae, Malvaceae and unidentified tricolporate angiosperms comprise between 3-
12% of the total count. The upper marine-influenced (late Early-Middle Miocene) section in
Sandy Cape-1 is dominated by cryptogams (total 27-60%) with occasionally high values of
Araucariaceae (Agathis/Wollemia), Nothofagus (Brassospora) and non-eucalypt Myrtaceae.
Casuarinaceae becomes relatively rare (