OFR 151.pdf - CRC LEME

Palaeo-southern Australia
Dryland communities included Austral Conifer Forest, which was dominated by araucarians,
podocarps and possibly pteridosperms. Conditions appear to have been effectively wetter
(humid-perhumid) than on the palaeo-northern margin. Owing to the very high palaeolatitude
(~80 0 S), the extensive development of conifer swamp forests in present-day southeastern
Australia and Tasmania may reflect reduced evapo-transpiration during summer rather than a
higher annual rainfall. Mean annual temperatures were cool-cold (microtherm range) and
almost certainly fell below freezing during the dark winters. One anomalous record in
Turonian-Santonian sediments in the Torquay Sub-basin is Spinizonocolpites, a type that
resembles pollen produced by the tropical mangrove palm Nypa (M.K. Macphail unpubl.
data).
6.6 Time Slice K-5. Early Campanian [83- ~70 Ma]
Zones: Lower Nothofagidites senectus Zone
Upper Nelsoniella aceras to Xenikoon australis Zones
Figure 7: Campanian (84 Ma) palaeogeography (from Veevers et al. 1991)
6.6.1 Palaeogeography
By the Campanian (Figure 7), the orientation of the Australian continent relative to the
geographic South Pole was similar to the present. The Australo-Antarctic Seaway between
Antarctica and Australia was some hundreds of kilometres wide at its western end and
extended eastwards along the present-day southern margin as far west as the west coast of
Tasmania (Veevers et al. 1991, Langford et al. 1995). Thin Campanian sediments in the Eyre
and Duntroon Basins suggest low sediment influx and/or strong marine circulation within this
seaway. Fluvial and lacustrine sediments continued to accumulate within fault-bounded
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