OFR 151.pdf - CRC LEME

Palaeo-central Australia
As for the Late Paleocene, the reconstruction of Early Eocene climates in central Australia is
hindered by the uncertain age of many assemblages and the heterogeneous nature of the
rainforest vegetation. For example, taxa that are now characteristic of warm temperate
rainforest (Cunoniaceae, Elaeocarpaceae) co-occur with Nothofagus in the Lake Eyre Basin,
whilst further to the north in the Alice Springs district, the rainforest vegetation, which is
dominated by Casuarinaceae (Gymnostoma) and Proteaceae, includes palms but lacks
Nothofagus. Nevertheless, the increasing dominance of microfloras by angiosperms other
than Nothofagus is weak evidence for relatively warm (upper mesotherm) and seasonally wet
to very wet (perhumid) conditions during the Early Eocene.
Palaeo-southern Australia
Palms such as Nypa were present in the southern Carnarvon and Perth Basins but the
relatively high diversity of gymnosperms and persistent presence of Nothofagus suggests that
Early Eocene climates were marginally cooler (mesotherm range) and wetter (humidperhumid)
or rainfall was more uniform in southwestern Australia than in northwestern
Australia. Similar relatively mild conditions may have extended as far east as the Eyre
Peninsula in South Australia due to the influence of warm water gyres within the Australo-
Antarctic Seaway.
Conditions in the south-east of the continent were wetter (perhumid) and equally warm (upper
mesotherm) although temperature regimes were more complex at the local scale. One
contributing factor is likely to have been higher SSTs within enclosed embayments such as
Macquarie Harbour than in embayments exposed to the open ocean. For example Nothofagus
(Brassospora) spp. appears to have remained relatively common in southeastern Tasmania
throughout the Early Eocene whilst differences in the relative abundance of Nypa pollen
imply that SSTs in the Gippsland Basin were slightly cooler than in Macquarie Harbour
during the late Early Eocene.
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