OFR 151.pdf - CRC LEME

Nothofagus-gymnosperm temperate rainforest within (Late Miocene, Late Pliocene)
predominantly wet sclerophyll forest types.
Inferred climate
The expansion of Nothofagus (Lophozonia) spp. is likely to be due to uniformly wet
(perhumid) and cool (upper microtherm) conditions on the upper slopes of the Southern
Highlands during an interval (Early Pliocene) when other sites in southern Australia
experienced increasing warmth. The most plausible explanation is that warm sea surface
temperatures and high relative sea levels resulted in increased orographic cloudiness, and
therefore effectively cooler wetter conditions, over the Southeastern Highlands.
3. Otway Basin
Grange Burn, at 180 m elevation, near Hamilton in south-western Victoria is located close to
the limits of marine transgression in the Otway Basin during Late Neogene time. The site
provides a record of an Early Pliocene environment that is unique in Australia for two
reasons. A regressive non-marine alluvium is preserved between a late Miocene-Early
Pliocene marine silt and a K/AR-dated 4.46 Ma old basalt. Fossils preserved in the alluvium
include the remains of plants and mammals animals whose NLRs are confined to coastal
northeastern Queensland (Flannery et al. 1992, Macphail 1996b). Commonly occurring
microfossils include Cyathea, Araucariaceae (Araucaria), Podocarpaceae (Dacrycarpus,
Podocarpus-Prumnopitys), Casuarinaceae and Myrtaceae (including Eucalyptus). Less
common or rare taxa are Dacrydium, Asteraceae, Eucalyptus spathulata-type, Nothofagus
(Brassospora, Fuscospora, Lophozonia) spp. and Poaceae.
Inferred climate
The combined microfloral and palaeontological evidence point to a mosaic vegetation of
Araucariaceae (dry) rainforest and open-canopy sclerophyll communities, which may have
been confined to the stream banks. There is no evidence that Nothofagus spp. were part of
these communities or present elsewhere in the district. Poaceae are suggested to have
colonised drier (interfluve) areas but there is no evidence that grasslands per se were part of
the regional dryland vegetation. Macphail (1996b) has proposed that climates were wet
(humid) and weakly seasonal. Mean annual temperatures are likely to have been very warm
(upper mesotherm).
4. Murray Basin
Marine transgressions during the Late Miocene and Early Pliocene resulted in the deposition
of marginal marine facies in the south-west sector of the basin. Examples are the
Bookpurnong Beds and basal Loxton-Parilla sands (Brown and Stephenson 1991).
Microfloras from restricted marine and estuarine facies are dominated by Araucariaceae,
Casuarinaceae and/or Myrtaceae, with relatively low and diminishing relative abundances of
Nothofagus (Brassospora) spp. Microfloras from paralic facies where the marine influence
was weak or absent are dominated by Nothofagus (Brassospora), Araucariaceae and
Casuarinaceae, with lower abundances of Myrtaceae. These facies are difficult to correlate
using plant microfossils and it is uncertain whether differences in pollen dominance are due to
the Neves Effect, edaphic-forcing or evidence that Nothofagus-dominated rainforest was
succeeded by drier, Araucariaceae-dominated, types of rainforest.
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