OFR 151.pdf - CRC LEME

Lophosoria, Dicksonia, Araucariaceae (Araucaria, Agathis/Wollemia), Podocarpaceae
(Dacrycarpus, Halocarpus, Microstrobos, Phyllocladus), Anacardiaceae, Cupanieae,
Elaeocarpaceae, Euphorbiaceae (Austrobuxus-type), Ilex, Loranthaceae, Myrtaceae (including
Austromyrtus-type, Eucalyptus), Proteaceae (including Agastachys-type, Beauprea,
Xylomelum occidentale-type), Sapotaceae and Winteraceae. The assemblages represent
Nothofagus-gymnosperm temperate rainforest.
A comparison of the macrofossil and microfossil data shows that the canopy dominants were
species within the Nothofagus subgenus Lophozonia, not the subgenus Brassospora, as
indicated by relative pollen abundance. The corollary is that Nothofagus (Brassospora) spp.
are over-represented by pollen.
Inferred climate
Climates were upper microtherm and uniformly very wet (perhumid).
4. West Coast
Lignites preserved in Tertiary palaeochannels near Zeehan and Balfour provide ‘snap shots’
of the Proteacidites tuberculatus Zone vegetation on the west coast (M.K. Macphail unpubl.
results). Both microfloras represent floristically simple Nothofagus-gymnosperm evergreen
rainforest.
The possibly older Zeehan microflora is dominated by Nothofagus (Brassospora) spp.,
Proteaceae (especially Agastachys-type) and Casuarinaceae. Lagarostrobos, Quintinia,
Trimeniaceae and a small Ilex grain are frequent. Rare taxa include Microstrobos, Gunnera,
Lactoridaceae (now endemic to the Juan Fernandez Islands off Chile), Myrtaceae, Nothofagus
(Lophozonia) and Strasburgeriaceae. Pollen dominance at the possibly younger Balfour site
is shared between Nothofagus (Brassospora) spp. (30%), Dacrydium (10%), Lagarostrobos
(15%), Podocarpus-Prumnopitys (11%), Casuarinaceae (6%) and Nothofagus (Fuscospora,
Nothofagus) spp. (5%). Frequent types include Araucaria (2%), Podosporites (2%),
Strasburgeriaceae (1%), Trimeniaceae (3%) and Ericales (2%). Rare taxa include
Lophosoria, Cupressaceae, Gunnera, Polygalaceae, Quintinia and Winteraceae. Cupanieae
are absent.
Inferred climate
Climates were cool (microtherm range) and uniformly wet (perhumid). Conditions do not
appear to have been significantly cooler at Zeehan than at Balfour despite differences in
elevation.
5. Central Plateau
Sites preserving diverse Oligo-Miocene microfloras occur at Cethana, Lemonthyme Creek,
Lea River, Link Road, Little Rapid River and Wilmot Dam in northwestern Tasmania
(Macphail et al. 1993, Macphail and Hill 1994, M.K. Macphail unpubl. results) and at
Monpeelyata, near Great Lake on the eastern margin of the Central Plateau (Macphail et al.
1991). In all cases the assemblages accumulated in palaeochannels incised into Jurassic or
older rocks. The microfloras represent Nothofagus-gymnosperm rainforests, which were
structurally less complex and floristically simpler than comparable rainforests growing in the
south-east of the mainland.
The earliest microfloras (Lemonthyme Creek and Wilmot Dam) are associated with probable
earliest Oligocene glacial deposits (Lemonthyme Glaciation). K/Ar dates of overlying basalts
confirm the sections are older than 26.7 Ma. Although assigned to the Proteacidites
tuberculatus Zone, based on Cyatheacidites annulatus, it is probable that this fern
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