OFR 151.pdf - CRC LEME

and, for Tertiary continental sequences, by the lack of a ‘local’ pollen-spore based
palynostratigraphy. For example in Queensland, Sajjadi and Playford’s important (2002a,
2002b) reviews of Early Cretaceous microfloras in the Eromanga Basin cites numerous
species described by J. McKellar (Geological Survey of Queensland in press) in an as yet
(2006) unpublished analysis of correlative microfloras in the Surat Basin. Areas for which
some additional palaeobotanical evidence have been published are (1) the Bundaberg Trough
in coastal southeastern Queensland (Dettmann and Clifford 2003) and The St. George Basin
(Lower Balonne district) in inland southeastern Queensland (Macphail 2004b). At the former
site, an Early Miocene assemblage includes what appears to be the first record of the late
Early to early Late Miocene zone index species Canthiumidites bellus in Queensland. Like its
probable correlative at Mt. Coolon in central Queensland (Beeston 1994), the microflora is
dominated by Nothofagus (Brassospora) spp., Casuarinaceae, Euphorbiaceae and Myrtaceae
but also includes rare taxa whose Nearest Living Relatives (NLRs) occur in cool temperate
rainforest as well as taxa whose NLRs occur in subtropical ‘dry’ rainforest. The probable
Pliocene sequences in the St. George Basin indicates climates were too dry to support
temperate rainforest angiosperms such as Nothofagus although temperate rainforest
gymnosperms survived along rivers and/or the adjacent uplands.
Central Australia
A recently recognised glacial diamicton confirms glaciers had developed some time during
the Berriasian to Valanginian in the Eromanga Basin (Alley and Frakes 2003). A recent PhD
study uses changes in Barremian to Aptian dinoflagellate populations to infer mid Cretaceous
palaeoclimates (Oosting 2004, Oosting et al. 2006). Otherwise, there have been few additions
to the palaeobotanical database although Late Eocene macrofloras at Nelly Creek in northern
South Australia continue to be a focus for macrofossil research (Hill and Cristophel 2001,
Conran et al. 2003). Palaeontological studies have added to knowledge of Oligo-Miocene
climates, e.g. Megirian et al. (2004), but the resolution provided by the land mammal
biostratigraphy remains poor. Age control based on lithostratigraphy may or may not be
reliable. For example, an organic interval within the Late Oligocene Etadunna Formation at
Lake Palankarinna in northern South Australia yielded an Early Eocene microflora (M.K.
Macphail unpubl. data). A possible Tertiary organic sequence intersected in a recent
Northern Territory Geological Survey drillhole was discarded, despite being ear-marked for
palynostratigraphic dating.
South-West Australia
Recent additions to the palaeobotanical database include detailed analyses of (1) Late
Jurassic-Early Cretaceous sequences in the offshore Vlaming Sub-basin of the Perth Basin
(Backhouse 2006, Macphail 2006c), (2) Late Jurassic-Cretaceous dredge samples from the
offshore Bremer and Denmark Sub-basins in the western Bight Basin (Macphail and Monteil
2004, Exon et al. 2005), (3) Late Eocene lignites preserved in palaeochannels in southern
south-west Western Australia (de Broekert 2003, Itzstein-Davey 2004, M.K. Macphail
unpubl. data), (4) Early Oligocene to possibly Early Miocene carbonaceous clays underlying a
highly important channel iron deposit (CID) at Yandi in the Pilbara region, northern southwest
Western Australia (Macphail and Stone 2004), and (5) mid Pliocene lake sediments
infilling a probable Early Cretaceous meteor impact crater at Yallalie, north of Perth (Atahan
et al. 2004, Dodson and Macphail 2004).
The offshore data provide a detailed record of Austral Conifer Forest communities before and
during the onset of rifting between Australia and Antarctica, and confirm (climate-forced)
provincialism of the araucarian and cryptogam floras had developed as early as the
Valanginian to Early Barremian. Microfloras preserved at Yandi demonstrate that climates at
higher elevations on the Hamersley Ranges were cooler (mesotherm range) and wetter (humid
4