OFR 151.pdf - CRC LEME
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OFR 151.pdf - CRC LEME

OFR 151.pdf - CRC LEME OFR 151.pdf - CRC LEME

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2. Lake Torrens Basin Abundant leaf impressions are preserved in probable Middle Eocene channel fill deposits (Willalinchina Sandstone) in the Billa Kalina Basin, north-west of Lake Torrens. These include the oldest confirmed remains of Eucalyptus in Australia as well as the casts of a reedlike plant (Callen and Cowley 1995). Probable correlatives of the Willalinchina Sandstone in the Woomera and Andamooka areas further to the west also preserve silcrete casts, in particular the moulds of leaves, and fruits (Offler 1969, cited in Callen and Cowley 1995, Lange 1978b). Fossils provisionally assigned to extant genera include Cupressaceae, Podocarpaceae (cf. Dacrycarpus, cf Podocarpus), Casuarinaceae, Myrtaceae (Angophora, Eucalyptus, Callistemon, Calathamnus, Leptospermum and Melaleuca), Proteaceae (cf .Banksia) and Santalaceae (Santalum). Inferred Climate The source vegetation was a mosaic of mesotherm rainforest and sclerophyll communities, which are presumed to have grown along rivers and across interfluves, respectively (Christophel 1994, Benbow et al. 1995). Foliar physiognomic analyses (Christophel and Greenwood 1989, Greenwood 1994, 1996) indicate mean air temperatures were within the upper mesotherm range (~18-21 0 C) in the southern Eyre Basin and possibly warmer (~21 0 C) at Poole Creek. Rainfall is seen as being moderate (1000 mm pa) but strongly seasonal (possibly monsoonal). 3.1.4 South-West Australia 1. Yilgarn Craton Palaeochannels incised into the south-western margin of the Yilgarn Craton preserve abundant plant impressions and petrifactions, e.g. the Kojunup, Pallinup and West Dale Floras (Hill and Merrifield 1993, Scriven et al. 1995, Barnes and Hill 1999b). These have been assigned a Middle Eocene-Oligocene age range, based on similarities with eastern Australia. Although the Middle-Late Eocene age is supported by microfloras preserved in other palaeochannels in the region, it is noted that the minimum age could be as young as mid Pliocene based on the similarities between the West Dale Flora and the independently-dated Yallalie flora in the same district (cf. Dodson and Macphail in press). The West Dale Flora is dominated by Myrtaceae and Proteaceae. Species assigned to extant families and genera include Agathis, Dacrycarpus, Cunoniaceae, Gymnostoma, Cunoniaceae (Codia), Lauraceae, Myrtaceae, Nothofagus and Proteaceae (cf. Banksieaephyllum). Sclerophyll features are present in many leaves but adaptations that minimize water loss through the stoma are absent (xeromorphic features). This suggests water was readily available but the parent plants were growing in nutrient-deficient soils. Inferred Climate The source vegetation appears to be a form of dry rainforest growing under seasonally wet (humid) and relatively warm (mesotherm range) conditions. If correct, then the presence of plicate Nothofagus leaves in the Late Eocene Kojunup flora (N. plicata) is anomalous since plicate leaves are more typical of deciduous species growing in cool-cold (microtherm range) climates. 227

3.1.5 Central southern Australia 1. St. Vincent Basin Leaves, fruit and flowers preserved at Maslin Bay and Golden Grove on the Fleurieu Peninsula, South Australia have been studied since the 1970s (Lange 1970, Christophel and Blackburn 1978, Blackburn 1981, Alley 1987, Christophel and Greenwood 1987b, Barrett and Christophel 1990, Christophel 1994, Rozefelds et al. 1992, Scriven 1994, Benbow et al. 1995). Both deposits are reliably dated by pollen as Middle Eocene (Lower Nothofagidites asperus Zone Equivalent). Many of the remains represent extinct species of taxa whose NLRs are confined to the subtropics and tropics. Examples are: Schizaeaceae (Lygodium), Araucariaceae (Agathis), Podocarpaceae (extinct genus), Araliaceae (extinct genus), Palmae (Maslin Bay only) Casuarinaceae (Gymnostoma), Cunoniaceae (Ceratopetalum), Ebenaceae (Diospyros/Austrodiospyros), Elaeocarpaceae (cf. Elaeocarpus/Sloanea), Lauraceae, Myrtaceae (extinct genera), Proteaceae (Banksieaephyllum, cf. Beauprea, cf. Neorites) and Sterculiaceae (Brachychiton). The closest modern analogue is warm temperate to subtropical rainforest growing on the north coast of New South Wales and Queensland (cf. Benbow et al. 1995). Inferred Climate Blackburn (1981) has proposed the climate at Maslin Bay was subtropical (upper mesotherm) and either uniformly wet (perhumid) or only weakly seasonal. Foliar physiognomic analyses (Greenwood (1994, 1996) indicate mean temperatures were in the upper mesotherm megatherm range at Maslin Bay (est. 20-27 0 C) and at Golden Grove (est. ~18 0 C). These estimates are inconsistent with the microfossil evidence. 3.1.6 South-East Australia 1. Southeastern Highlands Basalt with a minimum age of ~45 Ma (late Middle Eocene) overlie lacustrine mudstones at Nerriga on the Southeastern Highlands, New South Wales. The maximum age is Early Eocene, based on pollen (J. Owen cited in Hill 1978). The associated macroflora includes a Menispermataceae cf. Legnephora), Lauraceae and two cycads (Bowenia spp.) now restricted to northeastern Queensland and New Guinea (Hill 1978, 1980, 1986). Inferred Climate Foliar physiognomic analysis (Greenwood 1994) indicates wet to very wet (perhumid) climates with mean temperatures in the mesotherm range (est. 16-21 0 C). 2. Otway and Gippsland Basins Middle Eocene (Lower Nothofagidites asperus Zone) macrofloras are preserved in clay lenses in thick lignitic (brown coal) measures at Anglesea in the Torquay Sub-basin (Christophel et al. 1987, Christophel 1994) and in the Morwell Open-cut Mine (Traralgon 2 seam), in the Gippsland Basin (references in Holdgate and Sluiter 1991, Blackburn and Sluiter 1994, Holdgate et al. 2000). Both sequences appear to have accumulated in lowland freshwater swamps that were subject to marine flooding. The floras represent a mosaic of wetland and dryland communities. 228

3.1.5 Central southern Australia<br />

1. St. Vincent Basin<br />

Leaves, fruit and flowers preserved at Maslin Bay and Golden Grove on the Fleurieu<br />

Peninsula, South Australia have been studied since the 1970s (Lange 1970, Christophel and<br />

Blackburn 1978, Blackburn 1981, Alley 1987, Christophel and Greenwood 1987b, Barrett<br />

and Christophel 1990, Christophel 1994, Rozefelds et al. 1992, Scriven 1994, Benbow et al.<br />

1995). Both deposits are reliably dated by pollen as Middle Eocene (Lower Nothofagidites<br />

asperus Zone Equivalent). Many of the remains represent extinct species of taxa whose<br />

NLRs are confined to the subtropics and tropics. Examples are: Schizaeaceae (Lygodium),<br />

Araucariaceae (Agathis), Podocarpaceae (extinct genus), Araliaceae (extinct genus), Palmae<br />

(Maslin Bay only) Casuarinaceae (Gymnostoma), Cunoniaceae (Ceratopetalum), Ebenaceae<br />

(Diospyros/Austrodiospyros), Elaeocarpaceae (cf. Elaeocarpus/Sloanea), Lauraceae,<br />

Myrtaceae (extinct genera), Proteaceae (Banksieaephyllum, cf. Beauprea, cf. Neorites) and<br />

Sterculiaceae (Brachychiton). The closest modern analogue is warm temperate to subtropical<br />

rainforest growing on the north coast of New South Wales and Queensland (cf. Benbow et al.<br />

1995).<br />

Inferred Climate<br />

Blackburn (1981) has proposed the climate at Maslin Bay was subtropical (upper mesotherm)<br />

and either uniformly wet (perhumid) or only weakly seasonal. Foliar physiognomic analyses<br />

(Greenwood (1994, 1996) indicate mean temperatures were in the upper mesotherm<br />

megatherm range at Maslin Bay (est. 20-27 0 C) and at Golden Grove (est. ~18 0 C). These<br />

estimates are inconsistent with the microfossil evidence.<br />

3.1.6 South-East Australia<br />

1. Southeastern Highlands<br />

Basalt with a minimum age of ~45 Ma (late Middle Eocene) overlie lacustrine mudstones at<br />

Nerriga on the Southeastern Highlands, New South Wales. The maximum age is Early<br />

Eocene, based on pollen (J. Owen cited in Hill 1978). The associated macroflora includes a<br />

Menispermataceae cf. Legnephora), Lauraceae and two cycads (Bowenia spp.) now restricted<br />

to northeastern Queensland and New Guinea (Hill 1978, 1980, 1986).<br />

Inferred Climate<br />

Foliar physiognomic analysis (Greenwood 1994) indicates wet to very wet (perhumid)<br />

climates with mean temperatures in the mesotherm range (est. 16-21 0 C).<br />

2. Otway and Gippsland Basins<br />

Middle Eocene (Lower Nothofagidites asperus Zone) macrofloras are preserved in clay lenses<br />

in thick lignitic (brown coal) measures at Anglesea in the Torquay Sub-basin (Christophel et<br />

al. 1987, Christophel 1994) and in the Morwell Open-cut Mine (Traralgon 2 seam), in the<br />

Gippsland Basin (references in Holdgate and Sluiter 1991, Blackburn and Sluiter 1994,<br />

Holdgate et al. 2000). Both sequences appear to have accumulated in lowland freshwater<br />

swamps that were subject to marine flooding. The floras represent a mosaic of wetland and<br />

dryland communities.<br />

228

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