OFR 151.pdf - CRC LEME
OFR 151.pdf - CRC LEME 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. 93
7.6 Time Slice T-3. Middle-Late Eocene [49-33.7 Ma] Zones: Lower to Middle Nothofagidites asperus Zones Rhombodinium waipawaense to Gippslandica extensa (Corrudinium incompositum) Zones Figure 9: Middle Eocene (45 Ma) palaeogeography (from Veevers et al.1991 7.6.1 Palaeogeography During the Middle-Late Eocene Australia lay between palaeolatitudes of ~27 0 S to ~63 0 S (Figure 9). At about 43 Ma (late Middle Eocene), the Pacific Plate underwent a second swerve, increasing the velocity of northward drift from an average 70 mm yr -1 to 93 mm yr -1 (Veevers 1999). Co-eval events include the formation of monoclines, broad arches and domes in central Australia and grabens (some now filled with oil shale deposits) in coastal Queensland. Seismic and geological evidence indicate that the northern Bonaparte Basin suffered multiple meteor impacts during the same (Late Eocene) interval (Gorter 1999). Four cycles of eustatic are recognised in southern Australia (Harris 1985). The earliest evidence of the (southward flowing) Leeuwin Current in southwestern Western Australia is late Middle Eocene (McGowran et al. 1997). Palaeochannels incised into the southern edge of the Yilgarn Plateau were infilled with thin lignite measures (Clarke 2000). Further to the east, thick lignite sequences have accumulated in the Noarlunga and Willunga Embayments of the St. Vincent Basin (Fairburn 1998, 2000), at Anglesea in the Torquay Sub-basin and in the Gippsland Basin (Holdgate and Sluiter 1991, Holdgate et al. 2000). 94
- Page 43 and 44: Accordingly, only at sites with exc
- Page 45 and 46: 2.1.3 Palaeoecology Palaeoecology i
- Page 47 and 48: wind-pollinated trees and shrubs bu
- Page 49 and 50: 1. The usual practice of equating t
- Page 51 and 52: 1. Palaeontological evidence Like p
- Page 53 and 54: 5. Facies architecture and lithostr
- Page 55 and 56: Subsequent developments include mel
- Page 58 and 59: SECTION 4 (GEOGRAPHIC BOUNDARIES AN
- Page 60 and 61: SECTION 5 (EARLY CRETACEOUS CLIMATE
- Page 62 and 63: events on other continents and sugg
- Page 64 and 65: If these considerations apply to th
- Page 66 and 67: surrounding basins. Thick sands ero
- Page 68 and 69: Haig and Lynch 1993, Erbacher et al
- Page 70 and 71: SECTION 6 (LATE CRETACEOUS CLIMATES
- Page 72 and 73: has highlighted the roles played by
- Page 74 and 75: 6.4.2 Palaeobotany Cenomanian flora
- Page 76 and 77: Palaeo-southern Australia Dryland c
- Page 78 and 79: 6.7 Time Slice K-6. Late Campanian-
- Page 80 and 81: 7.1. Global backdrop SECTION 7 (TER
- Page 82 and 83: Explanations for the PETM are centr
- Page 84 and 85: East Antarctica and strengthening o
- Page 86 and 87: amplifying, pacing and potentially
- Page 88 and 89: southeastern Australia than elsewhe
- Page 90 and 91: 7.4 Time Slice T-1. Paleocene [65-5
- Page 92 and 93: Palaeo-southern Australia Unlike no
- Page 96 and 97: 7.6.2 Palaeobotany The palaeobotani
- Page 98 and 99: Zone microfloras imply temporary wa
- Page 100 and 101: in the Bass Basin, the basal Seaspr
- Page 102 and 103: Similarly it is difficult to summar
- Page 104 and 105: However, the data are emphatic that
- Page 106 and 107: margin of plateau were cooler (~7 0
- Page 108 and 109: fossil taxa that are morphologicall
- Page 110 and 111: during Late Pleistocene glacial max
- Page 112 and 113: SECTION 8 (CONCLUSIONS) Climatic in
- Page 114 and 115: • On present indications, Early C
- Page 116 and 117: TABLE 8a: INFERRED CRETACEOUS PALAE
- Page 118 and 119: 8.2 Results in prospect (recommenda
- Page 120 and 121: The 10 μm sieved, oxidised extract
- Page 122 and 123: phenology. The method also provides
- Page 124 and 125: SECTION 9 (REFERENCES) Acton, G.D.
- Page 126 and 127: Ashley, P.M., Duncan, R.A. and Feeb
- Page 128 and 129: Birks, H.J.B. and Gordon, A.D., 198
- Page 130 and 131: Burnham, R.J., 1989. Relationships
- Page 132 and 133: Clarke, J.D.A., 1994. Evolution of
- Page 134 and 135: Dettmann, M.E. and Playford, G., 19
- Page 136 and 137: Evans, P.R., 1970b. Palynology of H
- Page 138 and 139: Godthelp, H., Archer, M., Cifelli,
- Page 140 and 141: Harris, W.K., 1974. Biostratigraphy
- Page 142 and 143: Hill, R.S., 1994b. Nothofagus smith
7.6 Time Slice T-3. Middle-Late Eocene [49-33.7 Ma]<br />
Zones: Lower to Middle Nothofagidites asperus Zones<br />
Rhombodinium waipawaense to Gippslandica extensa (Corrudinium<br />
incompositum) Zones<br />
Figure 9: Middle Eocene (45 Ma) palaeogeography (from Veevers et al.1991<br />
7.6.1 Palaeogeography<br />
During the Middle-Late Eocene Australia lay between palaeolatitudes of ~27 0 S to ~63 0 S<br />
(Figure 9). At about 43 Ma (late Middle Eocene), the Pacific Plate underwent a second<br />
swerve, increasing the velocity of northward drift from an average 70 mm yr -1 to 93 mm yr -1<br />
(Veevers 1999). Co-eval events include the formation of monoclines, broad arches and<br />
domes in central Australia and grabens (some now filled with oil shale deposits) in coastal<br />
Queensland. Seismic and geological evidence indicate that the northern Bonaparte Basin<br />
suffered multiple meteor impacts during the same (Late Eocene) interval (Gorter 1999). Four<br />
cycles of eustatic are recognised in southern Australia (Harris 1985). The earliest evidence of<br />
the (southward flowing) Leeuwin Current in southwestern Western Australia is late Middle<br />
Eocene (McGowran et al. 1997). Palaeochannels incised into the southern edge of the<br />
Yilgarn Plateau were infilled with thin lignite measures (Clarke 2000). Further to the east,<br />
thick lignite sequences have accumulated in the Noarlunga and Willunga Embayments of the<br />
St. Vincent Basin (Fairburn 1998, 2000), at Anglesea in the Torquay Sub-basin and in the<br />
Gippsland Basin (Holdgate and Sluiter 1991, Holdgate et al. 2000).<br />
94
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