- Title
- A new perspective on Late Eocene and Oligocene vegetation and paleoclimates of South-eastern Australia
- Creator
- Sluiter, Ian; Holdgate, Guy; Reichgelt, Tammo; Greenwood, David; Kershaw, A. P.; Schultz, Nick
- Date
- 2022
- Type
- Text; Journal article
- Identifier
- http://researchonline.federation.edu.au/vital/access/HandleResolver/1959.17/187948
- Identifier
- vital:17186
- Identifier
-
https://doi.org/10.1016/j.palaeo.2022.110985
- Identifier
- ISSN:0031-0182 (ISSN)
- Abstract
- We present a composite terrestrial pollen record of latest Eocene through Oligocene (35.5–23 Ma) vegetation and climate change from the Gippsland Basin of south-eastern Australia. Climates were overwhelmingly mesothermic through this time period, with mean annual temperature (MAT) varying between 13 and 18 °C, with an average of 16 °C. We provide evidence to support a cooling trend through the Eocene–Oligocene Transition (EOT), but also identify three subsequent warming cycles through the Oligocene, leading to more seasonal climates at the termination of the Epoch. One of the warming episodes in the Early Oligocene appears to have also occurred at two other southern hemisphere sites at the Drake Passage as well as off eastern Tasmania, based on recent research. Similarities with sea surface temperature records from modern high southern latitudes which also record similar cycles of warming and cooling, are presented and discussed. Annual precipitation varied between 1200 and 1700 mm/yr, with an average of 1470 mm/yr through the sequence. Notwithstanding the extinction of Nothofagus sg. Brassospora from Australia and some now microthermic humid restricted Podocarpaceae conifer taxa, the rainforest vegetation of lowland south-eastern Australia is reconstructed to have been similar to present day Australian Evergreen Notophyll Vine Forests existing under the sub-tropical Köppen-Geiger climate class Cfa (humid subtropical) for most of the sequence. Short periods of cooler climates, such as occurred through the EOT when MAT was ~ 13 °C, may have supported vegetation similar to modern day Evergreen Microphyll Fern Forest. Of potentially greater significance, however, was a warm period in the Early to early Late Oligocene (32–26 Ma) when MAT was 17–18 °C, accompanied by small but important increases in Araucariaceae pollen. At this time, Araucarian Notophyll/Microphyll Vine Forest likely occurred regionally. © 2022 Elsevier B.V.
- Publisher
- Elsevier B.V.
- Relation
- Palaeogeography, Palaeoclimatology, Palaeoecology Vol. 596, no. (2022), p.
- Rights
- All metadata describing materials held in, or linked to, the repository is freely available under a CC0 licence
- Rights
- Copyright © 2022 Elsevier B.V.
- Subject
- 4301 Archaeology; 3709 Physical geography and environmental geoscience; Australia; Eocene–Oligocene; Paleoclimates; Palynology; Vegetation
- Reviewed
- Funder
- We thank Luis Palazzesi and an anonymous reviewer for the significant improvements they suggested for this paper. We also thank the Geological Survey of Victoria and the former State Electricity Commission of Victoria for sampling access to the cores used in this study. Alan Partridge is thanked for samples of the W-1 core and for dating of samples from the latest Late Eocene of core WW-7 and Oligocene LY2766 and LY2768 cores. Prof. Bob Hill and The University of Adelaide are acknowledged for a small grant from that institution which paid for the pollen processing of most of the T0 seam coals used in this study. Prof. Hill is also thanked for helpful discussions and dialogue with respect to modern climate studies of plant taxa found as fossil pollen in our study. Prof. Brian McGowran is thanked for ongoing support, dialogue and rigorous discussions with respect to the Gippsland Basin and south-east Australian Cenozoic stratigraphy. David Greenwood received funding from the Natural Sciences and Engineering Research Council of Canada (2016-04337).
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