PALAEOCLIMATESMelbourne University, October 31, 2024
From 2pm onwards
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Registration (Symposium Registration and Dinner RSVP)
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Participants can also register on site on the day. Cash payment only. Detailed Program
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13.30 - 14.00
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Registration (coffee and tea available)
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14.00 - 14.05
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Dr. Anne-Marie Tosolini (GSAV Chair)
Symposium Opening |
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14.05 - 14.30
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Dr. Ashleigh Hood, Sedimentology (University of Melbourne)
The Cryogenian glaciations: A snowball Earth or a dynamic ice age? AbSTRACT
TBC bIO
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14.30 - 14.55
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Dr. Vera Korasidis, Palynology (University of Melbourne)
New palynological insights on the Paleocene Eocene Thermal Maximum AbSTRACT
To better understand the effect of the Paleocene-Eocene Thermal Maximum (PETM) on continental ecosystems, we studied new palynological samples from the Bighorn Basin (BHB), northwestern Wyoming, USA. We see palm and fern abundances increase in the last 20–40 ka of the Paleocene, then dramatically with the onset of the carbon isotope excursion (CIE) defining the base of the PETM. Palynomorphs of plant groups with modern temperate climate distributions are absent from the CIE body, and this is when tropical plants are most diverse and abundant. During the CIE recovery, pollen of mesophytic/wetland plants become more common while tropical taxa persist. In the post-CIE early Eocene tropical taxa are rare and temperate forms abundant, similar to the late but not latest Paleocene. We interpret palynofloral changes to indicate warming in the latest Paleocene, rapid warming and drying with the CIE onset, dry tropical climates through the CIE body, a return to wetter floodplains during a very warm CIE recovery, and cooler wet conditions in the post-PETM early Eocene. These rapid, climatically forced changes in floral composition occurred without major extinction, perhaps indicating nearby refugia in which plants adapted to cooler and wetter climates persisted through the PETM. We also examined possible changes in pollination mode during the PETM as inferred from three lines of evidence: the prevalence of fossil pollen preserved as clumps, the pollination mode of nearest living relatives (NLR) and angiosperm pollen morphological diversity. All three suggest animal pollination became more common and wind pollination less common during the PETM. The decrease in wind pollination during the PETM reflects the basin-scale extirpation of wind-pollinated lineages, and their replacement by dominantly animal-pollinated lineages due to rapid warming and drying. The hotter and more seasonally dry climates not only facilitated the northward range shift of plant taxa, but also their insect and/or vertebrate pollinators. bIO
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14.55 - 15.20
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Dr. Andrew Gunn, Geomorphology (Monash University)
Climate memory in giant dunes AbSTRACT
Dune morphology and stratigraphy typically expresses local wind climate. As dunes grow, however, the time it would take for morphology to adjust and represent a new wind climate grows. Climate changes on timescales similar to this dune readjustment timescale on Earth. This overlap in timescales may mean that some dunes on Earth’s surface have morphologies which are consistent with modern climate, and others don’t. Here we employ topography and climate data to quantify the timescales of dune readjustment and climate persistence for the Rub' al Khali. We find a diversity of cases: some where climate has been remarkably consistent through the glacial cycles, some where climate has changed but dune morphology has equilibrated to modern climate, and some where dune morphology represents an old climate and not modern climate. These results are synthesized in a framework that allows us to delineate the size below which dune morphology represents modern climate, and above which it still remembers a different past climate. bIO
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15.20 - 15.45
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Afternoon tea break (coffee, tea and snacks available)
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15.45 - 16.10
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Tim Ziegler, Vertebrate Palaeontology (Collections Manager - Melbourne Museum)
A new Pleistocene vertebrate fossil locality informing palaeoenvironment and ecology in subaerial Naarm (Port Phillip) AbSTRACT
The Werribee Fan is a newly recognised, diverse vertebrate fossil deposit from an outcropping of the Pleistocene Deutgam Silt near Cocoroc, Victoria. This local fauna differs markedly in its patterns of abundance and correlation from proximal fossil localities at Keilor, Lancefield, and the Western District Lakes. The dominance of browsing marsupials, particularly among the largest taxa, is suggestive of a heretofore unobserved habitat or depositional context for a southern Victorian fossil site. Taphonomic evidence supports a model of deposition within an oxygenated, low-energy terrestrial subaquatic environment. The Werribee Fan Local Fauna potentially represents the fauna and ecosystem that occupied an unflooded Naarm (Port Phillip) during a Late Pleistocene glacial interval. It can inform palaeoecological reconstructions of faunal dispersal across the newly emergent Bassian land-bridge and illustrate subaerial Naarm’s ecosystem immediately prior to, or coincident with First Peoples’ presence in south-eastern Australia. Avenues for further research on chronology, habitat, climate, and landscape geomorphology are presented. To date, the following taxa are recognised from the site: Palorchestes azael; Palorchestes cf. parvus; Diprotodontidae cf. Diprotodon optatum; Macropus giganteus; M. g. titan; Notamacropus rufogriseus; Protemnodon anak; Protemnodon cf. mamkurra; Procoptodon rapha; Sthenurus andersoni; Sthenurinae cf. Simosthenurus, Vombatus ursinus; Lasiorhinus krefftii; Thylacoleo carnifex; Sarcophilus laniarius and Aves cf. Megapodiidae. Other small to medium (critical weight range) marsupials represented are yet indeterminate to species. bIO
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16.10 - 16.35
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Dr. Levan Tielidze, Glaciology (Monash University)
Late Quaternary glacier-climate reconstructions from the Southern Alps, New Zealand AbSTRACT
Using geomorphological mapping and sixty-six cosmogenic 10Be surface exposure ages obtained from ice sculpted bedrock surfaces and deposited moraine landforms, we constrain the local Last Glacial Maximum and subsequent timing of last glacial termination in the Ahuriri River valley, Southern Alps of New Zealand. Using the maximum elevation of lateral moraine (MELM) and accumulation area ratio (AAR) methods, along with application of a temperature lapse rate, we estimate the equilibrium-line altitude (ELA) and associated temperatures from the same periods. The largest glacial event in the Ahuriri River valley occurred at 19.8±0.3 ka when the former Ahuriri Glacier reached its maximum extent, which coincides with the global Last Glacial Maximum. By 16.7±0.3 ka, ice had retreated ~18 km up-valley from the LGM position and deglaciation was accompanied by the formation of a shallow proglacial lake. Surface exposure ages from moraines situated in a tributary of the upper Ahuriri River valley indicate that a subsequent advance of the palaeo glacier culminated at 14.5±0.3 ka, while the next readvance or still stand occurred at 13.6±0.3 ka. About 1000 yr later (12.6±0.2 ka), the former glacier built another prominent terminal moraine ridge in the lower section of the upper right tributary valley. Reconstructions of past glacier geometries indicate that the local ELA was depressed by ~880 m and climate was 5±1 °C colder than present (1981–2010) at 19.8±0.3 ka, while ELA was depressed by ~770 m and climate was 4.4±0.9 °C colder at 16.7±0.3 ka. Subsequent estimations suggest ELA elevations at 14.5±0.3 ka, 13.6±0.3 ka, and 12.6±0.2 ka were ≤700 m, ≤630 m, and ~360 m lower than today. This equates to air temperatures of ≤3.9 °C, ≤3.5 °C, and 2.3±0.7 °C colder than today, assuming no changes in past precipitation. The new constraints from glacial records in the Ahuriri River valley offer the opportunity to test hypotheses about the climate system, to better understand the processes that drove ice retreat and readvance during the Last Glacial Maximum and subsequent termination. bIO
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16.35 - 15.00
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Dr. Josephine Brown, Atmospheric Science (University of Melbourne)
What past climates can tell us about the future: a modelling perspective AbSTRACT
Climate models can be used to simulate a range of past climates as well as providing projections of future climate. Simulations of past warm climates such as the Pliocene can be compared with reconstructions to evaluate changes in rainfall and atmospheric circulation, providing detailed information about the last time that greenhouse gases were at current levels. We can also use simulations of Holocene and glacial climates to examine changes in regional climate features such as the Australian monsoon in response to altered seasonal and annual average temperatures. Model results from the Australian ACCESS-ESM1.5 model are compared with results from the Paleoclimate Modelling Intercomparison Project to identify common model responses to past changes, including shifts in tropical and subtropical climates over the Australian region. bIO
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15.00 - 18.00
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Drinks and nibbles
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18.00 - 19.00
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Professor Kliti Grice, Geochemistry (Curtin University)
Selwyn Keynote, Public Lecture Title TBC AbSTRACT
TBC bIO
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19.30
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Symposium Dinner
Café Corretto, Lygon St, Carlton (registration required, additional cost) |
Convenors: Dr Anne-Marie Tosolini, Dr Vera Korasidis, Dr Ashleigh Hood
