HR: 1340h
AN: PP23B-1333    [Abstracts]
TI: Ground truthing Ordovician climate models using spatial analyses of chitinozoans and graptolites
AU: * Vandenbroucke, T
EM: Thijs.vandenbroucke@ugent.be
AF: Postdoctoral Fellow of the Research Foundation - Flanders, Research Unit Palaeontology, Ghent University, Krijgslaan 281 / S 8, Ghent, 9000, Belgium
AU: Armstrong, H
EM: h.a.armstrong@durham.ac.uk
AF: Palaeozoic Environments Group, Department of Earth Sciences, Science Labs, Durham, DH1 3LE, United Kingdom
AU: Williams, M
EM: mri@leicester.ac.uk
AF: Department of Geology, University of Leicester, University Road, Leicester, LE1 7RH, United Kingdom
AU: Zalasiewicz, J
EM: jaz1@leicester.ac.uk
AF: Department of Geology, University of Leicester, University Road, Leicester, LE1 7RH, United Kingdom
AB: Rapid and extreme changes in climate occurred during the middle to late Ordovician, culminating in one of the major glaciations of the Phanerozoic. The causal mechanisms and duration of the latter remain contentious and to date workers have largely relied on region-specific studies. Few climate simulation models for this time interval have been produced and new General Circulation Climate Models (GCMs) have yet to be tested. Here we examine the potential for using planktonic chitinozoans and graptolites as water mass indicators to ground truth Ordovician climate model predictions of ocean state. In the same way that Cenozoic and Mesozoic planktonic foraminifer and calcareous nannoplankton distributions can be used to track ocean surface and deep watermasses. At the core of our research strategy is the compilation of a high stratigraphical resolution biogeographical relational database of species occurrences, palaeoenvironmental and ocean-climate proxy data. This will be used to compile surface water (and where possible depth assemblage) palaeobiogeographic maps of chitinozoan and graptolite distributions. These can then be retro-tested against GCM maps of surface currents and used to identify latitudinal temperature/climate belts and gradient. We have identified the key time intervals which characterise the critical climate transitions as the N. gracilis graptolite Biozone (extreme greenhouse climate), the Boda Warm Event (Rawtheyan, "transitional") and the Hirnantian (icehouse climate). These are stratigraphically well-constrained and represented globally. In this poster we will present preliminary results from our analysis the gracilis Bizone timeslice. This will form a baseline condition for future research.
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
DE: 4944 Micropaleontology (0459, 3030)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting