Abstract


THE EVOLUTION OF THE GREAT BARRIER REEF OVER THE PAST 30 KA - NEW INSIGHTS FROM IODP EXPEDITION 325

Sediments cored from the shelf edge of the Great Barrier Reef (GBR) during Integrated Ocean Drilling Program (IODP) Expedition 325 constrain the evolution of the GBR over the past 30 ka. This was a period of abrupt and major environmental perturbations, and responses of the GBR to these changes are largely unknown. We investigate the geomorphic, chronostratigraphic and biologic development of the GBR from 30 to 10 ka, using all available multibeam, seismic, C14 and U-Th dating, sedimentologic, and coralgal assemblage data. We define five distinct reef sequences over the past 30 ka, and discuss their chronostratigraphic development and paleoenvironmental settings. We document a highly dynamic system characterized by recurrent growth and demise of reef sequences as sea level fell to the Last Glacial Maximum (LGM) and then flooded across the shelf during the deglaciation. A major reef drowning event before the establishment of the modern GBR was likely caused by poor water quality associated with increased shelf flooding and sediment flux during the rise. As a system of reefs, the GBR has a remarkable capacity to migrate both seawards and landwards, despite major changes in sea level (e.g., meltwater pulses) and sea surface temperatures. This capacity - and the ability to re-seed itself locally - suggests the GBR was more resilient than previously described. Finally, we discuss the broader implications of the Exp. 325 record for understanding global reef demise and resilience, and for constraining relative sea-level changes.

Authors

Webster, J. M., The University of Sydney, Australia, jody.webster@sydney.edu.au

Braga, J. C., Universidad de Granada, Spain, jbraga@ugr.es

Humblet, M., Nagoya University, Japan, humblet.marc@f.mbox.nagoya-u.ac.jp

Potts, D. C., University of California, Santa Cruz, USA, potts@ucsc.edu

Iryu, Y., Tohoku University, Japan, iryu@m.tohoku.ac.jp

Yokoyama, Y., University of Tokyo, Japan, yokoyama@aori.u-tokyo.ac.jp

Fujita, K., University of the Ryukyus, Japan, fujitaka@sci.u-ryukyu.ac.jp

Bourillot, R., Institut Polytechnique de Bordeaux, France, raphael.bourillot@ipb.fr

Esat, T. M., The Australian National University, Australia, Tezer.Esat@anu.edu.au

Fallon, S., The Australian National University, Australia, stewart.fallon@anu.edu.au

Thompson, W. G., Woods Hole Oceanographic Institution, USA, wthompson@whoi.edu

Thomas, T. L., University of Edinburgh, Australia, alex.thomas@ed.ac.uk

Kan, H., Kyushu University, Japan, kan@scs.kyushu-u.ac.jp

McGregor, H. V., University of Wollongong, Australia, mcgregor@uow.edu.au

Hinestrosa, G., The University of Sydney, Australia, The University of Sydney

Details

Oral presentation

Session #:34
Date: 06/23/2016
Time: 14:00
Location: 311

Presentation is given by student: No