Hot off the press! Sea-level change & reef development on Australia’s north-west shelf over the past 50,000 years

sliceHi All, please find below a new paper recently published in a Special Publication of the International Association of Sedimentologists (IAS).

Webster, J. M., Dechnik, B., Sanborn, K., Yokoyama, Y., Braga, J. C., Willem, R., Humblet, M., Beaman, R. J., Nothdurft, L., Webb, G. E., Jian-xin, Z., Murphy, R. J., Gallagher, Stephen J., O’Leary, M.J., Paumard, V. 2022. Coral reef development and sea-level changes over the past 50,000 years: new evidence from the northwest shelf of Australia. In: Coral Reefs and Sea-Level Change: Quaternary Records and Modelling (Eds G.F. Camoin and N. Hallmann), Int. Assoc. Sedimentol. Spec. Publ., 49, 215–273. https://doi.org/10.54780/iassp49/08

NWS_fig_1b

In this study we investigated a unique suite of sea-bed rock drill cores that were originally recovered for geotechnical surveys on the northwest shelf. Combining 3D seismic and multibeam bathymetry, with core logging, hyperspectral scanning, petrologic, mineralogic and sedimentary facies analysis, palaeoenvironmental reconstruction using reef assemblages and extensive radiometric dating, we explored reef development and sea-level changes over the past 50,000 years.NWS_fig6_coral

This paper represents an incredible team effort and it’s been great fun to integrate such diverse and rich data sets. Global sea level changes and ice sheet dynamics during Marine Isotope Stage 3 (MIS 3) continues to be controversial, and there are relatively few high quality coral reef records that span this interval around the world.

Highlights

  • 3D seismic-derived & multibeam bathymetry datasets record complex submerged landscapes (-60 to -110 mbsl) (multigeneration reefs, linear shorelines, tidal-estuarine settings)
  • Two drill transects record four chrono-stratigraphic units (Units 1-4) => internal consistent -75-106 mbsl, shallow to deep depositional reef/platform settings.
  • Application of sophisticated & multi proxy approach used (SEM, XRD and hyperspectral imaging) to reveal complex lithologic & diagenetic patterns.
  • Chronologic data (14C-AMS, U/Th ages) spans 7 to > 50 ka. Complex pattern of platform growth& demise (exposure) in response to repeated sea-level fluctuations MIS 4 to MIS 1.
  • 10-15 m thick coral reef development (Unit 2) during MIS 3; RSL ~63-75 mbsl during MIS 3 (45.95-39.23 + 0.2 ka) => consistent with RSL for Huon Penn.
  • Reef was unable to fully re-establish itself following deglacial reflooding, deeper rhodoliths (13.2-10.7 ka)=> RSL was too fast &/or poor paleowater quality.

This study represent the first step in an exciting new program of collaboration between the University of Sydney, University of Western Australia and industry partners to understand Plio-Pleistocene carbonate platform development, sea level and environmental changes on the northwest shelf and in comparison with ongoing work in the Great Barrier Reef.

We hope that this paper will be of interest to the wider scientific community working on coral reef growth and demise, sea level change and ice sheet dynamics during the relatively poorly constrained MIS3-4 intervals, submerged landscapes and human migration pathways in this fascinating region.

Please do not hesitate to contact me via email (jody.webster@sydney.edu.au) or Research Gate if you would like a PDF copy of this publication.

Cheers

Jody

#MarineScienceSydneyUni

NWS_fig12_chrono_strat

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