Tidal dynamics drive ooid formation in the Capricorn Channel since the Last Glacial Maximum

Katherine C. Lee*, Jody M. Webster, Tristan Salles, Eleanor E. Mawson, Jon Hill

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Relative sea-level changes can dramatically alter coastal geomorphology and coastlines, which, in turn, can fundamentally alter tidal regimes. The Great Barrier Reef (GBR) has undergone around 120 m of relative sea level (RSL) rise since the Last Glacial Maximum, ∼20,000 years ago (ka). Ooid grains (sand sized carbonate sediment) that formed in shallow water (>5 m depth) and under prolonged hydrodynamics forcing are now found at depth ranging between 100 and 120 m under the present day GBR Gulf of Capricorn. The apparent inconsistency between preferential conditions for their formation and the actual environment where they are found at present-day could be used to infer past regional hydrodynamic conditions. Here, we focus on the regional changes in the GBR tidal dynamics over the last 16.8 ka to show that sea-level rise on the GBR has caused significant changes on tidal patterns and dynamics. To do so, we used the first multi-scale palaeo-tidal finite element coastal tidal model of the GBR over five time slices (present day, ∼10 ka, ∼12 ka, ∼15 ka and 16.8 ka), representing the position of RSL at 0 m, 20 m, 45 m, 75 m and 96 m below present. We show that favourable conditions for ooid formation only existed for a short period of time between 16.8 and 11 ka. At that time, the Gulf of Capricorn was a wide shallow shelf with strong currents constantly agitating grains, providing rapid burial, exposure and re-burial cycles. We show that these conditions only existed for a short period of time and hence explain the presence of ooid grain formation in the GBR at that time. We propose ooids formed within the Capricorn Channel at a time of lower RSL than expected and then underwent sub-tidal transportation to their final deposition place via tidal currents, explaining the inconsistency with their age and the depth at which they were found.

Original languageEnglish
Article number106944
Number of pages11
JournalMarine Geology
Early online date24 Nov 2022
Publication statusPublished - 1 Dec 2022

Bibliographical note

Funding Information:
KCL acknowledges the NERC ACCE DTP for funding. The authors would like to thank the two anonymous reviewers for their comments. This project was undertaken on the Viking Cluster, which is a high performance compute facility provided by the University of York. We are grateful for computational support from the University of York High Performance Computing service, Viking and the Research Computing team.

Publisher Copyright:
© 2022 The Authors


  • Great Barrier Reef
  • Numerical model
  • Ooids
  • Palaeotides
  • Sediment

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