Hot off the press! Ooids, paleo-tides & sea level changes in the southern Great Barrier Reef


Please join me in congratulating GRG collaborator Katie Lee and the team on the publication of a new paper in the journal Marine Geology.

Lee, K.C., Webster, J.M., Salles, T., Mawson, E.E. and Hill, J., 2022. Tidal dynamics drive ooid formation in the CapricornChannel since the Last Glacial Maximum. Marine Geology, 454.


Marshall, J.F. and Davies, P.J., 1975. High-magnesium calcite ooids from the Great Barrier Reef. Journal of sedimentary petrology, 45(1): 285-291

This innovative study uses numerical simulations to explain the formation of these enigmatic carbonate grains ooids due to very strong tidal currents during lower sea levels following the end of the Last Ice Age across a large section of the southern Great Barrier Reef (GBR). We have known about these strange grains since the mid 1970s but by applying some sophisticated paleo-tide modelling at different lower sea level positions we’ve been able to explain why and where they formed in this area.


  • First palaeo numerical model of the Great Barrier Reef tidal systems.
  • Tidal dynamics have dramatically changed over the last 16,800 years.
  • It was possible for ooid grains to form ∼16,000 years ago on the Great Barrier Reef.
  • Our analysis suggests that ooid grains were formed away from the final deposition site.
  • Tidal dynamics of the Great Barrier Reef are strongly connected to sea level change.

ooid_3Moving forward our collaborative team (USYD, QUT, Geoscience Australia and several international partners) will investigate a wealth of new marine geophysical and samples data that we collected on recent expeditions (RV Falkor & RV Investigator) to the Capricorn Channel to better understand the evolution of the coast, shelf and coral reef system(s) since the Last Ice Age in this relatively poorly studied region of the GBR.

Bravo to Katie and the team!





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