HOT OFF THE PRESS! Non-classical crystallisation of very high magnesium calcite and magnesite in the Coorong Lakes, Australia.

Please join me in congratulating GRG collaborator Dr Bree Morgan on the publication of her new paper in the journal Sedimentology.

Raudsepp, M. J., Wilson, S. A., Morgan, B., Patel, A., Johnston, S. G., Gagen, E. J., & Fallon, S. J. (2022). Non‐classical crystallization of very high magnesium calcite and magnesite in the Coorong Lakes, Australia. Sedimentology.

Every wondered why Ca-Mg carbonates do not always precipitate from solution they are supersaturated in? This new research explores the connection between the dolomite problem and the rare carbonate mineralogy found in the sediments of the Coorong Lakes, South Australia. It is a collaboration between the University of Alberta, the Geocoastal Research Group, South Cross Geosciences, The University of Queensland and the Australian National University.

Key Points of the Paper:

  • Presents new insights into the impact of crystallisation pathways on the ‘Dolomite Problem’
  • Demonstrates very high magnesium carbonate (VHMC, also referred to as protodolomite) and magnesite form via non-classical crystallisation in the Coorong Lakes
  • Highlights VHMC, dolomite and magnesite do not precipitate from waters they are supersaturated in due to undersaturation in amorphous calcium magnesium carbonate precursors
  • Shows nanocrystals in the Coorong Lakes are preserved in the top 1 m of sediment for up to 6000 years

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