Non‐classical crystallization of very high magnesium calcite and magnesite in the Coorong Lakes, Australia

The Coorong Lakes, South Australia, are one of the models for unravelling the ‘Dolomite Problem’. Critically, today only a few modern environments remain where large quantities of very high magnesium calcite (VHMC; Ca0.5Mg0.5CO3; also described as protodolomite or disordered dolomite) and magnesite...

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Bibliographic Details
Published in:Sedimentology 2022-08, Vol.69 (5), p.2246-2266
Main Authors: Raudsepp, Maija J., Wilson, Sasha, Morgan, Bree, Patel, Avni, Johnston, Scott G., Gagen, Emma J., Fallon, Stewart J., Tosca, Nicholas
Format: Article
Language:English
Subjects:
Aragonite
Calcite
Calcium
Calcium carbonate
Calcium magnesium carbonate
Carbonate minerals
Carbonates
Chemical analysis
Chemical precipitation
Crystal lattices
Crystal structure
Crystallinity
Crystallites
Crystallization
Crystals
Dolomite
Dolostone
Electron microscopy
Evaporation
Laboratories
Laboratory experimentation
lacustrine carbonates
Lakes
Magnesite
Magnesium
Magnesium carbonate
Minerals
Morphology
Nanocrystals
non‐classical crystallization
Phases
Precipitation
Seawater
Sediments
Stromatolites
Surface water
Transmission electron microscopy
very high magnesium calcite
Water analysis
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Summary:The Coorong Lakes, South Australia, are one of the models for unravelling the ‘Dolomite Problem’. Critically, today only a few modern environments remain where large quantities of very high magnesium calcite (VHMC; Ca0.5Mg0.5CO3; also described as protodolomite or disordered dolomite) and magnesite (MgCO3) precipitate. Previously conducted laboratory studies demonstrate that carbonate minerals can precipitate via classical and non‐classical crystallization pathways. This study uses the preserved crystal sizes, morphologies and microstructures of Ca–Mg carbonates in the Coorong Lakes (Milne Lake, Pellet Lake and North Stromatolite Lake) to evaluate which crystallization pathway most likely occurred. In the fine‐grained sediments of these lakes, very high magnesium calcite and magnesite occur as aggregate particles of nanocrystals (
ISSN:0037-0746
1365-3091
DOI:10.1111/sed.12991