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标题：Ikaite nucleation at 35 °C challenges the use of glendonite as a paleotemperature indicator
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作者：Elin Tollefsen ; Tonci Balic-Zunic ; Carl-Magnus Mörth 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2020
卷号：10
期号：1
页码：1-10
DOI：10.1038/s41598-020-64751-5
出版社：Springer Nature
摘要：Glendonites have been found worldwide in marine sediments from the Neoproterozoic Era to the Quaternary Period. The precursor of glendonite, ikaite (CaCO3 · 6H2O), is metastable and has only been observed in nature at temperatures 7 °C. Here we investigate the nucleation range for ikaite as a function of temperature and pH. We found that ikaite precipitated at temperatures of at least 35 °C at pH 9.3 −10.3 from a mixture of natural seawater and sodium carbonate rich solution. At pH 9.3, we observed pseudomorphic replacement of ikaite by porous calcite during the duration of the experiment (c. 5 hours). These results imply that ikaite can form at relatively high temperatures but will then be rapidly replaced by a calcite pseudomorph. This finding challenges the use of glendonites as paleotemperature indicators.