Ikaite nucleation at 35 °C challenges the use of glendonite as a paleotemperature indicator.

ABSTRACT: 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. Therefore, glendonites in the sedimentary record are commonly used as paleotemperature indicators. However, several laboratory experiments have shown that the mineral can nucleate 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 durati

SUBMITTER: Tollefsen E 

PROVIDER: S-EPMC7235076 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature