The magnesium-to-calcium (Mg/Ca) and strontium-to-calcium (Sr/Ca) ratios in certified reference materials (CRMs) and natural carbonate samples have been analysed using an inductively coupled plasma optical emission spectrometer (ICP-OES) for method validation. The CRMs included ECRM 752-1, a limestone standard and NIST SRM 915a, a pure calcium carbonate standard, while the marine carbonates included planktonic foraminifera ( Globigerinoides ruber ) from the southeastern Arabian Sea and large benthic foraminifera ( Nummulites ) from the Palaeogene Jaisalmer Basin, Rajasthan, India. The study achieved high precision and accurate analysis of Mg/Ca and Sr/Ca ratios. The observed values for ECRM 752-1 were consistent with certified data, exhibiting relative standard deviations (RSD) of 2.15% for Mg/Ca and 2.07% for Sr/Ca. Further, the SST reconstructions from Mg/Ca measurements of G. ruber indicated a temperature increase of approximately 4°C from the Last Glacial Maximum (LGM) to the Holocene. In contrast, the lower Mg/Ca and Sr/Ca ratios in Nummulites suggest post-depositional alteration, emphasising the necessity of considering diagenetic effects before deriving palaeotemperature, particularly for deep geological past samples. The reliability of ICP-OES in generating quality geochemical data for palaeothermometry is emphasised.
Alam et al. (Thu,) studied this question.