IODP-359_Data_SSN
Description
The dataset contains 20 Ma long records of stable oxygen isotope (δ¹⁸O) from planktic foraminifera and trace metal geochemistry from bulk sediment samples. The sediment samples were collected during International Ocean Discovery Program (IODP) Expedition 359 (Sites U1467 and U1468) from the Maldives Inner Sea, situated in the western equatorial Indian Ocean.
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For the trace metal analysis, the marine sediment samples were acid digested in an acid mixture composed of hydrofluoric acid (HF), nitric acid (HNO₃), and perchloric acid (HClO₄) in a ratio of 7:3:1, respectively and analysed in High Resolution – Inductively Coupled Plasma – Mass Spectrometer (HR-ICP-MS) (Nu Instruments Attom ES series) at the CSIR-National Institute of Oceanography, Goa, India. To ensure the accuracy and reliability of the analytical results, marine sediment (PACS-3), National Research Council of Canada, was utilized as standard reference material. This standard was measured after every 10 samples, which yielded an accuracy of better than 5%. The precision of the data was better than ±2.5% for all the elements, calculated from duplicate samples. For stable oxygen isotope analysis, planktic foraminifera shells of Globigerinoides ruber (G. ruber) and Trilobatus quadrilobatus (T. quadrilobatus) were handpicked in the size range of 250–355 μm using a stereo-zoom binocular microscope (Meiji Techno EMZ-5). The anlysis was done on Thermo Fisher Scientific Delta V Plus Isotope Ratio Mass Spectrometer (IRMS) coupled with a ConFlo IV and a Gasbench II at the Indian Institute of Tropical Meteorology, Pune, India. The international standards NBS18, and NBS19 were used. The long-term external accuracy of δ18O is 0.1 ‰ (1 standard deviation) or better.