Rb, Sr, Sm and Nd elemental concentrations and Sr and Nd isotopic ratios of 13 Chinese rock reference materials using isotope dilution TIMS and MC–ICP–MS

Abstract

The suitability of 13 Chinese silicate rock certified reference materials for Sr and Nd isotope analyses was investigated. To indicate their homogeneity and to provide information values, we report Sr and Nd isotopic data and Rb, Sr, Sm and Nd concentrations for reference materials GBW07 103–105, 109–113 and 121–125 spanning a broad compositional range. Test portions were spiked with tracers enriched in ⁸⁷Rb–⁸⁴Sr and ¹⁴⁹Sm–^145,146,150Nd and digested using HF, HNO₃, and HClO₄ acid-dissolution procedures. Chemical purification involved cation-exchange and HEHEHP or Ln resins. Analyses involved different instruments at four laboratories, including thermal ionisation mass spectrometry (TIMS) and multicollector–inductively coupled plasma–mass spectrometry (MC–ICP–MS). This study provides a comprehensive report of the Rb–Sr and Sm–Nd isotopic compositions of the reference materials, and the results indicate that the materials are comparable to those of well-characterised and widely utilized reference materials from the US Geological Survey and the Geological Survey of Japan. This is the first report of the Sr and Nd isotopic composition of standards GBW07111, GBW07112, GBW07121, GBW07122, GBW07123, GBW07124 and GBW07125. Our results are useful for quality control and assurance between laboratories and provide a robust reference-rock dataset for future studies involving classical Sr and Nd isotopic geochemistry.