Precise determination of Sr and Nd isotopic compositions of Chinese Standard Reference samples GSR-1, GSR-2, GSR-3 and GBW07315 by TIMS

Abstract

In this contribution, the Sr and Nd isotopic compositions of four Chinese National Standards are investigated to verify whether they meet the requirements of international reference materials. Powdered samples were digested using conventional HF and HNO3 acid dissolution protocols, and chemical purification was performed using Sr Spec, AG 50W-X12 and LN resin. All measurements were carried out on a Thermal Ionization Mass Spectrometry (TIMS) at Laoshan Laboratory. We report Sr and Nd isotopic compositions of the four standards as the follows:

 GSR-1 (granite): ⁸⁷Sr/ ⁸⁶Sr = 0.738296 ± 0.000019 (2SD, n = 30), ¹⁴³Nd/ ¹⁴⁴Nd = 0.512210 ± 0.000012 (2SD, n = 17)

 GSR-2 (andesite): ⁸⁷Sr/ ⁸⁶Sr = 0.704929 ± 0.000012 (2SD, n = 45), ¹⁴³Nd/ ¹⁴⁴Nd = 0.512377 ± 0.000014 (2SD, n = 17)

 GSR-3 (basalt): ⁸⁷Sr/ ⁸⁶Sr =0.704093 ± 0.000010 (2SD, n = 52), ¹⁴³Nd/ ¹⁴⁴Nd = 0.512885 ± 0.000018 (2SD, n = 17)

 GBW07315 (marine sediment): ⁸⁷Sr/ ⁸⁶Sr =0.710261 ± 0.000011 (2SD, n = 15), ¹⁴³Nd/ ¹⁴⁴Nd = 0.512359 ± 0.000011 (2SD, n = 17)

 These results represent an extensive examination of the four Chinese geochemical rock materials. The long-term (half a year) results support that they are suitable to be used as reference materials for Sr and Nd isotopic compositions.