Assessment of hafnium and iron isotope compositions of Chinese national igneous rock standard materials GSR-1 (granite), GSR-2 (andesite), and GSR-3 (basalt)

In this contribution, we investigate the suitability of three igneous rock standards distributed by the Chinese Academy of Geological Sciences as international standard reference materials for Hf-Fe isotope determinations. We report Lu-Hf concentrations and Hf-Fe isotope compositions of Chinese National Standards (CNS) GSR-1 (granite), GSR-2 (andesite), and GSR-3 (basalt) in order to assess their homogeneity and give the first benchmark values. Experiments using spiked (isotope dilution) and non-spiked samples reveal an overall homogeneous Hf isotope composition for CNS GSR-2 and GSR-3 with 176Hf/177Hf = 0.282641 ± 6 (MSWD = 1.5, n = 10) and 0.282985 ± 04 (MSWD = 0.48, n = 10), respectively. In contrast to GSR-2 and GSR-3, two out of ten analyses of GSR-1 show elevated Hf concentrations in conjunction with less radiogenic Hf isotope compositions, considerably lower to -10.6 and -16.8