ID-TIMS Sm-Nd and Sr Isotope Ratios of Reference Material Basalt Ribeirão Preto (BRP-1)

Abstract

This work presents Sm-Nd and Sr isotopic ratios of the BRP-1 (“Basalt Ribeirão Preto”) reference material (RM) based on repeated TIMS measurements over twelve years carried out by the LAGIR laboratory, Brazil. The BRP-1 RM was produced by the Brazilian Geological Survey from a ca. 130 Ma within-plate basalt, collected from a quarry near Ribeirão Preto city in the Paraná basin. Isotope ratios were measured using a TRITON mass spectrometer. Instrumental bias and fractionation corrections were performed based on repeated measurements of the certified RMs JNdi-1 and NIST SRM 987. The measured Nd and Sr isotopic ratios of BRP-1 are: ¹⁴³Nd/¹⁴⁴Nd = 0.512408 ± 0.000010 (2s), and ⁸⁷Sr/⁸⁶Sr = 0.706011 ± 0.000017 (2s). The mass fractions of Sm and Nd are 11.0 ± 0.2 and 51.9 ± 0.6 μg g^-1, respectively, showing no significant differences compared with the accepted values from the literature. No significant difference between measurements was observed, whether digesting samples in single or batch mode, using metal-jacketed PTFE bombs or PFA vials, or with or without the addition of a spike. The accuracy of these results was evaluated through the measurement of well-characterised USGS RMs, such as AGV-1, BCR-1, BHVO-1, G-2 and GSP-1.