Comprehensive Chemical and Isotopic Analyses of Basalt and Sediment Reference Materials

Abstract

International audienceGeochemical studies of geological samples require the precise determination of their major and trace element contents and, when measured, of their isotopic compositions. It is now commonly accepted that the accuracy and precision of geochemical analyses are best estimated by the concomitant analysis of international reference materials run as unknown samples. Although the composition of a wide selection of basalts is relatively well constrained, this is far from being the case for sedimentary materials. We present here a comprehensive set of major and trace element data as well as Nd, Hf, Sr and Pb isotopic compositions for thirteen commonly used international reference materials - eight magmatic rocks (BHVO-2, BR, BE-N, BR 24, AGV-1, BIR-1, UB-N, RGM-1) and five sediments (JLk-1, JSd-1, JSd-2, JSd-3, LKSD-1). We determined the concentrations of over forty elements in the magmatic rocks together with Sr, Nd, Hf and Pb isotopic compositions. Our trace element results were both accurate (difference ≤ 3%) and precise (reproducibility at 1s ≤ 3%) and the isotopic results were very similar to other published values. In contrast, we observed a significant chemical and isotopic variability in the sedimentary materials, which we attribute to mineral heterogeneities in the powders. Despite the limitation imposed by this heterogeneity, our work presents a complete set of data determined with a precision not yet achieved in the literature for sedimentary material. We also provide the first Nd, Hf and Pb isotopic measurements for the five sediments, which are commonly used by the geochemical community. Our study of both basalt and sediment reference materials represents a comprehensive and self-consistent set of geochemical data and can therefore be considered as a reference database for the community. Les études géochimiques des échantillons géologiques exigent la détermination précise de leurs teneurs en éléments majeurs et traces et, lorsqu'elle est mesurée, de leurs compositions isotopiques. Il est maintenant communément admis que l'exactitude et la précision des analyses géochimiques sont les mieux estimées par l'analyse simultanée, comme échantillons inconnus, de matériaux de référence internationaux. La composition d'une large sélection de basaltes est relativement bien contrainte, ce qui est loin d'être le cas pour les matériaux sédimentaires. Nous présentons ici un jeu complet de données d'éléments majeurs et traces ainsi que les compositions isotopiques du Nd, de l'Hf, du Sr et du Pb pour treize matériaux de référence internationaux couramment utilisés - huit roches magmatiques (BHVO-2, BR, BE-N, BR 24, AGV-1, BIR-1, UB-N, RGM-1) et cinq sédiments (JLk-1, JSD-1, JSD-2, JSD-3, LKSD-1). Nous avons déterminé les concentrations de plus de quarante éléments dans les roches magmatiques ainsi que leurs compositions isotopiques du Sr, du Nd, de l'Hf et du Pb. Nos résultats pour les éléments traces sont à la fois précis (différence ≤ 3%) et justes (reproducibilitéà 1s ≤ 3%) et les résultats isotopiques...

Combined petrological, geochemical and isotopic modeling of a plume source: Example of Gambier Island, Pitcairn chain

“…Trace elements were analyzed in Grenoble by Inductively Coupled Plasma Mass Spectrometry (ICP-MS), using an Agilent 7500ce and following the method described in Chauvel et al (2011). Both precision and reproducibility of the measurements were better than 5%, as confirmed by the repeated analyses of geological reference materials BEN and BHVO-2 run as unknown (see Table A1).…”

“…Most major element data were previously published by Caroff (1992) and Caroff et al (1993) but we had to obtain data for two samples. Those were measured by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) in Grenoble, using the method of Chauvel et al (2011). The signal was calibrated using BHVO-2.…”

“…Nd, Hf, Pb, and Sr were isolated using ion exchange chromatography techniques described in Chauvel et al (2011). Powders used to isolate Sr and Pb were strongly leached with HCl before dissolution.…”

Fred’s Flow (Canada) and Murphy Well (Australia): thick komatiitic lava flows with contrasting compositions, emplacement mechanisms and water contents

“…Trace elements were analysed using an Agilent 7500CE quadripole ICP-MS at the University of Grenoble following the method of Chauvel et al (2010). For 5 days at 140 °C, 100 mg of sample was dissolved in steel-jacketed Teflon bombs in a mixture of ultrapure concentrated HClO 4 and distilled 24N HF.…”

“…In the three analyses obtained at ISTerre, Grenoble, using the ICPMS method described by Chauvel et al (2010) (Supplementary material 4; Fig. 5), only the mobile elements such as Cs, Rb, Ba, Sr and Pb vary widely.…”