Publication Date:
2022-10-26
Description:
© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Wiedenbeck, M., Trumbull, R. B., Rosner, M., Boyce, A., Fournelle, J. H., Franchi, I. A., Halama, R., Harris, C., Lacey, J. H., Marschall, H., Meixner, A., Pack, A., von Strandmann, P. A. E. P., Spicuzza, M. J., Valley, J. W., & Wilke, F. D. H. Tourmaline reference materials for the In situ analysis of oxygen and lithium isotope ratio compositions. Geostandards and Geoanalytical Research, (2020), doi:10.1111/ggr.12362.
Description:
Three tourmaline reference materials sourced from the Harvard Mineralogical and Geological Museum (schorl 112566, dravite 108796 and elbaite 98144), which are already widely used for the calibration of in situ boron isotope measurements, are characterised here for their oxygen and lithium isotope compositions. Homogeneity tests by secondary ion mass spectrometry (SIMS) showed that at sub‐nanogram test portion masses, their 18O/16O and 7Li/6Li isotope ratios are constant within ± 0.27‰ and ± 2.2‰ (1s), respectively. The lithium mass fractions of the three materials vary over three orders of magnitude. SIMS homogeneity tests showed variations in 7Li/28Si between 8% and 14% (1s), which provides a measure of the heterogeneity of the Li contents in these three materials. Here, we provide recommended values for δ18O, Δ’17O and δ7Li for the three Harvard tourmaline reference materials based on results from bulk mineral analyses from multiple, independent laboratories using laser‐ and stepwise fluorination gas mass spectrometry (for O), and solution multi‐collector inductively coupled plasma‐mass spectroscopy (for Li). These bulk data also allow us to assess the degree of inter‐laboratory bias that might be present in such data sets. This work also re‐evaluates the major element chemical composition of the materials by electron probe microanalysis and investigates these presence of a chemical matrix effect on SIMS instrumental mass fractionation with regard to δ18O determinations, which was found to be 〈 1.6‰ between these three materials. The final table presented here provides a summary of the isotope ratio values that we have determined for these three materials. Depending on their starting mass, either 128 or 512 splits have been produced of each material, assuring their availability for many years into the future.
Description:
JWV and MJS (University of Wisconsin) are supported by the U.S. National Science Foundation (EAR‐1524336) and Department of Energy (DE‐FG02‐93‐ER14389). MR acknowledges the use of the NSF‐supported WHOI ICP‐MS facility and thanks Larry Ball and Jerzy Blusztajn for their assistance. Analyses at Bristol were supported by NERC grant NER/C510983/1.
Finally, we wish to thank the Harvard Museum for ongoing support of such projects. Open access funding enabled and organized by ProjektDEAL.
Keywords:
Tourmaline
;
Lithium isotopes
;
Oxygen isotopes
;
Reference materials
;
SIMS
;
Matrix effect
Repository Name:
Woods Hole Open Access Server
Type:
Article
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