Biotite Reference Materials for Secondary Ion Mass Spectrometry 18O/16O Measurements. Issue 2 (20th October 2016)

• Record Type: Journal Article
• Authors: Siron, Guillaume; Baumgartner, Lukas; Bouvier, Anne‐Sophie; Putlitz, Benita; Vennemann, Torsten
• Is Part Of: Geostandards and geoanalytical research. Volume 41:Issue 2(2017)
• Page Start: 243
• Page End: 253
• Publication Date: 2016-10-20
• Subjects: oxygen isotopes -- secondary ion mass spectrometry -- ion microprobe -- biotite -- reference material; Analytical geochemistry -- Periodicals; Géochimie analytique -- Périodiques; 551.9
• DOI: 10.1111/ggr.12148
• Languages: English
• ISSNs: 1639-4488

Abstract

Abstract : Five new biotite reference materials were calibrated at the SwissSIMS laboratory (University of Lausanne) for oxygen isotope determination by secondary ion mass spectrometry (SIMS) and are available to the scientific community. The oxygen isotope composition of the biotites, UNIL_B1 to B5, was determined by laser‐heating fluorination to be 11.4 ± 0.11‰, 8.6 ± 0.15‰, 6.1 ± 0.04‰, 7.1 ± 0.05‰ and 7.6 ± 0.04‰, respectively. SIMS analyses on spots smaller than 20 μm gave a measurement repeatability of 0.3‰ (2 standard deviation, 2 s ). The matrix effect due to solid solution in natural biotite could be expressed as a linear function of X Mg and X F for biotite. No effect was found for different crystallographic orientations. SIMS analysis allows the oxygen isotope composition of biotite to be measured with a measurement uncertainty of 0.3–0.4‰ (2 s ) for biotites with similar major element compositions. A measurement uncertainty of 0.5‰ (2 s ) is realistic when F poor biotites (lower than 0.2% m/m oxides ) within the compositional range of X Mg of 0.3–0.9 were compared from different sessions. The linear correlation with F content offers a reasonable working curve for F‐rich biotites, but additional reference materials are needed to confirm the model. Key Points: Matrix effect for biotite with low fluorine content (e.g., below 0.2% m/m oxides) can be modelled with X Mg only between 0.3 and 0.9. Matrix effect for biotite with variable F content require a multivariate correction scheme using X Mg and X F as variables. No crystal orientation effect was found at the level of precision of 0.3‰ (2 s ).