Inter‐laboratory Characterisation of Apatite Reference Materials for Chlorine Isotope Analysis

Słaby, Ewa
Wiedenbeck, Michael
Barnes, Jaime D.
Bonifacie, Magali
Sturchio, Neil C.
Bardoux, Gérard
Couffignal, Frédéric
Glodny, Johannes

Heraty, Linnea
John, Timm

Kusebauch, Christof
Mayanna, Sathish
Wilke, Franziska D. H.
Deput, Ewa
DOI: https://doi.org/10.1111/ggr.12366
Persistent URL: http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/8441
Wiedenbeck, Michael; 1GFZ German Research Centre for Geosciences Telegrafenberg Potsdam 14473 Germany
Barnes, Jaime D.; 3Department of Geological Sciences University of Texas Austin TX 78712 USA
Bonifacie, Magali; 4Institut de Physique du Globe de Paris CNRS Université de Paris Paris F‐75005 France
Sturchio, Neil C.; 6Department of Earth Sciences University of Delaware 255 Academy Street Newark DE 19716 USA
Bardoux, Gérard; 4Institut de Physique du Globe de Paris CNRS Université de Paris Paris F‐75005 France
Couffignal, Frédéric; 1GFZ German Research Centre for Geosciences Telegrafenberg Potsdam 14473 Germany
Glodny, Johannes; 1GFZ German Research Centre for Geosciences Telegrafenberg Potsdam 14473 Germany
Heraty, Linnea; 6Department of Earth Sciences University of Delaware 255 Academy Street Newark DE 19716 USA
John, Timm; 7Institut für Geologische Wissenschaften Freie Universität Berlin Malteserstrasse 74‐100 Berlin 12449 Germany
Kusebauch, Christof; 1GFZ German Research Centre for Geosciences Telegrafenberg Potsdam 14473 Germany
Mayanna, Sathish; 1GFZ German Research Centre for Geosciences Telegrafenberg Potsdam 14473 Germany
Wilke, Franziska D. H.; 1GFZ German Research Centre for Geosciences Telegrafenberg Potsdam 14473 Germany
Deput, Ewa; 2Institute of Geological Sciences Polish Academy of SciencesResearch Centre in Warsaw Twarda 51/55 Warsaw 00‐818 Poland
Abstract
Here we report on a set of six apatite reference materials (chlorapatites MGMH#133648, TUBAF#38 and fluorapatites MGMH#128441A, TUBAF#37, 40, 50) which we have characterised for their chlorine isotope ratios; these RMs span a range of Cl mass fractions within the apatite Ca10(PO4)6(F,Cl,OH)2 solid solution series. Numerous apatite specimens, obtained from mineralogical collections, were initially screened for 37Cl/35Cl homogeneity using SIMS followed by δ37Cl characterisation by gas source mass spectrometry using both dual‐inlet and continuous‐flow modes. We also report major and key trace element compositions as determined by EPMA. The repeatability of our SIMS results was better than ± 0.10% (1s) for the five samples with > 0.5% m/m Cl and ± 0.19% (1s) for the low Cl abundance material (0.27% m/m). We also observed a small, but significant crystal orientation effect of 0.38% between the mean 37Cl/35Cl ratios measured on three oriented apatite fragments. Furthermore, the results of GS‐IRMS analyses show small but systematic offset of δ37ClSMOC values between the three laboratories. Nonetheless, all studied samples have comparable chlorine isotope compositions, with mean 103δ37ClSMOC values between +0.09 and +0.42 and in all cases with 1s ≤ ± 0.25.
Key Points:
Six apatite reference materials having various Cl mass fractions were characterised for chlorine isotope ratios by SIMS and three GS‐IRMS laboratories.
A small, but significant, crystal orientation effect was recorded by SIMS analyses.
Correlation of instrumental mass fractionation factor with Cl mass fraction is visible along the apatite solid solution series.
Subjects
chlorine isotopesapatite
matrix effect
crystal orientation effect
secondary ion mass spectrometry