Abstract
In this contribution, we report the results for the characterization of the BB zircon, a newly developed zircon reference material from Sri Lanka, via secondary ion mass spectrometry (SIMS) and multiple-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS). The focus of this work was to further investigate the applicability of the BB zircon as a reference material for micro-beam analysis, including Li, O, and Hf isotopes. The SIMS analyses reveal that BB zircon is characterized by significant localized variations in Li concentration and isotopic ratio, which makes it unsuitable as a lithium isotope reference material. The SIMS-determined δ18O values are 13.81‰ ± 0.39‰ (2SD, BB16) and 13.61‰ ± 0.40‰ (2SD, BB40), which, combined with previous studies, indicates that there is no evidence of conspicuous O isotope heterogeneity within individual BB zircon megacrysts. The mean 176Hf/177Hf ratio of BB16 determined by solution MC-ICP-MS is 0.281669 ± 0.000012 (2SD, n = 29) indistinguishable from results achieved by laser ablation (LA)-MC-ICP-MS. Based on the SIMS and MC-ICP-MS data, BB zircon is proposed as a reference material for the O isotope and Hf isotope determination.
Highlights
Micro-beam analytical techniques, including secondary ion mass spectrometry (SIMS) and laser ablation multiple-collector inductively coupled plasma-mass spectrometry (LA-MC-ICP-MS), have been increasingly used by many laboratories world-wide for U–Pb geochronology [1,2,3] and for isotope geochemistry [4,5,6,7,8]
Li isotopes measured by SIMS are recognized as an important tracer in weathering processes in the crust and crustal recycling into the mantle [7,9], SIMS oxygen isotope data are applied to constrain petrogenetic conditions/mechanisms, magma sources, and any possible fluid-wall rock interactions [4,6,10], and hafnium isotopes analyzed via LA-MC-ICP-MS are considered as important tracers for magmatic processes and the evolution of global reservoirs [5,11]
The heterogeneity of Li isotopic compositions and concentrations revealed by this study indicates that BB zircon is unusable as a reference material for micro-beam Li isotopic analysis
Summary
Micro-beam analytical techniques, including secondary ion mass spectrometry (SIMS) and laser ablation multiple-collector inductively coupled plasma-mass spectrometry (LA-MC-ICP-MS), have been increasingly used by many laboratories world-wide for U–Pb geochronology [1,2,3] and for isotope geochemistry [4,5,6,7,8]. Li isotopes measured by SIMS are recognized as an important tracer in weathering processes in the crust and crustal recycling into the mantle [7,9], SIMS oxygen isotope data are applied to constrain petrogenetic conditions/mechanisms, magma sources, and any possible fluid-wall rock interactions [4,6,10], and hafnium isotopes analyzed via LA-MC-ICP-MS are considered as important tracers for magmatic processes and the evolution of global reservoirs [5,11]. A matrix-matched reference material is necessary for accurate micro-beam isotope measurements to correct for instrument-induced mass bias and to assess external reproducibility. A number of natural zircons were identified as reference materials by previous
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