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New Reference Materials,Analytical Procedures and Data Reduction Strategies for Sr Isotope Measurements in Geological Materials by LA-MC-ICP-MS |
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| Authors: | Jacob Mulder Graham Hagen-Peter Teresa Ubide Rasmus Andreasen Ellen Kooijman Melanie Kielman-Schmitt Yue-Xing Feng Bence Paul Andreas Karlsson Christian Tegner Charles Lesher Fidel Costa |
| Institution: | 1. School of Earth and Environmental Sciences, The University of Queensland, Queensland, Australia;2. Department of Geoscience, Aarhus University, Denmark
Geological Survey of, Norway;3. Department of Geoscience, Aarhus University, Denmark;4. The Vegacenter, Swedish Museum of Natural History, Sweden;5. Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China;6. School of Geography, Earth and Atmospheric Sciences, The University of Melbourne, Victoria, Australia Elemental Scientific Lasers, LLC. Bozeman, Montana, USA;7. Department of Geoscience, Aarhus University, Denmark Department of Earth and Planetary Sciences, University of California, Davis, California, USA;8. Institut de Physique du Globe de Paris, France |
| Abstract: | Laser ablation multi-collector mass spectrometry (LA-MC-ICP-MS) has emerged as the technique of choice for in situ measurements of Sr isotopes in geological minerals. However, the method poses analytical challenges and there is no widely adopted standardised approach to collecting these data or correcting the numerous potential isobaric inferences. Here, we outline practical analytical procedures and data reduction strategies to help establish a consistent framework for collecting and correcting Sr isotope measurements in geological materials by LA-MC-ICP-MS. We characterise a new set of plagioclase reference materials, which are available for distribution to the community, and present a new data reduction scheme for the Iolite software package to correct isobaric interferences for different materials and analytical conditions. Our tests show that a combination of Kr-baseline subtraction, Rb-peak-stripping using βRb derived from a bracketing glass reference material, and a CaCa or CaAr correction for plagioclase and CaCa or CaAr + REE2+ correction for rock glasses, yields the most accurate and precise 87Sr/86Sr measurements for these materials. Using the analytical and correction procedures outlined herein, spot analyses using a beam diameter of 100 μm or rastering with a 50–65 μm diameter beam can readily achieve < 100 ppm 2SE repeatability ("internal") precision for 87Sr/86Sr measurements for materials with < 1000 μg g-1 Sr. |
| Keywords: | laser ablation-inductively coupled plasma-mass spectrometry isotopes microanalysis reference material strontium multi-collector ICP-MS interference correction in situ techniques |