An inter-laboratory comparison of cosmogenic 3He and radiogenic 4He in the CRONUS-P pyroxene standard |
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| Institution: | 1. CRPG, Université de Lorraine, UMR 7358, CNRS, Vandoeuvre-lès-Nancy, France;2. Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA, USA;3. Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA;4. Deutsches GeoForschungsZentrum GFZ, Potsdam, Germany;5. Lamont-Doherty Earth Observatory, Geochemistry, Palisades, NY, USA;6. Department of Earth and Environmental Sciences, Columbia University, New York, NY, USA;7. Department of Geosciences, NSF Arizona AMS Laboratory, Tucson, AZ, USA;8. School of Mathematics and Statistics, University of Glasgow, Glasgow, Scotland, UK;9. Department Earth and Planetary Science, University of California, Berkeley, CA, USA;10. Scottish Universities Environmental Research Centre, Glasgow, UK;1. Graduate School “Human Development in Landscapes”, University Kiel, Neufeldstraße 10, D-24118 Kiel, Germany;2. Landesamt für Denkmalpflege, Dendrochronologisches Labor, Fischersteig 9, D-78343 Hemmenhofen, Germany;1. Department of Applied Physics, Okayama University of Science, Okayama, 700-0005, Japan;2. Humanities and Social Sciences, Nara Women''s University, Nara, 630-8506, Japan;3. Department of Environmental Systems, Rissho University, Kumagaya, 360-0194, Japan;1. Institute for Nuclear Physics, University of Cologne, Germany;2. Division for Nuclear Chemistry, University of Cologne, Germany;1. Department of Ecological Sciences, Millennium Institute of Ecology and Biodiversity, Center for Climate Research and Resilience, and Millennium Nucleus Paleoclimate of the Southern Hemisphere, Universidad de Chile, Santiago, Chile;2. School of Earth and Climate Sciences and Climate Change Institute, University of Maine, Orono, ME 04469, USA;3. Observatorio Volcanológico de los Andes del Sur, Servicio Nacional de Geología y Minería, Temuco, Chile;4. Department of Geology, University of Cincinnati, Cincinnati, 500 Geology/Physics Building, Cincinnati, OH 45221, USA;5. Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY, USA |
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| Abstract: | This study reports an inter-laboratory comparison of the 3He and 4He concentrations measured in the pyroxene material CRONUS-P. This forms part of the CRONUS-Earth and CRONUS-EU programs, which also produced a series of natural reference materials for in situ produced 26Al, 10Be, 14C, 21Ne and 36Cl.Six laboratories (GFZ Potsdam, Caltech Pasadena, CRPG Nancy, SUERC Glasgow, BGC Berkeley, Lamont New York) participated in this intercomparison experiment, analyzing between 5 and 22 aliquots each. Intra-laboratory results yield 3He concentrations that are consistent with the reported analytical uncertainties, which suggests that 3He is homogeneous within CRONUS-P. The inter-laboratory dataset (66 determinations from the 6 different labs) is characterized by a global weighted mean of (5.02 ± 0.12) × 109 at g−1 with an overdispersion of 5.6% (2σ). 4He is characterized by a larger variability than 3He, and by an inter-lab global weighted mean of (3.60 ± 0.18) × 1013 at g−1 (2σ) with an overdispersion of 10.4% (2σ).There are, however, some systematic differences between the six laboratories. More precisely, 2 laboratories obtained mean 3He concentrations that are about 6% higher than the clustered other 4 laboratories. This systematic bias is larger than the analytical uncertainty and not related to the CRONUS-P material (see Schaefer et al., 2015). Reasons for these inter-laboratory offsets are difficult to identify but are discussed below. To improve the precision of cosmogenic 3He dating, we suggest that future studies presenting cosmogenic 3He results also report the 3He concentration measured in the CRONUS-P material in the lab(s) used in a given study. |
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| Keywords: | Cosmogenic Radiogenic CRONUS-P Standard Calibration |
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