Abstract
Cosmogenic Ne isotopes are used for constraining the timing and rate of cosmological and Earth surface processes. We combined an automated gas extraction (laser) and purification system with a Thermo Fisher ARGUS VI mass spectrometer for high through-put, high precision Ne isotope analysis. For extra-terrestrial material with high cosmogenic Ne concentrations, we used multi-collection on Faraday detectors. Multiple measurements (n = 26) of 1.67 × 10−8 cm3 air-derived 20Ne yielded an uncertainty of 0.32%, and 21Ne/20Ne = 0.17% and 22Ne/20Ne = 0.09%. We reproduced the isotope composition of cosmogenic Ne in the Bruderheim chondrite and Imilac pallasite in a sub-ten mg sample. For lower Ne amounts that are typical of terrestrial samples, an electron multiplier detector was used in peak jumping mode. Repeated analysis of 3.2 × 10−11 cm3 STP 20Ne from air reproduced 21Ne/20Ne and 22Ne/20Ne with 1.1% and 0.58%, respectively, and 20Ne intensity with 1.7% (n = 103) over a 4-month period. Multiple (n = 8) analysis of cosmogenic Ne in CREU-1 quartz yielded 3.25 ± 0.24 × 108 atoms/g (2 s), which overlaps with the global mean value. The repeatability is comparable to the best data reported in the international experiments performed so far on samples that are 2–5× smaller. The ability to make precise Ne isotope determinations in terrestrial and extra-terrestrial samples that are significantly smaller than previously analysed suggests that the new system holds great promise for studies with limited material.
Highlights
Cosmogenic Ne was proven to be an adept recorder of the timing and rates of surface processes on the Earth and Moon [1,2,3] and the time of meteorite release from parent bodies [4]
Improvements in mass spectrometry in the last ten years, in particular the ability to resolve some of main isobaric interferences [8,9,10], will lead to better and faster cosmogenic Ne determinations
We report the use of a Thermo Fisher ARGUS VI mass spectrometer with an automated gas extraction and purification system for the determination of cosmogenic Ne in both extra-terrestrial and terrestrial material
Summary
Cosmogenic Ne was proven to be an adept recorder of the timing and rates of surface processes on the Earth and Moon [1,2,3] and the time of meteorite release from parent bodies [4]. We report the use of a Thermo Fisher ARGUS VI mass spectrometer with an automated gas extraction and purification system for the determination of cosmogenic Ne in both extra-terrestrial and terrestrial material. It is a low resolution instrument [11], which requires low background levels and a good understanding of isobaric interferences [6]. We demonstrate the multi-collection Faraday technique with new analysis of cosmogenic Ne in sub-ten mg samples of Bruderheim chondrite and Imilac pallasite and the peak-jumping CDD analysis of 19.9 mg aliquots of CREU-1 quartz. We use this study to demonstrate how significant reduction in sample size affects uncertainty and the implication of that in cosmogenic Ne dating
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