New System for Measuring Cosmogenic Ne in Terrestrial and Extra-Terrestrial Rocks

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 x 10(-8) cm(3) air-derived Ne-20 yielded an uncertainty of 0.32%, and Ne-21/Ne-20 = 0.17% and Ne-22/Ne-20 = 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 x 10(-11) cm(3) STP Ne-20 from air reproduced Ne-21/Ne-20 and Ne-22/Ne-20 with 1.1% and 0.58%, respectively, and Ne-20 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 x 10(8) 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 2-5x 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.

Automated summary

Cosmogenic Ne isotopes analysis was conducted using an automated gas extraction and high-throughput mass spectrometer, achieving high precision and repeatability. The system showed great promise for studies with limited material, providing accurate Ne isotope determinations for both terrestrial and extra-terrestrial samples.