Japan Geoscience Union Meeting 2019

Presentation information

[J] Oral

M (Multidisciplinary and Interdisciplinary) » M-TT Technology & Techniques

[M-TT48] Frontiers in Geochemistry

Sun. May 26, 2019 1:45 PM - 3:15 PM 201A (2F)

convener:Hirochika Sumino(Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo), Tetsuya Yokoyama(Department of Earth and Planetary Sciences, School of Science, Tokyo Institute of Technology), Hajime Obata(Marine inorganic chemistry division, Atmosphere and Ocean Research Institute, University of Tokyo), Chairperson:Hirochika Sumino, Hajime Obata(Atmosphere and Ocean Research Institute, University of Tokyo), Tetsuya Yokoyama(Tokyo Institute of Technology)

2:00 PM - 2:15 PM

[MTT48-02] Rapid in situ analyses of hydrogen and sulfur isotope ratios in basaltic glass by SIMS and their appilications

*Kenji Shimizu1, Takayuki Ushikubo1, Tomokazu Murai2, Fumihiro Matsuura2, Yuichiro Ueno2 (1.Kochi Core Center, Japan Agency for Marine-Earth Science and Technology, 2.Tokyo Institute of Technology)

Keywords:SIMS, hydrogen isotope, sulfur isotope, basaltic glass

We developed rapid and accurate in situ analyses of hydrogen and sulfur isotope ratios of basaltic glass using high-resolution, multi-collection secondary ion mass spectrometry (CAMECA IMS-1280HR). Hydrogen and sulfur isotopes of standard basaltic glasses were determined by a high-temperature conversion elemental analyzer/isotope ratio mass spectrometer (IRMS) and IRMS, respectively. For the in situ analysis of sulfur isotopes, a defocused Cs beam (~0.5 nA; ~10 µm diameter) was used, but for hydrogen isotopes, we used a larger defocused beam (~5 nA; ~15 µm diameter) to decrease the hydrogen background. For analyses of D/H (34S/32S) ratios, 16OH (32S) and 16OD (34S) were measured in multi-detection mode with a Faraday cup and an axial electron multiplier, respectively. Each measurement lasted 6–7 minutes. Precisions (2 standard errors) for D/H and 34S/32S ratios were ~6 ‰ (H2O > 1 wt%) and ~0.6 ‰ (S > 1000 ppm), respectively. Our developed method for rapid and high spatial resolution analysis can determine concentrations of volatiles, hydrogen and sulfur isotopes in a single small melt inclusion of ~30 µm diameter. Using this method, we analyzed hydrogen and sulfur isotope ratios of submarine basaltic glasses from mid-oceanic ridges and oceanic islands of Hawaii and confirmed that their D/H and S isotope ratios were consistent with reported values.