Off-Mount Calibration and One New Potential Pyrrhotite Reference Material for Sulfur Isotope Measurement by Secondary Ion Mass Spectrometry

• Published in: Geostandards and Geoanalytical Research
• Main Authors: Li, Rucao, Xia, Xiaoping, Yang, Shenghong, Chen, Huayong, Yang, Qing
• Format: Report
• Language: English
• Published: WILEY 2019
• Subjects: Geochemistry & Geophysics; off-mount calibration; secondary ion mass spectrometry; pyrrhotite; reference material; sulfur isotopes; SULFIDE MINERALS; TRACE-ELEMENTS; PYRITE; SIMS; GOLD; DELTA-S-34; OXYGEN; Northern Finland
• Online Access: http://ir.gig.ac.cn/handle/344008/53037; https://doi.org/10.1111/ggr.12244

Sulfur isotope measurements in three sulfide (two pyrite and one pyrrhotite) samples on two epoxy mounts showed that the mount-to-mount variation of raw delta S-34 values was negligible when secondary ion mass spectrometry (SIMS) analytical settings remained stable. In consequence, an off-mount calibration procedure for SIMS sulfur isotope analysis was applied in this study. YP136 is a pyrrhotite sample collected from northern Finland. Examination of thin sections with a polarising microscope, backscattered electron image analyses and wavelength dispersive spectrometry mapping showed that the sample grains display no internal growth or other zoning. A total of 318 sulfur isotope (spot) measurements conducted on more than 100 randomly selected grains yielded highly consistent sulfur isotope ratios. The repeatability of all the analytical results of S-34/S-32 was 0.3 parts per thousand (2s, n = 318), which is the same as that of the well-characterised pyrite reference materials PPP-1 and UWPy-1. Its delta S-34 value determined by gas mass spectrometry was 1.5 +/- 0.1 parts per thousand (2s, n = 11), which agrees with the SIMS data (1.5 +/- 0.3 parts per thousand, 2s) calibrated by pyrrhotite reference material Po-10. Therefore, YP136 pyrrhotite is considered a candidate reference material for in situ sulfur isotope determination.