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

Abstract

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 d 34 S 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 34 S/ 32 S was 0.3‰ (2s, n = 318), which is the same as that of the well-characterised pyrite reference materials PPP-1 and UWPy-1. Its d 34 S value determined by gas mass spectrometry was 1.5 ± 0.1‰ (2s, n = 11), which agrees with the SIMS data (1.5 ± 0.3‰, 2s) calibrated by pyrrhotite reference material Po-10. Therefore, YP136 pyrrhotite is considered a candidate reference material for in situ sulfur isotope determination.

A new synthesis scheme of pyrite and chalcopyrite reference materials for in situ iron and sulfur isotope analysis using LA-MC-ICP-MS

“…In addition, the d 34 S V-CDT values of pyrite PPP-1 and pyrrhotite YP136 were determined by fs-LA-MC-ICP-MS, and PAS-Cpy600 was used as the external standard. The measured d 34 S V-CDT values of PPP-1 and PY136 are 5.46 AE 0.33& (2SD, n ¼ 10) and 1.45 AE 0.09& (2SD, n ¼ 10), which are consistent with the reference values of 5.30 AE 0.20& (Gilbert et al 21 ) and 1.50 AE 0.06& (Li et al 40 ), respectively. These results are listed in Tables S8 and S9, † and also prove the analytical feasibility based on our new synthesis standards.…”

“…Natural pyrites Aa018 and LY from Chen et al, 27 and pyrrhotite JC-Po and pentlandite JC-Pn from Chen et al 17 were used as the reference materials for in situ Fe isotope analysis. Pyrite PPP-1 from Gilbert et al 21 and pyrrhotite YP136 from Li et al 40 were used for in situ S isotope analysis.…”

“…Then the d 34 S YP136 was converted to d 34 S V-CDT , based on the d 34 S V-CDT value of YP136 ¼ 1.5 AE 0.1&. 40 The S isotope data reduction was also conducted using ISO-Compass soware. 50 The measurement results of PPP-1 were 5.36 AE 0.31& (2SD, n ¼ 30), which were consistent with reference value within the uncertainty (Table S2 †).…”

“…12 and 13) and PPP-1, 21 pyrrhotite YP136 (ref. 40) and JC-Po, 17 pentlandite JC-Pn, 17 State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan, 430074, PR China. E-mail: tuyaken@hotmail.com; Fax: +86-27-67885096; Tel: +86-27-67885096 † Electronic supplementary information (ESI) available: (A) The photographs of chalcopyrite HTS4-6, 20 GC, 14 Cpy-1 (ref.…”

Oxygen isotope homogeneity assessment for apatite U‐Th‐Pb geochronology reference materials

“…External spot error was calculated as the quadratic sum of the internal spot precision, and the standard deviation on the repeated analyses of the normalising reference material. If the MSWD ≤1, the sample is considered isotopically homogeneous within uncertainty . The MSWD of all GEMS 203 (0.75), Kovdor (0.81), and McClure (0.89) are <1, which indicates O‐isotopic homogeneity within the measurement precision.…”