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Rhenium–Osmium Isotope Measurements in Marine Shale Reference Material SBC ‐1: Implications for Method Validation and Quality Control
Author(s) -
Li Jie,
Yin Lu
Publication year - 2019
Publication title -
geostandards and geoanalytical research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.037
H-Index - 73
eISSN - 1751-908X
pISSN - 1639-4488
DOI - 10.1111/ggr.12267
Subject(s) - aqua regia , chemistry , oil shale , mass spectrometry , mineralogy , digestion (alchemy) , chondrite , rhenium , isotope , analytical chemistry (journal) , geology , environmental chemistry , chromatography , metal , meteorite , inorganic chemistry , paleontology , physics , organic chemistry , astronomy , quantum mechanics
In this study, the USGS black shale reference material SBC ‐1 was investigated as a matrix‐matched reference material for both intra‐laboratory calibration and inter‐laboratory comparison of high‐precision Re‐Os dating for organic‐rich sedimentary rocks. This reference material was analysed for Re‐Os isotopic composition by three digestion protocols – inverse aqua regia , CrO 3 ‐H 2 SO 4 and H 2 O 2 ‐ HNO 3 . The results for SBC ‐1 obtained by inverse aqua regia digestion yielded similar Re mass fractions but slightly (~ 5%) higher Os mass fractions and lower 187 Os/ 188 Os values than the CrO 3 ‐H 2 SO 4 and H 2 O 2 ‐ HNO 3 digestions. The data set of inverse aqua regia digestion exhibited strong correlations in plots of 187 Os/ 188 Os vs. 1/ 192 Os and 187 Os/ 188 Os vs. 187 Re/ 188 Os, which may signify the incorporation of detrital Re and Os into organic matter in the Re‐Os system. Similar correlations were also observed for the CrO 3 ‐H 2 SO 4 digestion data set, but not for that of H 2 O 2 ‐ HNO 3 . The data indicate that there is an amount of non‐hydrogenous Os in SBC ‐1 and that CrO 3 ‐H 2 SO 4 and H 2 O 2 ‐ HNO 3 digestions would minimise liberation of the non‐hydrogenous Os component. We propose that SBC ‐1 may be a more suitable reference material to monitor the influence of detrital Re and Os on Re‐Os isochron age data, especially for samples with less organic matter and more siliceous detritus.