Assessment of Different Digestion Procedures for Mo Isotope Measurements of Black and Grey Shales Using the Double Spike Technique

Jin Li; Xiangkun Zhu; Suohan Tang

doi:10.1007/s12583-021-1520-1

Volume 33 Issue 1

Feb 2022

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Journal of Earth Science > 2022 > 33(1): 76-81.

Jin Li, Xiangkun Zhu, Suohan Tang. Assessment of Different Digestion Procedures for Mo Isotope Measurements of Black and Grey Shales Using the Double Spike Technique. Journal of Earth Science, 2022, 33(1): 76-81. doi: 10.1007/s12583-021-1520-1

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Jin Li, Xiangkun Zhu, Suohan Tang. Assessment of Different Digestion Procedures for Mo Isotope Measurements of Black and Grey Shales Using the Double Spike Technique. Journal of Earth Science, 2022, 33(1): 76-81. doi: 10.1007/s12583-021-1520-1

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Assessment of Different Digestion Procedures for Mo Isotope Measurements of Black and Grey Shales Using the Double Spike Technique

doi: 10.1007/s12583-021-1520-1

MNR Key Laboratory of Isotope Geology, MNR Key Laboratory of Deep-Earth Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China

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Corresponding author: Xiangkun Zhu, xiangkun@cags.ac.cn
Received Date: 02 Feb 2021
Accepted Date: 26 Jul 2021
Publish Date: 28 Feb 2022

Abstract

Abstract

This study investigates the behavior of Mo and Mo isotopes (δ⁹⁸Mo) in shales following leaching with HCl and HNO₃ with the aim of simplifying the shale dissolution procedure. Up to 6% of the Mo was lost and the Mo isotopes were unaffected when shales were leached using 9 M HCl after ashing. Bulk sample digestion or leaching by 4 M or more concentrated HCl after ashing were all found to be acceptable and reliable approaches to the analysis of Mo isotopes in shales. After black shale (CAGS-BS) was leached with 2 M HCl, 1 M HCl, and 9 M HNO₃, the Mo concentration ([Mo]) in the leachate was lower and δ⁹⁸Mo was heavier than that obtained from bulk digestion. A Mo isotope mass-balance model showed that the δ⁹⁸Mo in the residues was lighter than the δ⁹⁸Mo from the bulk digestion of CAGS-BS and of crustal igneous rocks. No more Mo was lost, nor did Mo isotope fractionation, if the double spike was added before rather than after ashing and followed by bulk digestion or leaching with 9 M HCl. For efficiency, leaching using 4 M or more concentrated HCl after ashing is preferred for Mo isotope measurements.
- Mo isotopes,
- double spike,
- ashing,
- bulk digestion,
- leaching

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References(31)

References

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Assessment of Different Digestion Procedures for Mo Isotope Measurements of Black and Grey Shales Using the Double Spike Technique

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