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<p><i>In situ</i> U-Pb dating of carbonates is very common in the fields of mining and petroleum geology. However, carbonate minerals generally have low U, high common Pb, multiple generations, and uneven elemental distribution, often resulting in relatively low dating precision. Hence, the success rate in U-Pb dating of carbonates by the traditional spot analysis method is generally low. This paper, through combining a mapping method for U-Pb dating with a proprietary visualization and analysis software, ChronoVA, conducted a comparison of the data obtained by both the spot analysis and the mapping method for 3 carbonate standards and 2 unknown natural geological samples. We successfully developed a U-Pb dating method for carbonate rocks via LA-SF-ICP-MS elemental mapping and discussed the advantages and limitations of this method. Results show that in comparison with the traditional spot analysis method, the mapping approach has the following advantages: (1) reducing the downhole fractionation effect; (2) simplifying the analytical processes; (3) the elemental imaging data can help to identify multi-generation and mineral inclusions, ensuring the obtained carbonate U-Pb age having an interpretable geological meaning; (4) a large amount of mapping data can significantly improve the accuracy of the dating results. Despite these advantages, in carbonate samples with extremely high common Pb content and high Pb/U ratio, it might be difficult to obtain reliable ages even via the mapping method. In addition, it was understood that the carbonate standard WC-1, which is the most commonly used at present, could be inhomogeneous, and on occasion does not satisfy the SK model in spot analysis.</p>

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An improved U-Pb dating method for carbonates via LA-SF-ICP-MS mapping and its applications

  • 期刊论文

  • 发表日期：

    2025年4月16日

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  • Lili Gui,
  • Xuesong Lu,
  • Fangyue Wang,
  • Can Ge,
  • Lin Jiang,
  • Shaobo Liu,
  • Wuren Xie,
  • Weiyan Chen,
  • Junjia Fan,
  • Hai Wu,
  • Saijun Wu,
  • Yingying Wang,
  • Shihua Yao,
  • Mengzhen Hao

摘要

In situ U-Pb dating of carbonates is very common in the fields of mining and petroleum geology. However, carbonate minerals generally have low U, high common Pb, multiple generations, and uneven elemental distribution, often resulting in relatively low dating precision. Hence, the success rate in U-Pb dating of carbonates by the traditional spot analysis method is generally low. This paper, through combining a mapping method for U-Pb dating with a proprietary visualization and analysis software, ChronoVA, conducted a comparison of the data obtained by both the spot analysis and the mapping method for 3 carbonate standards and 2 unknown natural geological samples. We successfully developed a U-Pb dating method for carbonate rocks via LA-SF-ICP-MS elemental mapping and discussed the advantages and limitations of this method. Results show that in comparison with the traditional spot analysis method, the mapping approach has the following advantages: (1) reducing the downhole fractionation effect; (2) simplifying the analytical processes; (3) the elemental imaging data can help to identify multi-generation and mineral inclusions, ensuring the obtained carbonate U-Pb age having an interpretable geological meaning; (4) a large amount of mapping data can significantly improve the accuracy of the dating results. Despite these advantages, in carbonate samples with extremely high common Pb content and high Pb/U ratio, it might be difficult to obtain reliable ages even via the mapping method. In addition, it was understood that the carbonate standard WC-1, which is the most commonly used at present, could be inhomogeneous, and on occasion does not satisfy the SK model in spot analysis.