PXCG-1 and PXCG-2: two reference materials for gypsum U–Th dating.
In: JAAS (Journal of Analytical Atomic Spectrometry), Jg. 39 (2024-06-01), Heft 6, S. 1461-1469
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Zugriff:
Gypsum is a widespread mineral in various sedimentary deposits. It precipitates from natural aqueous systems with trace amounts of U but almost no Th, rendering it a potentially valuable U–Th geochronometer. However, no gypsum RM for U–Th dating has been available. In this work, two natural gypsum reference materials (PXCG-1, PXCG-2) from the PiXiao cave, southwest China were prepared and characterized for U–Th dating. U–Th contents and isotope ratios were measured on a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS) using the isotope dilution technique. Data from three different laboratories show good agreement in 238 U content, δ 234 U ( 234 U/ 238 U relative to secular equilibrium value), 230 Th/ 238 U activity ratio, and 230 Th ages (corrected) (corrected by assuming the initial 230 Th/ 232 Th ratio of the average crust value). The recommended values with the uncertainties (2σ) of these two gypsum RMs, 238 U content = 1844 ± 39 ng g −1 , δ 234 U = 229.3 ± 3.9‰, 230 Th/ 238 Uactivity = 0.5741 ± 0.0036, 230 Th ages (corrected) = 66.97 ± 0.31 ka BP for PXCG-1, and 238 U content = 1636 ± 50 ng g −1 , δ 234 U = 61.0 ± 2.4‰, 230 Th/ 238 Uactivity = 0.9797 ± 0.0034, 230 Th ages (corrected) = 260.82 ± 3.39 ka BP for PXCG-2, respectively. Information values of 232 Th content, 230 Th/ 232 Th atomic ratio, 230 Th age (uncorrected), and δ 234 Uinitial are also provided. PXCG-1 and PXCG-2 are the first reported gypsum age RMs for U–Th dating, making them a useful complement to the widely distributed carbonate age reference materials for U–Th disequilibrium dating in Pleistocene–Holocene deposits. [ABSTRACT FROM AUTHOR]
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Titel: |
PXCG-1 and PXCG-2: two reference materials for gypsum U–Th dating.
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Autor/in / Beteiligte Person: | Wang, Xuefeng ; Xiao, Zhengyi ; Xu, Chunxue ; Zhou, Wenlong ; Jia, Xue ; Ning, Youfeng ; Cheng, Hai ; Liu, Yue ; Shao, Qingfeng ; Wang, Lisheng ; Ma, Zhibang ; Duan, Wuhui ; Wang, Xiangli ; Tan, Ming ; Xiao, Jule ; Li, Xianhua |
Zeitschrift: | JAAS (Journal of Analytical Atomic Spectrometry), Jg. 39 (2024-06-01), Heft 6, S. 1461-1469 |
Veröffentlichung: | 2024 |
Medientyp: | academicJournal |
ISSN: | 0267-9477 (print) |
DOI: | 10.1039/d4ja00067f |
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