Abstract
230Th/U dating can provide high-precision age constraints on Quaternary hydrothermal sulfides. However, low content of U and Th often involves extraction chemistry for the separation and enrichment of U and Th, but these chemical processes are very complex. We developed a simplified procedure consisting of total sample dissolution and single-column extraction chemistry, which can reduce the time and improve the accuracy of the dating. Concentrated HCl-HF followed by HNO3 was added to ensure complete dissolution. A single column filled with 0.4 mL of AG 1-X8 anion resin was used, then 8 M HNO3, 8 M HCl and 0.1 M HNO3 were used to elute most of the matrix metals, Th and U. This process provided more than 95% recoveries for U and Th, and negligible blanks. Meanwhile, Pb and Bi interferences were tested and showed no effect on the U and Th isotope ratio. The 230Th/238U activity of the Geological Survey of Japan geochemical reference material JZn-1 in secular equilibrium was determined and showed a radioactive equilibrium (1.00 ± 0.01, n = 5, all errors 2σ) and an in-house standard QS-1 was consistent to 0.0078 ± 0.0001 (n = 8, ±2σ) with an average age of 705 ± 10 yrs BP (n = 8, ±2σ). The technique greatly shortens the sample preparation time and allows more concise and effective analysis of U-Th isotopes. It is ideally suited for the high-precision 230Th/U dating of Quaternary submarine hydrothermal sulfides and sulfides from other settings.
Highlights
Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
The dissolving efficiency performed better than others [6,7,9]; the separation of U and Th could be completed within one day and the accuracy and precision for the U and Th isotope ratios and the 230 Th age were improved. Using this method, repeated analyses of the Geological Survey of Japan geochemical reference material JZn-1 and an in-house hydrothermal sulfide standard QS-1 gave very consistent results, which suggest that QS-1 is potentially a very good Quaternary
The major elements were quantitatively determined by inductively coupled plasma optical emission spectrometry (ICP-OES, Thermo Fisher, USA) and uncertainty was within ±5%
Summary
Dating, called U-Th dating or 230 Th-234 U-238 U dating, is a conventional high-precision tool for dating Quaternary carbonate [1,2,3,4] and sulfides [4,5,6,7,8,9]. We obtained 249,630 ± 6025 yrs and 551 ± 65 yrs (unpublished data) for the same sulfide sample For these reasons, it was necessary to develop one more simple, accurate and reproducible method to reduce the sample mass, labor and time costs. The dissolving efficiency performed better than others [6,7,9]; the separation of U and Th could be completed within one day and the accuracy and precision for the U and Th isotope ratios and the 230 Th age were improved Using this method, repeated analyses of the Geological Survey of Japan geochemical reference material JZn-1 (about 65 Ma) and an in-house hydrothermal sulfide standard QS-1 gave very consistent results, which suggest that QS-1 is potentially a very good Quaternary
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
