Rapid Extraction Chemistry Using a Single Column for 230Th/U Dating of Quaternary Hydrothermal Sulfides
Rapid Extraction Chemistry Using a Single Column for 230Th/U Dating of Quaternary Hydrothermal Sulfides
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DOI：
10.3390/min11090983
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发表时间：
2021-09
期刊：
影响因子：
2.5
通讯作者：
Lisheng Wang;Ye-Jian Wang;Jun Ye;Xuefeng Wang;Jule Xiao;Z. Ma
中科院分区：
文献类型：
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作者：
Lisheng Wang;Ye-Jian Wang;Jun Ye;Xuefeng Wang;Jule Xiao;Z. Ma
230Th/U测年可提供高精度的第四纪热液硫化物年龄约束。然而，低U、Th含量往往涉及萃取化学来分离和富集铀和Th，但这些化学过程非常复杂。我们开发了一种简化的方法，包括全样品溶解和单柱萃取化学，可以缩短测年时间，提高测年精度。加入浓缩的HCl-HF，然后加入HNO3，以确保完全溶解。用0.4m L的AG1-X8阴离子树脂，用8M硝酸、8M盐酸和0.1M硝酸洗脱大部分基质金属Th和U，U和Th的回收率均在95%以上，空白很少。同时，对铅和铋的干扰进行了测试，对铀和钍的同位素比值没有影响。测定了日本地质调查局标准物质JZN-1长期平衡的~(230)TH/~(238)U活度，其放射性平衡(1.00±0.10，n=5，误差均为2σ)和室内标准QS-1一致为0.0078±0.0001(n=8，±2σ)，平均年龄为70±10年BP(n=8，±2σ)。该技术大大缩短了样品制备时间，并使U-Th同位素分析更加简洁有效。它非常适合于第四纪海底热液硫化物和其他环境中硫化物的高精度230Th/U测年。
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.