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.

The age of a submarine hydrothermal sulfide is a significant index for estimating the size of hydrothermal ore deposits. Uranium and thorium isotopes in the samples can be separated for ²³⁰Th-U dating. This article presents a method to purify and separate U and Th isotopes in submarine hydrothermal sulfide samples. Following this technique, the separated U and Th fractions can meet measuring requirements by multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS). The age of the hydrothermal sulfide sample can be calculated by measuring the present-day activity ratios of ²³⁰Th/²³⁸U and ²³⁴U/²³⁸U. A super clean room is necessary for this experiment. Cleaned regents and supplies are used to reduce the contamination during the sample processes. Balance, hotplate, and centrifuge are also used. The sulfide sample is powdered for analysis and less than 0.2 g sample is used. Briefly, the sample is weighed, dissolved, added to ²²⁹Th-²³³U-²³⁶U double spike solution, Fe co-precipitated, and separated on an anion-exchange resin extraction column. Approximately 50 ng U is consumed for ²³⁰Th-U dating of sulfides sample by MC-ICPMS.