Separation of Uranium and Thorium for 230 Th-U Dating of Submarine Hydrothermal Sulfides

The age of a submarinehydrothermal sulfideis 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 submarinehydrothermal sulfidesamples. 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 sulfidesample 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 regentsand supplies are used to reduce the contamination during the sample processes. Balance, hotplate, and centrifuge are also used. The sulfidesample 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 extractioncolumn. Approximately 50 ng U is consumed for 230Th-U dating of sulfidessample by MC-ICPMS.