Wang Lisheng, Wang Xuefeng, Ye Jun, Ma Zhibang, Yang Weifang, Xiao Jule
Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences; Institutions of Earth Science, Chinese Academy of Sciences; University of Chinese Academy of Sciences;
Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences; Institutions of Earth Science, Chinese Academy of Sciences.
J Vis Exp. 2019 May 20(147). doi: 10.3791/59098.
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 Th-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 Th/U and U/U. 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 Th-U-U double spike solution, Fe co-precipitated, and separated on an anion-exchange resin extraction column. Approximately 50 ng U is consumed for Th-U dating of sulfides sample by MC-ICPMS.
海底热液硫化物的年龄是估算热液矿床规模的一个重要指标。样品中的铀和钍同位素可进行分离以用于钍-铀测年。本文介绍了一种纯化和分离海底热液硫化物样品中铀和钍同位素的方法。按照该技术，分离出的铀和钍组分能够满足多接收电感耦合等离子体质谱仪（MC-ICPMS）的测量要求。通过测量钍/铀和铀/铀的现今活度比，可以计算热液硫化物样品的年龄。本实验需要一个超净室。使用经过净化的试剂和耗材以减少样品处理过程中的污染。还会用到天平、加热板和离心机。将硫化物样品研磨成粉末用于分析，使用的样品量少于0.2 g。简要来说，先对样品称重、溶解，加入钍-铀-铀双稀释剂溶液，共沉淀铁，然后在阴离子交换树脂萃取柱上进行分离。MC-ICPMS对硫化物样品进行钍-铀测年大约消耗50 ng铀。
