Variations in 238U/235U in uranium ore deposits: Isotopic signatures of the U reduction process?
Variations in 238U/235U in uranium ore deposits: Isotopic signatures of the U reduction process?
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DOI：
10.1130/g25550a.1
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发表时间：
2009-07-01
期刊：
影响因子：
5.8
通讯作者：
Glessner, Justin J. G.
中科院分区：
文献类型：
--
作者：
Bopp, Charles John, IV;Lundstrom, Craig C.;Glessner, Justin J. G.
高精度测量U-238/U-235的能力为研究铀在环境中的归宿和迁移提供了一个重要的新机会。用多接收电感耦合等离子体质谱仪测定了两个不同类型矿床的6个铀矿石样品中U-238/U-235的比值。在低温下从地下水沉淀的铀矿石与高温下从热液矿床沉淀的铀矿石之间观察到铀-238/铀-235的显著偏移，这加强了以前的观察，但缺乏所需的精确度。具体而言，发现板状砂岩型铀矿床的铀-235贫化，低温矿床和高温矿床之间的总偏移量约为1.0%。我们认为这种偏移反映了与环境温度地下水中铀的化学还原过程中的核场位移效应有关的温度依赖性分馏。
The ability to measure U-238/U-235 to high precision presents an important new opportunity to study the fate and transport of uranium in the environment. The ratio of U-238/U-235 was determined by multicollector-inductively coupled plasma-mass spectrometer in six uranium ore samples representing two different classes of deposits. Significant offsets in U-238/U-235 are observed between uranium ores precipitated from groundwaters at low temperature versus hydrothermal deposits precipitated at high temperatures, reinforcing an observation made previously but lacking the needed precision. Specifically, tabular sandstone-type uranium deposits were found to be depleted in U-235, with a total offset between low-temperature deposits and higher temperature deposits of approximate to 1.0%. We attribute this offset to reflect a temperature-dependent fractionation related to the nuclear field shift effect during chemical reduction of uranium in ambient temperature groundwaters.