巴音戈壁盆地塔木素地区流体改造与铀成矿

Relationship of Fluid Transformation and Uranium Mineralization in Tamusu Area of Bayingobi Basin,Inner Mongolia

内蒙古巴音戈壁盆地塔木素地区的铀矿化与中国北方其他盆地的层间氧化带砂岩型和泥岩型铀矿化明显不同。在该地区的铀矿化岩石中,砂岩和泥岩几乎各占一半,并且出现不同类型的后期改造。笔者通过野外露头、岩心观察和室内微观分析,发现该地区的矿化岩石发育赤铁矿化、褐铁矿化、黄钾铁矾化、碳酸盐化、石膏化和绿泥石化等多种蚀变。在查明各蚀变带特征的基础上,讨论了巴音戈壁组上段蚀变带的期次及与铀矿化的关系。研究认为,以赤铁矿化、褐铁矿化、黄钾铁矾化为标志的红色、黄色岩石氧化作用发育时间较早,而碳酸盐化、石膏化和绿泥石化较晚;铀矿化分布受氧化作用控制,而灰绿色蚀变所代表的后期热流体叠加作用,使铀矿化进一步富集。

Tamusu uranium deposit in Bayingebi basin is different to Yili interlayer oxidation zone sand- stone type uranium deposit and Nuheting mudstone type uranium deposit. In this deposit, sandstone and mudstone is almost half and half of the target layer and with widely alterations in ores. Through the field outcrop survey, core observation and microscopic analysis, the author found that alteration in this area include hematite, limonitization, carbonation, gypsum, chloritization. Based on the discussion of different alteration zones, the order of alteration zones in the upper member of Bayingobi formation and their relationship with uranium mineralization were summarized. It was found that the red and yellow ox- idation developed earlier than carbonation, gypsum and chloritization, and the distribution of uranium mineralization was controlled by oxidation, while the later hydrothermal fluid superposition represented by grayish green rock made the uranium mineralization richer.