电子探针化学测年在攀枝花大田晶质铀矿中的应用及其意义

发布时间：2018-05-15 23:33

本文选题：晶质铀矿 + 电子探针定年　；参考：《岩矿测试》2017年06期

【摘要】：晶质铀矿和沥青铀矿是热液铀矿床的主要工业铀矿物,在研究热液铀矿床成因及成矿规律方面具有重要的意义。攀枝花大田地区是我国混合岩型热液铀矿分布区,已发现粗粒特富铀矿滚石(铀含量10%)及较富基岩矿石(铀含量为0.1%~2%),主要铀矿物为晶质铀矿,对两种晶质铀矿成分及形成时代的研究对该区混合岩型热液铀矿成矿规律研究具有重要的价值。本文通过对大田地区滚石中的晶质铀矿和基岩矿石中的晶质铀矿进行矿物学及电子探针分析,研究了晶质铀矿的成分及形成时代。结果表明:(1)大田地区滚石和基岩矿石中的晶质铀矿除铅之外化学成分较为相似,两类矿石晶质铀矿中UO_2含量为77.36%~84.04%,ThO_2含量为0.98%~5.59%,PbO含量为1.79%~8.8%,其中滚石晶质铀矿中的铅含量低于基岩晶质铀矿,钍含量高于基岩晶质铀矿;(2)电子探针化学定年结果表明,基岩矿石晶质铀矿的形成时代为774.9~785.5 Ma,滚石晶质铀矿的形成时代为783.7 Ma,与传统同位素测年结果(775~777.6 Ma)非常一致,一方面说明滚石晶质铀矿和基岩晶质铀矿为同一时代的产物,另一方面说明电子探针原位测年方法是可靠的;(3)在后期的热液蚀变中,晶质铀矿先后发生了硅化、碳酸盐化及赤铁矿化,蚀变发生的时间分别为730.6Ma、699.8 Ma和664.0 Ma。此结论对研究攀枝花大田地区热液铀矿成矿时代及成矿作用过程提供了依据。
[Abstract]:Crystalline uranium deposits and asphaltene uranium deposits are the main industrial uranium deposits in hydrothermal uranium deposits, which is of great significance in studying the genesis and metallogenic regularity of hydrothermal uranium deposits. The Panzhihua Datian area is the distribution area of mixed rock type hydrothermal uranium deposits in China. It has been found that the coarse grained Uranium-rich uranium ore (uranium content 10) and the relatively rich bedrock ore (uranium content 0.1%) and the main uranium ore are crystalline uranium deposits. The study on the composition and formation age of two kinds of crystalline uranium deposits is of great value for the study of the metallogenic regularity of mixed rock type hydrothermal uranium deposits in this area. Based on mineralogical and electron probe analysis of uraninite ore in rolling rock and bedrock ore in Datian area, the composition and forming age of uraninite have been studied in this paper. The results show that the chemical composition of the uraninite ore except lead in the rolling stone and bedrock ore in Datian area is similar. The UO_2 content of the two types of uranium ores is 77.36 / 84.04 and the content of Tho _ 2 is 0.98 / 5.59 respectively. The content of PBO is 1.79 and 8.8.The content of lead in the uranite is lower than that in the crystalline uranium ore of bedrock, and the content of thorium is higher than that of the crystalline uranium ore of bedrock. The results of electron probe chemical dating show that the content of lead in the uranite is lower than that in the crystalline uranium ore of the bedrock rock, and the content of thorium is higher than that of the crystalline uranium ore of the bedrock. The formation age of crystalline uranium deposit in bedrock ore is 774.9 ~ 785.5 Ma, and the age of uranium ore in rolling rock is 783.7 MaA, which is very consistent with the result of traditional isotopic dating. On the one hand, it shows that the uraniferous ore and the crystalline uranium deposit of bedrock are the products of the same age. On the other hand, it is shown that the in situ electron probe dating method is reliable. In the later hydrothermal alteration, the uraninite occurred successively in silicification, carbonization and hematitization, and the time of alteration was 730.6 Ma 699.8 Ma and 664.0 Ma, respectively. This conclusion provides a basis for studying the metallogenic age and metallogenic process of hydrothermal uranium deposits in the Panzhihua Datian area.
【作者单位】：成都理工大学地球科学学院;核工业280研究所;四川省地质矿产勘查开发局106地质队;
【基金】：中国核工业地质局科研项目(201637,201638)
【分类号】：P597.3;P619.14

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