【作者】 徐争启； 欧阳鑫东； 张成江； 姚建； 陈友良；

【Author】 XU Zheng-qi;OUYANG Xin-dong;ZHANG Cheng-jiang;YAO Jian;CHEN You-jiang;Chengdu University of Technology;No.280 Institute Reaserch,CNNC;

【机构】 成都理工大学； 核工业二八○研究所；

【摘要】 攀枝花大田地区地处康滇地轴中南段,是我国重要的混合岩型热液铀矿分布区。近年来,在该区发现了巨粒晶质铀矿,具有重要的研究价值。本文通过矿物学及电子探针微区分析,并参考前人的方法,对晶质铀矿的成分及年代学特征进行了分析。本研究一方面对电子探针原位定年技术进行了探索;另一方面,对大田地区铀成矿时代进行了厘定,对该区铀成矿规律研究具有重要的促进作用。研究结果表明,大田地区滚石中的晶质铀矿和基岩矿石中的晶质铀矿具有相似的特点,晶质铀矿中UO₂的含量在77%～84%,此外,晶质铀矿中含有一定量的铅和钍,PbO、ThO₂分别达到0.98%～5.59%,1.79%～8.8%,其中滚石中晶质铀矿铅含量低于基岩晶质铀矿,钍含量则是滚石晶质铀矿高于基岩晶质铀矿。采用电子探针原位定年技术,按照法国学者朗香等人的算法,分别计算了滚石和基岩晶质铀矿形成年龄,结果滚石晶质铀矿为779.87 Ma,基岩矿石晶质铀矿为774.7～805 Ma。为了验证原位分析测试的可靠性,对滚石晶质铀矿采用传统的同位素测年分析方法获得了775～777.6 Ma的年龄,与采用电子探针原位分析测年结果非常一致,说明电子探针原位测年方法是可信的。此外,对晶质铀矿中其他元素分析,估算了该元素可能的进入晶质铀矿的时代,认为在后期的热液蚀变中,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755.5 Ma、717.71Ma和679.33 Ma。更多还原

【Abstract】 Panzhihua Datian area,which is located in the southern of Kangdian axis,is China’s important area of migmatite type hydrothermal uranium deposit.In recent years,Coarse-grain uraninite were found in this area,and it has important research value.Through mineralogy and electron microprobe analysis,composition and chronology of uraninite are studied.On the one hand,the electron probe in situ dating technique was explored.On the other hand,the uranium metallogenic epoch was determined in the field.It has an important role in promoting uranium metallogenic regularity.The results show that uraninitein the rolling stones and bedrock have similar characteristics,the content of UO₂ inuraniniteis about 77%～84%,in addition,ThO₂,PbO about 1.79%～8.8%and 0.98%～5.59%respectively.The lead of uraninite in the rolling stones is lower than the bedrock,but thorium content inuraninite is higher the rolling stones than bedrock.By using electron probe in situ dating technique,according to the French scholar Ranchin G.’s algorithm,the age of uraninite in rolling stone and bedrock are calculated respectively.The age of uraninite is 779.87 Ma in rolling stones,774.7～805 Ma in the bedrock ore.In order to test the reliability analysis of the age in situ,uraninite age were 775～777.6 Ma by traditional dating analysis age.The dating results are very consistent with the in situ electron probe analysis,so electron probe in situ dating method is credible.In addition,the analysis of other elements in the era of uraninite,the ages of the element entering the uraninite were estimated.The hydrothermal alteration in the late were the silicification,carbonate and hematitization,the time of alteration were 755.5 Ma,717.71 Ma and 679.33 Ma.更多还原