摘要
晶质铀矿是一种副矿物,在花岗岩中广泛产出。铀离子价态变化和比值对岩浆氧逸度,有一定的指示意义。本次研究以四川米易海塔地区混合岩中石英质脉体中的粗粒晶质铀矿为研究对象,借助X射线粉晶衍射和X射线光电子能谱测试两种方法,分析样品铀元素价态变化以及对氧逸度的指示意义。X射线粉晶衍射获得样品主要成分为晶质铀矿和少量石英,样品的晶胞参数分别为0.5487 nm和0.5441 nm,计算其含氧系数分别为2.00和2.23。X射线光电子能谱测试分析得到,样品中四价铀的峰值结合能介于380.15~380.46 eV,半峰宽介于1.93~1.94 eV;六价铀的峰值结合能介于381.49~381.98 eV,半峰宽介于1.51~1.92 eV,U^(6+)/U^(4+)比值介于(U^(6+)/U^(4+)=0.13~0.31)。氧逸度热力学计算得到米易海塔地区粗粒晶质铀矿形成时的氧逸度(lgfo_(2))介于-22.12~-21.36。依据近似温度和计算出的氧逸度值,做lgfo_(2)-T协变曲线图。米易海塔地区粗粒晶质铀矿形成时的氧逸度投图数据结果落入FMQ平衡线之上,较为接近MH平衡线。可以推测米易海塔地区与粗粒晶质铀矿共生的石英脉形成时为还原环境。
Uraninite is an accessory mineral that occurs widely in granite.The change and ratio of uranium ion valence state can be used to indicate magmatic oxygen fugacity.Utilizing X-ray powder diffraction(XRD)and X-ray photoelectron spectroscopy(XPS),the coarse-grained uraninite in quartz vein of migmatite in Haita area of Miyi County,Sichuan province is studied to analyze the changes of uranium valence state and the indication to oxygen fugacity in the samples.The main composition of the samples obtained by X-ray powder diffraction is uraninite with a small amount of quartz,with the cell parameters of 0.5487 nm and 0.5441 nm,respectively,and with the calculated oxygen content coefficients of 2.00 and 2.23,respectively.X-ray photoelectron spectroscopy analysis shows that the peak binding energy of uranium tetra in the sample is between 380.15 to 380.46 eV,and the half peak width is between 1.93 to 1.94 eV.The peak binding energy of uranium hxavalent is 381.49 to 381.98 eV,the half-peak width is 1.51 to 1.92 eV,and the ratio of U^(6+)/U^(4+)ranges from 0.13 to 0.31.The oxygen fugacity(lgfo_(2))obtained from thermodynamic calculation of oxygen fugacity during the formation of coarse-grained uranium ore is between-22.12 and-21.36.According to the approximate temperature and the calculated oxygen fugacity value,the lgfo_(2)-T covariant graph shows that the oxygen fugacity projection data of coarse-grained uranium ore falls above the FMQ equilibrium line and is close to the MH equilibrium line.It can be inferred that the quartz vein symbiotic with coarse-grained uranium deposits in Haita area was formed in a reduction environment.
作者
刘映君
徐争启
尹明辉
张苏恒
田建民
姚建
Liu Yingjun;Xu Zhengqi;Yin Minghui;Zhang Suheng;Tian Jianmin;Yao Jian(College of Earth Sciences,Chengdu University of Technology,Chengdu 610059,Sichuan,China;Key Laboratory of Geosciences and Nuclear Technology of Sichuan Province,Chengdu 610059,Sichuan,China;Key Laboratory of Earth Exploration and Information Technology,Ministry of Education,Chengdu 610059,China;The 280 Institute of Nuclear Industry,Guanghan 618300,Sichuan China)
出处
《矿物岩石》
CAS
CSCD
北大核心
2022年第1期98-107,共10页
Mineralogy and Petrology
基金
国家自然科学基金“康滇地轴粗粒晶质铀矿标型特征及形成机理”(编号:41872079)
中国核工业地质局科研项目“康滇地轴新元古代铀成矿关键控矿因素研究”(编号:201807)
成都理工大学珠峰科学研究计划(编号:2021ZF11413)
四川省应用基础研究项目“四川冕宁—攀枝花地区新元古代铀成矿作用及成矿机理研究”(编号:2020YJ0361)。
关键词
晶质铀矿
X射线光电子能谱
氧逸度
海塔地区
uraninite
X-ray photoelectron spectroscopy
oxygen fugacity
Haita area