冀北张麻井铀钼矿床黄铁矿化蚀变岩地球化学迁移特征及与成矿关系亲缘性的讨论

张麻井铀钼矿床是中国北方最大的与火山岩有关的热液铀矿床，围岩蚀变广泛发育，其中黄铁矿化在该矿床分布虽较为局限，但是与铀钼成矿关系密切。为了研究黄铁矿化蚀变与铀、钼成矿的亲缘关系，文章对张麻井的黄铁矿化蚀变岩进行主、微量元素分析，并选择Yb作为不活动组分，使用质量平衡迁移计算方法， 利用Grant公式对其组分迁移进行定量计算。岩石地球化学特征显示，黄铁矿化蚀变岩的TFeO含量极高，介于11.24%~24.57%之间(平均18.45%)，其中Fe2O3含量10.78%~25.25% （平均18.64%）、FeO含量1.43%~1.90% （平均1.69%），Fe2O3/FeO比值平均为10.99，有可能受到后期氧化。黄铁矿化蚀变岩在Isocon图解上等浓度线斜率小于1，表明整体发生了组分的带入，带入的主要组分为大量的TFeO（131倍），成矿元素Mo（884倍）、Pb（11倍）、U（4.9倍）、V（2.8倍）、Ta（0.44倍）、Cu（0.64倍），碱金属Na2O（0.45倍），以及Cd（424倍）、Bi（13倍） 等；带出的主要组分有碱金属Li（-0.73）、K2O（-0.17），成矿元素Zn（-0.38）、Cr（-0.37），以及Eu（-0.58）、Sc（-0.25） 等。其中SiO2略微减少（-0.03），带入的Mo含量远大于U的含量，据此认为黄铁矿化与钼成矿关系更为密切。

Geochemical Migration Characteristics of Alteration of Pyritized Rocks and Their Genetic Relationship with Pyritization in the Zhangmajing Uranium-Molybdenum Deposit in Northern Hebei Province,China

The Zhangmajing uranium deposit is the largest volcanic-related hydrothermal uranium deposit in northern China, whichwall-rock alteration was widely developed. The distribution of pyrite mineralization in this deposit is relatively limited, but closely related to mineralization. In order to study the relationship between pyrite transformation and uranium mineralization, molybdenummineralization, the main trace element analysis of the pyrite-altered rock in Zhangmajing was carried out. This paper used the massbalance migration method using Yb as the inactive component to calculate its component migration with the Grant formula. Thegeochemical characteristics of the rocks showed that the content of TFeO in pyrite altered rock was extremely high, ranging from11.24% to 24.57% (average 18.45%), of which Fe2O3 content was 10.78%~25.25% (average 18.64%), FeO content was 1.43%~1.90%(average 1.69% ). The average Fe2O3/FeO ratio was 10.99, which might be affected by subsequent oxidation. The slope of theiso-concentration line of the pyrite-altered rock was less than 1 in the Isocon diagram, indicating that the whole component had beentaken in. The taken-in component was mainly the large amount of TFeO (131 times), ore-forming element including Mo (884 times), Pb(11 times), U (4.9 times), V (2.8 times), Ta (0.44 times), Cu (0.64 times), and alkali metal Na2O (0.45 times), and Cd (424 times), Bi (13times), etc. In addition, the alkali metal Li (-0.73), K2O (-0.17), ore-forming elements Zn (-0.38), Cr (-0.37), and Eu (-0.58), Sc(-0.25) and other components were taken out. Among them, SiO2 was slightly reduced (-0.03), and the taken-in Mo content was muchhigher than U which had relatively consistent migration characteristics with those of molybdenum ore. It could be concluded that tpyrite altered rocks were closely molybdenum mineralization.