相山李家岭铀矿床热液蚀变作用地球化学特征

李家岭铀矿床是最近几年在相山西部发现的一个铀矿床。矿床热液蚀变特别发育并存在明显的蚀变分带现象，在对钻孔岩心样详细的野外和室内岩相学观测基础上，将李家岭铀矿床铀矿化段分为矿化中心带、矿旁蚀变带、近矿蚀变带和远矿蚀变带，其热液蚀变强度依次减弱。运用标准化Isocon图解法表明，热液蚀变带中，CaO、FeO、Fe₂O₃、Na₂O明显增加，这与发育赤铁矿化、钠长石化、碳酸盐化相一致；K₂O明显降低，这是由于钠长石交代钾长石造成K的大量迁出；而MnO、MgO在各蚀变带中呈现“此消彼长”的特征，显示出热液蚀变交代过程中并不是简单地扩散渗滤交代，可能存在对流平衡的元素迁移方式。Th、Y、Zr、Hf等微量元素变化与铀含量一致，对铀矿化具有很好地指示作用。HREE与铀矿化关系密切，随着蚀变程度增强，HREE明显增加，显示成矿流体富含HREE，并具有深源性。

Hydrothermal Alteration and Its Geochemical Characteristics of Lijialing Deposit in Xiangshan Uranium Ore Deposit

Lijialing uranium deposit is a new uranium deposit of discovered in western Xiangshan in recent years. Hydrothermal alteration develops strongly and obvious alteration zoning phenomenon exists in this deposit. Based on detailed field and indoor petrography observation on the drilled well samples, this paper divided uranium mineralization period into center zone, near-ore alteration zone, near-ore alteration zone and far-ore alteration zone, of which the hydrothermal alteration intensity decreases gradually. Standardized Isocon graphic method shows that in the hydrothermal alteration zone, CaO, FeO, Fe₂O₃, Na₂O contents increase significantly, with accordance to the development of hematite, albitization and carbonatization facies. K₂O content decreases obviously, which is caused by that albite replace potash feldspar and then the K element is migrated from potash feldspar; while MnO and MgO display a characteristic of inversely proportional relationship, which shows that hydrothermal alteration metasomatic process is not only a kind of diffusion infiltration metasomatism, but also a kind of element migration pattern with convective equilibrium.The content changes of the trace elements such as Th, Y, Zr and Hf are consistent with those of uranium, indicating that those elements can be used for prospecting uranium mineralization. HREE contents are closely relative to the uranium mineralization. With enhancement of the alteration degree, the HREE contents increase more and more, which indicates that the ore forming fluid is rich in HREE, and is deeply derived.