云南东川大梁子铀矿床微量、稀土元素地球化学特征及其意义

Geochemical Characteristics and Significance of Trace and Rare Earth Elements of Daliangzi Uranium Deposit in Dongchuan, Yunnan

近年来在云南东川地区发现的大梁子铀矿产于中元古界昆阳群大营盘组黑色岩系中,通过采集矿区具有代表性的矿石及围岩样品开展微量元素及稀土元素研究,初步查明了矿区微量元素分布特征及成矿环境。大营盘组含矿黑色岩系以U、 Ni、 V、 P、 Cu、 As、 Mo和Ag组合为特征,且富含有机碳。稀土元素总量平均值为201.8×10^(-6),δEu和δCe均小于1,为负异常,沉积环境为深海相还原环境。在沉积过程中,黑色岩系中的有机碳对U、 Ni、 V、 Cu等成矿元素有较强的吸附作用,经沉积成岩成矿作用而富集成矿。后期的构造活动形成北东向断裂破碎带,为热液活动提供了通道及成矿物质进一步富集的场所, U、 Cu等元素沿北东向F2断裂富集。因此,东川大梁子铀矿床是一个受黑色岩系及北东向F2断裂共同控制的碳硅泥岩型铀矿床。

Daliangzi uranium deposit is a new found deposit in Dongchuan of Yunnan in recent years. It occured in the black rock series of Dayingpan Formation of Mecozoic Kunyang Group. The distribution characteristics of trace elements and metallogenic environment in this deposit were preliminarily identified through the analysis of trace elements and rare earth elements by collecting representative ore and surrounding rock samples. The mineral-bearing black rock strata of the Daying formation are characterized by the combination of U,Ni,V,P,Cu,As,Mo and Ag,and rich in organic carbon. The average value of the total amount of rare earth is 201.8 ppm. The δEu and δCe are both less than 1,which is a negative anomaly. The sedimentary environment was a deep-sea phase reduction environment. In the sedimentary process,the organic carbon in the black rock series had a strong adsorption effect on metallogenic elements such as U,Ni,V and Cu,and is rich in integrated minerals through sedimentary diagenesis. The tectonic movement in the late formed north-east fault fracture zone,which provided a channel for hydrothermal activity and the enrichment place of the ore-forming material. The U,Cu and other minerals formed secondary enrichment uranium mineralization belt along the north-east F2 fault. Therefore,the Daliangzi uranium deposit in Dongchuan is a carbonaceous-silliceous-argillaceous type uranium deposit which are jointly controlled by the black rock system and the north-east F2 fault.