陕南蟒岭矿集区天明一带萤石矿床稀土元素地球化学特征及其成矿意义

REE geochemical characteristics and their metallogenic significance of Tianming fluorite deposit in Mangling ore gathering area,southern Shaanxi Province

天明一带萤石矿床位于陕南蟒岭矿集区东部,该矿集区是陕南重要的萤石矿产地之一。本文通过对该萤石矿床矿石样品的分析测试,研究其稀土元素地球化学特征,初步探讨成矿流体性质、成矿环境及矿化作用过程。研究表明,该矿床矿石稀土元素含量偏低,ΣREE介于25.69×10^(-6)~43.23×10^(-6),平均36.64×10^(-6),LREE/HREE介于3.30~10.65,平均6.72。δEu=0.76~1.45,多数为正Eu异常,δCe=0.75~0.97,表现出弱负Ce异常,Eu、Ce异常暗示萤石矿床形成于中低温、氧化的环境。矿石La/Ho-Y/Ho图解、(La+Y)-Y/La图解指示成矿物质和流体可能来自富氟的蟒岭花岗质岩浆,有外缘物质的加入或混染作用,围岩地层中的碳酸盐岩可能参与其中。Tb/Ca-Tb/La图解显示矿床属热液成因,Tb/Ca-Tb/La、Tb/La-Sm/Nd图解暗示可能经历了多个期次的成矿活动。推测天明一带萤石矿床为浅成中低温热液成因,其成矿可能与蟒岭花岗质岩浆热液相关。

The Tianming area fluorite deposit is located in the east of the Pythonling ore collection area in southern Shaanxi Province,which is one of the important fluorite ore areas in southern Shaanxi Province.Fluorite ore samples that collected from Tianming deposit have been tested,and their REE geochemical characteristics have been studied,and the characteristics of ore-forming fluid,ore-forming environment and mineralization process have also been preliminarily discussed in this paper.It is found that,the fluorite ore in Tianming area has low content of rare earth elements,ΣREE=25.69×10^(-6)-43.23×10^(-6),average 36.64×10^(-6),LREE/HREE=3.30-10.65,average 6.72.δEu=0.76-1.45,Most of the samples are positive Eu anomalies.δCe=0.75-0.97,weak Ce negative.The Eu and Ce anomalies suggest that the fluorite ore has been formed in a medium-low temperature and oxidized environment.By studying the ore La/Ho-Y/Ho diagram,(La+Y)-Y/La diagram and geological characteristics of the deposit,the ore-forming fluid may come from F-rich Manling granitic magmas,and there have been exogenous substance addtion or component exchange during the process of mineralization.Marble in the surrounding rock strata may have contributed part of ore-forming materials.The Tb/Ca-Tb/La diagram shows that the deposit is a hydrothermal deposit,and the Tb/Ca-Tb/La and Tb/La-Sm/Nd diagram suggest that there may have undergone multiple stages of mineralization.It is inferred that Tianming fluorite deposit is a meso-low temperature epithermal deposit,and its mineralization may be related to Mangling granitic magmatic hydrothermal.