湖南雪峰山地区长界基性-超基性岩体橄榄岩地球化学特征与镍矿化成因  

Geochemical characteristics of peridotite and genesis of Ni mineralization from Changjie basic-ultrabasic rocks in Xuefengshan area,Hunan

作　　者：邹源 石少华 岑敏 范鹏飞 田磊 杨斌[3] ZOU Yuan;SHI Shao-hua;CEN Min;FAN Peng-fei;TIAN Lei;YANG Bin(Hunan Institute of Geological Survey,Changsha 410116,China;Changsha Uranium Geology Research Institute,CNNC,Changsha 410007,China;School of Geosciences and Info-Physics,Central South University,Changsha 410083,China)

机构地区：[1]湖南省地质调查所,长沙410116 [2]核工业二三○研究所,长沙410007 [3]中南大学地球科学与信息物理学院,长沙410083

出　　处：《桂林理工大学学报》2022年第2期295-304,共10页Journal of Guilin University of Technology

基　　金：湖南省矿业权价款地质勘查项目(20160308);湖南省地质矿产勘查开发局科研项目(201702)。

摘　　要：湖南雪峰山地区长界基性-超基性岩体位于江南造山带西段,毗邻桂北宝坛地区,橄榄岩中发育低品位镍矿。岩石化学及地球化学分析结果表明,长界橄榄岩具有低SiO_(2)(36.03%~40.95%)、Al_(2)O_(3)(5.39%~6.54%)、TiO_(2)(0.42%~0.54%)和全碱(Na_(2)O+K_(2)O,0.11%~0.36%),而高MgO(25.0%~27.5%)特征;稀土特征总体显示为稀土元素总量低(ΣREE平均为24.3×10^(-6)),轻稀土元素相对富集(LREE/HREE均值为3.61);微量元素Ba、Nb、P负异常,Rb及放射性元素Th、U正异常。结合区域构造演化和橄榄岩形成时代,推断研究区在新元古代处于造山后伸展环境,起源于受俯冲流体交代的岩浆沿构造薄弱部位上侵上涌,当侵入到现存岩浆房时,遭受了不同程度的地壳物质的同化混染作用,地壳物质加入使S达到饱和,从而发生硫化物就地熔离形成浸染状矿化。The Changjie basic-ultrabasic rocks in Xuefengshan area of Hunan are located in the western segment of the Jiangnan orogenic belt,close to Baotan area in northern Guangxi.Low-grade nickel ore is developed in peridotite.Petrochemical and geochemical analysis show that the Changjie peridotite shows the characteristics of low SiO_(2)(36.03%-40.95%),Al_(2)O_(3)(5.39%^(-6).54%),TiO_(2)(0.42%-0.54%)and total alkali(Na_(2)O+K_(2)O)(0.11%-0.36%)content and high MgO(25.0%-27.5%)content.The characteristics of rare earth generally show that the total amount of REE in the Changjie peridotite is low(ΣREE is 24.3×10^(-6) on average),but LREE is enriched compared with the HREE(LREE/HREE average is 3.61).Trace elements show negative anomalies of Ba,Nb and P,and positive anomalies of Rb and radioactive elements Th and U.From regional tectonic evolution and peridotite formation age,it is inferred that the study area is in a post orogenic extensional environment at Neoproterozoic.The magma was originated from the metasomatism of subduction fluid intruded and upwelling in the weak part of the structure.When intruding into the existing magma chamber,it was subjected to different degrees of assimilation and contamination of crustal materials.The addition of crustal materials made sulfur saturated,thus sulfides melted and dissociated in situ to form disseminated mineralization.

关 键 词：橄榄岩 地球化学特征 镍矿成因 造山后伸展环境 长界 

分 类 号：P588.125[天文地球—岩石学] P618.630.1[天文地球—地质学]