相山铀矿田西部煌斑岩年代学、地球化学及幔源流体的证据  

Geochronology,geochemistry of lamprophyre and evidence of mantle fluid in the western part of Xiangshan uranium orefield

作　　者：刘龙 张树明[2,3] 饶泽煌[2,4] 张鑫[2,3] 夏寅初 万康[2] 欧阳军勇 吴志春 LIU Long;ZHANG Shuming;RAO Zehuang;ZHANG Xin;XIA Yinchu;WAN Kang;OUYANG Junyong;WU Zhichun(Gandong College,Fuzhou 344000,Jiangxi,China;State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,Jiangxi,China;Fundamental Science on Radioactive Geology and Exploration Laboratory,East China University of Technology,Nanchang 330013,Jiangxi,China;No.261 Geological Party,Nuclear Industry Geological Bureau of Jiangxi Province,Yingtan 335001,Jiangxi,China)

机构地区：[1]赣东学院,江西抚州344000 [2]东华理工大学核资源与环境国家重点实验室,江西南昌330013 [3]东华理工大学放射性地质与勘探技术国防重点学科实验室,江西南昌330013 [4]江西省核工业地质局261大队,江西鹰潭335001

出　　处：《中国地质》2024年第3期898-911,共14页Geology in China

基　　金：国家自然科学基金(41862006、41802247);赣东学院博士科研启动基金(122000802);江西省研究生创新专项基金(YC2020-B159)联合资助。

摘　　要：【研究目的】幔源岩浆是探讨深部动力学演化和铀成矿的研究对象,相山铀矿田基性岩脉是探讨区域岩浆演化和铀成矿的关键所在。【研究方法】本文对矿区西部煌斑岩脉进行了系统的岩石学、地质年代学和地球化学综合研究。【研究结果】本区存在3期煌斑岩,分别为134 Ma、120~125 Ma和84.5 Ma。该区煌斑岩为钠质碱性煌斑岩,富集LILE和LREE,亏损HFSE,具明显的Ta-Nb-Ti负异常,具有岛弧玄武岩和大陆地壳的微量元素特征。该区煌斑岩为部分熔融和结晶分异共同作用的产物,经历了橄榄石、单斜辉石的结晶分异作用,在岩浆上侵过程中受到明显上地壳物质的混染。该区煌斑岩形成于伸展作用下的板内拉张构造环境,未受到古太平洋板块俯冲作用的影响。其源区应为软流圈亏损地幔与岩石圈富集地幔的混合,且主要体现为软流圈亏损地幔特征。【结论】第一期煌斑岩矿岩时差大,仅为后期铀的沉淀富集提供有利条件;后两期煌斑岩矿岩时差小,不仅为相山矿田铀矿化提供了幔源流体(ΣCO_(2)矿化剂和He),也为铀沉淀富集提供还原障。This paper is the result of mineral exploration engineering.[Objective]Mantle-derived magma generally provied an object to reveal geodynamic evolution in the depth and uranium mineralization.The mafic dikes in the west of Xiangshan uranium deposit are regarded as a key aspect to understand the regional tectono-magmatic evolution and uranium mineralization.[Methods]In this paper,the comprehensive research of petrology,geochronology and geochemistry were carried on the lamprophyre in the west of Xiangshan uranium deposit.[Results]There are three stages of lamprophyre in this area,which are 134 Ma,120-125 Ma and 84.5 Ma.The lamprophyre is sodium-alkaline lamprophyre and characterized with the enrichment of LILE and LREE,depletion of HFSE,and obvious negative anomaly of Ta-Nb-Ti.The lamprophyre is the product of partal melting from the source region and crystallisation differentiation,which experienced the crystallization differentiation of olivine and clinopyroxene as well as strong assimilation and contamination of upper crustal meterials during the magmatic intrusion.The lamprophyre was formed in the extentional entraplate tensioned tectonic environment,and was not affected by the subduction of the ancient Pacific Plate.The source region is a mixture of asthenospheric depleted mantle(main source)and lithospheric enriched mantle,which is mainly characterized by asthenospheric depleted mantle.[Conclusions]The first period of lamprophyres is much older than the age of uranium mineralization,only providing favorable conditions for uranium accumulation.The later two periods of lamprophyres are closely associated with uranium deposits on space and time,possibly providing mantle hydrothemal fluids(ΣCO_(2) and He)and a favorable reducing environment for uranium enrichment and deposition.

关 键 词：年代学 地球化学 源区性质 煌斑岩 相山矿田 矿产勘查工程 江西 

分 类 号：P619.14[天文地球—矿床学]