四川会理芭蕉箐地区钠长岩地球化学、年代学特征及其意义  

Geochemical and Chronological Characteristics and Significance of Albite in Bajiaojing Area,Huili,Sichuan

作　　者：刘亚杰 徐争启 宋昊[1,2] 李涛 张苏恒[1] 姚建 Liu Yajie;Xu Zhengqi;Song Hao;Li Tao;Zhang Suheng;Yao Jian(Applied Nuclear Techniques in Geosciences Key Laboratory of Sichuan Province,Chengdu 610059,China;College of Earth Sciences,Chengdu University of Technology,Chengdu 610059,China;Key Laboratory of Earth Exploration and Information Techniques,Ministry of Education,Chengdu 610059,China;280 Institute of Nuclear Industry,Guanghan 618300,China)

机构地区：[1]地学核技术四川省重点实验室,四川成都610059 [2]成都理工大学地球科学学院,四川成都610059 [3]地球勘探与信息技术教育部重点实验室,四川成都610059 [4]核工业二八〇研究所,四川广汉618300

出　　处：《地球科学》2024年第3期893-906,共14页Earth Science

基　　金：国家自然科学基金项目(No.41872079);中国核工业地质局科研项目(No.202137-3);成都理工大学珠峰科学研究计划项目(No.2021ZF11413);四川省应用基础研究项目(No.2020YJ0361)。

摘　　要：四川会理芭蕉箐地区位于康滇地轴中南段,是我国少有的元古宙产铀地区,其构造条件复杂,研究程度低,钠长岩作为本区重要的含铀岩石,对其更是鲜有报道,严重限制了进一步的铀矿勘查.在结合前人研究的基础上,通过对芭蕉箐地区1841铀矿化点的野外地质调查、钠长岩元素地球化学分析及锆石U-Pb年代学测试分析,发现研究区钠长岩分为岩浆钠长岩与交代钠长岩,样品富集Th、U、Zr、REE等元素,相对贫Ba、K、Sr、Rb等元素,测年结果显示两类钠长岩主要峰值年龄为~2.3 Ga与~1.8 Ga.钠长岩岩石来源主要为下地壳变质泥岩部分熔融且有幔源物质加入,形成于陆内拉张构造环境.其原岩的形成与2.4~2.3 Ga期间发生在扬子地台西南缘的碰撞事件有关,并在1.8 Ga左右经历岩浆作用形成钠长岩,同时铀元素在此处大量富集.其年代学数据记录的两次岩浆活动,是Columbia超大陆聚合在扬子地块西南缘的响应.Located in the middle and southern part of the Kangdian axis,Bajiaojing area in Huili,Sichuan Province is a rare Proterozoic uranium mining area in China.However,the relevant study is insufficient due to its complex structural conditions,and hardly any research has been reported on albite,an important uranium bearing rock in this area,which seriously restricts further uranium exploration.On the basis of previous studies,through the field geological survey of 1841 uranium mineralization points in Bajiaojing area,the geochemical analysis of rock elements of albite and the test analysis of zircon U-Pb chronology,it is found that albite in the study area is divided into magmatic albite and metasomatic albite.The samples are enriched in Th,U,Zr and REE,and relatively depleted in Ba,K,Sr and Rb.The dating results show that the two main peak ages are~2.3 Ga and~1.8 Ga.The albite is mainly derived from the partial melting of metamorphic mudstone in the lower crust and the addition of mantle derived materials,which was formed in the tectonic environment of intracontinental rift.The formation of its protolith is related to the collision event in the southwest margin of the Yangtze platform during 2.4-2.3 Ga,and underwent magmatism at about 1.8 Ga to form albite,and U element is enriched here.The two magmatic activities recorded by its chronological data are the response of the convergence of Columbia supercontinent in the southwest margin of the Yangtze block.

关 键 词：扬子陆块西南缘 Columbia超大陆 钠长岩 地球化学 锆石U-PB定年 岩石学 

分 类 号：P597[天文地球—地球化学]