桂北新元古代清明山花岗岩地球化学特征及其地质意义  

Geochemical characteristics and geological significance of Neoproterozoic Qingmingshan granite in northern Guangxi

作　　者：刘兴源 曹杰 李赛赛[1,2] 张洪瑞[4] 吴江波 辛良伟 王秋宇 王建强 LIU Xingyuan;CAO Jie;LI Saisai;ZHANG Hongrui;WU Jiangbo;XIN Liangwei;WANG Qiuyu;WANG Jianqiang(Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resources in Guangxi,Guilin University of Technology,Guilin 541006,China;College of Earth Sciences,Guilin University of Technology,Guilin 541006,China;Shandong Zhengyuan Geological Resources Exploration Co.,Ltd.,Jinan 250101,China;Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China)

机构地区：[1]桂林理工大学有色金属矿产勘查与资源高效利用省部共建协同创新中心,广西桂林541006 [2]桂林理工大学地球科学学院,广西桂林541006 [3]山东正元地质资源勘查有限责任公司,济南250101 [4]中国地质科学院地质研究所,北京100037

出　　处：《桂林理工大学学报》2023年第3期351-363,共13页Journal of Guilin University of Technology

基　　金：国家自然科学基金项目(42262026);广西自然科学基金项目(2020GXNSFAA297091)。

摘　　要：为理清江南造山带西段新元古代构造背景,对桂北清明山花岗岩岩相学、锆石U-Pb年代学及Hf同位素特征、全岩主微量元素地球化学等进行了研究。LA-ICP-MS锆石U-Pb定年结果表明,清明山花岗岩成岩年龄为823.8±1.8 Ma。岩体为富钾酸性岩浆岩,呈现出强过铝质,轻重稀土弱-中等分馏,中等负Eu异常,富集Rb、Th、U、Pb等,亏损Ba、Nb、Sr、Ti等特征,为S型花岗岩。花岗岩锆石ε_(Hf)(t)值为-5.8--2.6,对应二阶段模式年龄(T_(DM2))为1863-2060 Ma,指示其主要由古元古代陆壳物质部分熔融形成。根据桂北新元古代清明山花岗岩地球化学特征及区域研究资料,判断其为后碰撞构造环境的产物。In order to clarify the Neoproterozoic tectonic setting of the western segment of Jiangnan orogenic belt,the petrography,zircon U-Pb chronology,characteristics of Hf isotope,major and trace elements geo-chemistry of Qingmingshan granite in northern Guangxi are studied.LA-ICP-MS zircon U-Pb dating results show that the diagenetic age of Qingmingshan granite is 823.8±1.8 Ma.Geochemical study shows that the po-tassium-rich magmatic rocks are S-type granites with strong peraluminite,moderate to weak fractionation be-tween light and heavy rare earth elements,moderate negative Eu anomalies,enrichment of Rb,Th,U,Pb,and depletion of Ba,Nb,Sr,Ti.Zircon ε_(Hf)(t)values mainly range from-5.8 to-2.6,corresponding to the two-stage model ages(T_(DM2))from 1863 to 2060 Ma.It indicates that Qingmingshan granite was mainly formed by melting of Paleoproterozoic continental crust material.According to the geochemical characteristics and re-gional research data of the Neoproterozoic Qingmingshan granite in northern Guangxi,it is concluded that it is the product of post-collisional tectonic environment.

关 键 词：花岗岩 地球化学 后碰撞 江南造山带 清明山 桂北 

分 类 号：P619.22.2[天文地球—矿床学] P597.3[天文地球—地质学]