桂东北贺州英安岩锆石年代学、Hf同位素研究及其地质意义  

LA-ICP-MS Zircon U-Pb Dating and Hf Isotopic Composition of Dacite in Hezhou, Northeastern Guangxi

作　　者：王永强 时毓[1,2] 李响[3] 刘希军[1,2] 唐远兰 孙艺容 WANG Yongqiang;SHI Yu;LI Xiang;LIU Xijun;TANG Yuanlan;SUN Yirong(Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration,Guilin University of Technology,Guilin 541004,China;Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resources,Guilin University of Technology,Guilin 541004,China;Wuhan Center of Geological Survey,China Geological Survey,Wuhan 430205,China)

机构地区：[1]桂林理工大学广西隐伏金属矿产勘查重点实验室,桂林541004 [2]桂林理工大学有色金属矿产勘查与资源高效利用协同创新中心,桂林541004 [3]中国地质调查局武汉地质调查中心,武汉430205

出　　处：《高校地质学报》2022年第2期141-152,共12页Geological Journal of China Universities

基　　金：国家自然科学基金项目(41862003,41562005);广西杰出自然科学基金项目(2019GXNSFFA245005,2018GXNSFFA281009)联合资助。

摘　　要：研究区位于南岭成矿带西段湘—桂交界处,该区中生代岩浆活动频繁,成岩成矿作用显著,尤以燕山期最为强烈。为厘定桂东北贺州开山镇孔子庙英安岩的成岩时代和探讨其岩浆源区,文章对其进行了LA-ICP-MS锆石U-Pb定年和锆石Lu-Hf同位素研究。锆石U-Pb定年结果限定了英安岩的侵位年龄为157.1±0.9 Ma。锆石Lu-Hf同位素分析显示,其εHf(t)值变化范围较大(-5.68~-0.97),对应的T;值主要分布在1.26~1.54 Ga,指示原岩主要来源于中元古代结晶基底地壳物质,并可能伴随有少量幔源物质的混入。结合前人对华南燕山期成岩成矿作用的研究,认为研究区英安岩与桂东北地区燕山早期形成的岩体及矿床同属华南燕山期第一次大规模岩浆活动的产物,英安岩的形成可能与华南燕山期岩石圈的板内伸展—减薄作用有关。The study area is located at the junction of Hunan and Guangxi in the western part of Nanling metallogenic belt, where Mesozoic magmatic activity is frequent and the diagenesis and mineralization are remarkable, especially during Yanshanian. In order to determine the formation age of kongzimiao dacite in Kaishan Town, Hezhou, northeastern Guangxi, and to discuss its source property, LA-ICP-MS zircon U-Pb dating and Lu-Hf isotope are obtained. zircon U-Pb age of 157.1±0.9 Ma displayed the formation age of the dacite. Zircons grains have a wide range of isotopic composition(εHf(t) values rang from-5.68 to-0.97), with corresponding two-stage Hf isotope model age(T;) varying from 1.26~1.54 Ga, suggesting that the protolith was predominantly derived from the crystalline basement crust in Mesoproterozoic, and may be accompanied by a small amount of mantle-derived materials. Combined with the previous studies on the Yanshanian diagenesis and mineralization in South China, it is considered that the dacite in the study area and the early Yanshanian rocks and deposits in Northeast Guangxi are the products of the first large-scale magmatic activity in the Yanshanian in South China, and the formation of dacite may be related to the intraplate extension thinning of the Yanshanian lithosphere in South China.

关 键 词：桂东北 英安岩 锆石U-Pb年龄 LU-HF同位素 燕山期 

分 类 号：P597[天文地球—地球化学]