湘中白马山复式岩体年代学、Hf同位素、地球化学及岩石成因  

Geochronology,Hf Isotope,Geochemistry and Petrogenesis of the Baimashan Granitic Complex in the Central Hunan Province

作　　者：刘贤红 刘德亮 娄元林 潘思远 肖涛 刘小坚 张珍力 Liu Xianhong;Liu Deliang;Lou Yuanlin;Pan Siyuan;Xiao Tao;Liu Xiaojian;Zhang Zhenli(Changsha Natural Resources Comprehensive Survey Center,China Geological Survey,Changsha,Hunan 410600,China;Collaborative Innovation Center for Exploration of Strategic Mineral Resources,China University of Geosciences,Wuhan 430074,China;Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China;School of Earth Science and Resources,China University of Geosciences,Beijing 100083,China)

机构地区：[1]中国地质调查局长沙自然资源综合调查中心,湖南长沙410600 [2]中国地质大学紧缺战略矿产资源协同创新中心,湖北武汉430074 [3]中国地质科学院矿产资源研究所,北京100037 [4]中国地质大学地球科学与资源学院,北京100083

出　　处：《地球科学》2025年第2期609-620,共12页Earth Science

基　　金：中国地质调查局“湖南怀化-邵阳金矿重点调查区调查评价”(No.DD20230386);湖北省自然科学基金面上类项目(No.2021CFB499);自然资源部新一轮找矿突破战略行动科技支撑项目“湖南雪峰金锑成矿带控矿构造解析与找矿预测”(No.ZKKJ202408).

摘　　要：为深入探讨华南早古生代和早中生代的构造演化、岩浆活动及其资源成矿效应,对湘中地区白马山复式岩体进行了系统的野外调查,并开展了锆石年代学、Hf同位素及地球化学研究.锆石LA-ICP-MS U-Pb年龄分析结果显示,白马山岩体水车超单元糜棱岩化花岗岩和龙潭−小沙江超单元黑云母花岗闪长岩的加权平均年龄分别为409±2 Ma和211±1 Ma,二者分别为加里东晚期和印支晚期岩浆活动的产物.加里东期糜棱岩化花岗岩具有高硅、高碱和强过铝质的特征,表现出强烈的负Eu异常,结合其富集的Hf同位素组成[εHf(t)=−13.4~−5.4],可推测其应为古元古代沉积岩的部分熔融产生的S型花岗岩.印支期黑云母花岗闪长岩则具有低硅、高碱和准铝质的特征,显示出中等强度的负Eu异常,且其εHf(t)值(−10.3~−7.4)较负、模式年龄古老(1.71~1.89 Ga),为古元古代变火成岩与部分变沉积岩重熔形成的I型花岗岩.白马山复式岩体的加里东期和印支期超单元可能均形成于陆内造山的构造环境中.加里东期岩体与区域W矿化之间、印支期岩体与区内Au-Sb-W矿化之间分别具有密切的成因联系,表明这些岩体具有良好的Au-Sb-W成矿潜力.In order to thoroughly investigate the tectonic evolution,magmatic activities,and their effects on mineral resource formation during the Early Paleozoic and Early Mesozoic eras in South China,systematic field investigations were conducted in the Baimashan complex located in the central Hunan region.Additionally,zircon geochronological analysis,Hf isotope studies,and geochemical assessments were performed.Zircon LA-ICP-MS U-Pb dating illustrates that the weighted mean ages of the Shuiche mylonitized granite and the Longtan-Xiaoshajiang biotite granodiorite within the Baimashan granitic complex are 409±2 Ma and 211±1 Ma,respectively.These ages correspond to the Late Caledonian and Indosinian magmatic events,respectively.The Caledonian mylonitized granite is characterized by high silica,high alkali and strong peraluminosity,accompanied by a pronounced negative Eu anomaly.This,combined with its enriched Hf isotopic composition[εHf(t)=−13.4 to−5.4],indicates that it is likely a S-type granite formed through partial melting of Paleoproterozoic sedimentary rocks.In contrast,the Indosinian biotite granodiorite exhibits low-silica,high-alkalinity and aluminous,displaying a moderate Eu-negative anomaly with a relatively negativeεHf(t)value(−10.3 to−7.4)and an ancient modal age(1.71 to 1.89 Ga).This granodiorite can be categorised as a Paleoproterozoic meta-igneous mixing of partially metasomatised sedimentary rocks remelted to form I type granites.The Caledonian and Indosinian superunits of the Baimashan complex may have been formed in a tectonic environment of intra-plate orogeny.There is a strong genetic connection between the Caledonian rocks and the regional W mineralization,as well as between the Indosinian granitic rocks and the Au-Sb-W mineralization in the area.These rocks exhibit significant potential for Au-Sb-W mineralization.

关 键 词：白马山复式岩体 年代学 地球化学 岩石成因 

分 类 号：P619.222[天文地球—矿床学]