华北克拉通东南缘1.90~1.80 Ga陆-陆碰撞作用:来自胶北地体花岗-绿岩带的证据  

Ca.1.90-1.80 Ga continent-continent collision in southeastern North China Craton:Evidence from the granite-greenstone belt in the Jiaobei Terrane

作　　者：石康兴 王长明[1] 杜斌[1] 陈奇 祝佳萱 饶世成 段泓羽 SHI Kangxing;WANG Changming;DU Bin;CHEN Qi;ZHU Jiaxuan;RAO Shicheng;DUAN Hongyu(School of Earth Sciences and Resources,China University of Geosciences(Beijing),Beijing 100083,China)

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《地学前缘》2021年第6期295-317,共23页Earth Science Frontiers

基　　金：国家重点研发计划项目(2020YFA0714803);国家自然科学基金面上项目(41872080);地质过程与矿产资源国家重点实验室科技部专项经费项目(MSFGPMR201804);中央高校基本科研业务费项目(2652017223)。

摘　　要：胶北地体位于华北克拉通东南缘,其太古宙古元古代的岩石组合包括斜长角闪岩、TTG片麻岩、花岗闪长岩、片岩和表壳岩等,显示出典型的花岗绿岩带岩石系列特征,这一岩石系列对了解华北克拉通前寒武纪构造演化以及微陆块碰撞拼合过程具有重要的科学研究意义。本文通过详细的LA-ICP-MS锆石U-Pb年代学分析显示,胶北地体古元古代斜长角闪岩原岩、TTG片麻岩原岩和花岗闪长岩的结晶年龄分别为(1881±18)Ma、(1852±16)Ma和(1840±9)Ma,同时记录了(2332±32)Ma、(2244±25)Ma、(1935±21)Ma的继承年龄和(1796±17)Ma的变质年龄。锆石Lu-Hf同位素结果显示εHf(t)介于-4.7到3.9之间,地壳模式年龄(T_(DMc))介于2784~2289 Ma之间,表明胶北地体古元古代花岗绿岩带岩石系列的形成在一定程度上受到了大陆地壳的混染作用。胶北地体古元古代斜长角闪岩具有低硅、高铁、轻重稀土元素分异较弱以及无明显Ce、Eu异常的特点,微量元素显示Nb、Ta负异常和Rb、Pb、K正异常的特征,与板内玄武岩的特征一致。TTG片麻岩和花岗闪长岩呈现出轻稀土元素富集型以及无明显Ce异常的特点,微量元素Nb、Ta、Ti、P的负异常和Rb、Pb、Zr、Hf的正异常等特征,与后碰撞花岗岩和板内花岗岩一致。地球化学特征表明:胶北地体古元古代花岗绿岩带岩石系列的母岩浆是通过玄武质熔体的部分熔融作用产生的。结合前人研究,本文补充了相关岩石的年龄、同位素和地球化学证据,提出胶北地体存在1.90~1.80 Ga陆-陆碰撞作用,对理解华北克拉通古元古代陆-陆碰撞作用具有重要意义。The Jiaobei Terrane is located in the southeastern part of the North China Craton(NCC),and its Archean-Paleoproterozoic lithological assemblage,including amphibolite,TTG gneiss,granodiorite,schist and supracrustal rocks,suggests a typical granite-greenstone succession.This succession offers a significant insight into the history of Precambrian tectonic evolution of the NCC and the collision-amalgamation process of microcontinents.Here we investigated a suite of amphibolite,TTG gneiss and granodiorite from the Jiaobei Terrane to understand their genesis.Detailed LA-ICP-MS U-Pd dating of zircons from the magmatic grains yielded ages of 1881±18 Ma for amphibolite,1852±16 Ma for TTG gneiss and 1840±9 Ma for granodiorite.The inherited ages of 2332±32 Ma,2244±25 Ma,1935±21 Ma and the metamorphic age of 1796±17 Ma were also recorded for these zircons.The zircon Lu-Hf isotope show theεHf(t)values ranging from-4.7 to 3.9 and the crustal model ages(T_(DMc))in a range of 27842289 Ma.The results suggest that the formation of the Paleoproterozoic granite-greenstone succession in the Jiaobei Terrane is partly contaminated by the continental crust.The geochemical features of amphibolite are similar to within-plate basalt,with low SiO_(2),high FeO^(T),weak differentiation between light(LREE)and heavy REEs(HREE)and absence of obvious Ce and Eu anomalies,negative Nb and Ta anomalies and positive Rb,Pb and K anomalies.The TTG gneiss and granodiorite show enrichment of LREE and absence of obvious Ce anomaly,negative Nb,Ta,Ti and P anomalies and positive Rb,Pb,Zr and Hf anomalies.They display transitional features from post-collisional granite to within-plate granite.The parent magma of the Paleoproterozoic granite-greenstone succession in the Jiaobei Terrane is generated from the partial melts of basalts.Based on the previous studies,this paper supplements geochronological,isotopic and geochemical data of the related rocks,and proposes a ca.1.901.80 Ga continent-continent collision process in the Jiaobei Terrane.Our results

关 键 词：U-PB年代学 LU-HF同位素 地球化学 胶北地体 陆-陆碰撞 

分 类 号：P581[天文地球—岩石学] P597[天文地球—地质学]