熊耳山地区穆册二长岩体地球化学特征、U-Pb年龄及构造背景  

Geochemical characteristics, U-Pb ages and tectonic setting of the Muce Monzonite in Xiong’er Mountains

作　　者：武甜甜 雷万杉[1,2] 焦建刚[1,2] 赵太平[3] 高昕宇[3] WU Tiantian;LEI Wanshan;JIAO Jiangang;ZHAO Taiping;GAO Xinyu(School of Earth Science and Resources,Chang’an University,Xi’an,710054;Key Laboratory of Western China’s Mineral Resources and Geological Engineering,Ministry of Education,Xi’an,710054;Key Laboratory for Metallogenic Dynamics,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou,510640)

机构地区：[1]长安大学地球科学与资源学院,西安710054 [2]西部矿产资源与地质工程教育部重点实验室,西安710054 [3]中国科学院广州地球化学研究所,广州510640

出　　处：《地质论评》2019年第4期873-893,共21页Geological Review

基　　金：国家重点研发项目(编号:2016YFC0600106);国家自然基金资助项目(编号:41602064);中央高校基本科研业务费项目(编号:300102278203和310827151057)的成果~~

摘　　要：华北克拉通古元古代的构造格局是学术界关注的焦点之一,位于华北克拉通南缘的穆册二长岩体为该研究提供了新的证据。穆册岩体主体为黑云角闪二长岩,边部见二长斑岩,并被同期二长花岗岩脉侵入。二长岩的LA-ICP-MS锆石U-Pb定年为2172±8 Ma(MSWD=0.58,n=17)和2186±7 Ma(MSWD=0.60,n=19),二长花岗岩年龄为2174±8 Ma(MSWD=0.45,n=19),显示该二长岩体形成于古元古代。穆册二长岩不仅具有造山后地球化学特征,还具有典型的岛弧岩浆岩的地球化学特征。综合分析,穆册二长岩可能在古元古代经历了岛弧和裂谷两种环境的共同影响。Objectives:The Muce monzonite in Xiong’er Mountains is distributed in the southern margin of the North China Craton.It is of great geological significance to study the tectonic evolution of the southern margin of the North China Craton.Combined with petrological study,geochemical characteristics of the monzonite and the LA-ICP-MS zircon U-Pb age,we briefly discuss the formation age,origin and tectonic background of the monzonite.Methods:Based on the field work,through the microscope observation,the whole rock chemical analysis and LA-IPC-MS U-Pb zircon dating of Muce monzonitic feldspar and monzogranite were carried out.Results:The geochemical analysis of the Muce monzonite shows that that belongs to type A genetic type and is formed in the rifting environment under the extensional structure.The monzonite is riched in large ion lithophile elements(LILEs) Rb,Ba,Sr,Pb and light rare earth elements(LREEs).The monzonite is deficient in high field strength elements(HFSEs) Th,Nb,Zr,and strong depletion of Ti and Ta,which show the characteristics of typical island arc magmatic rocks.LA-ICP-MS U-Pb zircon dating of the monzonite samples yield the ages of 2172±8 Ma(MSWD = 0.58,n = 17) and 2186±7 Ma(MSWD = 0.60,n = 19).Respectivesly,monzogranite sample gets a LA-ICP-MS U-Pb zircon age of 2174±8 Ma(MSWD = 0.45,n = 19),indicating the Muce monzonite was formed in Paleoproterozoic.Conclusions:Combined with the previous study,it is considered that the Muce monzonite was formed in the Paleoproterozoic and may have experienced the influence of rifting and island arc.

关 键 词：穆册二长岩 古元古代 岛弧岩浆 熊耳山 华北克拉通南缘 

分 类 号：P588.1[天文地球—岩石学] P597.3[天文地球—地质学] P534.3