黑龙江太平岭早侏罗世花岗岩成因及壳幔混合作用  

Petrogenesis and Crust-mantle Mixing of Early Jurassic Granites in the Taipingling Mountains,Heilongjiang Province

作　　者：吕长禄[1,2] 徐东海[1,2] 李新鹏 郝兴中[1,3] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]黑龙江省地质调查研究总院,黑龙江哈尔滨150036 [3]山东省地质调查院,山东济南250013

出　　处：《现代地质》2012年第4期635-646,共12页Geoscience

基　　金：中国地质调查局黑龙江牡丹江市幅(L52C004003);绥芬河市幅(L52C004004)区调修测项目(200413000014)

摘　　要：位于黑龙江省牡丹江一带的太平岭是兴蒙造山带的重要组成部分,在该区广泛分布大量花岗岩。这些花岗岩的SHRIMP锆石U-Pb年龄介于179～204 Ma之间,表明形成于早侏罗世,而非以往认为的晚三叠世。岩体的岩性以花岗闪长岩为主,其中普遍含有细粒闪长质包体,而二长花岗岩-正长花岗岩中偶见细粒闪长质包体。岩石学、岩相学和地球化学研究表明这些花岗岩为壳幔岩浆混合成因。太平岭早侏罗世花岗岩具有比较均一的Sr、Nd、Pb同位素成分,εNd(t)值介于-3.2～+2.3之间,(87Sr/86Sr)i值主要集中在0.704～0.706之间,进一步表明岩石的源区与幔源物质有密切的联系。花岗岩显示火山弧花岗岩的特点,代表了以挤压为主的构造环境,表明岩石可能与古太平洋板块俯冲作用有关。The Taipingling Mountains in Mudanjiang,Heilongjiang Province is an important component of the Xing’an-Mongolian Orogenic Belt.The granitic rocks are widely distributed in the area.Zircon SHRIMP U-Pb age of these granites ranges from 179 Ma to 204 Ma,which indicate that they formed in the Early Jurassic,rather than the Late Triassic by former traditional understanding.The main lithology of the batholith is granodiorite,which are abundant in fine-grained dioritic enclaves.The fine-grained dioritic enclaves are rarely found in the monzonitic granite and syenogranite.The petrologic,petrographic and geochemical studies in this paper show that the Taipingling granites are generated by magma mixing of crustal and mantle materials.The Early Jurassic Taipingling granites have homogeneous Sr,Nd,and Pb isotopic compositions,with εNd（t）ranging from-3.2 to＋2.3,and（87Sr/86Sr）i ranging from 0.704 to 0.706.This further suggests that the rocks are strongly mantle-related.The granites show volcanic arc granite characteristics,which implies it is related to the environment dominated by compression.The origin of the Taipingling granites is tectonically linked to the subduction of the paleo-Pacific plate.

关 键 词：太平岭 早侏罗世 花岗岩 闪长质包体 古太平洋板块 黑龙江 

分 类 号：P588.121[天文地球—岩石学]