黑龙江塔溪地区中侏罗世侵入岩地球化学特征、成因及构造环境  

Geochemistry, Petrogenesis and Tectonic Setting of the Middle Jurassic Taxi Plutons in Heilongjiang

作　　者：杨文鹏 李成禄 杨元江 符安宗 郑博 周腾飞 赵瑞君 YANG Wenpeng;LI Chenglu;YANG Yuanjiang;FU Anzong;ZHENG Bo;ZHOU Tengfei;ZHAO Ruijun(Heilongjiang Institute of Natural Resources Survey,Harbin,Heilongjiang 150036,China;Heilongjiang Key Laboratory of Black Soil and Water Resources Research,Harbin,Heilongjiang 150036,China)

机构地区：[1]黑龙江省自然资源调查院,黑龙江哈尔滨150036 [2]黑龙江省黑土地水土资源研究重点实验室,黑龙江哈尔滨150036

出　　处：《现代地质》2023年第2期390-403,共14页Geoscience

基　　金：黑龙江省重点研发计划项目(GA21A204);黑龙江省总工会职工创新补助资助项目(2021-30);中国地质调查局项目(1212011220430);黑龙江省地质矿产局科研项目(科研2020-1)。

摘　　要：为丰富对兴蒙造山带东端中生代构造背景的认识,选取贺根山—嫩江—黑河构造带内塔溪地区的石英二长岩、石英闪长岩及石英正长岩开展岩相学、年代学和地球化学研究。结果表明,石英闪长岩的LA-ICP-MS锆石U-Pb定年结果为(167.2±1.3)Ma,形成于中侏罗世。根据微量元素地球化学特征可将塔溪地区侵入岩划分为高Sr型和低Sr型两类,早期侵入的石英闪长岩为高Sr型,晚期侵入的石英二长岩和石英正长岩为低Sr型。高Sr型与低Sr型侵入体在主量、微量和稀土元素特征上均存在明显差异,具有类似I型和A型花岗岩的过渡特征,属复合型侵入岩体。该侵入岩体的形成与中生代强烈的陆内伸展造山和蒙古—鄂霍次克洋与法拉隆板块的双向俯冲闭合过程有关,是地壳在挤压增厚向伸展减薄转变的背景下,软流圈地幔上隆及玄武质岩浆底侵于下地壳并混染地壳物质部分熔融的产物。塔溪地区侵入岩体的存在,表明中侏罗世期间存在一次重要的地壳挤压增厚向伸展减薄转换事件,同时其形成时代也限定了蒙古—鄂霍次克洋东段的闭合时间应为中侏罗世。To enrich the understanding on the Mesozoic tectonic setting of the eastern Xingmeng orogenic belt,a study of the petrology,geochronology and geochemistry of the quartz monzonite,quartz monzodiorite and quartz syenite of Taxi plutons in the Hengenshan-Nenjiang-Heihe tectonic belt were reported.LA-ICP-MS zircon U-Pb dating yielded Middle Jurassic age(167.2±1.3 Ma)for the quartz monzonite.Intrusive rocks in Taxi can be divided into high-Sr and low-Sr ones:the early quartz monzodiorite is high-Sr,while the late quartz monzonite and quartz syenite are low-Sr.Our results indicate that the high-Sr and low-Sr intrusive rocks have rather different features of major element,trace element and rare earth element.All these data suggest that they show transition features from I-type to A-type granites,and should be defined as I-and A-type composite pluton.The emplacement was likely related to the subduction and closure of the Mongol-Okhotsk Ocean and the Farallon plate beneath Eurasia and Mesozoic intracontinental extension.The emplacement occurred under the tectonic background from crustal compression/thickening to extension,causing asthenospheric mantle upwelling and the mantle-derived basaltic magma underplating.This may have triggered partial melting of the lower crust and mantle,forming granitic magma.The presence of composite pluton is confirmed at Taxi,indicating that the crust in the region may have transitioned from compression and thickening to extension in the Middle Jurassic,which constrains the closure of the eastern Mongol-Okhotsk Ocean.

关 键 词：锆石U-PB年龄 中侏罗世 复合型侵入岩 底侵作用 蒙古—鄂霍次克洋闭合 塔溪地区 

分 类 号：P588.12[天文地球—岩石学]