吉林庆岭地区花岗质糜棱岩的发现及其年代学与地球化学特征  

The discovery of granitic mylonite in Qingling area of Jilin Province and its geochronology and geochemical characteristics

作　　者：王存柱 张彬[1] 郑大贺 李国郡 马超 WANG Cunzhu;ZHANG Bin;ZHENG Dahe;LI Guojun;MA Chao(Mudanjiang Natural Resources Comprehensive Survey Centre,CGS,Mudanjiang 157021,Heilongjiang,China)

机构地区：[1]中国地质调查局牡丹江自然资源综合调查中心,黑龙江牡丹江市157000

出　　处：《华北地质》2025年第1期11-23,57,共14页North China Geology

基　　金：中国地质调查局项目“吉林夹皮沟—海沟金矿重点调查区调查评价(DD20230382)”。

摘　　要：【研究目的】吉林庆岭地区花岗质糜棱岩大地构造位置位于华北板块北缘东段,其岩石成因和形成环境的研究对古亚洲洋构造域演化及其与古太平洋构造域构造体制转换具有重要意义。【研究方法】本文首次对其进行了岩相学、岩石地球化学、LA-ICP-MS锆石U-Pb年代学以及黑云母^(40)Ar/^(39)Ar年代学研究,确定其岩石成因、形成构造背景以及侵位年龄和变形年龄。【研究结果】花岗质糜棱岩锆石为半自形—自形,震荡生长环带明显,暗示其岩浆成因。测年结果显示花岗质糜棱岩形成于291±3.0 Ma,为早二叠世岩浆事件的产物。EBSD组构分析显示本区岩石经历了中高温—中低温—低温的递退过程,黑云母^(40)Ar/^(39)Ar坪年龄为182.01±0.38 Ma,暗示其变质变形时代为早侏罗世。岩石具高硅(68.26%~75.91%)、高铝(12.32%~15.17%)、贫铁(Fe_(2)O_(3)为0.03~3.38)等特征,地球化学特征显示为过铝质。岩石富集轻稀土元素,亏损重稀土元素,轻重稀土元素分异明显。【结论】上述特征表明其为下地壳泥质岩石的部分熔融的产物。结合区域地质特征,早二叠世花岗质糜棱岩的侵位应与古亚洲洋向南俯冲有关;花岗质糜棱岩早侏罗世发生变质变形,可能与古太平洋板块开始向欧亚大陆板块俯冲有关。[Objective]The tectonic location of granitic mylonite in Qingling area of Jilin Province is located in the eastern part of the northern margin of the North China plate.The research is the great significance to the evolution of the Paleo-Asian Ocean tectonic domain and its transformation with the tectonic system of the Paleo-Pacific tectonic domain.[Methods]In this paper,it is the first time to study the petrography,LA-ICP-MS zircon U-Pb chronology and geochemical characteristics of the rock to determine its emplacement age,petrogenseis and its tectonic background.[Results]The zircon of granitic mylonite is semi-automorphicautomorphic and the oscillatory growth zone is obvious,suggesting its magmatic origin.The dating results show that the granitic mylonite was formed at 291±3.0 Ma,which is the product of the Early Permian magmatic event.The^(40)Ar/^(39)Ar plateau age of biotite is 182.01±0.38 Ma,suggesting that the metamorphic deformation age is Early Jurassic.EBSD fabric analysis shows that the rocks in this area have undergone a regressive process of medium-high temperature to medium-low temperature to low temperature.The rock is characterized by high silicon(68.26%-75.91%),high aluminum(12.32%-15.17%),poor iron(Fe_(2)O_(3)is 0.03-3.38),and geochemical characteristics show peraluminous.The rocks are enriched in light rare earth elements,depleted in heavy rare earth elements,and the differentiation of light and heavy rare earth elements is obvious.[Conclusions]The above characteristics indicate that it is the product of partial melting of argillaceous rocks in the lower crust.The^(40)Ar/^(39)Ar plateau age of biotite is 182.01±0.38 Ma,suggesting that its metamorphic deformation is Early Jurassic.Combined with regional geological characteristics,the emplacement of Early Permian granitic mylonite should be related to the southward subduction of the Paleo-Asian Ocean.The metamorphic deformation of the granitic mylonite occurred in the early Jurassic,which may be related to the subduction of the Paleo-Pacific pla

关 键 词：花岗质糜棱岩 锆石U-PB年龄 地球化学特征 黑云母40Ar/39Ar坪年龄 吉林庆岭 

分 类 号：P581[天文地球—岩石学] P588.121[天文地球—地质学]