华北克拉通冀东兴隆麻粒岩的变质演化及其构造意义  

Metamorphic evolution of the granulites and its geological implications in the Xinglong area of the eastern Hebei terrane,North Craton China

作　　者：陈滋元 王国栋[2] 李天琦 周嘉仪 刘依琳 肖玲玲 CHEN ZiYuan;WANG GuoDong;LI TianQi;ZHOU JiaYi;LIU YiLin;XIAO LingLing(School of Civil and Resource Engineering,University of Science and Technology Beijing,Beijing 100083,China;Shandong Provincial Key Laboratory of Water and Soil Conservation and Environmental Protection,School of Resources and Environment,Linyi University,Linyi 276000,China;Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China)

机构地区：[1]北京科技大学土木与资源工程学院,北京100083 [2]临沂大学资源环境学院,山东省水土保持与环境保育重点实验室,临沂276000 [3]自然资源部深地动力学重点实验室,中国地质科学院地质研究所,北京100037

出　　处：《岩石学报》2024年第11期3398-3425,共28页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(42072219、41802201);山东省自然科学基金项目(ZR2023MD058);自然资源部深地动力学重点实验室自主(开放)研究课题(J1901-16);北京科技大学采矿工程专业地质类实验课程数字化建设研究与探索项目(JG2021M02)联合资助.

摘　　要：冀东地体位于华北克拉通东部陆块,其新太古代时期的构造热演化过程仍存较大争议,大致存在三种不同的观点:水平构造模式、简单地幔柱模式和重力凹沉(sagduction)模式。其中,关于变质演化的认知差异是上述争论的重要焦点之一。位于冀东地体西侧的兴隆变质杂岩,是探究华北克拉通东部陆块新太古代构造热演化历史的理想载体。本文对杂岩中的石榴二辉麻粒岩、石榴斜方辉石麻粒岩以及长英质脉体进行了岩石学和锆石U-Pb年代学研究。研究结果表明,麻粒岩中保存了进变质(M1)、变质峰期(M2)和退变质(M3)三个阶段的变质矿物组合:进变质阶段矿物组合为黑云母、石英,偶见角闪石、钾长石、斜长石和钛铁矿,变质温压条件为608~667℃/0.40~0.50GPa;峰期阶段矿物组合为石榴子石、角闪石、斜方辉石、黑云母、斜长石、钾长石、石英、钛铁矿和/或单斜辉石,变质温压条件为763~867℃/0.93~1.13GPa;退变质阶段矿物组合为石榴子石、角闪石、黑云母、斜方辉石、斜长石、钾长石、石英、钛铁矿和/或磁铁矿,变质温压条件为674~734℃/0.88~0.93GPa。因此,岩石记录了进变质阶段升温升压以及峰后降压降温型的逆时针变质作用P-T轨迹。锆石U-Pb年代学研究表明,两类麻粒岩的原岩形成于2534~2531Ma,随后于2523~2515Ma发生麻粒岩相变质作用。与麻粒岩同期变质的片麻岩中发育长英质脉体,后者中的锆石记录了与麻粒岩一致的约2534Ma的岩浆年龄和约2524Ma的变质年龄。结合前人研究,推测冀东地体新太古代末期发生的变质-岩浆事件可能与区域上的垂直构造模式下的重力凹沉构造活动有关。The eastern Hebei terrane in the Eastern Block of the North China Craton(NCC)is controversial about its tectonic-thermal evolution during the Neoarchean period,which are mainly divided into three mainly models:the horizontal tectonism model,the mantle plume model and the sagduction model.One of the key issues of the three viewpoints mentioned above is the differing understanding of metamorphic evolution.The Xinglong metamorphic complex lies in the western part of the eastern Hebei terrane,and acts as an ideal subject for exploring the tectonic-thermal evolution history of the Neoarchean in the Eastern Block of the NCC.This study presents investigations into petrology and zircon U-Pb geochronology for one garnet two-pyroxene granulite sample,one garnet-orthopyroxene granulite sample and one felsic vein sample exposed in the Xinglong metamorphic complex.Three generations of mineral assemblages can be recognized for the granulites,including the prograde(M1),metamorphic peak(M2),and retrograde mineral assemblages(M3).The prograde mineral assemblages consist of biotite+quartz±amphibole±K-feldspar±plagioclase±ilmenite,and the metamorphic temperatures and pressures are:608~667℃/0.40~0.50GPa.The peak mineral assemblage consists of garnet+amphibole+orthopyroxene+biotite+plagioclase+K-feldspar+quartz+ilmenite or clinopyroxene formed at 763~867℃/0.93~1.13GPa.The retrograde mineral assemblage is composed of garnet+amphibole+biotite+orthopyroxene+plagioclase+K-feldspar+quartz+ilmenite or magnetite,recording the temperature and pressure conditions of 674~734℃/0.88~0.93GPa.Consequently,the rocks exhibit an anticlockwise metamorphic P-T path,showing an increase in temperature and pressure during the prograde stage,followed by a decrease in both after reaching the peak stage.Zircon U-Pb dating shows that the protoliths of granulite were emplaced at 2534~2531Ma,followed by granulite-facies metamorphism at 2523~2515Ma.The felsic veins derived from the country gneisses that underwent contemporaneous metamorphism with the g

关 键 词：变质演化 U-PB年代学 麻粒岩 兴隆 冀东 华北克拉通 

分 类 号：P588.347[天文地球—岩石学] P597.3[天文地球—地质学]