桂东南云开岩群斜长角闪岩的变质作用PT轨迹及其动力学意义  

PT PATH OF METAMORPHISM OF AMPHIBOLITE IN YUNKAI GROUP COMPLEX IN SOUTHEASTERN GUANGXI AND ITS DYNAMIC SIGNIFICANCE

作　　者：覃小锋[1] 王核[1] 钟锋运[2] 周府生[2] 胡贵昂[2] 李广宁[2] 谢凌锋[2] 周开华[2] 潘艺文[2] 

机构地区：[1]中国科学院广州地球化学研究所,广东广州510640 [2]广西区域地质调查研究院,广西桂林541003

出　　处：《大地构造与成矿学》2007年第2期234-244,共11页Geotectonica et Metallogenia

基　　金：中国地质调查局"1:25万玉林市幅区域地质调查"项目(200213000029)资助

摘　　要：桂东南中新元古界云开岩群是一套中浅变质岩系,并形成一系列绿片岩相-角闪岩相的递增变质带,通过对云开岩群角闪岩相变质带(十字石-蓝晶石带)中斜长角闪岩变质作用的PT轨迹的系统研究显示,其包括了由早期绿片岩相变质阶段(M1)→峰期角闪岩相变质阶段(M2)→近等温降压变质阶段(M3)→近等压降温变质阶段(M4)→晚期绿片岩相退变质阶段(M5)五个阶段的顺时针PT演化轨迹,其地质动力学过程属于典型的板块俯冲碰撞→抬升模式,表明云开地块北缘造山带的地质构造演化经历了俯冲碰撞及碰撞后的快速抬升过程。Meso-Neoproterozoic Yunkai Group complex is lithologically composed of the middle-low grade metamorphic series in southeastern Guangxi, which formed a series of zones of progressive metamorphism from greenschist facies to amphibolite facies. Systematical research of amphibolite in the amphibolite facie metamorphic zone （staurolite-kyanite zone） from Yunkai Group complex shows that these rocks mainly experienced five metamorphism evolutions stages： the early greenschist-facies progressive metamorphism stage （M1 ） , the peak amphibolite-facies stage （M2） , the constant temperature and depressed metamorphism stage （M3 ） , the constant pressure and decreased temperature metamorphism stage （M4 ） and the late greenschist-facies retrograde metamorphism stage （M5 ） , which together compose a clockwise revolving PT path. The geodynamic process falls in the mode of plate-plate collision orogenics-uplift, which indicates that the geological evolution of the collision orogen in the northern margin of Yunkai land block experienced collision, subduction and subsequent rapid uplift.

关 键 词：云开岩群 变质作用PT轨迹 斜长角闪岩 桂东南地区 

分 类 号：P588.3[天文地球—岩石学] P542[天文地球—地质学]