【摘要】 徐淮地区中生代侵入杂岩中角闪岩和片麻岩类捕虏体的主要元素、微量元素地球化学特征及其岩相学的研究表明,它们经历了两期变质作用的改造,即早期的榴辉岩相变质和晚期的角闪岩相退化变质。其原岩为拉斑玄武质岩石,在其形成过程中有较强的陆壳物质混染;部分捕虏体可能代表了本区深部地壳的物质组成,且具有华北地块基底的性质。中生代早期该区上地幔是多种岩石构成的构造混杂岩带,深部地壳主要由片麻岩类、角闪岩类和少量石榴辉石岩类组成。早白垩世时期深部地壳主要由一套快速折返至下地壳的榴辉岩相变质岩石所构成,它们普遍发生了角闪岩相退化变质,并与原下部地壳的深变质岩(片麻岩和角闪岩)混杂在一起,构成了一个构造混杂体。更多还原

【Abstract】 On the basis of the major and trace element geochemical characters as well as petrography of this complex,the study indicates that the complex had undergone two rebuilds of metamorphism,i.e.earlier eclogite facies high-pressure(HP),and ultra-high pressure metamorphism(UHPM) and later amphibolite facies retrogressive metamorphism.Its protolith belongs to tholeiite with drastic contamination of continental substance during its forming process.Part of the xenoliths is probably similar to the lower part of the crust in chemical composition in this region,and possesses the feature of the basement of the North China Craton. Many kinds of rocks from the upper mantle in Early Mesozoic consist of a suit of tectonic complex.The lower part of the crust is composed of amphibolite,gneiss and a little of garnet-clinopyroxenite,forming a suit of rocks of eclogite facies metamorphite that turned back quickly into the lower part of the crust.These rocks widely underwent the amphibolite facies retrogressive metamorphism,and intermixed with katametamorphite of the original lower part of the crust(amphibolite and gneiss) forming a tectonic complex.更多还原