关于大别山榴辉岩相变质作用

On the eclogite facies metamorphism in the Dabie Mountains

大别山产出的榴辉岩相岩石包括石榴橄榄岩、榴辉岩、榴云片岩、榴辉片麻岩、榴玉英岩和榴辉大理岩等不同系列，它们均分布于花岗质片麻岩中。矿物共生序列研究表明，榴辉岩相岩石经历了从绿帘角闪岩相、柯石英榴辉岩相、角闪榴辉岩相、绿帘角闪岩相到绿片岩相的演化过程。花岗质片麻岩及变质火山—沉积岩系并未经历超高压变质作用，但却与榴辉岩相岩石经历了同一期绿帘角闪岩相变质事件。

Eclogite facies rocks from the Dabie Mountains are mainly composed of garnet peridotite, eclogite, garnet phengite schist, eclogitic gneiss, garnet jadeite quartzite and eclogitic marble, which often occurs within granitic gneisses. The paragenetic sequence in eclogite indicates that eclogite facies rocks experienced progressive metamorphism from epidote amphibolite facies to coesite eclogite facies and retrograde metamorphism from amphibole eclogite facies through epidote amphibolite facies to greenschist facies. Granitic gneisses and metamorphosed volcanic sedimentary rocks were not subjected to ultrahigh pressure metamorphism, but they together with eclogite facies rocks underwent the same epidote amphibolite facies metamorphic event. This may imply that the two rock units were juxtaposed at crustal levels during the late continental collision in the Dabie Mountains.