大别山区变质岩中蓝晶石的几种退变质反应及其所指示的动力学过程

Some Retrograde Metamorphic Reactions in Metamorphic Rocks in Dabie Mountains，Central China and Their Implication for Metamorphic Kinetics

蓝晶石在大别山含柯石英和不含柯石英的榴辉岩、高压变质的副片麻岩、非高压变质的宿松群的变质沉积岩中都是重要的变质矿物。它们多有冠状或其它的变质反应结构，形成多样化的退变质反应矿物。有些退变质反应是十分罕见的。本文报道了８种蓝晶石的矿物组合和退变质反应，推测和计算了变质反应的温度－压力条件，从而探讨了它们代表的近等温降压、升温降压和流体为重要因素的降温降压的不同的动力学过程。这些数据与用其它变质矿物所得到的温度压力条件和ＰＴｔ演化基本一致。为探讨大别山超高压变质带的构造演化提供了新的依据。

Kyanite, as a indicating metamorphic mineral, occurs in various metamorphic rocks in Dabie Mountains, central China, for example in eclogite, coesite-bearing eclogite, high-pressure metamorphic paragneiss, not-high pressure metasedimentary rocks of the Susong Group. Kyanites commonly have corona texture and other metamorphic reaction texture, the secondary metamorphic minerals are diverse. Eight kyanitebearing mineral assemblages and their different retrograde metamorphic reactions are reported in this paper.Their estimated metamorphic P-T conditions and PTt paths indicate their individual metamorphic kinetic processes of iso-temperature decompressing metamorphism, and decreasing pressure with incraesing temperature metamorphism, and decraesing temperature and pressure metamorphism accompanied by fluid action. These metamorphic kenitic processes are identical with that obtainted from other metamorphic minerals and reaction.