大别山碧溪岭未经历超高压变质的片麻状花岗岩

关于大别山超高压变质带中与榴辉岩密切伴生的花岗片麻岩是否也经历了超高压变质作用一直是个争议的问题。笔者最近在碧溪岭片麻状花岗岩中首次发现了可靠的岩相学和矿物学证据 ,证明该岩石只遭受到绿片岩相变质作用的改造 ,而未曾记录超高压变质矿物组合。根据片麻状花岗岩与围岩接触部位强烈糜棱岩化的发育 ,认为超高压岩石在抬升到地壳范围时与以花岗质岩石为主构成的扬子陆壳发生了大规模的构造并置。

Gneissic Granite did not Experience Ultrahigh-Pressure Metamorphism from Bixiling, the Dabie Mountains

There has been much debate on whether or not the coarse grained granitic gneisses closely associated with eclogites have experienced ultrahigh pressure metamorphism in the Dabie Mountains. The recent discovery of petrogrphical and mineralogical evidences suggest that the Bixiling gneissic granite have never been transformed into ultrahigh-pressure assemblage, and only subjected to greenschist facies metamorphism. According to the development of mylonitization between gneissic granite and its country rocks, it is considered that a large scale tectonic juxtaposition of ultrahigh-pressure rocks and the Yangtze continental crust mainly composed of granitoids occurred at high crustal level during exhumation.