辽河群变质序列再讨论

辽河群的原岩以泥质和泥砂质岩石为主,其经历了绿片岩相至角闪岩相变质作用,产生了丰富的变质矿物(矿物组合).不同变质级别的矿物组合,是各自在变质作用峰期生成的,它们是空间上的并列关系,绝非时间上的先后关系,不能依此划分变质阶段和幕次,更不能用它们来做P-T-t轨迹.同一矿物组合内,通过滑动反应和综合反应,矿物之间达到一定温压条件下的平衡共生关系,各种矿物变质程度是相同的,形成时间是同时的或交错的.有的研究者认为,变质矿物形成序列为Chl→Bt→Gt→Stau→And(Ky)→Sill(Cord),这种观点是值得商榷的.

FURTHER DISCUSSION ON THE METAMORPHIC SEQUENCE OF LIAOHE GROUP

The original rocks of Liaohe Group are dominated by muddy and silty rocks,which experienced greenschist to amphibolite facies metamorphism,resulting in a rich composition of metamorphic minerals. The metamorphic mineral assemblages of different levels are generated at each peak period of metamorphism. They just coexist in space,but have no relationship of time. It cannot be relied on to divide metamorphic stages and episodes,nor be used to make the P-T-t track. In the same mineral assemblage,with sliding reaction and complex response,the minerals reach a balanced coexistence under certain temperature and pressure conditions. The metamorphic degrees of various minerals are the same,while the formation time is simultaneous or not. Some researchers believe that the metamorphic mineral formation sequence is Chl→Bt→Gt→Stau→And(Ky)→Sill(Cord),which is debatable.