许多岩石含有一个变质幕跟随另一变质幕的迹象,如被花岗岩侵入的片岩表现出热变质效应迭加在区域变质效应之上。重复变质或者多相变质作用系指几幕相同类型的变质作用。退变质作用是作用于较高级变质岩之上的一种较低级的变质过程,如泥质岩在一个相中转变为硅线石片麻岩,在后一相中退变为绢云一绿泥千糜岩。 Many rocks contain a sign that a metamorphic curtain follows another metamorphic change. For example, intrusive schists show the effect of thermal metamorphism superimposed on regional metamorphism. Repeated metamorphism or multiphase metamorphism refers to several types of the same type of metamorphism. The retrograde metamorphism is a lower-level metamorphism that acts on higher metamorphic rocks. For example, the mudstone is transformed into sillimanite in one phase and degenerated into sericite-green in the latter phase Microstam