This is a model of telemagmatic metamorphism and a character of coal metamorphism early - middle jurassic in northwest of china 属于区域岩浆热变质作用的一种模式,也是西北地区早中侏罗世煤变质的特点之一。
Medium - rank bituminites are formed by pneumato - hydrothermal metamorphism on the basis of burial metamorphism , and it is partial 深大断裂带及其附近局部发育的中级烟煤是在深成变质基础上,叠加了高温气液热变质作用而形成。