煤岩构造变形与动力变质作用

Tectonic deformation and dynamic metamorphism of coal

煤岩是一种对温度、压力等地质环境因素十分敏感的有机岩,地质演化过程中的各种构造-热事件必然导致煤岩发生一系列物理与化学结构的变化,并形成不同类型的构造煤。在构造应力作用下,煤岩不仅发生脆性和韧性变形,而且还产生不同程度的动力变质作用。因而,关于煤岩构造变形与动力变质作用的研究不仅具有重要的科学意义,而且在煤层气资源评价以及煤与瓦斯突出危险性预测方面也具有重要的实际意义。文中在已有研究成果基础上,通过对构造煤系列Ro,max、XRD和NMR(CP/MAS+TOSS)等测试和实验方法的对比研究,深入分析了煤岩不同构造变形和动力变质特征,进一步探讨了构造应力下煤岩动力变质作用的机理。研究成果表明,在构造应力作用下,煤岩脆性变形主要是通过破裂面上快速机械摩擦转化为热能而引起煤岩化学结构与其成分的改变;而韧性变形煤主要是通过局部区域应变能的积累而引起煤岩化学结构的破坏,从而发生不同机制的动力变质作用。

Coal is an organic rock which is sensitive to geological environmental factors such as temperature and pressure. Various tectonothermal events of the geological evolution must have caused a series of changes in physical, chemical structures of coal and thus formed different tectonically deformed coals. The effect of tectonic stress would induce the brittle and ductile deformation of coal, as well as its dynamic metamorphism at different degrees. Therefore the research about tectonic deformation and dynamic metamorphism of coal is not only of important scientific significance but also very important for the evaluation in resources of coalbed methane and the prediction of dangerous coal and gas outbursts. Based on the existing research results, different tectonic deformation and dynamic metamorphism in coal have been intensively studied through the R XRD and NMR（CP/MAS＋TOSS）. Also the mechanism of dynamic metamorphism about coal under tectonic stress has been discussed. The results show that, under the influence of tectonic stress to the brittle deformation of coal, the rapid mechanical friction on the plane of fracture in the brittle deformation of coal can be translated into heat energy causing the changes of its chemical structure and composition of coal; while as to the ductile deformation coal, the accumulation of local regional strain energy can result in the failure of its chemical structure. Thus the dynamic metamorphism of different deformational mechanisms would have taken place.