Abstract:

Based on X-ray Diffraction (XRD) analysis of tectonically-deformed coals with different deformation types and extent,
the evolution of the tectonically-deformed coals and their stress-strain environments were studied. The results show that the space
between aromatic layers(d 002) of weak-deformed coals decrease in stepfunction with the step point of about R o,max=0.69%, as the
rank of coalification increases, and change a little following the step point; the d 002 of scaly coal Ⅱ is smallest, crumpled-mylonitic
coal’s d 002, which is almost equal to flaky coal Ⅱ’s d 002, is between the d 002 of weak-deformed coals and scaly coal Ⅱ, and the d 002
of crumpled coal is slightly larger than that of crumpled-mylonitic coal. The other parameter L c changes in a coordinate way with
d 002. It is indicated that tectonically-deformed coals with various deformation types and extent are corresponding to different types
and extent of stress-strain action, which change the macro- and microtexture of coal as well as the texture of aromatic nucleus.
The effect of each stress-strain environment upon the aromatic nucleus of coal is different. The stress-strain environments forming
tectonically-deformed coals can be classified into three types, i.e. brittle cataclastic, ductile, and shearing. Weak and moderate
brittle cataclastic deformation actions have little effects on the development of aromatic nucleus of coal. Ductile and shearing
deformation actions are featured by conditions of certain temperature and confining pressure and directional stress action,

respectively. The former are benefit for shedding of small radicles and developing of new aromatic rings, the later are helpful to
the ordering of molecular structure. Both of them promote the growth of aromatic nucleus in coal.