Abstract: The Deformation Metamorphism of Tectonic Coal and Its Application in Geological Mining Hazards

CAO, YUNXING and LIU RUIXUN

Deformed coal is called tectonic coal which is further classified as cataclastic coal, granular coal, and mylonite coal. All three kinds of tectonic coal have generated dynamometamorphism during their deformation period. Compared with normal coal, their physical and chemical properties changed:

1. The basic structure unit (BSU) of tectonic coal increased. Compared to bituminous coal, the Lc of BSU of the tectonic coal increases while La stays constant. Compared to anthracites, La of BSU of tectonic coal increases while Lc stays constant.

2. The free radical content of bituminite in the tectonic coal is higher than that of normal coal. The free radical content of metaanthracitic tectonic coal is decreased.

3. The reflectence and hydrocarbon content of tectonic coal is increased.

All of above facts suggest that the physical and mechanical properties of tectonic coal was changed by structural stress during the geological history. This kind of change is called deformation metamorphism or dynamometamorphism of coal.

Our studies show that the zone with tectonic coal will have a propensity for gas and coal outbursts and spontaneous combustion. Geologists and mining engineers of China consider tectonic coal as a useful indicator used for forecasting outburst zone and dangerous zone of spontaneous combustion of coal.

AAPG Search and Discovery Article #90939©1997 AAPG Eastern Section and TSOP, Lexington, Kentucky