Geological models and structural controls of tectonically deformed coal in Tucheng syncline,western Guizhou Province

The development and distribution law of tectonically deformed coal(TDC) is one of the important research contents in the exploration and sweet spot prediction of coalbed methane in structural-complicated area. The structural feature and its control mechanism of the TDC development in Tucheng syncline were discussed based on the analysis of the field and underground geological surveys,deformation and development characteristics of TDC. The results show that the deformation characteristics of the Tucheng NW-trending arc fault-fold belt are characterized by ‘fault-fold arc combination pattern,basement fault control,local intense deformation and rapid deformation attenuation’. The NW- trending Tucheng branchy open inclined syncline,with apparent internal structural differentiation,can be further divid- ed into NE gently limb weak deformation zone,SW steeply limb intense deformation zone and NW complex structural hinge zone. According to the characteristics of TDC development and its response to the structural deformation,10 geo- logical models of the TDC development in Tucheng syncline were proposed. These 10 geological models can be classi- fied into fold-related and fault-related TDC types. The widely developed fold-related TDCs, with relatively singular TDC types,are the dominant factor of vertical differentiation of coal structure. The locally developed fault-related TDCs are generally intensely deformed and the deformation sequence is relatively complete.