黔西土城向斜构造煤发育模式及构造控制

构造复杂区构造煤发育及其分布规律是煤层气勘探与甜点区评价的重要研究内容之一。在野外构造系统观测和矿井构造特征分析的基础上,结合矿井井下煤体结构观测与构造煤发育特征分析,探讨了黔西土城向斜的构造特征及其对构造煤发育的控制机理。研究表明:土城NW向弧形断褶带具有"弧形断褶组合,基底断裂控制,局部变形强烈,变形衰减迅速"的构造变形特征,而土城向斜为一NW向延伸的短轴开阔斜歪向斜,向斜内部构造分异显著,可以进一步划分为NE翼单斜弱变形区、SW翼陡立强变形区和NW部构造复杂区;依据构造煤发育及其分布对构造的响应特征,提出了土城向斜构造煤发育的10种地质模式,并进一步将其归纳为褶皱成因型和断裂成因型两大类型,其中褶皱成因型构造煤发育普遍、类型较为单一,是煤体结构垂向分异的主导因素;断裂成因型构造煤分布较为局限,但常发育强变形构造煤、且构造煤变形序列相对较为完整。

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 divided 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 geological models of the TDC development in Tucheng syncline were proposed.These 10 geological models can be classified 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.