柴达木盆地西部裂缝的成因机制和分布模式

Genesis and distribution pattern of fractures in western Qaidam basin

柴达木盆地西部不同构造带裂缝的发育特征既有区别又有联系 ,可归纳为“南翼山型”、“咸水泉型”和“狮子沟型”。裂缝发育的组合型式与成因机制与变形方式、变形强度以及边界作用条件等相关。通过对裂缝成因类型与构造带变形强度 (应变量 )之间的定量分析 ,认为挤压褶皱区裂缝的分布模式共有 3种 :横张裂缝 +纵张裂缝 +顺层缝 (Ⅰ型 ) ;横张裂缝 +纵张裂缝 +平面共轭剪裂缝 +顺层缝 (Ⅱ型 ) ;横张裂缝 +纵张裂缝 +顺层缝 +平面共轭剪裂缝 +剖面 (共轭 )剪裂缝(Ⅲ型 )。可见 ,变形强度越大 ,裂缝的组合型式就越复杂。就总体而言 。

Fractures in different structural zones in western Qaidam basin can be divided into 3 types, namely 'Nanyishan type', 'Xianshuiquan type' and 'Shizigou type'. The combination patterns and genesis of the fractures are correlated with the mode and strength of deformation and boundary conditions. Quantitative analysis of the relationship between the genetic types of fractures and the deformational strength (strain) of structural zones shows that there are 3 distribution patterns of fractures in compressed and folded region, including transverse tensile fractures+longitudinal tensile fractures+bedding fractures (type Ⅰ), transverse tensile fractures+longitudinal tensile fractures+planar conjugate shear fractures+bedding fractures (type Ⅱ), and transverse tensile fractures+longitudinal tensile fractures+bedding fractures+planar conjugate shear fractures+profile (conjugate) shear fractures (type Ⅲ). The larger the deformation strength is, the more complex the combination patterns of fractures would be. As a whole, the structural fractures in western Qaidam basin are mainly transverse and longitudinal tensile fractures.