Abstract:

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.

Key words: fractures, tensile fracture, genesis, distribution pattern, outcrop