Differential deformation characteristics and genetic mechanism of boundary normal faults in Wangfu Fault Depression, Songliao Basin

Abstract

In order to reveal the differential deformation characteristics of the Wangfu Fault Depression in Songliao Basin and study the regularity of the deformation mechanism of boundary normal faults, this paper, based on the structural analysis and fault differential analysis, discusses the controlling factors and genetic mechanism of differential deformation of boundary normal faults in combination with the advantages of tectonophysical simulation in "continuous forward modeling" and "control variables". The results show that: (1) According to the intensity of fault activity, four regional tectonic evolution stages can be divided. The boundary normal faults in the west of Wangfu Fault Depression is the most active, but the dip angle of the faults gradually increases from north to south, showing a "convex" shape locally. (2) Combining tectonophysical simulation with actual geological background, it is showed that the shape of boundary normal fault was controlled by three main factors, including lateral lithologic change, syntectonic sedimentation and pre-existing uplift of basement. If boundary normal faults are developed in strata with different lithology at the same time, or accompanied by strong syntectonic sedimentation, the dip angle will change. In addition, the extension of the fault near the hard basement bulge will change its trend and continue to spread around the bulge top, resulting in the local appearance of "uplift".

Keywords

• boundary normal fault
• differential deformation
• tectonophysical simulation
• controlling factors
• wangfu fault depression
• songliao basin