Structural styles and impact of fault subsidence in the lake fuxian basin and adjacent area

Abstract

Lake Fuxian is a tectonic lake located on the Yunnan–Guizhou Plateau in southwest China. It is the deepest freshwater tectonic lake in the Yunnan Plateau. The present study focused on examining the structural changes, faulting patterns, and their influence on fault subsidence in the Lake Fuxian basin. Seismic interpretation showed uplift in the SSW area and subsidence in the NNE region. Subsidence is more pronounced on the northern survey lines, where the sedimentary strata had a maximum sedimentation of 1200 m. The seismic interpretation findings showed a horst block in the southern basin and a graben block in the northern half of the basin. L-14 demonstrated the steeper with maximum throw and parallel character of normal faults and provided the evidence of crustal extensional regime. Thirteen main faults were identified by fault modeling in the lake basin. The analysis of fault characteristics revealed that faults in the northern basin are characterized by greater depth, steeper angles, maximum displacement, and are actively moving owing to low resistance and negative asperity values, and poor edge detection values. Faults in the southern basin have an opposite character to those in the northern basin. Major faults in the northern lake basin have a stronger influence of fault subsidence compared to faults in the center and southern lake basins. Overall, the lake Fuxian basin showed horst-graben structure with parallel normal faulting with a crustal extensional regime.