Structural Style And Formation Mechanism Of Yudong-madong Fault Belt In Tarim Basin

Yudong-Madong fault belt is a thin-skinned fault-and-thrust belt detached on rock salt in Tarim Basin.It has not been studied yet as a whole deformation system.Based on seismic profile interpretation,this dissertation first studies the overall distribution of major faults in the area,analyzes structural changes of each fault belt along track and summarizes major structural style in different subareas.The result shows that the main structural style is listric fault and related fault-bent fold in Yudong subarea,listric fault-reformed detachment fold in Madong subarea,flat-slope-flat style fault-reformed detachment fold in Tangbei area.Next,the kinematic models of three representative structural styles are constructed using fault-related folding theory,and the overall evolution of three regional section across the structural belts has been established using balanced section technique.It shows that Yudong-Madong fault belt formed during Late Ordovician to Early Silurian through different kinematic processes in different subareas,with the cross-sectional deformation becoming more intense from southwest to northeast.After Permian,low-amplitude fold formed in strata above the original structural belts.In Cenozoic,structural deformation was dominated by regional titling.Through comparison,the main controlling factors of structural style differences in the study area are middle Cambrian rock salt thickness,thickness of Querquek Formation in upper Ordovician and structural transfer phenomena.The existence of rock salt is considered to be crucial to explain the hinterland-vergence of nearly all the thrusts in Yudong-Madong area.Finally,combined with early study of deposition,fault movement and tectonics of Tarim Basin in Early Paleozoic,the structure of foreland basin in southeastern Tarim basin in this period was restored to shed light on the dynamic aspect of the formation of Yudong-Madong fault belt.