Investigating Thrust-fault Growth and Segment Linkage Using Displacement Distribution Analysis In The Active Duzhanzi Thrust Fault Zone, Northern Tian Shan of China

Few studies investigate the detailed character of thrust-fault population or their along-strike fault-displacement patterns. Due to scarce data, key questions about thrust-fault growth and scaling laws remain poorly resolved. Our study present new displacement-length data collected from well-exposed thrust faults within the Dushanzi Thrust Fault Zone (DTFZ), an active thrust fault-fold system in the Northern Tianshan of China. Numerous surface-rupturing thrust faults cut through upper Quaternary glacial outwash terraces and younger alluvial fans. Based on 0.5m-resolution LiDAR-derived DEMs, we measured along-strike displacement and length on ~30 fault strands to construct the three-dimensional deformation field recorded by these deformed marker surfaces. Three fault segments constitute the DTFZ, and present different geometrical structure and displacement patterns from each other. Through detailed analysis of displacement distribution and geometrical attributes of thrust faults, we constrain the growth and propagation history of faults and of the systems that they form.

The scaling relationship between maximum displacement (D_max) and fault length (L) measured from thrust faults within the DTFZ display similar linear scaling to other thrust faults, but different D_max/L ratios from geological thrust fault and earthquake rupture. It may account for these discrepancies on the D_max/L ratio that displacement in the DTFZ is accumulative displacements of several earthquake, and only for ~ 12 ky since formation of the outwash surfaces, rather than total displacement since the fault initiation. Two conceptual models, single-fault model and segment-linkage model, are applied to explain the growth of fault or fault array and the changes of D_max/L ratios during the fault evolution.