Investigating thrust-fault growth and segment linkage using displacement distribution analysis in the active Duzhanzi thrust fault zone, Northern Tian Shan of China

Abstract

Few studies investigate the detailed character of thrust-fault population or their along-strike fault-displacement patterns. Our study presents 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 0.5 m-resolution LiDAR-derived DEMs, we measured along-strike displacement and lengths of ~30 fault strands to construct a three-dimensional deformation field recorded by these deformed marker surfaces. Three fault segments constitute the DTFZ, and each presents different geometric structures and displacement patterns. Through detailed analysis of the 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 (Dmax) and fault length (L) measured from thrust faults within the DTFZ displays similar linear scaling to other thrust faults, but different Dmax/L ratios due to underestimated displacement of the DTFZ. Two conceptual models: a single-fault model and segment-linkage model are explored to explain the growth of faults or fault systems and the changes of Dmax/L ratios during fault evolution.