Early Jurassic Soft‐Sediment Deformation Interpreted as Seismites in the Wuqia Pull‐Apart Basin and the Strike‐Slip Talas–Ferghana Fault, Xinjiang, China

Abstract

Abstract: The early Jurassic soft‐sediment deformation occurring within lacustrine sandstone is distributed mainly in the Wuqia region of SW Tianshan Mountains, Xinjiang, western China. Triggered by earthquakes, such deformation was found to occur in three beds overlying the lower Jurassic Kangsu Formation. The main styles of deformation structures comprise load cast, ball‐and‐pillow, droplet, cusps, homogeneous layer, and liquefied unconformity. The deformation layers reflect a series of three strong earthquakes at the end of early Jurassic in the Wuqia region. The differences of deformation mechanisms undergone might represent the varying magnitudes of the earthquake events. During the early Jurassic, the Wuqia region was located in a pull‐apart basin controlled by the significant Talas–Ferghana strike‐slip fault in central Asia, which initiated the soft‐sediment deformation induced by earthquakes. Our research suggests that the paleoseismic magnitudes could have ranged from Ms 6.5 to 7.