Seismically triggered soft-sediment deformation structures in Tashkorgan lacustrine sediments, northeastern Pamir, China

Abstract Soft-sediment deformation structures (SSDSs) are widely developed in the lacustrine sediments of paleo-dammed lakes in tectonically active regions and contain a wealth of information on regional fault activity. In this study, multiple SSDSs (load structures, small-scale slump structures, droplets, diapir and pillow structures, silty-clay pillars and large-scale slump structures) were identified in the strata of the Late Pleistocene lacustrine sediments in the Tashkorgan River drainage in northeastern Pamir. The deformation mechanisms of the SSDSs were related to the liquefaction, fluidization and thixotropic behaviors. The regional tectonic settings and SSDS features point toward a trigger mechanism with seismic activities and indicate that the seismogenic faults were possibly related to the southern part of the Kongur Shan extensional system. Accelerator mass spectrometry (AMS) radiocarbon dating data showed that the SSDSs in the Tashkorgan lacustrine sediments formed 30,221-29,932 cal BP and 25,825-25,317 cal BP. The results of this study improve our understanding of fault activity and geodynamic processes in northeastern Pamir during the Late Pleistocene.