Late Quaternary Activity And Its Environmental Effects Of The N-S Trend Kharta Fault In Xainza-Dinggye Rift,Southern Tibet

The east-west extension of the southern Tibet region has formed seven N-S rifts to the south of the Bangong suture zone.The genetic mechanism,initial development time,location and slip rate recorded abundant information during the evolution of the Tibet Plateau.The Xainza-Dinggye Rift is the third one from east to west.The activity of the Kharta fault in the southernmost part of the rift not only controls the uplift of the Ama Drime Massif,but also the evolution of the paleolake in the upper Arun Catchment.Activity of the fault shows spatially difference:the fault trace of the southern section is obvious,and it is scattered to the north to a number of secondary faults.Based on the previous research,we?1?Using sfm technology collected the ortho images and DEM of the lake terraces and alluvial fans offset by Cuomai fault,identified 11 terraces and at least 3 stages of alluvial fans through detailed geomorphic mapping.The vertical displacement of T8,T7-1,T6 and T5-7 is 5.8±0.7 m,8.5±1.2 m,7.8±1.2 m,7.9±1.7 m,respectively;the vertical displacement of alluvial fan F2 and F2-1 is 4.2±0.8 m and 4.5±0.5 m,respectively.The CRN depth profile method constrained abandoned ages of the T5-7 terrace and the F2 are 95⁺²⁵/_-1515 ka and 56±6ka.There are two depositional discontinuities within 2m depth beneath the surface of F2,which is determined to be 108±12 ka,96±11 ka.Therefore,we constrained the slip rate as 0.09±0.03mm/yr in middle section since⁹5 ka and 0.08±0.02 mm/yr in the south since⁵6 ka.?2?Measured the height of the lake shoreline in the upper Arun Catchment,found that the highest water level is>4402 m,and the typical low water level is 4267 m,which is in sharp contrast with the downstream geomorphological features,indicating that river damming occurred near the Kharta fault before captured by Arun river in the Yo Ri site.?3?Two landslides provide new evidence of the Kharta fault activity since the Holocene,geometry and kinematic data implies that the activity of Kharta fault can lead to large and high speed landslides,capable of causing a river damming.