Late Quaternary Activity Research Along Gyaring Co Fault

A key piece of information needed to evaluate deformation models of Tibet is the late Quaternary activity of faults in the plateau. Gyaring Co Fault, which is one of the most active en echelon secondary faults along Karakoram-Jiali Fault Zone. Previous studies mainly focused on south-eastern segment, and lack of basic geomorphologic investigation and overall understanding of its late Quaternary activity along with considerable controversy on the geometric distribution and slip rate. Based on the synthesis of high resolution satellite images and field observations along the middle segment, I draw the following conclusions:(1) A long and narrow rift zone is controlled by the Gyaring Co Fault, which general develop4stages alluvial fans,0-2ka,2-4ka,6-12ka,30-100ka respectively, which are similar to river terraces,0.5-1.5ka,2.5-3.5ka,4-12ka,10-60ka respectively, while low lake terraces(<20m) was formed in Holocene, but the ages of higher lake sediments(>30m) are about30-120ka.(2) Characters of landforms’distribution along the rift zone indicate Gyaring Co Fault translated into a long (>240km) normal slip fault before late Quaternary and can be divided into3segments:the north-western, middle, south-eastern. The activity of north-western and south-eastern segments (～40-50km) and dominated by normal faulting, while middle segment (～150km) is the most active and dominated by strike-slip faulting.(3) Holocene dip-slip rate of Gyaring Co Fault may be about0.3mm/yr and may exceed0.6mm/yr in the late Quaternary, while late Quaternary right-slip rate is constrained by4-20mm/yr and is probably about8mm/yr throughout late Quaternary.(4) Along with other low active faults in the Tibet, therefore, the deformation of Tibet is likely to be continuum rather than rigid, and the deformation stress may be distributed in the entire plateau and probably deform diffusion model to adjust the Indian and Eurasian plate collision.