Activity and segmentation of Gyaring Co fault  zone in central Qingzang plateau

Gyaring Co fault zone is an important fault in central Qingzang plateau. Result of analysis of ETM remote sensing images and field observations indicate that the fault consists of a series of NW-SE echelon branches. From the offset of alluvium fans, alluvium terrace, stream channels and mountain ridge, we can see that main faults manifested activity mainly in dextral slip with subsidiary extension, although there are some difference between segments. The fault zone can be divided into three segments based on fault structure and activity, taking the activity of Shenzha-Dingjie graben into consideration. The northwestern segment is a right-lateral strike-slip fault characterized by continuous linear feature in the images, with relatively weak extensional activity. The middle segment is a wide rift valley bounded by two lateral faults with strong extensional activity.The southeastern segment is a narrow rift valley controlled by lateral faults with weak activity, and the valley subsided as a whole due to east west graben extension. Based on the geomorphologic characteristics of the fault zone a fault model may be assumed: the deep part of the fault moves in dextral strike-slip and its shallow part changes to normal flower structure owing to the extension.