Characteristics of landscape and erosion in the Eastern Pamir and their implications for regional fault connections

Abstract

The Tashkurgan normal fault in the Eastern Pamir is located at the strain transition zone between the dextral strike-slip faulting of the Karakoram fault in the south and the east-west extension of the Kongur Shan extensional system (KES) in the north. Thus, its tectonic evolution and relationship with the KES and the Karakoram fault carry important implications for the strain partition and deformation history of the Pamirs. However, the Tashkurgan fault lacks systematic documentation of its evolution and its relationship to other regional tectonic structures. In order to constrain the tectonic activity of the Tashkurgan fault, we analyze the landscape and 10Be-derived erosion rates in the footwall of the Tashkurgan fault. Our results reveal that both the values of the geomorphological indices and erosion rates increase from the northern segment of the fault towards the central segment and then decrease again southwards but with a further increase in the southernmost segment. We interpret that this pattern is closely related to the fault-related uplift of the Tashkurgan fault except that the southernmost segment is mainly affected by fractured rocks. These observations together with previous studies suggest that the Tashkurgan fault is the southern segment of the KES and extension along the KES has been initiated from the north and transferred to the Tashkurgan fault through the Tagharma fault. Therefore, we infer that the normal faulting of the Tashkurgan fault, and probably the whole KES, may lack a kinematic connection to the dextral slip system in the south.