The Pamir-Tian Shan convergence zone （Fig. 1） is a unique example to understand ongoing intracontinental mountain building within India-Eurasia collision system (Fig. 2a). Unfortunately, much of the region is remote, and thus the regional kinematics has been poorly understood. Although much of its late Cenozoic deformation is explained by the collision and subsequent penetration of India into Eurasia, and a complete kinematic description of tectonic deformation over the Pamir and Tian Shan has not been available.
Based on detailed analysis of satellite imagery combined with field geologic and geomorphic observations, we have mapped late Cenozoic folds and faults in the northeastern Pamir-Tian Shan convergence zone. It is a unique example to understand intracontinental ongoing mountain building within India-Eurasia collision system. In the front of northeastern Pamir, our investigations reveal that the NW-WNW-trending folds display a right-stepping en echelon pattern and NW-WNW-striking faults are mainly characterized by south-dipping thrusts with an extensive dextral strike-slip component. Drainage systems across the active faults show a systematic right-lateral offset. In contrast, structural style of the ENE trending fold-and-thrust beltsare predominated by south-north directed shortening in southwest of the Tian Shan. Our results also infer that oblique thrusting accommodate a long-term dextral slip rate of ca. 4.0 mm/yr during late Cenozoic time in north of the Pamir topographic front. Tectono-stratigraphic evidence suggests that the tectonic deformation initiated atca. 3-5 Ma in the study area. We suggest that intracontinental mountain building in the Pamir-Tian Shan convergence zone should be attributed to thecrustal shortening caused by folding and thrusting as well as block rotation related to strike-slip faulting within India-Eurasia collision system.
Fig. 1(a) Cenozoic tectonic map of the northeastern Pamir-Tian Shan convergence zone constructed from analysis of satellite images and field observations；（b）Geologic cross-section showing the structural styles of the fault-and-fold belt in the northeastern Pamir-Tian Shan convergence zone
Fig. 2 (a) Major late Cenozoic faults along the Pamir indentor and adjacent area. Northward push of the Pamir and western Kunlun onto the Tarim accompanied crustal thickening and uplift of the Pamir and renewed shortening along the northern margin of Tibet. Reactivated shortening within the Tian Shan resulted in thrusting southward onto the northwestern margin of the Tarim. (b) 3D diagram illustrating the current lithospheric structure, deformation styles and geomorphic features across the northeastern Pamir-Tian Shan convergence zone.
For detailed information, please see：Bihong Fu et al. Slip partitioning in the northeast Pamir–Tian Shan convergence zone. Tectonophysics, 2010, 483: 344~364.
