Intradecadal Fluctuations and Three-Dimensional Crustal Kinematic Deformation of the Tianshan and Pamir Derived From Multi-Geodetic Imaging

The uplift of the Tianshan and Pamir Mountains/Areas are caused by active intracontinental tectonic movements. The dynamic mechanism is controversial and has aroused great interest among scholars. In this study, we investigate the present three-dimensional (3-D) crustal deformation in the Tianshan and Pamir areas from multi-geodetic observations from 2002 to 2021. The continuous water deficit throughout Tianshan and Pamir locates mainly in glacier-covered areas, at a total rate of -0.8 cm w.e./yr, inducing spatial surface uplifting at rates of similar to 0.2-0.5 mm/yr. These Global Positioning System (GPS)-derived velocities in the vertical deformation of the Tianshan and Pamir were corrected based on surface elastic loading models and the Gravity Recovery and Climate Experiment Follow-On (GRACE/GFO)-inferred hydrological loading deformation, and interpolated using the GPS imaging method for a higher 3-D crustal deformation spatial resolution. In conclusion, surface hydrology is one of the driven factors affecting the regional vertical velocity field observed by GPS. The kinematic crustal shortening and vertical tectonic uplift are integrated within different blocks, which illustrate the contemporary dynamics throughout the Tianshan and Pamir. The relevant spatial characteristics between the 3-D crustal deformation and dynamic tomography along the Tianshan indicate that the relatively weaker lithosphere beneath the central Tianshan is subject to strong compression, which induces the present-day crustal uplift.

Automated summary

The present-day crustal deformation in the Tianshan and Pamir areas is investigated through multi-geodetic observations. Surface hydrology is found to be one of the factors affecting the regional vertical velocity field observed by GPS. The relatively weaker lithosphere beneath the central Tianshan is subject to strong compression, leading to the present-day crustal uplift.