Distinct Orogenic Processes in the South‐ and North‐Central Tien Shan From Receiver Functions

Abstract

Uplifting mechanisms for the Tien Shan, an active intracontinental orogenic belt, have been under debate for decades, a key issue being how the convergence has been accommodated at depth. Here we investigate the Moho structure across the Central Tien Shan by common‐conversion‐point imaging and H‐k‐c stacking of receiver functions from a dense array. The observed Moho exhibits distinct characteristics among subblocks. A southward‐dipping diffuse Moho is imaged in the South‐Central Tien Shan (SCTS), in contrast with the relatively flat and sharp Moho beneath the Tarim Basin. This feature along with the large Moho offset beneath the South‐Boundary Fault suggests that the shortening and thickening of the Tien Shan crust rather than the underthrusting of the Tarim Basin are responsible for the uplift of the SCTS. In the North‐Central Tien Shan, however, the imaged Moho doublet provides direct evidence for the underthrusting of the Kazakh Shield accommodating the convergence there.

Deep Crustal Contact Between the Pamir and Tarim Basin Deduced From Receiver Functions

“…(2019) and Zhang et al. (2020) have also been included in Figure 3a. The intermediate‐depth earthquakes at depths greater than 50 km from Bloch et al.…”

Seismic Imaging of Crust Beneath the Western Tibet‐Pamir and Western Himalaya Using Ambient Noise and Earthquake Data

“…Farther north, the Moho has been mapped at 44-60 km in the Tarim Basin and 55-60 km beneath the Tien Shan (Kao et al, 2001;Vinnik et al, 2004;Q. Xu et al, 2021;B. Zhang et al, 2020).…”

“…Earthquakes also accompany the unusually deep Moho beneath Kunlun to a depth of 90 km (Huang et al., 2011). Farther north, the Moho has been mapped at 44–60 km in the Tarim Basin and 55–60 km beneath the Tien Shan (Kao et al., 2001; Vinnik et al., 2004; Q. Xu et al., 2021; B. Zhang et al., 2020). The sedimentary cover in the Tarim Basin ranges from Proterozoic to Neogene age, with variable thickness from a maximum of up to 15 km in the depression center to 5 km in the central uplift area (Jia, 1997; Kao et al., 2001).…”

The characteristics of active deformation and strain distribution in the eastern Tian Shan

“…2,500 km in central Asia with several peaks over 7,000 m above sea level, has experienced complex orogenic processes with prominent spatial variations in lithospheric structures, as revealed by geophysical observations (e.g. Gao et al, 2013; Li et al, 2016; Zhang, Bao, & Xu, 2020; Zhao, Liu, Lu, Zhang, & Zhao, 2001). Geological evidence indicates that it formed in the Palaeozoic and was reactivated during the Cenozoic (Allen et al, 1993; Deng et al, 2000; Hendrix et al, 1992; Molnar & Tapponnier, 1975; Tapponnier & Molnar, 1979; Yin et al, 1998).…”