Lateral growth of NE Tibetan Plateau restricted by the Asian lithosphere: Results from a dense seismic profile

Abstract

We present high-resolution receiver function images along a 700-km long dense seismic array extending from northern Tibetan Plateau to the Alxa block, crossing the entire Qilian thrust belt (QTB). The dense stations, with less than ~2 km station intervals, allow the receiver functions to unveil unprecedented details of crustal structures across the northern frontier of the growing Tibetan Plateau. The migration image shows a thickened and strongly deformed QTB crust, with an uneven Moho and complex internal structures that are indicative of pure-shear shortening. The Alxa block, in contrast, has a thinner crust, a flat Moho, and little internal crustal deformation. These results suggest that the lateral growth of NE Tibetan Plateau is restricted by the strong Asian lithosphere, which shows no visible subduction beneath the Tibetan Plateau as previously suggested.

Reworking of ancient tectonic amalgamation belt beneath the central north of North China Craton revealed by dense seismic observations

“…Similarly, Wang et al (2019) imaged the fault damage zone of the San Jacinto Fault near Anza using a dense array of ambient noise tomography. The unprecedented details of the growing crustal structure along various boundaries of the Tibetan Plateau were unveiled by a series of short-period dense arrays (e.g., Shen et al, 2020Shen et al, , 2022Tian et al, 2021). Furthermore, the existence of Paleoproterozoic residual subduction in the craton…”

Remnants of the Amalgamation of the East and West Cathaysia Blocks Revealed by a Short-period Dense Seismic Array

“…In the early studies, Yuan et al (1997) proposed the moveout correction methods based on the INDEPTH short-period seismic array, and Zhu (2000) developed the common conversion point (CCP) migration method based on the LARSE short-period seismic array. More recently, based on 473 seismometers, Shen et al (2020) suggested that a pure shear shortening model beneath the Qilian Mountains can explain the lateral growth of the northern front of the Tibetan Plateau. Moreover, based on a dense array of 340 seismometers, Tian et al (2021) found that the lateral growth of the northeastern front of the Tibetan Plateau can be represented with a model incorporating upper crustal overthrusting and lower crustal underthrusting beneath the Liupan Shan area.…”

New Magnetotelluric Data Reveal Deep Fault Boundaries and Contrasting Late Cenozoic Fault Kinematics Between the Qilian Shan Thrust Wedge and Beishan‐Alxa Block, Western China

“…Yellow triangles further east are station locations from a previously published MT section. Gray lines are Mesozoic rift‐bounding normal faults (small rectangles on fault line indicate hanging wall) adapted from Chen et al., 2014; C. Zhang et al., 2018) (c) Hillshaded image of SRTM 30m DEM showing major faults and densely spaced MT survey stations in the Wenshushan and Heishan area (d) Simplified end‐member models for the interaction between the Northern Tibetan Plateau and the Beishan‐Alxa block (adapted from Zuza et al., 2018; Shen et al., 2020). The left panel shows a steep boundary fault separating Northern Tibet deforming belt (Qilian Shan thrust wedge) from the Beishan‐Alxa block (Darby et al., 2005; Wei et al., 2022).…”

“…The northwestern Hexi Corridor can be considered a broken foreland basin (Horton et al, 2022) with basementcored uplifts like the Heishan and Kuantanshan and Cretaceous rift basins such as the Yumen, Jiuxi and Jiudong Basins that are overlapped and largely concealed by widespread Tertiary-Quaternary alluvial deposits (Figure 1, Vincent & Allen, 1999;. In addition, the western Hexi Corridor includes important crustal boundaries separating the Qilian Shan Precambrian-Paleozoic terrane amalgam (Xiao et al, 2009) Zuza et al, 2018;Shen et al, 2020). The left panel shows a steep boundary fault separating Northern Tibet deforming belt (Qilian Shan thrust wedge) from the Beishan-Alxa block (Darby et al, 2005;Wei et al, 2022).…”