S wave Velocity Structure of the Crust and Upper Mantle Beneath Shanxi Rift, Central North China Craton and its Tectonic Implications

Yan Cai,Andreas Rietbrock,Weilai Wang,Jianping Wu,Jing Liu,Lihua Fang,Shuang Yi

doi:10.1029/2020tc006239

Yan Cai, Andreas Rietbrock + Show 5 more

Open Access

https://doi.org/10.1029/2020tc006239

Copy DOI

Abstract

AbstractThe Shanxi rift is located in the central part of the North China Craton (NCC). With strong tectonic deformation and intense seismic activity, its crust‐mantle deformation and deep structure have always attracted wide attention. Using teleseismic events observed in a dense network of 610 temporary and 127 permanent stations in the central NCC, we obtained the crust‐mantle S wave velocity structures by the joint inversion method of receiver functions and surface wave dispersion data. Our results show that the crust thickens in the northern part of the Shanxi rift (41 km) and thins in the southern part (35 km). The Taiyuan and Linfen basins, located in the central part, have high‐velocity zones in the lower crust and upper mantle; beneath the Yuncheng basin in the south, there are low‐velocity zones in the lower crust and uppermost mantle (30–80 km); the Datong basin, located in the northern part of the rift, exhibits a wide range of low‐velocity anomalies in the middle to lower crust and upper mantle. We speculate that the destruction of the NCC and associated lithospheric thinning had a significant impact on the southern part of the rift, but is still in its early stage in the central part, which retains most of the craton features. An upwelling of the asthenospheric magma occurred beneath the western part of the Datong basin. The horizontal deflection of the asthenospheric flow causes low‐velocity anomalies in its surrounding area, which is consistent with LAB topography.

Highlights

As the oldest and most severely damaged craton in the world (Fan, 1992; Kusky & Li, 2003; Zhao et al, 2005), the North China Craton (NCC) consists of the North China basin in the east, the Ordos block in the west, and the Shanxi rift in the center (Kusky & Li, 2003; Kusky et al, 2007; Santosh et al, 2010; Zhao et al, 2005) (Figure 1)
The results show that the North China basin is underlain by a thin crust of about 32 km, and it increases to nearly 40 km in the Taihang mountain
In the western part of the Datong basin, the crust is thicker than 41 km, and it decreases to about 38 km in the eastern part

Summary

Introduction

As the oldest and most severely damaged craton in the world (Fan, 1992; Kusky & Li, 2003; Zhao et al, 2005), the North China Craton (NCC) consists of the North China basin in the east, the Ordos block in the west, and the Shanxi rift in the center (Kusky & Li, 2003; Kusky et al, 2007; Santosh et al, 2010; Zhao et al, 2005) (Figure 1). The Shanxi rift composes of Datong basin, Xinding basin, Taiyuan basin, Linfen basin, and Yuncheng basin It is located between these two contrasting blocks with a different structure and deformation history (Figure 1), and records a wealth of valuable information on the deformation and evolution of the NCC. This feature makes the Shanxi rift a unique place to study the evolution process of the NCC from east to west and to further explore the intercoupling relationship between the stable Ordos block and the stretched North China basin.

Methods

Results

Discussion

Conclusion