Adjoint traveltime tomography unravels a scenario of horizontal mantle flow beneath the North China craton

Abstract

The North China craton (NCC) was dominated by tectonic extension from late Cretaceous to Cenozoic, yet seismic studies on the relationship between crust extension and lithospheric mantle deformation are scarce. Here we present a three dimensional radially anisotropic model of NCC derived from adjoint traveltime tomography to address this issue. We find a prominent low S-wave velocity anomaly at lithospheric mantle depths beneath the Taihang Mountains, which extends eastward with a gradually decreasing amplitude. The horizontally elongated low-velocity anomaly is also featured by a distinctive positive radial anisotropy (VSH > VSV). Combining geodetic and other seismic measurements, we speculate the presence of a horizontal mantle flow beneath central and eastern NCC, which led to the extension of the overlying crust. We suggest that the rollback of Western Pacific slab likely played a pivotal role in generating the horizontal mantle flow at lithospheric depth beneath the central and eastern NCC.

New Maps of Global Geological Provinces and Tectonic Plates

“…The eastern half of the North China Craton also experienced widespread volcanism in the Mesozoic and Cenozoic related to Pacific subduction (Wu et al, 2019). While there is no metamorphic evidence for resetting of high-temperature thermochronometers, there is ample evidence for significant modification of the lithosphere (Kusky et al, 2007;Yang et al, 2018;Li et al, 2019;Dong et al, 2021).…”

Seismic Tomography of the Trans-North China Orogen and Its Dynamic Implications

“…In fact, recent tomographic images have illustrated that the mantle lithosphere has been modified partially under the TNCO and its adjacent areas (Xu et al, 2018b;Yao et al, 2020;Dong et al, 2021). The lithospheric delamination and mechanical erosion assumed to account for the mechanisms of the lithospheric modification are still under debate (Wang et al, 2018;Wu et al, 2019).…”

“…Seismic tomography is a powerful tool to image the Earth's interior structure. In the past 2 decades, a number of seismic tomography inversions have been performed to construct the 3-D velocity models, focusing on the crustal and upper mantel structures of the TNCO and its adjacent areas (e.g., Zhao, 2004;Huang and Zhao, 2006;Lei, 2012;Xu et al, 2018b;Tao et al, 2018;Dong et al, 2021). Due to the differences in the used data and methods, there are still some contradictions between these models, such as the constraints on the origin of the Datong volcano and lithospheric thinning beneath the TNCO and its adjacent areas.…”