Two anisotropic layers in central orogenic belt of North China Craton

We present evidence of two layers of anisotropy in Earth's upper mantle beneath the central orogenic belt of the North China Craton from teleseismic shear-wave splitting analysis. A one-layer model is in disagreement with the well-constrained azimuth-dependent splitting parameters for stations in the central orogenic belt; however, two layers of anisotropy improve the fit to the data. At the bottom layer, the fast polarization directions are subparallel to the absolute plate motion, indicating the presence of the current strain within the subcratonic asthenosphere related to the interactions between the surrounding plates. In contrast, at the top layer, the fast polarization directions are consistent with the strikes of the local surface faults, confirming a combined contribution of the past orogenies in the lithosphere.

Research Highlights
► Azimuth-dependent shear-wave splitting parameters.
► Two layers of anisotropy beneath the North China Craton.
► Contribution of the lithosphere and asthenosphere to the Earth's internal anisotropy.