Journal of Asian Earth Sciences | 2019
A new crustal thickness model for mainland China derived from EIGEN-6C4 gravity data
Abstract
Abstract In this study, we present a new crustal thickness model of mainland China created from the inversion of EIGEN-6C4 global gravity model. We took advantage of a high-resolution gravimetric data and the regularized inversion, based on the Gauss-Newton formulation of Bott’s equation to resolve the Moho topography. The inversion process uses tesseroids to account for the earth curvature. Moho depth modeling for such a massive landmass cannot ignore the earth’s curvature. The Bouguer effect, terrain effect, and gravity effect due to sediments were also corrected and calculated in a spherical approximation. The resulting crustal thickness model was validated with 2992 seismological data points and compared with continental-scale crustal thickness models for mainland China. The final crustal thickness model shows a minimum value of ∼26\u202fkm in Eastern China to a thick crust of over 75\u202fkm under the Tibetan Plateau. Nevertheless, the results also show a considerable difference in unconstrained areas of the Tibetan plateau with a crustal thickness of ∼20\u202fkm and ∼6\u202fkm in sedimentary areas. The tectonic terranes show similar depth estimates for all the continental scale models of mainland China, but the lateral variation differs considerably. The results also expose two East-West fold belt trends on the Tibetan Plateau, a 44\u202fkm thick crust between Western and Eastern China, and a 37\u202fkm NNE trend line, which separates the stable eastern cratonic blocks from the thinned crustal blocks. Overall, our high-resolution model yields an improved representation of crustal features over previously gravity crustal thickness models of mainland China.