Crustal thickness and Poisson's ratios in eastern China estimated jointly by receiver function and gravity data

Abstract

SUMMARY Crustal thickness and Poisson's ratio have played significant roles in determining the crustal structure, compositions and deformation. We improved the algorithm for joint estimation by receiver function and gravity data on the optimization of initial model, sediment-correction, as well as estimation of associated density parameter, and utilized it to estimate the crustal thickness and Poisson's ratios in eastern China. The uncertainty analyses verified the reliability of our model. Our results demonstrate that the crustal thickness in eastern China increases gradually from east (about 26.6 km) to west (about 62.4 km) with an NNE-trending gradient zone along the line of Great Khingan-Taihang-Wuling Orogenic belt. The crustal Poisson's ratios in eastern China, ranging from 0.19 to 0.31, reflect the characteristics of different tectonic blocks. Low crustal Poisson's ratios are mainly presented along the sutural and orogenic belts between tectonic blocks. Low Poisson's ratio associated with the Central Asian Orogenic Belt accretionary wedge suggests that it extends further east than previously thought, beneath the Songliao Basin (between the city line of Sonid Right Banner-Linxi-Tongliao-Jilin-Wangqing and Bayan-Huade-Chifeng-Liaoyuan-Helong). After reducing the influence of the sediment, banded-like high-Poisson's ratios show up in Sichuan Basin and Ordos Basin. Combined with the magnetic data and petrophysical properties, we speculate it to be the intrusions of intermediate-basic rocks in the basement. High Poisson's ratios presented in the northern Songliao Basin may be related to multistage magmatic intrusions and eruptions since Meso-Cenozoic. High Poisson's ratios in Panxi rift are related to magmatic activities caused by mantle plumes.