Crustal structure in the Anyuan Coal Mine and its adjacent areas of Jiangxi Province by P-wave receiver functions

Abstract

We collected high-quality teleseismic events recorded by 12 broadband seismographs deployed in the Anyuan Coal Mine and its adjacent areas in Pingxiang City, Jiangxi Province for nearly two years. The H-κ-c stacking method was employed to obtain the crustal thickness and Poisson's ratio distribution, then the characteristics of crustal structure below the stations were obtained by using the time-domain linear inversion method. The crustal thickness in the Anyuan Coal Mine and its adjacent areas ranges from approximately 32 ∼ 35 ​km, with an average thickness of 33 ​km, which is consistent with the crustal thickness results in South China from previous studies using the receiver function method. The average Poisson's ratio of the crustal bulk composition in the study area varies between 0.22 and 0.25, which is lower than the global value with a 0.27 average, indicating a predominantly intermediate-acidic or felsic crustal composition. There is a weak negative correlation between Poisson's ratio and crustal thickness estimates in the Anyuan Coal Mine and its adjacent areas, suggesting that the absence of mafic-ultramafic materials in the lower crust is associated with the process of crustal delamination. The velocity inversion results indicate that the crustal structure including three velocity discontinuity interfaces, with the first at a depth of approximately 1.5 ​km, the second at about 10 ∼ 15 ​km, and the third being the Moho. The study also indicates that the results obtained by the H-κ-c stacking method are significantly better than those obtained by the H-κ method, effectively reducing the standard deviation and dispersion of crustal thickness and vP/vS ratio.