利用远震P波接收函数研究中国福建地区地壳厚度和泊松比

Crustal thickness and Poisson's ratio are important parameters for understanding the crustal structure and the material composition of the Earth, which can provide an important basis for regional structure and dynamics research. Based on the teleseismic waveform data of 88 seismic stations with relatively uniform distribution in Fujian Province from 2014 to 2017, we calculated P-ware receiver functions. For each station, we estimated crustal thicknesses and average Poisson' s ratio using the H-k stacking. We also collected and compared the existing results, and finally integrate our results with the previous results obtained by the receiver function method to obtain crustal thickness and Poisson' s Ratio under 117 seismic stations in Fujian, which revealed the crustal structure and Poisson's ratio variation characteristics of the Fujian, southeast China. The results show that : (1) the overall thickness of the crust in the study is relatively thin, ranges from 27. 4 km to 34. 3 km, with an average number of 31. 4 km. Further, the crustal thickness gradually decreases from the northwest to the southeast. The crustal thickness in the study exhibits significant small-scale transversal variation, showing obvious zonal and massive characteristics, which is related to the distribution of major deep faults in the crust. In this paper, the results of more intensive stations further verified that the crustal thickness in the study had a transitional characteristic of gradual thinning from the continental crust to the oceanic crust, and reveals new local crustal undulation. It also implied that the crustal thickness is nonlinear thinning from inland to coastal areas, and there is small-scale transversal heterogeneity in Fujian Province. (2) The average Poisson's ratio is 0. 25, ranges from 0. 20 to 0. 30. It is quite high in the north and low in the south. The distribution of Poisson's ratio is closely linked to the material composition and mineral content of the crust. The Poisson's ratio in coastal areas is higher than that in inland areas, which may be related to the higher heat flow in the coastal area and the process of mantle-derived material underplating. (3) The crust thickness is negatively correlated with the Poisson' s ratio. It is speculated that under the background of crustal extension, the paleo Pacific plate subducted the South China continent, and the mantle-derived materials entered the crust. Which caused the uplift of Moho interface and the increase of Poisson's ratio.