Crustal Structure Beneath Wuyishan Metallogenic Belt In South China Revealed By Receiver Function Method

In the mid-twentieth century,the proposal of plate tectonic theory has provided an effective explanation for the research on improving the ability to discover intracontinental deposits and understanding the relationship between mineralization,which has attention by domestic and foreign experts.The crust-mantle interaction is the inducing mechanism of metallogenic conditions,and the research on the crust-mantle structure in deep earth is one of the main objectives of current geoscience development.The Wuyishan metallogenic belt in the study area is located in the southeast of China,which is part of the Eurasian plate.The South China continent has been affected by plate subduction for a long time,The geological structure and lithosphere deformation mechanism are complicated and various.The South China continent is divided along the Jiangnan orogenic belt,which is composed of two large blocks of Yangtze and Cathaysia block.The region is rich in mineral species,which is a rare polymetallic metallogenic province in the world and an ideal base for studying intracontinental mineralization.The in-depth study of the fine structure of the crust and upper mantle in typical areas is helpful to the exploration of mineral resources and the monitoring and prevention of natural disasters such as earthquakes and volcanoes.This paper briefly introduces the regional geology of southeast China,and summarizes the existing crust-mantle structure in the study area.Using the continuous waveform data of about one month recorded by “Wanzai-Yongchun” linear short-period intensive seismic station,the receiver function is studied.The distribution characteristics of crustal thickness and velocity ratio under each station are calculated by using the H- grid search method based on the P-wave receiving function of high signal to noise ratio earthquakes selected manually.The high-resolution Moho interface undulation pattern from inland to coastal areas in the study area was obtained by using(Common Conversion Point,CCP)superposition imaging method.Compared with the existing geophysical data of Wuyishan metallogenic belt in South China mainland,the crustal structure characteristics of Wuyishan metallogenic belt are discussed.The results show that:(1)The crustal thickness of the study area is between 29km?33km,and the crustal thickness decreases from inland to southeast coast.The crustal thickness is positively correlated with the surface morphology.(2)The wave velocity ratio ranges from1.66?1.79,corresponding to the Poisson's ratio of 0.22?0.27.The Poisson's ratio increases from inland to coastal,and the local characteristics are correlated with magmatic activity and tectonic distribution.It is speculated that the crustal material composition is mainly composed of intermediate and acidic rocks.(3)The H- scan results and CCP superimposed profiles show that the Moho interface fluctuation characteristics have a certain correlation with several fault zones.Combined with the deep seismic sounding data obtained by predecessors in the region,it is speculated that the Zhenghe-Dapu fault belt is a deep fault,which extends directly to the bottom of the crust and is the junction of different tectonic units in the Wuyishan metallogenic belt.