Apply Receiver Function To Study Structure Of The Crust And Uppermost Mantle In Bohai Bay Basin

The theory of receiver function has been developed and improved since the 70s of the 20th century. It has been an important method to study the deep structure of the earth applying teleseismic records. This paper introduced the the basic theory, development and application of the receiver function in recent years. Based overall 6 seismic lines in North China area, we constructed the structure of the crust and uppermost mantle and got some important subsequence. Combing the theory and practice in Bohai Bay Basin, the content was discussed and explained in several impacts as following. At the first, based the basic theory of receiver function, we processed the teleseimic data in Bohai Bay Basin. The processing progress included selecting records, filtering, intercepting wave, transferring axes, devolution, stacking and waveform inversing, which were to knowledge the structure beneath the stations. In the second, we got the receiver functions of all the 107 stations from station 003 to station 218, and picked up the phases of P, Ps, PpPs and so on. The Ps phases associated fiercely with the Moho. The waves of the receiver function in mountain area were easy, while those in Basin area were complex because of the difficulty in picking the Ps phases. The waveform inversion in mountain area was done better than that in Bohai Bay Basin, which was contributed to the thick sedimentary. In the third, the crust showed roughly layered structure and laterally homogeneous feature. There were 5 layers in the 50 km depth beneath the stations, including sedimentary, upper crust, middle crust, lower crust and uppermost mantle. The sedimentary showed large different between mountain range and basin area. The upper crust was associated sedimentary, and its thickness and depth varied as the different stations attributed to the difference in tomography and location. The low-velocity layer was found in the middle crust. The thickness of the low crust largely reduced from mountains to basin, in contrast to the sedimentary. The last, the depth of the Moho varied greatly in the study region, from 31 km to 40 km. It rose from mountains to basin, revealing that the crust is thinning. As a whole, the characteristics of crust showed it was thicker in the west, mountain area, while that was thinner in the east, basin area. The mantle material ascended rapidly in North China area in the late Mesozofc. The crust thinning from northwest to southeast was response to rise of mantle-source material.