Mantle Reflection in the Southern Songliao Basin Reveals the Process of the Ancient Block Convergence: Evidence from the Large Dynamite Shots of Deep Seismic Reflection Profiling

Abstract:

Deep seismic reflection profile technology is recognized as one of the important methods to explore the fine structure of lithosphere. This paper deals with the near vertical reflection data of five cannon in the deep seismic reflection section which spans songke No.2 well in Songliao Basin and has a full coverage length of 100km. In order to achieve the end-to-end connection of the first coverage section, two medium cannon data are added. In the process of data processing, in order to improve the signal-to-noise ratio, some single gun data receiving systems adopt double line receiving. According to the processing results of the gun data in this paper, through the data screening and splicing, the gun near vertical reflection single section of the whole line is obtained, and the lower crust and Moho structure, especially the strong reflection at the top of the upper mantle, are clearly obtained. Mantle reflection under large basins in the world usually reflects the subduction and convergence traces of ancient plates. Mantle reflection has also been found in Sichuan Basin and Songliao Basin in China to reveal the subduction of ancient blocks. In recent years, new ancient to Archean geological ages have been discovered successively in the south of Songliao Basin, but less in the north of the Songliao basin. Therefore, this paper speculates that the northward dipping mantle reflection found in the south of the profile may reflect the early northward subduction and convergence of the old blocks in the south of Songliao basin.

This research is supported by the National Natural Science Foundation of China (41430213, 41590863), the Geological Survey of China ( Grant nos.DD20160207 and DD20190010) and the Pearl River talent program of China 2117ZT07Z066.