| Deep seismic reflection is one if the most effective techniques in probing deep geological problems, such as fine structure of the lithosphere, plate subduction, thrusting nappe within crust, crust-mantle interaction, etc, which has been widely accepted by earth scientists. In this paper, Two lines of profile(CJ01and CJ02) was yield out after a careful analyzing and processing of deep seismic reflection data while take consideration of the rule of local region tectonic evolution. Based on that result, a detailed and comprehensive analysis of the structure and tectonic evolution of the cross-section was revealed, which provide reliable and detailed evidence in understanding the deep structure and dynamic evolution of the Yangtze River (Lower Yangtze) region. The study shows that:1Normal angle of Kirchhoff pre-stack time migration is the key to solve complex tectonic zone using deep reflection seismic migration imaging technology, which can expand and focuses the reflected energy of underground bin and get the inclination range of impedance interface underground, is also required in seismic interpretation procedure. Although some experimental work has been done and some significant results has been achieved in using this method, however, Application to those actual seismic data is not very satisfactory, I will continue to refine this promising migration methods in the next work term, in order to realize a new practical method which could to adapt to complex structure and apply to low SNR (signal to noise ratio) seismic data.2The main problems of deep seismic reflection data processing including: low signal to noise ratio of seismic data, complexity of underground structures and hard seismic statics corrections. In order to ensure that the results could truly reflected the geology structure underground, An tightly integrated way of processing-interpretation-reprocessing was used in the data processing procedure, that means every step of the obtained results would do a re-adjustment and re-pick of parameters combined with the local region geological tectonic evolution during processes of the seismic data; Each step of main processing was first tested, then practical application would be applied after credible results obtained, finally the satisfactory stacked profile was achieved with high SNR and good continuity of phase axis. 3Based on the interpretation of two deep seismic reflection profiles obtained by innovative approach mentioned above, the main geological understanding of the Yangtze River and related area around as follows:(1) The Yangtze plate is subducting beneath the North China plate in the way of crocodile-type under the action of north-south compressional stress filed, causing the middle and lower part of Yangtze crust detachment occurs.(2) Combined profiles showed that there is a huge overthrust tectonic system controls the structural framework of lower Yangtze and Jiangnan orogenic belt, and the characteristics of stress field progressively enhanced from northwest to south.(3) The distribution pattern of deep magma chamber is generally determine while a detailed description of the crust/mantle interaction processes and large-scale mantle magma intrusion is the reason which caused a large distribution of igneous rocks on the surface of studied area based on these deep seismic reflection profiles.(4) Intensive imbricated reflected wave group from crust/mantle boundary could be reflection of Chinese plate subducting slab remnants or Dislocation of Yangtze plate under the extrusion stress field.(5) Tan-Lu fault is a tectonic structure formed after the collision rather than duration of the collision. Which has a nature of strike-slip kind. This cult also clearly in control of the magmatic activity of Dabie area, especially in the Yangtze River region.it possibly plays a limited impact on tectonic framework around related area.(6) The inverted splay and left-handed character type is present in the Yangtze River fault zone and Chuhe fault zone. |
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