Meso-Cenozoic inversion structures developed in northern Songliao Basin represent the third tectonic evolution stage of the basin following the rifting stage and the depression stage of thermal cooling. The paper collects systematically 30 regional seismic reflection profiles laid out to cover the Da'an-Dedu Fault and its adjacent14 3-D seismic projects, and on this basis, accurately tracks and interprets a total of seven seismic reflection horizons of T₀₆, T₁, T₁₁, T₂, T₃, T₄ and T₅. At the same time, geological age of key reflection horizons is re-determined based on 52 boreholes data, the distribution characteristics and pattern of different periods are analyzed, and the geometric configuration and deformation characteristics and mechanisms of Meso-Cenozoic inversion structures developed in the northern Songliao Basin are discussed in particular. The study concludes that the inversion structure is the main deformation model of Da'an-Dedu Fault in the late Mesozoic and early Cenozoic, which coincides to the geometric shape and deformation mechanism of the "thrust-fold" structures.
Based on the experimental shallow seismic exploration results of section line No.10 and No.11 in the research area, we find that the small faults, which are widely developed on the top of anticline and disconnect the reflection interface of T₀₆, represent the latest activity of Da'an-Dedu Fault, and the deformed layer formed in mid-Pleistocene may indicate the latest activity time of Da'an-Dedu Fault, which is mid-Pleistocene.
In addition, according to the study on shallow seismic exploration results, modern earthquake activity and focal mechanism solutions, we strongly believe that the latest activity of "thrust-fold" inversion structures of the Da'an-Dedu Fault has an obvious effect on the near surface reflection layers, which offsets the lower-middle Pliocene and controls the moderate-strong earthquake activity of the research area and the adjacent areas. These structures should be regarded as one of the most important and typical seismogenic structures in the interior of Songliao Basin and in the Northeast China region. Based on this, we can understand scientifically the deformation process of the interior of Songliao tectonic block through the research of structural deformation of Da'an-Dedu Fault developed inside the block after the late Cenozoic era, and the future earthquake activities controlled by the Da'an-Dedu Fault.

The Yabrai range-front fault is a normal fault,which is about 120km long,trends N60°E and distributes along the southeast margin of the Alashan block. In this paper,we focus on the geomorphology and kinematics of the Yabrai range-front fault,and discuss the implications of the fault for the regional tectonics.
This fault consists of three segments and the most active one is located in the southwest,which has a length of about 35km. The about 1～2m-high scarp,stretching almost the full segment,might be the result of the latest earthquake event. Fresh free surface indicates that the elapsed time of the last event should not be long.
The middle segment is about 31km in length. The results suggest that just a single fault is developed along the piedmont of the Yabrai Shan,and there is no evidence of recent activity on this fault. In contrast to the simple geometric structure of the middle segment,the northeast segment consists of several faults. The scarps of the most recent earthquake event,which are clear but discontinuous,are about 0.5～1.5m high and some are up to 2m. Although the scarps along the southwest and northeast segments of the fault are similar,it is difficult to suggest they are caused by the same earthquake without precise dating.
The seismic reflection profile suggests that the Yabrai range-front fault came into being as a normal fault in Cretaceous,when the Tibetan plateau did not emerge at that time. Therefore,we conclude that the Yabrai range-front fault is not the consequence of the Indo-Asian collision. But this region plays a great role in constraining the tectonic evolution of the Alashan block and therefore,the Tibetan plateau.