In response to the ongoing India-Eurasia collision in the late Cenozoic, the Tianshan orogenic belt was reactivated and experienced rapid uplift. Strong uplifted topography results in that the mountains propagate from the range front toward the foreland basin to form several fan-shaped foreland thrust belts both on its north and south sides. These foreland thrust belts accommodate the most north-south convergence strain and control the regional deformation pattern. However, in contrast to the well-studied foreland thrust belts, the kinematics and deformation rate of the transition area between different foreland thrust belts have not been well-documented. Therefore, it is still unclear how the crustal shortening in the foreland basins changes along the east-west direction. Further, the deformation characteristics and seismic hazard in this region are poorly understood because quantitative information on active deformation is lacking.

The Wensu foreland thrust belt is located in the Kalpin and Kuqa foreland thrust systems' transition areas. In contrast to the Kuqa and Kalpin foreland thrust belts at its east and west sides, the Wensu foreland thrust belt propagated approximately 20km toward the basin and only developed one row of active thrust fault-anticline belts, namely the North Wensu thrust fault-anticline belt. The North Wensu structural belt shows clear evidence of tectonic solid activity because the late Quaternary sediments and river terraces have been faulted. However, this structural belt's kinematics and late Quaternary deformation rate remain poorly constrained. This study quantifies its deformation mode based on field geological mapping across the anticline. Our results indicate that the North Wensu structural belt is a fault-bending fold. Based on interpretations of detailed high-resolution remote sensing images and field investigations, five levels of river terraces can be identified along the Kekeya River valley. By surveying of the displaced terraces with an unmanned drone, the crustal shortening values of ~20.7m、 ~35.3m and ~46.9m are determined for the T3, T4 and T5 terraces, respectively. Our optically stimulated luminescence(OSL)dating yields a depositional age of(9.02±0.55)ka for the T3 terrace, (24.23±1.58)ka for the T4 terrace, and(40.43±3.07)ka for the T5 terrace. Thus, we estimate a crustal shortening of ~1.31mm/a in the late Quaternary(since approximately 40ka), and approximately 2.29mm/a in the Holocene for the North Wensu structural belt. Our results indicate that the deformation rate of the North Wensu structural belt exhibits an obvious increase in the Holocene. This phenomenon indicates that the strong earthquake activity on the North Wensu thrust belt has increased significantly in the Holocene, implying an irregular activity habit of the strong earthquake recurrence cycle on this tectonic belt. The propagation deformation toward the basin of the Wensu foreland thrust belt is very limited. Therefore, we suggest that the foreland thrust belt is a thick-skinned nappe structure and is dominated by high-angle thrust faulting. The tectonic deformation in the Wensu region seems to be characterized by considered vertical growth. Although the deformation rate is small, the uplift amplitude is significant in this region.

The wedge-shaped deposit formed in front of fault scarp is called colluvial wedge. Repeated faulting by faults may produce multiple colluvial wedges, each of which represents a paleoseismic event. When there are two or more colluvial wedges, the new colluvial wedge is in sedimentary contact with the fault, while the old ones are in fault contact with the fault. The shape of colluvial wedge is usually in the form of horizontal triangle, and the sedimentary facies is usually of binary structure. The overall grain size decreases gradually from bottom to top. Soil layer generally develops on the top, and different types of soil are developed under different climate or soil environments. Another deposit in front of fault scarp is the sag pond graben. The graben in front of sag pond is generally a set of sedimentary assemblages of colluvial facies, alluvial diluvial facies and swamp facies. The area close to the fault, especially the main fault, is of colluvial facies, while the area away from the fault is of alluvial and pluvial facies and marshy facies. In an accumulative cycle, the size of the deposit decreases from bottom to top, and soil layers develop on the top or surface. Multiple pile-ups may be a marker for identifying multiple faulting events. The pile-up strata such as colluvial wedge and fault sag pond can be used as identification markers for paleoseismic events. Colluvial wedge and sag pond, as the identification markers for paleoearthquake, have been well applied to practical research. However, there is still lack of detailed research on the lithological structure and genetic evolution in the interior of colluvial wedge and sag pond sediment, meanwhile, there is still a deficiency in the analysis of the completeness and the regional characteristics of paleoearthquake by using colluvial wedge and sag pond sediment. This paper discusses the method of identifying paleoearthquake by using sag pond sediments and colluvial wedge. We discuss the lithologic combination and sedimentary evolution of sag pond and choose the surface rupture zone of the 1679 M8.0 earthquake on the Xiadian Fault as the research area. In this paper, the distribution range and filling sequence of sag pond are analyzed, using borehole exploration. Four paleoearthquake events are identified since 25ka to 12ka, based on the sag pond sediments and colluvial wedge. The in situ recurrence interval of these seismic events is 480a, 510a, 7 630a and 2 830a, respectively. The lithologic combination and sedimentary evolution law of the sag pond sediments caused by an ancient earthquake are discussed. The sag pond distribution range and filling sequence are determined by the surface elevation survey and drilling exploration. The exploratory trench exposes the sag pond filling strata sequence and lithologic combination. Based on this, we analyze the three sedimentation stages of sag pond sediments formed by a paleoearthquake event near the earthquake fault. It is believed that the filling sequence is composed from bottom to top of the colluvial wedge, the erosion surface or unconformity surface, the fine detrital sediments(containing biological debris)and paleosols. For the fault-sag ponds formed by active faults, the paleoearthquakes occurred near the unconformity or erosion surface of the sediments of the fault-plug ponds. An ancient earthquake event includes the combination of organic deposits such as sediments, clastic deposits, bioclasts, burrow, plant roots and other organic deposits on the vertical scour surface or unconformity. The time interval between two paleoseismic events is defined by two adjacent unconformities(or scour surfaces). According to the vertical facies association and chronological test results of the sediments in the Pangezhuang trough of the Xiatan Fault, four paleo-seismic events are identified since the late Pleistocene period of 25~12ka BP, with recurrence intervals of 480a, 510a, 7 630a and 2 830a, respectively.

Because of the frequent seismic activity in Songyuan in recent years, the modes of tectonic movement in this area since the Quaternary have attracted increasing consideration. This paper selects the Gudian Fault which locates between the southeast uplift and central depression of Songliao Basin as the research object. We discussed the Quaternary structural characteristics of the Gudian Fault using growth strata. Using the data of deep seismic reflection prospecting for oil, we determined the location, geometry and kinematics characteristics of the Gudian Fault. And using the shallow seismic reflection prospecting data, the combined drilling exploration data and TL data, we determined precisely the inversion tectonics feature of the fault since late Cenozoic. Based on the above data, we believe that the Gudian Fault is dominated mainly by thrust-folding since Quaternary. A set of growth strata is recognized by shallow seismic reflection exploration data. According to the overlap of growth strata and the relationship between deposition rate and uplift rate, we confirm that the uplift rate of Gudian Fault in the early of Early Pleistocene is less than 0.15mm/a. And according to the offlap of growth strata and the relationship between deposition rate and uplift rate, the uplift rate of the Gudian Fault is more than 0.091mm/a in the late of Early Pleistocene and more than 0.052mm/a in middle Pleistocene. According to the chronological data, it is determined that the uplift rate of the Gudian Fault is 0.046mm/y since 205ka.

The Gudian Fault in the southwest of Songyuan is an important fault in the central depression of the Songliao Basin. It was recognized from the petroleum exploration data. Based on the data, we conducted shallow seismic exploration, drilling exploration, age determination(OSL) and topography measurement. The fault features and its motion characteristics are analyzed with the results of shallow seismic exploration. With stratigraphic correlation and optical stimulated luminescence dating, the latest active age of the fault is determined. The surface relief of the region to the southeast of the drilling site is relatively larger than surrounding places. An 800m long section across the fault was measured by GPSRTK, and the deformation amount across the zone was calculated. Four conclusions are drawn in this paper:(1) The Gudian Fault is arcuate in shape and shows a property of inverse fault with a length of about 66km in the reflection interface T1(bottom of the upper Cretaceous Nenjiang Group). (2) The middle part of the fault rupture is wider than the ends, narrowing or dying out outwards. According to this feature and the rupture of the bottom of the fourth segment of the upper Cretaceous Nenjiang Group, the fault can be divided into three segments, e.g. Daliba Village-Gaizijing-Guyang segment, Guyang-Shenjingzi-Julongshan Village segment and Julongshan Village-Caiyuanzi segment. (3) The yellow silt layer at the base of the upper Pleistocene series ((33.66±3.27) ka BP~50ka BP) is offset by the Gudian Fault, while the upper tawny silt layer is not influenced by the fault. Thus, the fault belongs to late Pleistocene active fault. (4) The amount of geomorphic deformation around Shenjingzi is 9m. The depth of the bottom of the upper Pleistocene series is 11m and the Huangshan Group of the mid Pleistocene series exposes to the southeast of the deformation zone. Therefore, the throw of the bottom of the upper Pleistocene series is about 20m at the sides of the deformation zone. In addition, the Qianguo M6(3/4) earthquake occurred in Songyuan area in 1119 AD. Though some studies have been done, arguments still exist on the seismogenic structure of the Qianguo M6(3/4) earthquake. Combined with others studies, Gudian Fault is considered as the seismogenic structure of the Qianguo M6(3/4) earthquake.

Located in the south of the Songliao Basin, Songyuan City is one of the few high seismic intensity regions (Ⅷ degree regions) in Northeast China, where a magnitude 6(3/4) earthquake took place in 1119. Since 2013, many earthquakes of magnitude above 5 have occurred in Chaganhua Town which is 100km southwest of Songyuan. The faults in the study region are almost all in a concealed state and covered by the Quaternary system, therefore, geophysical investigation, drilling and other similar means are required to determine their distribution, occurrence, nature and active period. Many seismic explorations in this region aiming at surveying the oil bearing structure have been conducted by Jilin Oilfield, which provides detailed seismic exploration information for preliminary detection of active faults. In this paper, the main features of petroleum-related seismic data and major methods for extracting tectonic information are presented; on the plain, the trace information of the main structure is extracted by the t0 interface contour map which allows direct reflection of rises and falls of stratal interfaces and the tectonic characteristics of the corresponding geologic period; on the section, the "extending upwards" characteristics of faults are captured by tracing and marking geological phenomena in the reflective standard layer, faults, the surface of unconformity and so on. Under the comprehensive use of the "3D" structure in the interpretation of the results, accurate spatial distribution information of main faults are obtained in the study region, this offers an effective approach to preliminary judgment of the activity of faults in this region. Meanwhile, the active age of the target faults is identified by superimposing the deep and shallow seismic data and integrating with the drilling detection.