The M_S7.1 earthquake in Wushi, Xinjiang on January 23, 2024, represents the largest earthquake in the Tianshan seismic belt since the 1992 Suusamyr M_S7.3 earthquake in Kyrgyzstan. Preliminary precise aftershock localization and initial field investigations indicate an NE-trending aftershock zone with a length of 62km that is concentrated at the mountain-basin transition area. This event produced geological hazards, including slope instability, rockfalls, rolling stones, and ground fissures, primarily within a 30-kilometer radius around the epicenter. The epicenter, located approximately 7 kilometers north of the precise positioning in this study, witnessed a rapid decrease in geological hazards such as collapses, with no discernible fresh activity observed on the steep fault scarp along the mountainfront. Consequently, it is inferred that the causative fault for this main shock may be an NW-dipping reverse fault, with potential rupture not reaching the surface.

Moreover, a surface rupture zone with a general trend of N60°E, extending approximately 2 kilometers, and displaying a maximum vertical offset of 1m, was identified on the western side of the micro-epicenter at the Qialemati River. This rupture zone predominantly follows the pre-existing fault scarp on higher geomorphic surfaces, indicating that it is not new. Its characteristics are mainly controlled by a southeast-dipping reverse fault, opposite in dip to the causative fault of the main shock. The scale of this 2-kilometer-long surface rupture zone is notably smaller than the aftershock zone of the Wushi M_S7.1 earthquake. Further investigation is warranted to elucidate whether or not the M_S5.7 aftershock and the relationship between the SE-dipping reverse fault responsible for the surface rupture and the NW-dipping causative fault of the main shock produced it.

Fold scarps, a type of geomorphic scarp developed near the active hinge of active folds due to the local compressive stress, are formed by folding mechanisms of hinge migration or limb rotation. At present, there are several proven methods, which are only based on the fold scarp geometry combined with the occurrences of underlying beds and do not use the subsurface geometry of thrust fault and fold to obtain the folding history. The use of these methods is of great significance to illuminate the seismic hazards and tectonic processes associated with blind thrust systems.
The Sansuchang fold-thrust belt is a fault-propagation anticline controlled by the Sansuchang blind thrust fault located in the southern Longmen Shan foreland area. Previous study used the area-depth method to calculate the shortening history of the Sansuchang anticline since the late Pleistocene(73~93ka)based on the terrace deformation of Qingyijiang River. However, due to the serious erosion damage to the terrace after its formation, the shortening history obtained by incomplete terrace deformation needs to be further verified.
A~9km long scarp was found on the Dansi paleo-alluvial fan on the eastern limb of the Sansuchang fold-thrust belt. According to the detailed field investigation and the fold geometry built by the seismic profile, we found the scarp is near the synclinal hinge, which separates beds dipping 10°~17° and 43°~57° east and parallels with the Sansuchang fold hinge. Therefore, we determined the scarp is a fold scarp formed by the forelimb hinge migration of the fault-propagation fold.
The maximum height of the scarp, extracted by the swath topographic profile across the scarp, is about 28~35m. According to the parameters of the fold scarp height, the underlying beds dip angle near the fold scarp, and the quantitative geometric relationship between shortening and the blind Sansuchang thrust fault, it can be estimated that, after the deposition of the Dansi paleo-pluvial fan((185±19)ka), the anticline forelimb horizontal shortening rate is~0.1mm/a, the fault tip propagation rate of the Sansuchang blind fault is(0.5+0.3/-0.1)mm/a, and the total shortening rate of the Sansuchang anticline is(0.3+0.2/-0.1)mm/a.
The folding rates of the Sansuchang fold-thrust belt since the late middle Pleistocene has been obtained by the local deformation characteristics of the fold scarp in this study. The result is basically consistent with the shortening rate since late Pleistocene obtained by complete terrace deformation across the anticline, which proves that the shortening rate of the Sansuchang anticline is relatively stable at~0.3mm/a. It provides a new idea for studying the activity characteristics of fold-thrust belts in the southern Longmen Shan foreland thrust belt area with a fast denudation rate and discontinuous geomorphic surface.

At 02:04 a.m. on May 22, 2021, a M_S7.4 earthquake occurred in the Maduo County, Qinghai Province, China. Its epicenter is located within the Bayan Har block in the north-central Tibetan plateau, approximately 70km south of the eastern Kunlun fault system that defines the northern boundary of the block. In order to constrain the seismogenic fault and characterize the co-seismic surface ruptures of this earthquake, field investigations were conducted immediately after the earthquake, combined with analyses of the focal parameters, aftershock distribution, and InSAR inversion of this earthquake.
This preliminary study finds that the seismogenic fault of the Maduo M_S7.4 earthquake is the Jiangcuo segment of the Kunlunshankou-Jiangcuo Fault, which is an active NW-striking and left-lateral strike-slip fault. The total length of the co-seismic surface ruptures is approximately 160km. Multiple rupture patterns exist, mainly including linear shear fractures, obliquely distributed tensional and tensional-shear fractures, pressure ridges, and pull-apart basins. The earthquake also induced a large number of liquefaction structures and landslides in valleys and marshlands.
Based on strike variation and along-strike discontinuity due to the development of step-overs, the coseismic surface rupture zone can be subdivided into four segments, namely the Elinghu South, Huanghexiang, Dongcaoarlong, and Changmahexiang segments. The surface ruptures are quite continuous and prominent along the Elinghu south segment, western portion of the Huanghexiang segment, central portion of the Dongcaoarlong segment, and the Huanghexiang segment. Comparatively, coseismic surface ruptures of other portions are discontinuous. The coseismic strike-slip displacement is roughly determined to be 1~2m based on the displaced gullies, trails, and the width of cracks at releasing step-overs.

In the process of intense compression and shortening of the orogenic belt, a series of thrust faults and folds related to reverse faults developed in the piedmont. Determining the kinematic characteristics of these reverse faults and folds is of great significance for understanding the deformation mode of the orogenic belt. The Qilian Shan is located on the northeastern margin of the Tibetan plateau and is the front edge of the plateau expansion. The area has undergone strong tectonic activity since the Late Quaternary, with developed active structures and frequent earthquakes. There are a series of piedmont thrust faults and thrust related folds in the northern and southern margins of Qilian Shan. Compared with a large number of research results of active folds in Tian Shan area, the study of active folds in Qilian Shan is relatively weak. In the northern margin of the Qilian Shan, in addition to the study of individual active folds, most previous studies focused on the thrust faults in the northern margin of the Qilian Shan and the Hexi Corridor, and obtained the active characteristics of these faults. In the southern margin of Qilian Shan, that is, the northern margin of the Qaidam Basin, some studies have been carried out on paleoearthquakes and slip rate of the fault in the southern margin of Zongwulong Shan. However, the study on the late Quaternary folds in this area is relatively weak and there are only some sporadic works.
Shidiquan anticline is located in the intermountain basin surrounded by Zongwulong Shan and Hongshan in the northern margin of Qaidam Basin. It forms the first row fold structure in front of Zongwulong Shan with Huaitoutala and Delingha anticline. Constraining the tectonic geomorphic features of the Shidiquan anticline is of great significance for studying the crustal shortening in the northern margin of the Qaidam Basin and the expansion of the Qilian Shan to the Qaidam Basin. In this paper, the tectonic and geomorphic characteristics of Shidiquan anticline are obtained by means of geological mapping, high-precision differential GPS topographic profile survey, geological profile survey and cosmogenic nuclide dating. Field investigation shows that Shidiquan anticline is an asymmetric fold with steep south limb and gentle north limb, and is controlled by a blind reverse fault dipping northward. The age of the alluvial fan3 obtained from cosmogenic nuclide dating is(158.32±15.54)ka. This age coincides with the Gonghe Movement, indicating that the formation of Shidiquan anticline responds to the Gonghe Movement in the northeast margin of Tibetan plateau. The uplift rate of Shidiquan anticline since 158ka is(0.06±0.01)mm/a, and the shortening rate is(0.05±0.01)mm/a. The folding effect of Shidiquan anticline indicates that the folding of the intermountain basin in the northern margin of the Qaidam Basin, similar to the thrust shortening of the piedmont fault, plays an important role in regulating the shortening of the foreland crust.

On January 19, 2020, an M_W6.0 earthquake occurred in Xikeer town, Xinjiang, northwest China. This earthquake was another strong earthquake event that occurred on the Kepingtage fold-and-thrust belt(FTB)after the 2003 Bachu-Jiashi M_W6.3 earthquake. The Kepingtage FTB is bounded by the southern Tian Shan area to the north and the Tarim Basin to the south. The Kepingtage FTB is ~300km long from east to west and 60~140km wide from north to south. It is composed of a series of monoclinal or anticlinal mountains(fold-and-thrust)with a near east-west direction and parallel distribution. Combined with the focal mechanism, seismic reflection profiles, and interferometric synthetic aperture radar coseismic deformation, we can reveal the seismogenic structure of this earthquake. The Jiashi event was mainly of a horizontal compression movement; the slip distribution was concentrated at a depth of 4~6km, and the fault-slip angle was~15°. Our results show that the seismogenic structure of the Jiashi event is the Keping thrust fault at the leading edge of the Kepingtage FTB. We carried out detailed field surveys, measurements, and drone aerial photography of the earthquake area after the earthquake. In the magistoseismic area(Ⅷ degrees), a lot of seismic geological disasters were found, including ground fissures, sand liquefaction, and collapse. This paper summarizes and describes the characteristics of geological hazards from four observation points. In observation point 1, a large area of ground fissures were developed in the area of Xikeer overpass. According to the statistics of ground fissures of this area, the dominant direction of the ground fissures is NEE, the south-north extrusion uplift is 0.1~0.15m, and the horizontal displacement is 0.05~0.1m. In observation point 2, the earthquake caused serious damage to the Xikeer dam, creating the tensile fissures at the dam crest, with a maximum depth of 4m and a maximum length of 900m. In observation point 3, a series of ground fissures were observed parallel to the road in the west of Xikeer town, and the length of ground fissures is~500m. A large area of sand liquefaction developed along the ground fissures, and the liquefied material was gray brown argillaceous silty. In observation point 4, a series of large and huge fresh rock collapses developed in the Shankou gully north of the epicenter. The largest single collapse is 50~100m³, and the largest collapse range is about 200~300m². According to the field investigation and dynamic calculation results, the maximum horizontal deformation is 29.8cm, located downstream of the dam crest. The horizontal deformation upstream of the dam crest is 22.35cm. Because of the sand liquefaction that occurred behind the dam, local settling of the foundation behind the dam also occurred. The horizontal deformation upstream and downstream of the dam crest are inconsistent, which produced the longitudinal fissures on the dam crest. We collected a large amount of strong-motion earthquakes data from the 2020 Jiashi earthquake. By combining the fault strike and upper and lower wall effects, the PGAs of the foreshock, main shock, and aftershocks were fitted, and isoseismal lines were generated. The Xikeer dam is located at the region where the vibration intensity of the Jiashi event was the highest. The effects of the aftershocks were also superimposed mainly in this area. Notably, sand liquefaction and most of the fissures were caused by the main shock, while the aftershocks(M_S>4.0)exacerbated this damage. However, in this study, we could only determine the extent of the damage caused by the main shock, because our detailed field investigation and drilling were conducted in April 2020, after the main shock and aftershocks.

The Altyn Tagh Fault(ATF)is one of the most prominent active strike-slip faults in the India-Eurasia collision. Fresh features of surface ruptures, which are attributed to seismic events taking place in the last millennium, are identified at several sites along the Che'erchen River to Qingshui River section on the central part of ATF. Accurate chronology of these earthquake events would help understand the spatial-temporal relationship of the recent earthquakes. However, great difficulties are encountered. The central ATF is located in the arid area, and the vegetation cover is so limited that rare organic materials appropriate for radiocarbon dating can be found in the sediments. Luminescence dating technique may serve as an alternative to directly determine the burial ages of the earthquake related sediments. The optically stimulated luminescence(OSL)signal of quartz, which has been widely employed for luminescence dating, displays unwanted charateristics for accurate dating. Firstly, the quartz OSL signal is not sensitive to irradiation, which leads to low signal-to-noise ratio or even no measurable quartz OSL signal. Secondly, the targeted samples of the last millennium are very young, and the radiation dose received during the burial is expected to be less than 3~4Gy, which futher deteriorates the signal-to-noise ratio of the quartz OSL signal. Therefore, quartz OSL signal is not appropriate for dating the sediments relevant to the recent earthquakes on ATF.
The infrared stimulated luminescence(IRSL)signal of potassium feldspar is an alternative, and it is in usual an order of maginitude more sensitive to raidation than the quartz OSL signal. The enhanced signal-to-noise ratio makes it applicable to young samples. The post-IR IRSL signal has been successfully applied to date the sediments beyond the Holocene, however, the relatively slow bleaching of the post-IR IRSL signal poses challenges on applying it to young sediments, especially for the sediments deposited during the last millennium. In this study, we investigated the feasibility of using post-IR IRSL signal from potassium feldspar to date the earthquake events of the last millennium by employing modern sag pond deposits with different sorting and expected equivalent dose(D_e)of 0Gy. Choosing an appropriate measurement procedure and identifying the well bleached pottassium feldspar grains are essential for post-IR IRSL dating of young sediments. The non-fading characteristic of the post-IR IRSL₁₇₀ signal measured at 170℃ following a prior IR stimulation at 110℃ was verified by employing the D_e plateau test with respect to the signal integration interval and IR stimulation temperature together. Reducing the amount of potassium feldspar grains mounted on an aliquot would help reveal the among grains variation of bleaching level of post-IR IRSL₁₇₀ signal before depostion and identify the most sufficiently bleached grains. Therefore, the post-IR IRSL₁₇₀ D_e values of 2mm aliquots were measured for three samples with different sedimentary textures. The median of D_e distribution of well sorted and stratified sag pond deposits is consistent with the minimum D_e value inferred from the minimum age model(MAM-3) and finite mixture model(FMM), while for the poorly sorted deposits, the median is significantly overestimated compared with the minimum D_e values from the MAM-3 and the FMM. The minimum D_e values of 0.6~0.8Gy of all three samples are consistent with the unbleachable residual dose previously reported for post-IR IRSL signals measured at similar temperature for well bleached samples. It implies that by combined use of small aliquot and statistical age models, the well-bleached potassium feldspar grains could be identified. Such an intrinsic unbleachable component needs to be properly corrected when earthquake events of last millennium are to be dated in this area. Otherwise, the post-IR IRSL₁₇₀ age would be overestimated by 200~300a.
The post-IR IRSL₁₇₀ procedure investigated in this study is not only applicable for dating the paleoearthquake events along the Altyn Tagh Fault, but also with great potential to be applied to other tectonically active area. With consideration of the potential variability in post-IR IRSL signal characteristics of potassium feldspar grains from different origins, the signal stability needs to be routinely inspected. The modern analog sample would also be informative for justifying the measurement procedure and analytical method employed.

Tianshan is one of the longest and most active intracontinental orogenic belts in the world. Due to the collision between Indian and Eurasian plates since Cenozoic, the Tianshan has been suffering from intense compression, shortening and uplifting. With the continuous extension of deformation to the foreland direction, a series of active reverse fault fold belts have been formed. The Xihu anticline is the fourth row of active fold reverse fault zone on the leading edge of the north Tianshan foreland basin. For the north Tianshan Mountains, predecessors have carried out a lot of research on the activity of the second and third rows of the active fold-reverse faults, and achieved fruitful results. But there is no systematic study on the Quaternary activities of the Xihu anticline zone. How is the structural belt distributed in space?What are the geometric and kinematic characteristics?What are the fold types and growth mechanism?How does the deformation amount and characteristics of anticline change?In view of these problems, we chose Xihu anticline as the research object. Through the analysis of surface geology, topography and geomorphology and the interpretation of seismic reflection profile across the anticline, we studied the geometry, kinematic characteristics, fold type and growth mechanism of the structural belt, and calculated the shortening, uplift and interlayer strain of the anticline by area depth strain analysis.
In this paper, by interpreting the five seismic reflection profiles across the anticline belt, and combining the characteristics of surface geology and geomorphology, we studied the types, growth mechanism, geometry and kinematics characteristics, and deformation amount of the fold. The deformation length of Xihu anticline is more than 47km from west to east, in which the hidden length is more than 14km. The maximum deformation width of the exposed area is 8.5km. The Xihu anticline is characterized by small surface deformation, simple structural style and symmetrical occurrence. The interpretation of seismic reflection profile shows that the deep structural style of the anticline is relatively complex. In addition to the continuous development of a series of secondary faults in the interior of Xihu anticline, an anticline with small deformation amplitude(Xihubei anticline)is continuously developed in the north of Xihu anticline. The terrain high point of Xihu anticline is located about 12km west of Kuitun River. The deformation amplitude decreases rapidly to the east and decreases slowly to the west, which is consistent with the interpretation results of seismic reflection profile and the calculation results of shortening. The Xihu anticline is a detachment fold with the growth type of limb rotation. The deformation of Xihu anticline is calculated by area depth strain analysis method. The shortening of five seismic reflection sections A, B, C, D and E is(650±70) m, (1 070±70) m, (780±50) m, (200±40) m and(130±30) m, respectively. The shortening amount is the largest near the seismic reflection profile B of the anticline, and decreases gradually along the strike to the east and west ends of the anticline, with a more rapidly decrease to the east, which indicates that the topographic high point is also a structural high point. The excess area caused by the inflow of external material or outflow of internal matter is between -0.34km² to 0.56km². The average shortening of the Xihubei anticline is between(60±10) m and(130±40) m, and the excess area caused by the inflow of external material is between 0.50km² and 0.74km². The initial locations of the growth strata at the east part is about 1.9~2.0km underground, and the initial location of the growth strata at the west part is about 3.7km underground. We can see the strata overlying the Xihu anticline at 3.3km under ground, the strata above are basically not deformed, indicating that this section of the anticline is no longer active.

With the continuous collision of the India and Eurasia plate in Cenozoic, the Qilian Shan began to uplift strongly from 12Ma to 10Ma. Nowadays, Qilian Shan is still uplifting and expanding. In the northern part of Qilian Shan, tectonic activity extends to Hexi Corridor Basin, and has affected Alashan area. In the southern part of Qilian Shan, tectonic activity extends to Qaidam Basin, forming a series of thrust faults in the northern margin of Qaidam Basin and a series of fold deformations in the basin. The southern Zongwulong Shan Fault is located in the northeastern margin of Qaidam Basin, it is the boundary thrust fault between the southern margin of Qilian Shan and Qaidam Basin. GPS studies show that the total crustal shortening rate across the Qilian Shan is 5~8mm/a, which absorbs 20% of the convergence rate of the Indian-Eurasian plate. Concerning how the strain is distributed on individual fault in the Qilian Shan, previous studies mainly focused on the northern margin of the Qilian Shan and the Hexi Corridor Basin, while the study on the southern margin of the Qilian Shan was relatively weak. Therefore, the study of late Quaternary activity of southern Zongwulong Shan Fault in southern margin of Qilian Shan is of great significance to understand the strain distribution pattern in Qilian Shan and the propagation of the fault to the interior of Qaidam Basin. At the same time, because of the strong tectonic activity, the northern margin of Qaidam Basin is also a seismic-prone area. Determining the fault slip rate is also helpful to better understand the movement behaviors of faults and seismic risk assessment.Through remote sensing image interpretation and field geological survey, combined with GPS topographic profiling, cosmogenic nuclides and optically stimulated luminescence dating, we carried out a detailed study at Baijingtu site and Xujixiang site on the southern Zongwulong Shan Fault. The results show that the southern Zongwulong Shan Fault is a Holocene reverse fault, which faulted a series of piedmont alluvial fans and formed a series of fault scarps.The 43ka, 20ka and 11ka ages of the alluvial fan surfaces in this area can be well compared with the ages of terraces and alluvial fan surfaces in the northeastern margin of Tibetan Plateau, and its formation is mainly controlled by climatic factors. Based on the vertical dislocations of the alluvial fans in different periods in Baijingtu and Xujixiang areas, the average vertical slip rate of the southern Zongwulong Shan Fault since late Quaternary is(0.41±0.05)mm/a, and the average horizontal shortening rate is 0.47~0.80mm/a, accounting for about 10% of the crustal shortening in Qilian Shan. These results are helpful to further understand the strain distribution model in Qilian Shan and the tectonic deformation mechanism in the northern margin of Qaidam Basin. The deformation mechanism of the northern Qaidam Basin fault zone, which is composed of the southern Zongwulong Shan Fault, is rather complicated, and it is not a simple piggy-back thrusting style. These faults jointly control the tectonic activity characteristics of the northern Qaidam Basin.

In order to complete the field investigation to the 25 November 2016 Arketao M_W6.6 earthquake, ultra-low altitude remote-sensing data were obtained from miniature unmanned aerial vehicle. The surface rupture surveying has important significance for earthquake research. This paper selects the macro-epicenter of Arketao as the study area. The pictures were obtained with DJI Phantom 3 professional input into the software, the Digital Elevation Model (DEM), Digital Orthophoto Map (DOM) were acquired based on photogrammetry method using the overlapped optical remote-sensing images of UAV. Using these data, we can identify surface ruptures that have vertical dislocation.
We selected six feature points and drew the elevation profile. In the elevation profile map, we chose smooth part of the surface rupture sides and obtained the trend line. A stable point in the surface rupture was selected and the abscissa of the point was taken into the equation of two straight lines. Then subtracting the results of the two equations, we can get the vertical dislocation of the surface rupture. On this basis, we chose six feature points and determined their vertical dislocation, which are between 4.4cm and 10.4cm. What's more, taking Bulungkou Xiang in Xinjiang Uygur Autonomous Region for example, we speculated some surface ruptures that have vertical dislocation. It can provide a new method for identifying surface rupture in the field.
In addition, we get DEM data of the Bulunkou area where ambient conditions are very poor, by using miniature unmanned aerial vehicle and taking 255 photos. Putting those photos into the EasyUAV software, we got the area digital elevation of 2cm resolution. Comparing these data with RTK data, we summarized some practical problems and solutions in the practical operation and evaluated the accuracy of miniature unmanned aerial vehicle data. The Pearson Correlation Coefficient is 0.996 6. In terms of absolute elevation, the average result of UAV and RTK differs by 156.96m. In terms of relative elevation, the average result of UAV and RTK differs by 9.74m. Compared with the previous test of Pishan County, there is a notable divergence in the results. It shows that the data accuracy will be affected to some extent in the cold weather in high elevations. The specific impact needs further exploration.

The M_W6.6 Arketao earthquake occurred on November 25, 2016 in Muji Basin of the Kongur extensional system in the eastern Pamir. The region is the Pamir tectonic knot, one of the two structural knots where the India plate collides with the Eurasian plate. This region is one of the most active areas in mainland China. The seismogenic structure of the earthquake is preliminarily determined as the Muji dextral-slip fault which locates in the north of Kongur extensional system. Based on field surveys of seismic geological hazard, and combined with the characteristics of high altitude area and the focal mechanism solution, this paper summarizes the associated distribution and development characteristics of sandy soil liquefaction, ground fissures, collapse, and landslide. There are 2 macroscopic epicenters of the earthquake, that is, Weirima village and Bulake village. There are a lot of geological hazards distributed in the macroscopic epicenters. Sand liquefaction is mainly distributed in the south of Kalaarte River, and area of sand liquefaction is 1 000m². The liquefaction material gushed along the mouth of springs and ground fissures, because of the frozen soil below the surface. More than 60% of soil liquefactions are formed in the mouth of springs. According to the trenching, these liquefactions occurred in 1.8 meters underground in the gray green silty clay and silty sand layers. The ground fissures are mainly caused by brittle failure, and the deformation of upper frozen soil layer is caused by the deformation of lower soil layer. The ground fissures at Weirima village are distributed in a chessboard-like pattern in the flood plain of Kalaarte River. In the Bulake village, the main movement features of the ground fissure are tension and sinistral slip, and the directions of ground fissures are 90°~135°. The collapse and landslide are one of the important geological disasters in the disaster area. The rolling stones falling in landslide blocked the roads and smashed the wire rods, and the biggest rolling stone is 4 meters in length. We only found a small landslide in the earthquake area, but there are a large number of unstable slopes and potential landslides in the surroundings. The ground fissures associated with sand liquefaction are an important cause of serious damage to the buildings.

By dating detrital zircon U-Pb ages of deposition sequence in foreland basins, we can analyze the provenance of these zircons and further infer the tectonic history of the mountain belts. This is a new direction of the zircon U-Pb chronology. The precondition of using this method is that we have to have all-around understanding to the U-Pb ages of the rocks of the orogenic belts, while the varied topography, high altitude of the zircon U-Pb ages of the orogenic belts are very rare and uneven. This restricts the application of this method. Modern river deposits contain abundant geologic information of their provenances, so we can probe the zircon U-Pb ages of the geological bodies in the provenances by dating the detrital zircon U-Pb ages of modern rivers' deposits. We collected modern river deposits of 14 main rivers draining from Pamir, South Tian Shan and their convergence zone and conducted detrital zircon U-Pb dating. Combining with the massive bed rock zircon U-Pb ages of the magmatic rocks and the detrital zircon U-Pb ages of the modern fluvial deposit of other authors, we obtained the distribution characteristics of zircon U-Pb ages of different tectonic blocks of Pamir and South Tian Shan. Overlaying on the regional geological map, we pointed out the specific provenance geological bodies of different U-Pb age populations and speculated the existence of some new geological bodies. The results show that different tectonic blocks have different age peaks. The main age peaks of South Tian Shan are 270~289Ma and 428~449Ma, that of North Pamir are 205~224Ma and 448~477Ma, Central Pamir 36~40Ma, and South Pamir 80~82Ma and 102~106Ma. The Pamir syntaxis locates at the west end of the India-Eurasia collision zone. The northern boundary of the Pamir is the Main Pamir Thrust(MPT)and the Pamir Front Thrust(PFT). In the Cenozoic, because of the squeezing action of the India Plate, the Pamir thrust a lot toward the north and the internal terranes of the Pamir strongly uplifted. For the far-field effect of the India-Eurasia collision, the Tian Shan on the north margin of the Tarim Basin also uplifted intensely during this period. Extensive exhumation went along with these upliftings. The material of the exhumation was transported to the foreland basin by rivers, which formed the very thick Cenozoic deposition sequence. These age peaks can be used as characteristic ages to recognize these tectonic blocks. These results lay a solid foundation for tracing the convergence process of Pamir and South Tian Shan in Cenozoic with the help of detrital zircon U-Pb ages of sediments in the foreland basin.

The M_W6.6 Arketao earthquake,which occurred at 14:24:30 UTC 25 November 2016 was the largest earthquake to strike the sparsely inhabited Muji Basin of the Kongur extension system in the eastern Pamir since the M 7 1895 Tashkurgan earthquake.The preliminary field work,sentinel-1A radar interferometry,and relocated hypocenters of earthquake sequences show that the earthquake consists of at least two sub-events and ruptured at least 77km long of the active Muji dextral-slip fault,and the rupture from this right-lateral earthquake propagated mostly unilaterally to the east and up-dip.Tectonic surface rupture with dextral slip of up to 20cm was observed on two tens-meter long segments near the CENC epicenter and 32.6km to the east along the Muji Fault,the later was along a previously existing strand of the Holocene Muji fault scarps.Focal mechanisms are consistent with right-lateral motion along a plane striking 107°,dipping 76° to the south,with a rake of 174°.This plane is compatible with the observed tectonic surface rupture.More than 388 aftershocks were detected and located using a double-difference technique.The mainshock is relocated at the Muji Fault with a depth of 9.3km.The relocated hypocenters of the 2016 Arketao earthquake sequence showed a more than 85km long,less than 8km wide,and 5~13km deep,NWW trending streak of seismicity to the south of the Muji Fault.The focal mechanism and mapping of the surface rupture helped to document the south-dipping fault plane of the mainshock.The listric Muji Fault is outlined by the well-resolved south-dipping streak of seismicity.The 2016 Arketao M_W6.6 and 2015 Murghob M_W7.2 earthquakes highlight the importance role of strike-slip faulting in accommodating both east-west extensional and north-south compressional forces in the Pamir interior,and demonstrate that the present-day stress and deformation patterns in the northern Pamir plateau are dominant by east-west extension in the shallow upper crust.

The fold scarp, a type of geomorphic scarp on the land surface formed by folding without fault offsets on the surface, can be used to constrain folding and slip rates and kinematics and to reconstruct a folding history despite a lack of full constraints on the subsurface structure. Recently, the conceptual, geometric, and kinematic models of fold scarps formed by fault-bend folding(fault-bend fold scarp)were developed. But for other types of fold scarp, there are few detailed investigations till now.
Located at southern foreland of Chinese Tianshan, the Mingyaole anticline is interpreted to be a detachment fold. On the Kezilesu river terraces in the south limb, a series of detachment fold scarps occur. The height, width, and slope of fold scarps on the T₂ and T₃b terraces are ～16m/～40m/～25° and ～20m/～50m/～26° respectively. The scarp locations are correlated with an underlying synclinal hinge separating a 50° dip and a 15°dip domain and the strike of the scarp is parallel with the hinge. Detailed geologic and geomorphic mapping and dGPS survey data reveal important characteristics of detachment fold scarp. 1)The fold scarps are formed by synclinal hinge migration. 2)During initial growth, the height, width and slope of the fold scarp increase gradually. When the fold scarp's horizontal width increases to be at least twice that of the hinge, the slope will approach a maximum, and will subsequently remain constant even as the height and width continue to increase gradually. 3)The scarp height and underlying bedding dips on either side of the hinge can be used to calculate incremental shortening absorbed by the fold scarp. Based on the height ～16m of the fold scarp on the T₂ and its exposure age ～8.0ka, the shortening rate absorbed by south limb of the Mingyaole fold is estimated to be ～1.3mm/a. Despite similarities with fault-bend fold scarps, detachment-fold scarps have some pronounced differences, which suggest that the type of fold scarp should be defined prior to calculating folding rates.

The foreland basin of contractional orogen commonly occurs in thrust related fold. Quantitative constraint on fold's growing process is important to understand the spatial and temporal evolution of orogens, and for seismic hazard assessment and hydrocarbon resource prospect evaluation. Fluvial terrace, as a kind of widely distributed, easy dating and passively deformed geomorphic marker, is more and more applied to defining the growth mechanism and rates of active folds. Combining deformed fluvial terrace with pre-growth and growth strata, we can acquire the total shortening and the initiation age, and retrieve the whole evolving history of a fold.Based on geometry and kinematical characteristics, thrust related fold can be classified into fault bend fold, fault propagation fold and detachment fold. As occurred on the tip of a fault, the fault propagation fold and detachment fold are generally named fault tip fold. According to different stress situation, folding deformation includes no shear, simple shear and pure shear, and displays as two end-member models: kink band migration and limb rotation. In different models, the fluvial terrace shows different deformation characteristics, which can be used to distinguish the models.We summarized and discussed how to use deformed terraces to constrain the shortening rates and uplift rates of the sinusoidal and chevron flexural-slip fold, classical fault bend fold, as well as pure shear fault tip fold, and briefly introduced the conception of fold scarp. However, the natural fold is usually formed by combination of different mechanisms, which is much more complicated than the models mentioned. Therefore, the future study should be concentrated on modeling the fold produced by different mechanisms, rather than only one mechanism. In addition, we mentioned three different types of fold scarps: fold scarp occurring in classical fault bend fold and fold scarp formed by kink band migration and limb rotation in detachment fold.

In recent times, some moderate-large earthquakes occurred in active folds and thrusts, which seem not directly related with known active faults on the surface and did not form surface ruptures. Although such individual earthquakes might correspond to a known surface active fault, most of them occurred under active folds, formed by displacement of burial thrusts which are located at depth of tens kilometers beneath the folds. Stein named such earthquake as "folding earthquake". It is quite a challenging issue to study and assess the seismic hazards of folding earthquakes occurring in compressive tectonic regions with active folds and burial thrusts. Derived from active folding secondary faults such as flexural-slip faults, bend-moment faults, it is easier to identify that the fold itself. These secondary faults have coseismic slip at the surface and record the active history of seismogenic thrusts which provide an effective way to study the seismic activity of blind thrusts. Many flexural-slip fault scarps are developed on several terrace surfaces at the two limbs of Mingyaole anticline, located along the western margin of the Tarim Basin. These scarps mainly form on the limb of steep beds closest to active axial surfaces(dips of 74°～89°, 18°～20° and 45°～60°, separately), within a range of 50～1 200m from active axial surface, and most are 90～1 000m wide. Overall, the height of the flexural-slip fault scarps gradually deceases away from the active axial surface. These scarps occur at nearly equidistant or multiple distance spacing on the same terrace surface. The strike of the flexural-slip fault scarp is consistent with the strike of underlying bedrock, which is dominated by interbedded medium-thick layered sandstone or fine-grain sandstone with similar rock mechanical properties. Since the abandonment of terrace T3 at the south limb of the Mingyaole anticline, the shortening rate and uplift rate absorbed by flexural-slip faults are at least (1.0±0.2)mm/a, (1.2±0.1)mm/a, respectively. Movement of the flexural-slip faults is characterized by repeatability and neo-activity.

In the high-precision GPS positioning applications,the antenna phase center calibration significantly impacts the survey accuracy. This article introduces the experiment study of precise calibration of GPS antenna phase center variations based on automatic survey robot GPS which is funded by Crust Movement Observation Network of China project. In this paper,the main derivations of the principle and implementation procedure are described step by step. Comparing with the known calibration parameters,the horizontal accuracy is estimated about 2mm and the vertical accuracy is estimated about 3mm. This study is of practical significance to improve the accuracy of GPS positioning and to popularize the application of calibration of antenna phase center variation based on survey robot.

Folding growth in three dimensions involves shortening in transversal direction,uplift in vertical direction and lateral propagation in longitudinal direction. The impact of these three components changes along the fold's strike: the middle part is dominated by shortening and uplift,and deformation neighboring the fold tip involves not only shortening and uplift,but also strong lateral propagation. Previous studies are focused on the middle part,and the fold tip,a relatively special part,however,is poorly investigated. Thereby,how does the fold tip grow,what is the deformation difference between fold tip and the middle part,and how do terraces deform in response to folding growth？Our study to the southwestern tip of the Mingyaole anticline,located at the Pamir-Tianshan convergent zone,indicates terrace surfaces are strongly back-tilted,and display increasing dips with age,implying a limb rotation mechanism. According to the OSL ages of the T_2b,T_3b and T_4a,as well as a magnetostratigraphy age of underlying bedrock,rotation angle increments of the dip domain 46° display a parabola tendency with the age of<～0.35Ma,(93.9±18.7)ka,(82.6±16.5)ka and(19.4±2.9)ka,and the average rotation rate is>(0.13±0.01)°/ka,(0.08±0.02)°/ka,(0.05±0.01)°/ka and(0.04±0.01)°/ka,which display an obviously decreasing tendency too. However,the shortening rate absorbed by this dip domain keeps constant.The fluvial terraces display not only tilted and uplifted in response to the shortening and uplift of the fold,but deformed in response to lateral propagation. Toward west,density,width and depth of gullies on the terraces decrease,and elevation to the riverbed of the terrace surface,height of the terrace riser as well as rotation angles of terrace surfaces display a decreasing tendency too,both of which are consistent with the fold's western-ward propagation. Based on the magnetostratigraphy age of～1.6Ma at the Kapake valley section,the average western-ward lengthening rate is about 16～16.8mm/a.

Locating at eastern end of the Pamir Front Thrust(PFT),the Mushi anticline grows initiating from early-Pleistocene till now.The anticline,with a gentle south limb and steep north limb,outcrops Pliocene Atushi formation and lower-Pleistocene Xiyu formation.Topographic profiles and drainage pattern indicate the lateral growth of the anticline from west to east.Combining mapping data and seismic profiles from the neighboring area,we find the Mushi anticline is a detachment fold,with a total shortening of ～0.7km and a total uplift up to～1.5km.Northern part of the anticline is dominated by a series of wide,flat terraces.According to OSL samples,the age of the terrace T2a,T3and T4 is 15.8±2.4ka,55.1±10.3ka and 131.4±23.9ka respectively.Correlating with Marine Isotopic stages(MIS),the formation of terraces has some relationship with global climate change.As growing of the anticline,terrace surfaces deformed obviously,which is characterized by fault scarps,surface tilting or back-tilting,folding scarps and lateral tilting.Deforming patterns of the terrace surfaces indicate the Mushi anticline grows by limb rotation in late-Pleistocene.Using calculating models,we can confine the minimum shortening rate is 1.6±0.3mm/a and the minimum uplift rate is 1.9±0.3mm/a. Longitudinal profiles of terraces indicate the Mushi anticline grows laterally through limb rotation.According to relationship between uplift and lateral propagation,we can acquire a faster eastward lateral propagation rate of the anticline during the period of 131～16ka,with a rate about 14.6±3.6mm/a; however,since 16ka,the rate reduced to 1.7±0.3mm/a,implying the anticline tip stopped propagating to the east,and growing of the anticline was mainly dominated by lateral limb rotation in late Quaternary.

The Mushi anticline locates at the frontier Pamir arcuate nappe tectonics belt(PFT),which is a detachment fold with a gentle south limb and steep north limb,and its earth crust minimum shortening is ～0.7km with uplift up to 1.5km.The north limb fault of Mushi anticline is composed of a series of obsequent slope fault scarps,and the distribution of vertical displacements among different fault scarps presents a pattern of one increasing and the other decreasing.No matter of the entire western segment of the northern limb faults or a single fault,the displacement distribution is asymmetric,that is,high in the east and low in the west,and the same to displacement gradient.This may reflect the late Quaternary folding of Mushi anticline as being intensive in the east and feeble in the west.The fault may be a shallow,rootless secondary fault formed during the growth process of the anticline in order to accommodate the constantly decreased space of anticline nucleus as the fold tightened gradually.The late Quaternary shortening rate of the fault is 0.8mm/a,absorbing only one fifth of the nowadays crustal shortening rate of the region.The growth of Mushi anticline and the north limb fault of Mushi anticline both are in accordance with global fault dataset scaling relationship,that is,fault length is over 100m.The power-law regression scaling exponent of west segment of the northern limb fault of Mushi anticline is n=1.37(R²=0.88),and its specific value(k)of maximum fault displacement and fault length is far less than that of the Mushi anticline,which is ～4.3％,but 1～2 orders of magnitude larger than that of global fault dataset(10^-4～10^-5). This may show that the northern limb fault of Mushi anticline is the offshoot of several moderate strong earthquakes,and it is still in initial stages.

The western Tarim Basin is a convergent zone of the Southwestern Tianshan and the Pamir,and there have been big debates about its exact boundary.However,in the Mayikake Basin,the boundaries of two tectonic systems are very clear: the north-vergent Pamir Front Thrust is the leading edge of the Pamir,and south-vergent thrust at south limb of the Wulagen anticline,which was discovered in recent field study,is the south margin of the Southwestern Tianshan.The thrust created 7.5～17.6m high scarps on the Tk3(the high terrace of the Kezilesu river)and Tb3(the high terrace of the Bieertuokuoyi river),with an occurrence of 6°∠15°.To the west,the thrust cuts all terraces of the Bieertuokuoyi river and the underlying youngest alluvial fans ultimately.The total length of thrust trace is about 12km.As activity of the thrust,lots of subparallel flexural-slip scarps are formed on terrace surfaces,which make terrace surfaces obviously differential back-tilted(tilted to south),and the locations of tilted degrees changed are corresponding to locations of flexural-slip faults.Shortening at south limb of the Wulagen anticline is absorbed by the thrust and flexural-slip faults,which is about ～71.4m since abandonment of the high terrace.Regional correlation indicates the high terrace is the same surface as the T2 located at north limb of the Mushi anticline with the age of～16ka,which indicates the average shortening rate of south limb of the anticline in late Quaternary is～4.5mm/a.

The northern margin of the Pamir salient indented northward by ～300km during the late Cenozoic,however,the spatiotemporal evolution of this process is still poorly constrained.Regional deformation within the Pamir salient is asymmetric.Previous work has shown that deformation along the western flank of the Pamir was accommodated by northwest-directed radial thrusting and associated anticlockwise vertical axis rotation of the Pamir over the eastern margin of the Tajik Basin,along with a component of left-slip faulting along the Darvaz Fault.In contrast,subduction of the Tajik-Tarim Basin beneath the Pamir along the MPT was absorbed along the eastern margin of the salient by dextral-slip along the Kashgar-Yecheng transfer system,accompanied with Oligocene-Miocene northward underthrusting, thickening and widespread melting of the middle and lower crust beneath the Pamir,eventually led to east-west extension along the Kongur Shan extensional system at ～7～8Ma.The slip rate of the KYTS decreased substantially from 11～15mm/a to 1.7～5.3mm/a since at least 3～5Ma,termination of slip along the northern segment of the Karakorum Fault occurred almost at the same time.Late Quaternary and present active deformation in the Pamir is dominated by east-west extension along the Kongur Shan extensional system and north-south contraction along the PFT and the Atux-Kashi fold belts in the southern margin of Tianshan.