The Tian Shan is one of the most active intracontinental orogenic belts in the world. It has undergone complex deformation that has resulted in the formation of several fold-and-thrust belts (FTBs) in the piedmonts and intermontane basins. Investigating the deformation histories of these FTBs is important for understanding the tectonic propagation processes of the Tian Shan. Here, we gain insight into these crustal shortening processes by deciphering the Houyanshan structure, a typical fold-thrust belt in the eastern Chinese Tian Shan. We first describe a curved thrust ramp and related fold pairs of the structure using high-resolution remote sensing photography, deformation of fluvial terraces, and field-based geological cross-section. Combined with deformed terrace records and optically stimulated luminescence (OSL) dating results, the kinematic style allows us to yield a geologic shortening rate of 1.6 ± 0.2 mm/a since ~52 ka. Second, to reduce uncertainty in the seismic interpretation and quantify the amount and time of crustal shortening, we interpret three seismic reflection profiles by using the theory of quantitative fault-related fold, area-depth-strain (ADS), and reverse modeling analyses. These profiles provide direct evidence that this structure connects by means of a listric thrust ramp to a shallow detachment level. ADS analysis reveals that the maximum shortening of the Huoyanshan structure is ~4.5 km, which is consistent with the result of quantitative inverse modeling. Each of the structural analysis methods gives similar parameters, and the high consistency of results greatly improves the soundness of a given geologic interpretation. Finally, the shortening rate and total shortening amount suggest that the structure may have formed at 1.8–3.7 Ma, which is nearly synchronous around the Tibetan Plateau. Together, these results indicate that this combined geological and geomorphological analysis provides greater insight into deformation information than can be achieved by any individual technique in studying fold-and-thrust belts worldwide.

At local time 01 :45 on January 8, 2022, an earthquake of M(S)6. 9 occurred in Menyuan County (N37. 77 degrees, E101. 26 degrees), Haibei Prefecture, Qinghai Province, with a focal depth of 10 km. Based on the detail post-earthquake field investigation, it was confirmed that the epicenter of Menyuan M(S)6. 9 earthquake was located at the regional structural transformation area of Lenglongling fault and Tuoleshan fault,which were the part of middle-to-west segment of Qilian-Haiyuan fault, both faults were left-lateral strike-slip active faults in Holocene. The earthquake formed two obvious surface rupture zones with a total length of about 31 km. The northern main surface rupture mainly distributed along the western section of Lenglongling fault zone, starting from head of the Liuhuanggou in the east, passing through Daogou westward further ending at the lower Daquangou, with a length of about 22 km. Combining field measurement and verification by high-resolution UAV image, the maximum horizontal dislocation confirmed was 2.6 +/- 0.3 m in the middle segment of northern rupture, which decreased gradually to the two ends. From the field observation, it is concluded that the macro epicenter is located in the area between great bend of Liuhuanggou and the east of Daogou. The southwestern secondary rupture zone distributed on the partial eastern segment of Tuoleshan fault, which started from Daquanwo in the east to Yangchangzigou in the west and ends up at Daxigou, with a length of about 9 km, the maximum horizontal dislocation about 1.0 +/- 0.1 m. Two surface ruptures displayed left-stepped with a minimum 1.0 km wide distance. Overall, the slip behavior of the surface ruptures in the M(S)6. 9 earthquake was mainly left-lateral strike-slip with a slight thrust component. The patterns of surface rupture were typical and abundant, each secondary fracture was consisted of combination of echelon left-lateral tension or right-lateral compression, showing the typical strike-slip dislocation landforms, such as left-lateral dislocated small gullies, riverbed, pastoral barbed wire fence, road subgrade, ruts, sidewalks and animal footprints, etc. Besides, the surface rupture was also characterized by a series of typical deformation phenomena such as compressive ridges or mole tracks, tensile cracks, fault scarps, and so on. Furthermore, by comprehensive analysis of the co-seismic surface ruptures and the deep structure inferred from aftershock activity of Menyuan earthquake, the result shows that the seismogenic structure should be mainly the western segment of Lenglongling fault and the partial eastern segment of Tuoleshan fault. The Y-shaped bifurcated co-seismic surface rupture style between the regional structure transformation area was the joint action of these two faults. The 2022 Menyuan earthquake is a strong earthquake occurred on the Lenglongling main active fault after the Menyuan M(S)6. 4 earthquakes in 1986 and in 2016, both occurred on the northern sub-fault of Longlongling. Therefore, more attention should be paid to the potential larger earthquake activity in the Qilian-Haiyuan fault zone, especially in the west segment in the future.

The Qilian–Haiyuan fault zone in the northeastern Tibetan Plateau has been the source of strong earthquakes in the region. In its middle segment, the Jinqianghe fault is an important active fault within the Tianzhu seismic gap; however, little is known about its slip behavior. To present a new horizontal displacement distribution along this fault, we used WorldView‐2 stereo pairs and unmanned aerial vehicle‐based photogrammetry to construct digital elevation models to obtain a detailed tectono‐geomorphic interpretation and geomorphic offsets. The offset marker measurements yielded 135 geomorphic displacements and 8 offset clusters. Radiocarbon dating was used to establish the regional age sequence of the geomorphic units in offset fluvial terraces at four study sites. The displacements and ages linked the offset clusters with the geomorphic unit sequence; the Holocene strike‐slip rate of the Jinqianghe fault was estimated to 4.8–5.6 mm/a at ∼4–12 ka and 2.9–4.7 mm/a from ∼4 ka. Three recent earthquakes (with a recurrence interval of ∼1000 years) represent an active seismic period, revealing the potential seismic hazard along this fault because it has not ruptured in the last 1500 years.

The Qaidam Basin is the largest Cenozoic basin located on the northeastern margin of the Tibetan Plateau. The extremely thick Cenozoic sedimentary strata in the basin recorded regional tectonic deformation and associated climate change when the Tibetan Plateau grew outward to its margins. The Cenozoic strata in the Qaidam Basin have been historically subdivided into seven primary stratigraphic units: The Lulche, Xia Ganchaigou, Shang Ganchaigou, Xia Youshashan, Shang Youshashan_ Shizigou, and Qigequan formations. Although many studies have been performed in recent decades, the Qaidam Basin's inception, development and extinction are still unclear, which requires more work. such as high-resolution magnetostratigraphies. This paper focuses on the Lulehe section, which is the type section of the Lulehe Formation on the northern margin of the Qaidam Basin. The Lulehe section encompasses the Lulehe to Shizigou Formations. and the section was previously estimated to have been initially deposited 52 Ma. We collected paleomagnetic samples from 2041 sites in the Lulehe section to establish magnetic polarity sequences of the section. Constrained by the regional stratigraphic correlation, the recognized magnetic polarity sequences of the Lulehe section were anchored to chrons C12n-C3n.4n (31-5 Ma). Our correlation places the age of the Lulehe Formation at 30.9-23.7 Ma suggesting that the onset of sediment accumulation in the Qaidam Basin occurred ca. 31 Ma. Overlying the Lulehe Formation, the Xia Ganchaigou Formation was deposited from 23.7 to18.1 Ma. the Shang Ganchaigou Formation spans from 18.1 to 12.9 Ma. the Xia Youshashan Formation spans from 12.9 to 9.9 Ma, the Shang Youshashan Formation spans from 9.9 to 6.9 Ma. and Shizigou Formation is younger than 6.9 Ma. To characterize the sedimentary environments of strata within the Lulehe section, we undertook a detailed stratigraphic analysis. At the bottom of the section, the Lulehe Formation is characterized by alluvial facics (30.9-23 Ma). Upward, the Xia Ganchaigou Fonnation and Shang Ganchaigou Fonnation (23-13 Ma) arc interpreted to have formed in braided river, meandering river, and lacustrine environments. The sedimentary environments of the Xia Youshashan Formation and Shang Youshasahn Formation arc interpreted as delta-fan and braided river facics. An abrupt sedimentary environmental change from lacustrinc to delta-fan occurred ca. 13 Ma in the Lulehe section. This lithofacies change in the section may represent tectonic deformation of the South Qilian Shan in the northern Qaidam Basin. From ca. 11 Ma, coarse-grained clasts significantly increased upward in the section, and the sedimentary environment changed to braided river. This phenomenon suggests that the northern Qaidam Basin fault system propagated southward to the region adjacent to the Lulehe section. At the top of the Lulehe section, the Shizigou Formation is characterized by an alluvial fan system. Sediment accumulation rates in the Lulehe section from ca. 31 to ca. 5 Ma were calculated based on the Lulehe magnetostratigraphy. We found that the Lulehe section almost maintained a stable accumulation rate from ca. 31 to ca. 15 Ma with an accumulation rate of 170.6 m/Ma. From ca. 15 Ma. the accumulation rate in the study area increased significantly to 271.2 m/Ma, and the accumulation rate in the section decreased slightly to 204.3 m/Ma from 11 Ma. The variations in the accumulation rate ca. 15 and ca. 11 Ma in the Lulehe section are consistent with the sedimentary environment changes ca. 13 and ca. 11 Ma. The increase in the sedimentation rate ca. 15 Ma again suggests that the northern Qaidam Basin fault system began to be active. The decrease in the sedimentation accumulation rate ca. 11 Ma indicates that the Lulehe section was involved in tectonic deformation related to southward propagation of the northern Qaidam Basin fault system, which may have reduced the accommodation space in the Lulehe region on the northern basin margin. Overall. our results indicate that the Qaidam Basin experienced two-stage tectonic deformation beginning ca. 31 Ma and subsequently ca. 15 Ma. The Oligocene (31 Ma) deformation led to the formation of the Qaidam Basin. The northern basin margin has been intensively deformed by anticlines and synclines as a result of fault thrusting since the middle Miocene.

Earthquake-triggered landslides (EQTLs) are affected by both seismogenic faults and topography. Using landslide data associated with the 2008 MW7.9 Wenchuan earthquake, the distribution characteristics of EQTLs were identified. And the influence of topographical changes and fault dip angle changes on the distribution of EQTLs was analyzed. Fault dip angle had a controlling impact on EQTL spatial distribution. When the dip angle increased, EQTL distribution was concentrated in a certain range on both sides of the fault and decayed rapidly with distance from the fault. When dip angle decreased, the hanging wall effect became more obvious, and the number of landslides on the hanging wall gradually decreased with distance from the fault. In terms of topography, EQTLs were closely related to relative elevation differences, forming a single peak for a local relief range of 400–1600 m. For > 70

The deformation pattern and slip parti-tioning related to oblique underthrusting of the Tarim Basin in the eastern Tian Shan orogenic belt are not well understood be-cause interior deformation images are lack-ing. The Baoertu fault is an E-W-striking, similar to 350-km-long reactivated basement struc-ture within the eastern Tian Shan. In this study, we quantify its late Quaternary activ-ity based on interpretations of detailed high -resolution remote sensing images and field investigations. Three field observation sites along an similar to 80-km-long fault segment indicate that the Baoertu fault is characterized by sinistral thrust faulting. Based on surveying of the displaced geomorphic surfaces with an unmanned drone and dating of the late Quaternary sediments using radiocarbon and optically stimulated luminescence (OSL) methods, we estimate a late Quaternary left-lateral, strike-slip rate of 1.87 +/- 0.29 mm/yr and a N-S shortening rate of 0.26 +/- 0.04 mm/yr for this fault. The lithospheric Baoertu fault acts as a decoupling zone and accom-modates the left-lateral shearing caused by the oblique underthrusting of the Tarim Ba-sin. In the eastern Tian Shan orogenic belt, the oblique convergence is partitioned into thrust faulting across the entire range and sinistral slip faulting on the high-dip basement structure within the orogen. This active faulting pattern in the eastern Tian Shan of sinistral shearing in the center and thrust faulting on both sides can be viewed as giant, crustal-scale positive flower structures.

Earthquake deformation is crucial for understanding fault kinematics. Modern earthquakes (moment magnitude $M_{w} \geq 6$ ) have been well documented by geodetic techniques, such as radar interferometry and image correlation with unprecedented accuracy. Nonetheless, many large ( $M_{w} \geq 7$ ) historical earthquakes remain unexplored due to a lack of preearthquake data. In this article, we provide the first study of using Hexagon KeyHole-9 (KH-9) panoramic imagery to investigate historical earthquakes. We propose patch-based orthorectification and test the method from analog experiments with unmanned aerial vehicle (UAV) photographs. Using the $2013~M_{w}~7.7$ Balochistan as a case example, we demonstrate that KH-9 images can be used to retrieve meter-scale horizontal deformation. The displacements, derived from correlating KH-9 (preearthquake) and Sentinel-2 (postearthquake) images, are comparable with published studies. Applying the method to the $1981~M_{w}~7.1$ Sirch earthquake, we succeed to measure NS strike-slip motion (up to 5.9 ± 1.6 m) along the 1981 rupture and find that most of the accumulated strain energy may be released by motion along a 25-km-long segment of the Gowk fault. The southward propagation of the rupture may be prevented by the earlier $M_{w}~6.6$ Golbaf earthquake that released most of the accumulated strain in the south. The rapid decay of slip in the north seems to be associated with a 3-km-long, 1-km-wide step-over, which may have dissipated a large fraction of seismic energy. The KH-9 panoramic images show great potential for determining horizontal deformation, providing useful information about historical earthquakes that occurred before the era of modern geodesy.

Ground deformation is usually used as direct evidence for early warning of geological hazards. The Weihe Graben, located in the southern margin of the Ordos Plateau, is surrounded by many active faults. Earthquakes (e.g., the 1556 Huaxian M 8 earthquake), mine accidents and ground fissures are the major hazards that pose great threats to this densely populated region. In order to characterise both tectonic and anthropogenic activities in the Weihe Graben, we use Envisat data from 2003 to 2010 and Sentinel-1 data from 2014 to 2021, combined with levelling data from 1970 to 2014, to investigate the long-term ground deformation. We generate four InSAR rate maps using the small-baseline subset (SBAS) algorithm. The uncertainties of the InSAR rates are 1–2 mm/year by calculating the differences between the InSAR and levelling measurements. From the deformation time series, we found that most of the faults surrounding the Weihe Graben move at a relatively slow rate (<3 mm/year). Elastic dislocation modelling based on the InSAR and levelling data yields a slip rate of 2.3 ± 0.3 mm/year for the Huashan Fault, the seismogenic fault for the 1556 Huaxian earthquake. Anthropogenic deformation is much stronger than the tectonic deformation. We identified localised subsidence of 12 mines with a deformation rate ranging from 5 to 17 mm/year. The cities of Xi’an and Xianyang also show evident subsidence, which is likely to be caused by groundwater extraction. Land subsidence in Xi’an has slowed down from an average rate of 10–20 mm/year between 2003 and 2010 to about 5–10 mm/year between 2017 and 2020, but in Xianyang, subsidence has increased dramatically in the past five years from 1 mm/year to 7 mm/year. This is because new industrial and urban development centres have gradually moved from Xi’an to Xianyang. We identified a region bounded by the Kouzhen-Guanshan and Fufeng-Liquan Faults with strong subsidence, as a result of excessive extraction of groundwater. To quantify the effects of crustal groundwater unloading on faults, we calculated the static Coulomb stress changes on the two faults and found that Coulomb stress changes are localised in the upper 5 km with a magnitude of 0.01–0.02 bar/year. The Coulomb stress changes might be large enough (0.1 bar) to affect local seismicity if such excessive extraction of groundwater continued for 10 years.

The Dongbatu Shan (DBTS, also known as the Nanjie Shan), which interrupts the northern Tibetan foreland in the Dunhuang basin, is an active anticline. It has accommodated the northwestern growth of the eastern Altyn Tagh fault system (ATF). Although several thrust faults have been identified around the DBTS, their evolution history and influence on regional landscape have received little attention during the late-Quaternary. In this study, several geomorphic methods are used to investigate the interaction between drainage development and tectonic movement around DBTS. Based on high-resolution satellite images, field investigation, and cosmogenic nuclide 10Be dating method, the fluvial landform sequences around DBTS were constructed. Using quantitative geomorphology methods including landscape relief profile, asymmetry factor (AF), and transverse topographic symmetry factor (T), we hypothesize that drainage deflection is controlled by multi-segment fault growth. Combining the results of the above-mentioned methods, we propose that Yulin He, flowing across the DBTS, had gone through several abandonments since the late mid-Pleistocene due to the lateral propagation of DBTS. Affected by the discharge of channel and multi-segment fault growth, our research confirms that the direction of river abandonment may have decoupled with the mountain range propagation trend. Based on the chronology dating, the DBTS has gone through two severe uplifts since ∼208 ka and the shortening rate across the central DBTS is constrained to be ∼1.47 mm/yr since ∼83 ka. Given the fact that thrust faults are widely developed around DBTS, we propose that the flower-like structure formed by the northward growth of the eastern ATF could better explain the development of the secondary subparallel faults.

Paleoearthquake data obtained from fault trenching are essential for rebuilding the rupture history and understanding the rupture behavior of active faults. However, due to the lack of attention to stratigraphic sequences, the usual multiple trench constraining method may result in uncertainties of paleoearthquake sequences. In this study, we proposed an improved constraining method to generate stratigraphic sequences from multiple trenches of different drainages to obtain a paleoearthquake sequence of the Gulang fault. Single-trench stratigraphic sequences were built up by nineteen trenches excavated along the fault. Based on stratigraphic characteristics, we found the strata sedimented around the fault were derived from five drainages. The single-trench sequences were divided into five drainages to establish the composite sequence of multiple trenches through the correlation of stratigraphic units. Meanwhile, we used high-quality event indicators to pick out very likely earthquakes. Coupled with the dating samples, the events were used to determine the earthquake horizons in the composite sequence and to constrain the numbers and ages of events in each drainage. After combining the event sequences, six paleoearthquakes were determined along the Gulang fault since the late Pleistocene. Their occurrence timings are 13,700–10,400, 10,400–10,200, 8,560–7,295, 5,825–4,810, 4,285–3,200, and 2,615–2,240 a B.P. And their different rupture scenarios indicate that the fault might be composed of two rupture segments.

The Elashan fault (ELSF) and Qinghainanshan fault (QHNF), two major faults developed around the Qinghai Lake and Chaka-Gonghe basins, are of great importance for investigating the deformation model of the internal northeastern Tibetan Plateau. However, their late Pleistocene slip rates remain poorly constrained. In this study, we combine high-resolution topography acquired from unmanned aerial vehicles (UAV) and geomorphological dating to calculate the slip rates of the two faults. We visited the central ELSF and western QHNF and measured displaced terraces and stream channels. We collected Be-10 samples on the surface of terraces to constrain the abandonment ages. The dextral slip rate of the central segment of the Elashan fault is estimated to be 2.6 +/- 1.2 mm/yr. The uplift rates since the late Pleistocene of the Elashan and Qinghainanshan faults are 0.4 +/- 0.04 mm/yr and 0.2 +/- 0.03 mm/yr, respectively. Comparing the geological rates with the newly published global positioning system (GPS) rates, we find that the slip rates of the major strike-slip faults around the Qinghai Lake and Chaka-Gonghe basins are approximately consistent from the late Pleistocene to the present day. The overall NE shortening rates by summing up the geological slip rates on major faults between the East Kunlun and Haiyuan faults are similar to 3.4 mm/yr, smaller than the geodetic shortening rates (similar to 4.9 to 6.4 mm/yr), indicating that distributed deformation plays an important role in accommodating the regional deformation. By analyzing the geometrical and kinematic characteristics of the major faults surrounding the basins, we suggest that the kinematic deformation of the internal northeastern Tibet is a nonrigid bookshelf model that consists of counterclockwise rotation (similar to 0.8 degrees Myr(-1)) and distributed thrusting.

青藏高原向北东方向扩展的方式及最新扩展边界的位置,是目前青藏高原东北缘构造变形研究的热点.基于近年来对阿拉善地块南缘及邻区活动构造运动特征调查和定量研究结果,重点总结了阿拉善地块南缘活动断裂几何图像及运动特征,指出以前普遍认为的稳定阿拉善地块内部在新生代晚期发育了一系列规模不等、运动性质各异的活动断裂,这些活动断裂是青藏高原向外扩展过程中新生或先存断裂复活的结果,断裂对区域地貌的控制作用形成了阿拉善地块南缘的地貌和构造边界.综合新生代变形、构造地貌、低温年代学、大地测量与现代地震活动等资料和研究结果,认为青藏高原东北缘新生代中晚期以来发生了有序的向外扩展,形成了两个有重要意义的扩展边界:一是在10 Ma左右形成的以祁连山北缘断裂为主要边界控制构造的、完整清晰的青藏高原东北缘地貌及构造边界;二是在新生代晚期3～2 Ma形成的阿拉善地块南缘与祁连山北缘断裂近平行展布的、主要由逆冲断裂所组成的青藏高原扩展最新边界.在现今构造、地貌格局中,阿拉善地块南缘已成为青藏高原东北缘最新的组成部分.

The deformation pattern and strain partitioning in the Eastern Chinese Tian Shan are poorly known because of the lack of quantitative study of the kinematics and deformation rate of the major structure. Here we report a late Quaternary shortening rate for the most active reverse fault-and-fold in the Eastern Chinese Tian Shan. We quantified the kinematics and late Quaternary shortening rate of the Huoyanshan structure based on detailed high-resolution remote sensing image interpretations, field investigations and geological mapping. Six generations of folded terraces along the Tuyugou valley that showed the progressive folding process by the Huoyanshan structure were identified. A kinematic model of curved thrust fault propagation and folding allowed us to describe the terrace deformation pattern and subsurface fault geometry and calculate shortening across this structure. Combined with a regional age control of terrace T4 in the Tuyugou valley, a late Quaternary shortening rate of 2.0–3.2 mm/yr of the Huoyanshan structure was obtained. This is a relatively high shortening rate in the whole Eastern Chinese Tian Shan (roughly east of 88 E). This shortening rate of the Huoyanshan structure highlights that the ongoing India and Eurasia collision has affected the entire Tian Shan but shows two strain partitions: the main strain-absorption belt is located within the Eastern Chinese Tian Shan interior, but strain also occurs at the range-front foreland in the Western Tian Shan.

The Qilian Shan, located in the northeastern Tibet, is under strong tectonic activity and earthquake motion due to the propagation of the plateau. At the mountain front of the eastern Qilian Shan, the Tongziba River, in the southern Zhangye Basin, flows northward and successively cuts the Minle-Damaying Fault and the Yonggu Anticline, two parallel structures within the Frontal Thrust system of the Qilian Shan. Here we present a detailed record of seven strath terraces of this river that documents the history of active deformation of the two structures. Based on the estimated crustal shortening distance from the deformed terraces and the terrace formation age constrained by AMS C-14 and optically stimulated luminescence (OSL) dating, a horizontal slip rate of 1.4 +/- 0.5 mm/year of the Minle-Damaying Fault is constrained since 16.7 +/- 1.8 kyr, and a shortening rate of 1.3 +/- 0.4 mm/year across the Yonggu Anticline has been estimated in a similar time frame, respectively. In total, the shortening rate across the mountain front is estimated to be 2.7 +/- 0.6 mm/year. GPS data show a similar modern shortening rate in this area, which indicates the rate of crustal shortening may be comparable in the modern and 10(4)-year scales. Our study supports a higher crustal shortening rate along the mountain front of the eastern Qilian Shan than that of the western Qilian Shan since the Late Quaternary.

High‐resolution topographic data sets have now become increasingly available, which allows for remotely measuring and analyzing offset features and their associated slip distributions at a very high resolution along a fault, hence providing important insights into the fault behavior. The West Helanshan Fault is a Holocene active right‐lateral strike‐slip fault located at the junction of the Tibetan Plateau, Alashan, and Ordos blocks. In this study, a 2‐m‐resolution DEM of the West Helanshan Fault was built from the WorldView‐3 stereo satellite images (0.5 m). Combined with the high‐resolution topography acquired from the Unmanned Aerial Vehicle (UAV) images based on the Structure from Motion (SfM) method, a total of 180 lateral offsets and 201 vertical displacements were acquired along ~50 km of the fault. By statistical analysis of the offset observations and constructing the cumulative slip profiles, we conclude that large paleoearthquakes have produced characteristic slip accumulation along the fault with a right‐lateral slip of ~3 m and a vertical slip of ~1 m, rupturing at least two segments of the fault simultaneously, which corresponds to a moment magnitude of Mw 7.1 ~ 7.5. The cumulative slip profiles suggest that the fault has likely propagated northward over its lifetime, and the south segment may be the most mature section of the fault where larger coseismic slip of earthquake ruptures may occur. The ratio of lateral to vertical displacement has remained constant (~3:1) through multiple successive events, indicating that the fault has maintained the same kinematic style over the last few thousands of years.

The Hexi Corridor lies along the northeastern margin of the Tibetan Plateau forming its northern boundary. The late Cenozoic tectonic and landscape evolution of this area are key to understanding the growth of the Tibetan Plateau. We investigate the river profile morphology of 36 drainage areas located on the southern flanks of the Heli Shan, which is the outermost range of the Hexi Corridor. Here, bedrock channels are segmented by steep downstream channels and upper segments with lower gradients. A synthesis of tectonics, climate, lithology, and river reorganization indicates that this area has experienced accelerated tectonic uplift. We constrain the response times for knickpoint evolution based on a knickpoint celerity model and reconstruct paleo-channel profiles. Combined with onset ages for the growth of the Qilian Shan (10 Ma) and Yumu Shan (4 Ma), we propose that the Hexi Corridor and Heli Shan were affected by the outward growth of the Tibetan Plateau at 0.6-2.1 Ma ago. (C) 2020 Elsevier B.V. All rights reserved.

The Yulin River in the northern Tibetan Plateau, consists of multiple geomorphological features, including alluvial fans, fluvial terraces, and river profile knickpoints. Collectively, these provide a natural laboratory for exploring the late Quaternary fluvial landform evolution in response to both climatic change and tectonic activities in the region of the Altyn Tagh Fault. In this study, we investigated the distribution, sequences and sediment characteristics of the fluvial landforms along the Yulin River based on high-precision (0.5 m-resolution) Worldview satellite images and field observations. Mid-Pleistocene alluvial fans formed the highest fluvial landform surface into which ten major inset fluvial terraces were developed, distributed along three stream segments. Real-time kinematic global positioning system (RTK-GPS) measurement of terrace surfaces and the modern river longitudinal profiles was conducted across the Dongbatu Shan to show fluvial landform geometry and tectonic deformation. Fluvial terrace surfaces were deformed due to fault uplift as illustrated by spatially variable surface geometries. The chronological sequences of terraces along the Yulin River since 160 ka were reconstructed based on Be-10 terrestrial cosmogenic nuclides (TCNs) dating. Results indicated that river incision occurred mainly during periods of climate transition, suggesting that terrace evolution was partly controlled by climate changes. Moreover, terrace exposure ages showed an upstream younging trend along the river, demonstrating a probable response to knickpoint retreat. Combined with terrace deformation and ages, fault uplift rates were constrained, which were lower than the river incision rates during the Late Quaternary, indicating that crustal shortening was mainly absorbed by the growth of the regional anticline. Collectively, our results suggest that the evolution of fluvial landforms along the Yulin River is a function of interplay between regional tectonic activities and climatic changes, which is significant to understand the NW-outward splay of the Altyn Tagh Fault. (C) 2020 Elsevier B.V. All rights reserved.

The left-lateral slip rate of the Tianjingshan fault (TJSF) has been debated for several decades. Here, we measured displacements of geomorphic landforms and dated landform ages at two sites along the TJSF, to determine a late Pleistocene to Holocene slip rate of similar to 1.1 +/- 0.2 mm/yr. We also derived a slip rate of similar to 1.1 +/- 0.5 mm/yr using modem GPS data. Finally, by correlating available offset measurements with trenching-derived paleoseismic data, we obtained an average Holocene slip rate of similar to 1.2 +/- 0.1 mm/yr for the TJSF. These fault slip rates over different time scales are in good agreement and are well constrained to 1.1 +/- 0.2 mm/yr. The kinematics of the TJSF suggest that the TJSF has played an important role in accommodating the tectonic deformation of the northeastern Tibetan Plateau.

近年来,随着摄影测量技术的发展以及无人机技术的普及,利用无人机摄影测量技术快速获取断裂带上高精度和高分辨率的地形地貌数据已成为1种重要的技术手段.文中首先介绍了1种简单高效且成本较低的新型数字摄影测量技术——SfM(Structure from Motion)方法的基本原理与作业流程,并选取青海茶卡盆地北缘断裂上1个典型的断错地貌点进行了无人机航空影像数据的采集和处理,最终生成了空间分辨率为6.1cm的高分辨率数字高程模型(DEM),点云密度高达273点/m2,覆盖面积达0.463km2.其次,利用地形剖面分析方法提取了平行于断层方向的地形剖面和坡度剖面等数据,结合基于DEM生成的等高线图和坡度图,对复杂的多级地貌面进行了精细的解译和定量研究.最后,基于地貌精细解译的结果,通过DEM提取的地形剖面数据确定了T1-T3阶地的垂直位移分别为(1.01±0.06)m、(1.37±0.13)m和(3.10±0.11)m,T4和T5阶地垂直位移的下限分别为(3.77±0.14)m和(5.46±0.26)m,获取了通过传统遥感影像难以直接获得的垂直位移信息,展示了无人机摄影测量技术在活动构造定量研究中广阔的应用前景.