Based on ambient noise records from two short-period dense seismic arrays deployed in the Sanshui Basin, South China, we obtained the high-resolution S-wave velocity images with lateral resolution of 0.04 degrees & times; 0.04 degrees within a 5.5 km depth range of the Sanshui Basin. Combined with spatial distributions of the Gekeng salt mine and mantle-derived hydrogen H2, the deep structure control mechanism and fundamental controls on subsurface resource formation are discussed. Our results show that the Gekeng salt mine buried at a depth of 1.2-1.5 km corresponds to a distinct low-velocity anomaly in the shallow layer (0.5-2.5 km), and that its low-density and high-porosity characteristics are consistent with the loose water-bearing property of the salt rock reservoir. Shallow earthquakes of ML4.4 and Ms3.4 that occurred in the salt mining area in 1997 and 2023, respectively, have sources located near the transition zone of high-low velocity anomalies. Based on these results, it is speculated that salt mining activities such as high-pressure water injection and mined-out area collapses may lead to the stress imbalance of secondary faults in the mining area, superimposing the main tectonic stress direction in the area, and potentially inducing medium to small magnitude earthquakes. By comparing our work with previous results about the transmission channel of the natural hydrogen H2, it is inferred that geothermal activity promotes hydrothermal fluid to rise along the fault, causing recrystallization of surrounding rock and hydrothermal diagenesis, and resulting in high-velocity anomalies of shear wave velocity in geothermal fields. This study reveals the accumulation mechanism of salt mine and natural hydrogen: salt mines are controlled by sedimentary environment and tectonic activities of fault-depression basins, while hydrogen enrichment depends on the rift-fault-hydrothermal coupling system, which provides helpful information for safe development of salt mines and carbon-free energy exploration.

The different segments of thrust faults are typically connected by linking faults (e.g., lateral ramps, tear faults, or oblique ramps) that accommodate the differential movement and transfer stress in step-over zones. However, the activities and deep structures of linking faults on the Tibetan Plateau have received limited attention in previous studies. The Minle Fault, a strike-varying oblique ramp on the northeastern margin of the Tibetan Plateau, offsets multiple terraces of the Yudai and Hongshui Rivers and accommodates the deformation in the step-over zone between two thrust faults. In this study, 132 vertical offsets and partial strike-slip offsets along the Minle Fault were measured based on high-precision DEM, a terrace chronology framework was established using AMS C-14 dating, and a 2D kinematic model was constructed based on the surface fault offsets. The results indicate linear increasing vertical offsets along strike on each terrace, a listric deep structure with a flat detachment depth of similar to 2.5 km, and a late Quaternary dip-slip rate of similar to 1.1 mm/a for the Minle Fault. The Minle Fault, a thin-skinned oblique ramp formed during the Quaternary following the protrusion of the Yumu Shan, poses a potential earthquake hazard. On the actively growing Tibetan Plateau dominated by large strike-slip and thrust faults, the linking faults between them serve as critical adjusted structures, constituting an essential component in the evolution of the orogenic belt.

Establishing fault slip rates can help resolve the long‐standing question of whether continental deformation focuses along major block boundaries or is distributed more evenly across diffuse fault networks. In the northeastern Tibet Plateau, the ESE‐trending Haiyuan and Kunlun sinistral strike‐slip faults have well‐established slip rates of ∼4–8 mm/yr and ∼10–12 mm/yr, respectively, but the relative importance of intervening NNW‐trending dextral strike‐slip and E–W thrust faults is still controversial. We investigate late Quaternary activity along one of the most prominent of these faults, the NNW‐trending, multi‐segmented South Riyueshan fault (SRYSF). By quantifying geomorphic offsets using remotely sensed digital topography and dating them with Optically Stimulated Luminescence and Radiocarbon, we establish minimum slip rates of ∼3.6 mm/yr for the northern Guide segment and ∼1.7 mm/yr for the southern Duohemao segment. North of 35ºN, magnetotelluric data show the Guide segment and western Waligong segment terminating northwards into the Qinghai Nanshan and West Qinling thrusts, implying a lack of connectivity with the North Riyueshan fault (NRYSF). These multi mm/yr slip rates suggest an important role for NNW‐trending dextral strike‐slip faults in NE Tibet, accommodating shear between the Kunlun and Haiyuan faults by rotating counterclockwise about vertical axes. However, slip rate variations along the SRYSF (∼1.7–3.6 mm/yr) and NRYSF (∼1.1–2.4 mm/yr) caution that regions between these NNW‐trending faults are internally deforming. As well as highlighting limitations to block‐like deformation of NE Tibet, our work emphasizes the importance of measuring fault slip rates at multiple locations to account for variations both along strike and between parallel strands.

High-resolution three-dimensional (3D) data is pivotal for capturing the intricacies of fault geometry and the subtleties of offset geomorphic markers, providing essential constraints for delineating the spatial characteristics of active faults. By integrating various techniques, we can harness the full spectrum of advantages they offer in acquiring high-resolution topographic information, thereby enhancing our ability to discern and interpret the complex architecture of fault systems. The geometric structure, and segmentation characteristics of the Elashan fault, located between the Haiyuan and Eastern Kunlun faults, are not yet fully understood, which impeded our comprehensive understanding of the plateau's expansion and deformation process. We use high-resolution, multi-scale topographic data to decipher the geometric kinematics of the Elashan fault. We conclude that diverse contractional structures, such as leading and trailing contractional imbricate fans, a contractional duplex, and a dextral left-stepping restraining bend develop along different segments of the Elashan fault. The geometric and kinematic model of the Elashan fault aligns with that of a typical strike-slip contractional duplex, accommodating the differences in north-south crustal shortening on the northeastern margin of the Tibetan Plateau, thus forming a diverse array of strike-slip compressional tectonic deformation features. We also re-estimated the slip rate of the Elashan fault in the Xianquan segment to be 2.3-2.9 mm/yr, higher than the result of 1.1 +/- 0.3 mm/yr by Yuan et al. (2011), (). The significant slip rate on the dextral strike-slip fault, coupled with the nearly EW-trending thrust faults, implies substantial interaction within the Haiyuan-Kunlun "block."

The spatial variation in slip rates of large-scale strike-slip faults provides crucial support for the conceptual models of continental collision. However, the reasons for the decrease in slip rate of the East Kunlun Fault at the eastern margin of the Qaidam Basin on the Tibetan Plateau are still unclear. At the eastern margin of the Qaidam Basin, we identified four active strike-slip faults-two NW-SE-orientated dextral (the Xiariha Fault and Yingdeerkang Fault) and two E-W-orientated sinistral (the Reshui-Taosituohe Fault and Taosituohenan Fault)-and determined their slip rates using uncrewed aerial vehicle-based topography and optically stimulated luminescence dating. For the Xiariha Fault, from north to south slip rates are 1.39 +0.51/-0.34 mm/ yr, 1.19 +0.15/-0.14 mm/yr, and 0.9 +0.19/-0.16 mm/yr. The Yingdeerkang Fault slips at 0.66 +0.08/-0.07 mm/yr. The Reshui-Taosituohe Fault, from west to east, slips at 0.95 +0.22/-0.19 mm/yr and 1.20 +0.11/ -0.09 mm/yr. The Taosituohenan Fault, west to east, slips at 0.62 +0.12/-0.12 mm/yr to 1.01 +0.21/-0.19 mm/yr and 1.21 +0.43/ -0.25 mm/yr. We believe that the gradual decrease in slip rate of the East Kunlun Fault at the Tuosuo Lake segment toward the east is influenced by the activity of the four active strike-slip faults with a slip rate of similar to 1 mm/ yr along the eastern margin of the Qaidam Basin and the Elashan Fault. The decrease in fault slip rate is not solely attributed to the diverse structural styles of the fault itself but also to the strain absorption by the development of differently oriented faults around its periphery.

The Nalun-Nalati-Hongliuhe suture zone, which constitutes the central axis of the Tianshan Orogenic Belt (TSOB), has been reactivated during the late Cenozoic. The Nalati fault, located within the suture zone, facilitates the investigation of the internal structural deformation of the TSOB. However, existing studies focus on the eastern segment of the Nalati fault, its western segment, located in the interior of the Tianshan Orogenic Belt, has received scant attention. Consequently, there remains a substantial gap in understanding the distribution, activity, and paleoseismic events associated with the Nalati fault. This study concentrates on the Tekes segment within the Ili Prefecture, utilizing remote sensing and comprehensive field surveys to delineate its geometric distribution and left-lateral strike-slip characteristics. Moreover, Through trench analysis and radiocarbon dating, we have identified four significant paleoseismic events. Utilizing the unmanned aerial vehicle mapping and the LaDiCaoz_v2.1 code, we measured approximately 3.0 m of horizontal displacement from a single seismic event. The application of OxCal age correction has enabled precise dating of these events with 95.4% confidence: Event 1 (1668-2040 years BP), Event 2 (5386-5911 years BP), Event 3 (5897-6651 years BP), and Event 4 (6740-7321 years BP). Our findings imply that the Tekes segment of the Nalati fault remains active during the Holocene, indicating the high seismic hazard of the region. The average left-lateral slip rate along the Tekes segment is over 1.5 mm/yr during the Holocene. The Nalati fault accommodates approximately 1/3 of the total left-lateral shear strain within the TSOB.

Quantitatively characterizing the geometry, kinematics, and deformation rate of fold-thrust belts in intermontane basins is the key to understanding strain partitioning within the Tian Shan range. This work focuses on the Bayin anticline in the Youludusi Basin, a typical intermontane basin located within the eastern Tian Shan. The Kaidu River cuts through the Bayin anticline and has developed three levels of terraces (T-1-T-3) across the structure. By using cosmogenic nuclide and optically stimulated luminescence dating methods, the formation ages of terraces T-1 and T-3 are constrained to 11.54 +/- 0.55 ka and 42 + 7.0/-7.1 ka, respectively. When applying a listric thrust fault model to the Bayin anticline and using terraces as references, the vertical displacements are estimated to be 16.45 + 6.46/-3.19 m (T-1), 32.08 + 12.85/-6.19 m (T-2), and 95.93 + 38.94/-18.6 m (T-3), and the shortening amounts are 10.56 + 8.33/-5.04 m (T-1), 20.46 + 16.68/-9.64 m (T-2), and 61.24 + 50.22/-28.93 m (T-3). Based on this listric thrust fault model and terrace T-1-T-3 ages, the rate of fault slip controlling the growth of the Bayin anticline is determined to be 1.6 +/- 1.0 mm/yr, and the crustal shortening rate of the anticline is 1.0 + 0.7/-0.6 mm/yr. The estimated crustal shortening deformation of the Bayin anticline accounts for similar to 12 % of the total deformation in the Youludusi Basin. In terms of the entire orogenic belt, the crustal shortening absorbed in the southern, central, and northern parts accounts for 24 %-56 %, 46 %-71 %, and 19 %-74 %, respectively, of the total strain across the eastern Tian Shan. Therefore, we believe that the Eastern Tianshan undergoes uniform deformation.

The tectonic deformation of the southeastern margin of the Tibetan Plateau underwent significant changes before and after the Miocene, which led to the change of the deformation characteristics of the Sichuan-Yunnan block, and some local areas in the block also showed structural patterns inconsistent with the macroscopic clockwise rotation deformation. Moreover, the Chenghai fault (CF) in the Sichuan-Yunnan block was the seismogenic fault of the M 73/4 Yongsheng earthquake in 1515. However, the dense vegetation impeded the acquisition of surface deformation characteristics and small-scale horizontal offsets along the fault, resulting in its misty kinematic properties, roughly determined geometric distribution, and the highly controversial rupture parameters of the Yongsheng earthquake. Therefore, we used airborne light detection and ranging, which can penetrate vegetation to obtain high-resolution surface topography, to map the CF within 120 km. Combined with satellite images and field investigations, we determined that the CF consists of a series of secondary faults with simple geometric structures. Continuous offset linear landforms were preserved along the fault. 102 offsets below 30 m were statistically analyzed and the result revealed that the CF has a characteristic displacement of similar to 6 m and it may rupture as a united rupture segment in each large earthquake or its two rupture segments cascade rupture to generate large earthquakes. The magnitude of the Yongsheng earthquake in 1515 was estimated at 7.7. Finally, based on this study, the kinematic characteristics of the Dali terrane and Sichuan-Yunnan block, where the CF is located are discussed. We obtained the fine geometry of the Chenghai fault (CF) and determined its kinematic property We reestimated the magnitude of the Yongsheng earthquake in 1515 We discussed the seismogenic pattern of the CF and kinematic characteristics of the Dali terrane and Sichuan-Yunnan block

The tectonic deformation on the eastern margin of the Qaidam Basin, which has preserved complete sedimentary records, significantly influences the evolutionary model of the northeastern margin of the Tibetan Plateau. However, the deformation history in this area during the Holocene remains unclear. This study is based on the high-precision digital elevation model obtained through drone mapping technology, which identifies three active faults on the eastern margin of the Qaidam Basin: the Xiariha Fault (XRHF) and Yingdeerkang Fault Yingdeerkang Fault (YKF) are NW-SE-orientated dextral faults, whereas the Reshui-Taosituohe Fault (RTF) is a nearly east-west-orientated sinistral fault. Based on the optically stimulated luminescence dating of the landform surfaces, the rates of strike-slip offset are as follows: those of the XRHF range from 1.12 +/- 0.07 to 1.68 +/- 0.12 mm/yr and those of the YKF are from 0.99 +/- 0.06 to 2.29 +/- 0.13 mm/yr. Recent paleoseismic events occurred along the RTF at approximately 714-1,792 years BP and at 700 +/- 18 years BP, implying a recurring millennial pattern. Together, these faults possibly form a complex cross-fault system along the southeastern edge of the basin, heightening seismic risk. Deformation in the western part of the northeastern Tibetan Plateau is driven by slip on the Altyn Tagh Fault and compression in the Qaidam Basin. The central part experiences slip on the East Kunlun Fault, along with secondary faults, shortening, and block rotation. The eastern part primarily experiences slip along the Haiyuan Fault. The Xiariha, Yingdeerkang, and Reshui-Taosituohe faults (RTF) on the eastern margin of the Qaidam Basin have been active during the HoloceneThe paleoseismic recurrence interval of the RTF is estimated to be approximately 1,000 yearsThe eastern margin of the Qaidam Basin is expected to include a complex system of cross-faults, increasing the seismic hazard

青藏高原东南缘是检验青藏高原演化模型的理想实验场，也是全球地震活动最为频繁的地区之一.综述了青藏高原东南缘主要活动断裂十年和万年尺度的滑动习性研究和百年时间尺度区域地震活动分布，结合前人总结的百万年时间尺度的年代学研究，认为自中新世中晚期以来，青藏高原内部物质逐渐向东流出，受四川盆地阻挡，转而向东南缘地区作顺时针旋转运动，至晚第四纪时期，东南缘地区上地壳变形已由原本集中分布在大型走滑边界断裂和逆冲褶皱带转变为弥散式分布至区内次级断裂，形成了以鲜水河-小江断裂带和实皆断裂带为边界，围绕喜马拉雅东构造结作顺时针旋转的运动学特征.据此青藏高原东南缘变形可划分为两阶段，中新世早期及以前变形集中在大型边界断裂，符合刚性块体变形，至晚第四纪时期转为弥散式连续变形.基于水平滑动速率和地震活动性对比，青藏高原东南缘活动断裂可大致分为三级.一级断裂为边界断裂鲜水河-小江断裂带和实皆断裂带，水平滑动速率均≥10 mm/a，曾发生8级及以上地震和连续的7～7.9级强震，是东南缘地区晚第四纪以来一级构造格架；二级断裂往往控制东南缘地区强活动构造单元，水平滑动速率为～3～6 mm/a，通常发生过7～7.9级地震；三级断裂水平滑动速率一般≤2 mm/a，通常发生过7级以下地震，一般规模较小，但数量较多.此外，川滇地块晚第四纪变形特征发生转变，构造运动由原本的沿大型边界走滑断裂运动转变为鲜水河-小江断裂带周缘次级活动地块的旋转、平移和差异隆升.

Subsurface fault geometry and deformation rates can be estimated by combining the pattern of terrace deformation with kinematic model and geomorphic age. Quantifying the geometry, kinematics and deformation rate of the thrust-and-fold belt is the key to exploring tectonic deformation and strain distribution of the Tianshan intermontane basin. This is demonstrated by the Bayan anticline in Youlududsi basin in the eastern Chinese Tianshan. The Kaidu River, flowing through the central part of the Bayan anticline, has formed three terrace levels at tilted fold backlimbs. Based on the field geological investigation, warped and tilted terraces in the Bayan anticline are characterized by broad, continuous backlimbs and abrupt forelimbs and suggest folding through progressive limb rotation of listric thrust model. Combining with the kinematic model and geomorphic age, the slip rate and crustal shortening rate of the underlying fault in Bayan anticline is （0.35-0.06）-（0.35+0.16） mm/a and （0.23-0.04）-（0.23+0.10） mm/a, respectively. This shortening represents over 15%-20% of the total deformation in Youludusi basin and ～2% of the 8.5±0.5 mm/a total shortening rate measured from GPS velocity across the entire range in East Tianshan.Therefore,a significant fraction of the total Quaternary deformation is accommodated within the central part of the East Tianshan.

It has been accepted that a littoral fault zone (LFZ) exists at the Northern Jiangsu Province, but its geometric distribution and the late Quaternary activity are still controversial. In this study, to constrain its late Quaternary activity, we collected two high-resolution shallow-reflection seismic profiles crossing the northern segment of the littoral fault zone (NLFZ) in the Yellow Sea, using mini-multichannel seismograph. Four reflection interfaces were identified clearly in the reflection profiles, dividing Quaternary strata in the study area into four seismic units. Combined with the existing regional borehole data, it is inferred that these units correspond to strata in the Holocene, the Late Pleistocene, the Middle Pleistocene, and the Early Pleistocene. The breakpoints F1, F2, F3, F4, F5, and F6 correspond to the NLFZ, and the uppermost offset marker is the Late Pleistocene–Holocene interface. Therefore, the NLFZ is tentatively identified as a Late Pleistocene–Holocene active fault. Our method utilized to obtain high-resolution profiles also provides a good example for research studies at similar sites. Moreover, considering the regional tectonic background, its fault length, and long aseismic period, the NLFZ is capable of generating strong earthquakes of Mw 6.5 or above in the future, which needs further investigation. Finally, based on our profiles and previous studies, it is inferred that the kinematic properties of the LFZ transformed at the Middle Pleistocene, at least.

Abstract Strike-slip earthquakes near major subduction zones have received less attention than thrust or reverse earthquakes in subduction zone areas. The occurrence of the 2018 Palu Mw 7.5 earthquake in eastern Indonesia provides an unprecedented opportunity to investigate the characteristics of one of these events. The Palu earthquake occurred on the left-lateral, north–south-striking Palu–Koro fault, which is the main plate boundary structure accommodating the convergence between blocks in a triple junction area. It excited a significant tsunami, which unusually is associated with strike-slip earthquakes, and also ruptured at a supershear speed, which is mostly observed on strike-slip faults in continents. Based on our fieldwork, we speculate that the normal slip component of the offshore rupture section in Palu bay on the middle segment probably favours tsunami genesis. Our field investigation has revealed evidence of a simple geometry as well as slip partitioning of dip-slip and strike-slip motion on two subparallel strands on the main segment, both of which may have contributed to the supershear of the rupture propagation. Instead of only a transtensive behaviour of the middle segment, our results also illustrate the transpressional property of the northern and southern rupture segments, which shows more complex behaviour than that of a common continental strike-slip fault.

On May 22, 2021, a Mw 7.3 earthquake occurred in Maduo County, Qinghai Province with the epicenter of 34.59°N, 98.34°E. The distribution of aftershocks and surface ruptures suggested that the seismogenic structure might be the Jiangcuo fault (JF), <70 km south of East Kunlun fault (EKLF). Due to the high altitude and sparse human habitats, there are very few researches on the Jiangcuo fault, which makes us know little about the deformation features and even the geometry of Jiangcuo fault. In this study, we used the high-resolution pre-earthquake satellite images to interpret the spatial distribution and geometry of the Jiangcuo fault. Our results show that the Jiangcuo fault strikes nearly east, extending 180-km-long from Eling Lake to east of Changmahe Town. Based on the geometric features, the Jiangcuo fault could be divided into three segments characterized as the linear structures, fault valleys, scarps and systematic offset of channels. The boundary between Bayan Har Block and Qaidam Block is presented as a wide deformation zone named of Kunlun belt that is composed of East Kunlun fault and several branch faults around Anemaqen Mountain. Geometric analysis and deep lithosphere structure around Maduo County suggest that the Jiangcuo fault should be one of branch of East Kunlun fault at south, where the Kunlun fault developed as a giant flower structure. In addition, the seismic hazards potential of Jiangcuo fault should be given enough attention in the future, because west of the Jiangcuo fault, there is a rupture gap between the co-seismic surface ruptures of the 2001 Kunlun, 2021 Maduo and 1937 Huashixia Earthquakes.

The spatial pattern of slip rates along the Haiyuan fault zone may reveal deformation process along the northeastern margin of the Tibetan Plateau. By applying the 3D_Fault_Offsets code, we reevaluated the displacements of offset markers displaced by the Laohushan fault, the central segment of the Haiyuan fault zone. We introduced the Bayesian Age Model approach to provide optimum age control for the preserved offset markers. Multiple offsets and ages constrain the late Pleistocene slip rate to 4.4–4.8 mm/yr. The spatial pattern of strike‐slip rates of the Haiyuan fault zone indicates that the Madongshan and Liupanshan could be the main uplifts that absorbed the left‐lateral motion along the Haiyuan fault zone, due to a restraining bend between the Haiyuan and Qishan‐Mazhao fault zones. Furthermore, uniform slip rates along the main segments and slip rates decreasing toward fault tips are widely observed along some intensively studied strike‐slip faults, such as the Altyn Tagh, Kunlun, Death Valley‐Fish Lake Valley, Denali, San Andreas and Alpine faults. The results suggest that the constancy or similarity of the slip rates along the strike is closely related to block rotation and internal deformation, and the slip rates of strike‐slip faults usually change at the fault tip area converting from horizontal to vertical motion. In addition, strike‐slip fault can also take slip off of the main fault and distribute it between multiple active parallel strands.

青藏高原东北缘是青藏高原向NE扩展的最前缘,是理解高原扩张的最佳场所.日月山断裂是青藏高原东北缘一条NNW走向的右旋走滑断裂,对其开展活动性研究对于理解高原扩张有重要意义.目前对该断裂南段的晚第四纪活动性质研究较少,对其晚第四纪的活动特征认识尚且不足.文中基于日月山断裂南段的野外考察资料,通过高精度遥感影像解译并结合典型位错点无人机摄影测量等方法获得其精细的几何展布,根据断裂的展布特征自北向南将日月山断裂南段分为贵德和多禾茂2段.结合年代学研究,初步确定日月山断裂南段存在全新世活动,结合典型位错点多级地貌面定年与蒙特卡洛方法,厘定了贵德段和多禾茂段全新世以来的水平滑动速率分别为(3.37+0.55/-0.68)mm/a和(2.69+0.41/-0.38)mm/a.结合前人的研究资料分析认为,在NE向主应力下,鄂拉山和日月山等断裂发生右旋走滑和NE向压扁,共同吸收青藏高原东北缘块体NE向的地壳缩短.

Interpretation of fault slip‐rates inferred from tectonically offset fluvial landforms is often limited by uncertainties associated with difficulties to explicitly date fluvial incision across the fault. Here, we employed morphology‐based modeling to ameliorate this universal dating limitation for gullies that were differentially offset in a sinistral sense across the Altyn Tagh Fault near its eastern termination at ∼97°E. Using a stream‐power erosion model with locally calibrated coefficients we calculated across‐fault gully incision ages that decrease with offset magnitude, are up to threefold younger than the age of the terrace they incised and all‐together point toward time‐invariant slip. Luminescence dating of offset alluvial terraces at the same site suggests constant sinistral slip at 0.5 ± 0.1 mm/yr since 52 ± 4 ka. Our results suggest that the most juvenile phase of northeastward Pleistocene expansion of the Tibetan Plateau into previously stable parts of central Asia is marked by constant late Quaternary deformation rates.

AbstractThe Zheduotang fault (ZDTF) is located in the Kangding section of the Xianshuihe fault zone (XSHF). While the ZDTF plays an essential role in understanding the structural deformation pattern of the Kangding section. Little information is known about the paleoearthquake offsets and slip behavior of the ZDTF. It is therefore essential to analyze the seismic hazards in this area. Using UAV-based photogrammetry, high-resolution satellite images, and field observations, we mapped the surface trace of the fault in detail and measured the horizontal and vertical offsets geomorphological landforms along the fault. The binned cumulative offset probability density (COPD) distribution was calculated to analyze single-event and multievent cumulative offsets. We found that the ZDTF has scarps along its entire ~46 km length, and the offset distributions of its northwestern (NW) and southeastern (SE) sections feature different characteristics. The SE section follows a uniform slip model based on the relationship between cumulative and coseismic offsets. We estimated the maximum potential earthquake magnitudes of the NW section and SE section to be M6.6 and M7.0, respectively, from the measured offsets and empirical formulas. Finally, we discussed the seismic hazard of the ZDTF based on our findings and paleoearthquake data. The NW section is at risk of large earthquakes recurring in the future, whereas the SE section has a low risk of a >M7.0 earthquake recurring in the next 100 years. If these two sections rupture at the same event in the future, the maximum potential magnitude of the ZDTF is M7.2.

大陆架作为海陆相互作用的关键地区,对于研究大陆的构造演化、海陆变迁、海平面升降以及气候变化具有重要意义.然而由于不同研究方法的局限性,目前对大陆架沉积物年代学及其蕴含地质信息的认识仍然不足.南海是西太平洋最大的边缘海,是全球海洋沉积作用最为活跃的地区之一,也是海陆相互作用最为典型的区域.作为东亚大陆物质的主要沉积区,南海已经受到了学术界越来越多的关注.然而,目前的研究工作主要集中于沉积连续、信号记录稳定但沉积速率较慢、总体分辨率较低的深海区沉积物.相对而言,沉积速率较快、分辨率较高的浅海大陆架沉积为高分辨率年代学和古环境的研究提供了重要的地质材料,但由于大陆架沉积环境动荡导致沉积信号记录不稳定甚至缺失.针对南海大陆架沉积,尤其是对钻孔沉积物高分辨率年代学研究仍相对较少,限制了对南海构造与气候演化过程的认识.为了更好地限定南海北部陆架区更新世晚期沉积物的年代,研究其中蕴含的古环境信息,探讨东亚地区气候变化的驱动机制问题,同时为南海海域活动构造研究提供年代学框架,文中以南海北部DG钻孔为研究对象,在微体古生物化石和碳同位素年龄(14C)数据的基础上,利用大陆架沉积物磁化率与深海氧同位素的对比对其沉积物年代学进行了系统研究.基于此,结合色度和孢粉结果,对其古气候意义进行了初步探讨.结果表明,该钻孔沉积物的磁化率可对应于深海氧同位素的阶段1—阶段9(MIS 1—MIS 9),底部年龄约为300ka,磁化率低值区间对应于冰期,高值区间对应于间冰期.这与该钻孔沉积物中的孢粉和色度所记录的古环境信息相吻合.冰期时气候较为寒冷,水体变浅,沉积物搬运距离相对增大,矿物以氧化作用为主,主要形成弱磁性的磁性矿物(如赤铁矿),导致磁化率较低;间冰期时,气候相对暖湿,水体变深,沉积物搬运距离相对缩短,矿物以还原作用为主,主要形成强磁性的磁性矿物(如磁铁矿等),导致沉积物的磁化率显著增强.因此,南海大陆架北部更新世晚期沉积物的磁化率变化可以反映东亚地区更新世晚期以来冰期—间冰期气候旋回.磁化率与深海氧同位素的对比作为一种晚第四纪松散沉积物的相对定年方法,在南海北部陆架区更新世晚期沉积物定年方面是适用且可靠的,可为海洋大陆架沉积物定年和对比研究提供新的参考.

It is commonly assumed a thrust has a constant slip and uplifting rate along strike, however, this simplified model cannot always be consistent with field observations. The along strike slip patterns with variable offsets and rates contain plenty of information about the characteristics of the faulting behavior and its relationship with adjacent faults. The east Qilian Shan, located at the northeastern margin of the Tibetan Plateau, provides us an excellent opportunity to study the faulting behavior in a thrust-bounded range area. Besides the previously reported slip rates of the N-W trending tectonics across the region, we augmented the data by surveying the Fengle fault (FF), one of the north bounding thrusts of the Yongchangnan Shan. Another north bounding fault is the Kangningqiao Fault (KNF), east of the FF. Based on the vertical offsets and rates along the fault, we constructed the slip pattern along strike. The results show the vertical slip rate of the FF ranges from 0.7 ± 0.1 mm/a to 2.8 ± 1.3 mm/a across three surveyed sites. The slip rate decreases from the east to the west. The FF and KNF might be inferred as two segments of a single segmented thrust controlling the uplift of the Yongchangnan Shan. By comparing the uplift onsets in the study region, we discuss the northeastward propagated deformation along the northeastern margin of the Tibet plateau.