Search

The Yellow River Basin (YRB) is characterized by active geological and tectonic processes, rapid geomorphological evolution, and distinct climatic diversity. Correspondingly, major disasters in the YRB are characterized by varied types, extensive distributions, and sudden occurrences. In addition, major disasters in the YRB usually evolve into disaster chains that cause severe consequences. Therefore, major disasters in the YRB destroy ecologies and environments and influence geological and ecological safety in the basin. This paper systematically reviews research on geological and surface processes, major disaster effects, and risk mitigation in the YRB, discusses the trends and challenges of relevant research, analyzes the key scientific problems that need to be solved, and suggests prospects for future research based on the earth system science concept. Themes of research that should be focused on include geological, surface and climatic processes in the YRB and their interlinking disaster gestation mechanisms; formation mechanisms and disaster chain evolutions of giant landslides in the upper reach of the YRB; mechanisms and disaster chain effects of loess water-soil disasters in the middle reach of the YRB; occurrence patterns and amplifying effects of giant flood chains in the lower reach of the YRB; and risk mitigations of major disasters in the YRB. Key scientific problems that need to be solved are as follows: how to reveal the geological, surface and climatic processes that are coupled and interlinked with gestation mechanisms of major disasters; how to clarify the mutual feedback effects between major disasters and ecology; and how to develop a human-environmental harmony-based integrated risk mitigation system for major disasters. Prospects for future studies that follow the earth system science concept include the following: highlighting interdisciplinary research to reveal the interlinked disaster gestation mechanisms of the geology, surface and climate in the YRB in the past, present, and future; forming theories to clarify the regional patterns, dynamic mechanisms, and mutual-feedback effects between disaster chains and ecology in the YRB on land and in rivers in the region; solving technological bottlenecks to develop assessment models and mitigation theories for integrated risks in the YRB by following the human-environment harmony concept; and finally, establishing a demonstratable application pattern characterized by "whole-basin coverage" and "zonal controls", thereby guaranteeing ecological and geological safety in the basin and providing scientific support for ecological conservation and high-quality development of the YRB. [ABSTRACT FROM AUTHOR]

Knowledge of the kinematics of thrusts is the key to understanding mountain building processes in compressive ranges; however, relatively little attention has been paid to distributed deformation (on-fault and off-fault such as rotation and warping) across a thrust fault. Distributed deformation is widespread along the northern front of the Qilian Shan, in the NE Tibetan Plateau. In the Daciyao River, of the central North Qilian Shan, the East Yumu Shan Fault (EYF) splays into four parallel faults at the piedmont. The Daciyao River flows across the deformation zone and its terrace landform record provides a valuable geomorphic marker for reconstructing the cumulative deformation. Terrace deformation across the fault splays was estimated with measured longitudinal profiles using differential GPS, and the fault slip was reconstructed by applying the trishear model, a widely applied model used to explain the geometry of basement-related structures. At least 10 strath terraces are formed with bedrock bases developed into Neogene red beds along the mountain front. The age of one of the terraces (T8) was constrained by Optically Stimulated Luminescence (OSL) dating of the overlying aeolian loess, which provide a minimum age (68 ka) for the age of terrace abandonment. The survey data and trishear model results suggest that the fault splays are bending-moment faults (BMF), originating from a fault propagation fold. Based on the fault and fold geometry across the EYF, the total vertical slip rate is estimated as 0.9–1.2 mm/yr. Slip rates on the EYF are consistent along-strike during the Late Pleistocene but they are twice as high during the Holocene, indicating a high potential for large earthquakes along this fault. This work also indicates that to calculate accurate total slip rate, terrace heights must be measured outside of the distributed broad zone. • Distributed deformation study across the North Qilian Shan Fault • Dated strath river terraces used as markers to assess cumulative deformation patterns • Trishear model used to explain fault geometries • Fault splays are bending-moment faults linked to fault propagation folding. • Vertical slip rates increase into the Holocene, suggesting large earthquake potential. [ABSTRACT FROM AUTHOR]

In the piedmont of uplifting mountains, alluvial fan rivers undergo significant aggradation-degradation processes, which are usually attributed to climate change. An ongoing debate is whether this process requests the participation of glaciation. To address this debate, we need the knowledge of the quantitative relationship between the ratio of water to sediment flux (q w / q s) with the aggradation/degradation process. This study examined the aggradation and degradation processes in three alluvial rivers at the piedmont of the Qilian Shan (Shan referes to Mountain) and simulated the river processes by a one-dimensional numerical model based on the transport-limited principle. Along the studied piedmont rivers, field measurements show a magnitude of 120–200 m degradation and aggradation in the Late Pleistocene. Through simulation analysis, we explored how factors like the ratio of water to sediment flux (q w / q s), channel width, and sediment grain size influence river processes and longitudinal profiles, and found distinct morphologies in different processes, where aggradation is characterized by concave-up profiles, while degradation is characterized by convex-down profiles. Additionally, the water flux is inversely proportional to the time required for the river to reach a new equilibrium profile. The simulated degradation amplitude aligns closely with the measured data in the Qilian Shan, indicating that precipitation during the Last Glacial Maximum in the region amounted to approximately ∼32% of the Holocene precipitation. This supports the notion that changes in water flux or precipitation alone can induce significant piedmont deepening without the necessity of glaciation. • Built a model to quantify the link between water-sediment fluxes and river processes. • Simulated Qilian Shan piedmont river incision: ∼32% LGM precipitation vs. Holocene. • Precipitation alone can create deep canyons without requiring glaciation. [ABSTRACT FROM AUTHOR]

In compressive ranges, the kinematics of thrusts and related folds are the key to understanding mountain building processes; however, relatively little attention has been paid to folding on the hanging-wall of a thrust fault which has broken the surface. On the hanging-wall of the Yumu Shan thrust fault, which lies on the north side of the Yumu Shan at the NE edge of the Tibetan Plateau, we found that significant folding deformation had occurred simultaneously with faulting at the surface. To determine the kinematics of the folding and faulting, we surveyed deformed fluvial terrace surfaces across the fold and fault. The geometry of the surface of terrace T4 of the Liyuan River exhibits a faulting displacement of 55 ± 11 m at the fault trace, while in the hinterland, there is an active anticline with a wave length of ~4000 m. Limb rotation on the forelimb is recorded by the terrace geometry. Based on terrace geometry and the deformation of bedrock strata, we infer the geometry of the fault and fold, and conclude that the forelimb was formed by simple-shear deformation above the fault ramp, and that the backlimb was formed by the down-lowering of the fault dip angle. Using the geometry of the fault and fold and previous age control for the terraces, an average rock uplift of 1.2 ± 0.1 mm/a is estimated across the range, which produces a total fault slip rate of 1.8 ± 0.4 mm/a below the Yumu Shan. This new uplift rate indicates an onset age of 2.5 ± 0.5 Ma for the uplift of the Yumu Shan, suggesting that this is a young mountain range. This result suggests that the outward accretion of the NE Tibetan Plateau occurred at ~3 Ma, and it provides an insight into the kinematics of deformation within relatively recently deforming structures, suggesting that folding is a significant process in accommodating the crustal shortening where the thrusting has broken the surface. • The fault and fold are simultaneously deforming the Yumu Shan. • Terrace geometry indicates shear deformation above the active fault. • Outward accretion of the NE Tibetan Plateau occurred at ~3 Ma. [ABSTRACT FROM AUTHOR]

The eastern Altun Shan is a crucial part of the Altun orogenic belt within the Tibetan Plateau. Study of the uplift rate and the related features in this area provides important clues for understanding the uplift mechanism of the Tibetan Plateau as a whole. As an important geomorphic element in landscape development, the fluvial system can record the relationship between tectonic activity and climatic change. In recent years, studies of the Channel Steepness Index K sn , have been conducted by many researchers, using the geomorphological model of equilibrium channel longitudinal profiles, combining bedrock uplift and river incision and thus making it possible to extract rock uplift history from river profiles. This research show that regional rock uplift rate is a major factor in affecting the K sn index. Regional tectonic activity and intensity, therefore, can be evaluated from variation in the K sn index, which can provide a sensitive measure of uplift rate. In this paper, the Digital Elevation Map 'ASTER GDEM', with a spatial resolution of 30 m, was utilized as basic data, and combined with ArcGIS and MATLAB software to extract the K sn index from the equilibrium channel longitudinal profiles model. Meanwhile, we employed statistical methods to analyze the K sn index. Our results suggest that averaged K sn indices, obtained from the subrange A，B，C，D, and E of the eastern Altun Shan (from west to east), are 70.93, 139.03, 108.85, 134.44 and 165.39, respectively. Further analysis implies that the variation in this index can be correlated with the distribution pattern of uplift rates within different regions. Its value increases gradually from west to east, reflecting regional uplift rate. Along the western section of the eastern Altun Shan, the uplift rate is slower and characterized by strike-slip movements, while its eastern part has uplifted faster and is controlled by thrust fault systems. Moreover, in contrast with the southern Altun Shan, the uplift rate of the northern part is high. These variations in uplift rate seem to be linked with "the imbricated thrusting transformation-limited extrusion model" of the Tibetan Plateau. Our results can be correlated with previous work on the active characteristics along the eastern Altyn Tagh Fault (ATF). • Along the eastern Altun Shan, the obtained index K sn shows a rough tendency of increasing eastward. • The index K sn from the north front of the eastern Altun Shan is higher than that from the south flank. • This distribution pattern of the index K sn is translated into the different uplift along the eastern Altun Shan. • The difference in uplift rate can be evaluated well by the fluvial incision rate obtained by terrace archives. • The analysis of the index Ksn provides an excellent insight into the extrusion model of the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Strategic studies of gravel deposits, in particular using heavy-mineral analyses, have thrown light on the important unresolved question as to the timing of the initiation of the Yellow River drainage through the Sanmen Gorge, which linked the headwaters of that system in the Fenwei Basin and further upstream with the North China Plain and the Pacific Ocean in the east. Survey of the Sanmen Gorge reach revealed previously unrecognized gravel levels: a higher fifth terrace (T5) and a gravel that formed on a high-level planation surface that is preserved on the flanks of the gorge, below the Xiaoshan upland. This high-level gravel differs markedly from the Yellow River terraces, with a lack of material from the upstream catchment, and would appear to represent a small fluvial catchment that developed in the area during the formation of the planation surface, before the Sanmen Gorge was excavated. Comparison was also made with basin-fill gravels from the endorheic fluvio-lacustrine system that existed immediately upstream of the gorge, and was captured by the Yellow River when the latter was cut, and with the modern bedload gravel of the Yellow River in this reach. The former contains significant quantities of unstable hornblende, which implies more local derivation for the endorheic system, whereas the modern bedload resembles the terrace gravels in showing compositional maturity and long-distance transport from upstream within the catchment. The work reinforces a minimum age of 1.2 Ma for the formation of the Sanmen Gorge. • The gravel layer accumulated on the planation surface along the eastern front of the Xiaoshan represents a local river. • The local river sediments are different from the typical Yellow River gravels and the upper Sanmen Formation. • The Sanmen paleolake within the Fenwei basin was finally disrupted by the westward capture of this local river. • The Sanmen Gorge was excavated by the local river through the Xiaoshan separating the Fenwei basin and North China Plain. • The Yellow River integration may be attributed to the remarkable climatic fluctuation starting in the Mid-Pleistocene. [ABSTRACT FROM AUTHOR]

• Aeolian sand deposited in riverbed rather than floodplain sedimentary environment. • Low weathering intensity during the late Holocene between 3.3 and 1.0 ka. • Rapid aeolian sand accumulation after climate-driven hydrological events. Investigating fluvial-aeolian interactions is important for understanding Earth surface processes in arid regions. In this study, we conducted detailed grain size, geochemical, and heavy-mineral analyses of the 21.25-m-long HDZ core to determine the provenance of Holocene aeolian deposits in Inner Mongolia and their relationships with the Yellow River and surrounding desert areas. Significant differences in grain-size parameters and concentration of geochemical elements with stratigraphic depth were highlighted. Compositional data and heavy-mineral assemblages indicate that aeolian sediments blown into the Yellow River channel were largely derived from the Ulan Buh Desert or Kubq Desert and supplied by the Ten Tributaries during the rainy season. Chemical indices depicta particularly low weathering intensity during the late Holocene between 3.3 and 1.0 ka, when the dry-cool climate led to desert expansion in the Inner Mongolia region of the Yellow River. Starting from ∼2000 BP during the Han Dinasty, large-scale immigration, extensive agricultural activities, and intensified animal grazing compromised the stability of surface soil, leading to desertification and enhanced aeolian-sand transport across the Inner Mongolia region. Our research helps understand the extreme sensitivity of vulnerable dry environments to climate change at different time scales and provide a reference for provenance identificationin a region of extensive fluvial-aeolian interactions. [ABSTRACT FROM AUTHOR]

The fluvial archives in the upper-reach Yellow River basins provide important information about drainage history of the northeastern Tibetan Plateau (TP) associated with geomorphologic evolution and climate change. However, the Pliocene fluvial strata within this region have not been studied in detail, hence limiting the understanding of the late Cenozoic development of regional fluvial systems. In this paper, we present the results of a study of the geochronology, sedimentology, and provenance of the fluvial sequence of the Wuquan Formation in the Lanzhou Basin in the northeastern TP. Magnetostratigraphic and cosmogenic nuclide burial ages indicate that the Wuquan Formation was deposited during 3.6–2.2 Ma. Furthermore, sedimentary facies, gravel composition, paleocurrent data, and detrital zircon U Pb age spectra reveal that the fluvial sequence resembles the terraces of the Yellow River in terms of source area, flow direction, and depositional environment. Our results indicate that a paleo-drainage system flowing out of the northeastern TP was established by ca. 3.6 Ma and that the upstream parts of the Yellow River must have developed subsequently from this paleo-drainage system. The late Pliocene drainage system fits well with the dramatic uplift of the northeastern TP, an intensified Asian summer monsoon, and global increase in erosion rates, which may reflect interactions between geomorphic evolution, tectonic deformation, and climate change. [ABSTRACT FROM AUTHOR]

• We report detrital zircon U-Pb geochronology data from the Tengger Desert. • Tengger sediments were sourced from the Qilian Shan, local basements and Gobi Altay sources. • Precipitation is important for middle to late Quaternary desertification in China. Dust plays a critical role in global biogeochemical and carbon cycles. The deserts of northern China have been important East Asian dust sources throughout the Quaternary. The Tengger Desert, one such major arid dust-producing region in northern China, is thought to have started resembling its current form during the middle to late Pleistocene. As such, understanding the nature of the Tengger Desert's formation and the associated import, storage, and export of sediments are consequential for the regional, and potentially global, climate. The U-Pb detrital zircon geochronology data reported here from both present-day and middle to late Pleistocene Tengger Desert sediments support derivation from the Shiyang River system sourced from the Qilian Mountains mixed with sediments eroded from local basement uplifts and Gobi Altay sources. This interpretation is different from the view that sediments of this age were primarily transported to the Tengger Desert from the arid East Asian continental interior upwind. We note that this analysis suggests a common provenance for Quaternary sediments in the Tengger, Badain Jaran, and Mu Us Deserts wherein these deserts received riverine-sourced sediments from the Qilian Mountains and northeastern Tibetan Plateau. This observation highlights the importance of precipitation at elevation along the present-day margin of the East Asian summer monsoon in driving sediment supply during the middle to late Quaternary desertification within the East Asian continental interior. [ABSTRACT FROM AUTHOR]

Airborne dust derived from desertification in northern China can be transported to East Asia and other regions, impairing human health and affecting the global climate. This study of northern China dust provides an understanding of the mechanism of dust generation and transportation. The authors used dust storm and climatological data from 129 sites and normalized difference vegetation index (NDVI) datasets in northern China to analyze spatiotemporal characteristics and determine the main factors controlling dust storms occurring during 1960-2007. Dust storm-prone areas are consistent with the spatial distribution of northern China deserts where the average wind speed (AWS) is more than 2 m s−1, the mean annual temperature (MAT) ranges from 5° to 10°C, and the mean annual precipitation (MAP) is less than 450 mm. Dust storms commonly occur on spring afternoons in a 3- to 6-h pattern. The three predominant factors that can affect DSF are the maximum wind speed, AWS, and MAT. During 1960-2007, dust storm frequency (DSF) in most regions of northern China fluctuated but had a decreasing trend; this was mainly caused by a gradual reduction in wind speed. The effect of temperature on DSF is complex, as positive and negative correlations exist simultaneously. Temperatures can affect source material (dust, sand, etc.), cyclone activity, and vegetation growth status, which influence the generation of dust storms. NDVI and precipitation are negatively correlated with DSF, but the effect is weak. Vegetation can protect the topsoil environment and prevent dust storm creation but is affected by the primary decisive influence of precipitation. [ABSTRACT FROM AUTHOR]

Fluvial terraces are important geomorphic markers for modern valley development. When coupled with numeric ages, terraces can provide abundant information about tectonic, climatic, paleohydrological and the paleoenvironmental changes. On the basis of the paleomagnetic, electron spin resonance (ESR) and optically stimulated luminescence (OSL) dating, in addition to an investigation of local loess-paleosol sequences, we confirmed that 13 fluvial terraces were formed, and then preserved, along the course of the Upper Weihe River in the Sanyangchuan Basin over the past 1.2 Ma. Analyses of the characteristics and genesis of these terraces indicate that they resulted from the response of this particular river system to climate change over an orbital scale. These changes can further be placed within the context of local and regional tectonic uplift, and represent an alternation between lateral migration and vertical incision, dependent upon the predominance of climatic and tectonic controls during different periods. Most of the terraces are strikingly similar in that they have several meters of paleosols which have developed directly on top of fluvial deposits located on the terrace treads, suggesting that the abandonment of terraces due to river incision occurred during the transitions from glacial to interglacial climates. The temporal and spatial differences in the distribution patterns of terraces located on either side of the river valley indicate that a tectonic inversion occurred in Sanyangchuan Basin at ~0.62 Ma, and that this was characterized by a transition from overall uplift to depression induced by fault activity. Synthesized studies of the Basin's terraces indicate that formation of the modern valley of the Upper Weihe River may have begun in the late Early Pleistocene between 1.4-1.2 Ma. [ABSTRACT FROM AUTHOR]

• Afforestation boosts the atmospheric water cycle by increasing water vapor and precipitation. • Afforestation enhances evapotranspiration and precipitation recycling. • Afforestation causes an abnormal cyclone, thereby leading to increased moisture advection. • An intensified external atmospheric water cycle dominates the raised precipitation. • Afforestation causes more water vapor to be received by downwind areas. Afforestation is an efficient measure to mitigating climate change and achieving carbon neutrality. However, there is a growing concern regarding the impact of afforestation on water resource availability owing to the water consumption through evapotranspiration (ET). The Loess Plateau (LP) in China has implemented the largest afforestation program in the world, the Grain for Green Program (GFGP), to curtail severe soil erosion. However, the effects of large-scale afforestation on the atmospheric branch of the hydrological cycle (i.e., the atmospheric water cycle (AWC)) are poorly understood. Combining a regional climate model and an analytical precipitation recycling model, this study quantitatively investigated the responses of precipitation recycling and components of the atmospheric water cycle to the GFGP over the LP during the rainy season. Two long-term simulations with high resolution were conducted for the LP's regional climate under two scenarios: with and without the implementation of the GFGP. Results show that the GFGP intensified the AWC and increased the precipitation and atmospheric water vapor. The GFGP enhanced the ET and precipitation recycling ratio of the internal branch of the AWC, which contributed 15.51% of the increased precipitation. Meanwhile, the contribution of the external branch was 84.49%. In addition, both the inflow and outflow moisture fluxes showed increases induced by the GFGP; the inflow was larger than the outflow, leading to more moisture being retained on the LP. Moreover, the enhanced ET reinforced surface diabatic heating and caused an abnormal cyclone, resulting in more moisture being advected from the southern boundary, which can partly counteract the weakening East Asian summer monsoon. Furthermore, the GFGP has remotely strengthened the water vapor advection being received by downwind areas. This work advances the current understanding of the way large-scale afforestation affects the hydrological cycle from the viewpoint of the AWC, and can help direct future afforestation plans towards science-informed carbon neutrality and sustainable ecosystem management. [ABSTRACT FROM AUTHOR]

The Weihe River in central China is the largest tributary of the Yellow River and contains a well-developed strath terrace system. A new chronology for the past 1.11 Ma for a spectacular flight of strath terraces along the upper Weihe River near Longxi is defined based on field investigations of loess–paleosol sequences and magnetostratigraphy. All the strath terraces are strikingly similar, having several meters of paleosols that have developed directly on top of fluvial deposits located on the terrace treads. This suggests that the abandonment of each strath terrace by river incision occurred during the transition from glacial to interglacial climates. The average fluvial incision rates during 1.11–0.71 Ma and since 0.13 Ma are 0.35 and 0.32 m/ka, respectively. These incision rates are considerably higher than the average incision rate of 0.16 m/km for the intervening period between 0.71 and 0.13 Ma. Over all our results suggest that cyclic Quaternary climate change has been the main driving factor for strath terrace formation with enhanced episodic uplift. [ABSTRACT FROM AUTHOR]

• Deposits of a transverse river crossing the Yumu Shan are dated to 3.0–1.8 Ma. • Uplift of resistant rocks drives the change from transverse to longitudinal rivers. • A conceptual model describes shifts between transverse and longitudinal rivers. In an active thrust-fold belt, the drainage evolution, such as the alternation between transverse and longitudinal rivers, will influence the surface erosion within the range and the sedimentary sequence in the foreland basin. However, knowledge of the controls of changes in transverse or longitudinal drainage patterns in an uplifting range is limited. The Yumu Shan, on the northeastern margin of the Tibetan Plateau, is an example for a young and active thrust-fold range that shows evidence for drainage reversals since ∼3 Ma. The materials we used are the late Cenozoic depositional sequences around the Yumu Shan. Analyses of the lithology, grain size, roundness, and clast orientation of gravel deposits on the northern and southern flanks, combined with the results of cosmogenic nuclide burial dating, reveal that a transverse river, the Liyuan River, crossed the Yumu Shan range during 3.0–1.8 Ma by eroding weak Cenozoic sedimentary rocks. After 1.8 Ma, however, this transverse river was deflected and flowed along the edge of the range, and a longitudinal river developed along the back flank of the range. This process was synchronous with the exposure of resistant Paleozoic rocks by the continuous uplift of the range. After comparison with other potential controlling factors for drainage reversals, such as variations in rock uplift, climate or upstream aggradation, we find that the change in bedrock resistance was the most likely control on the change from a transverse to a longitudinal drainage pattern in this relatively young thrust-fold belt. Furthermore, through comparison with a series of active fold-thrust belts worldwide, we propose a simple conceptual model for the drainage evolution of active fold-thrust belts. In the earlier stage of the uplift, the exposed soft sedimentary rocks will cause transverse (antecedent) rivers to cross the range. After the continuous uplift of the range, resistant rocks cause the deflection of a transverse river and its change to a longitudinal river along the back flank of the range. In the final stage, after the several million years to around ten million years of uplift, with the development of a mature range, the local base level of the foreland will greatly fall, promoting a return to a transverse drainage pattern by headward erosion and capture of longitudinal rivers. [ABSTRACT FROM AUTHOR]

Abstract: Current understanding of late Mesozoic greenhouse climates is mainly based on palaeoclimatic information from oceanic and coastal marine sedimentary rocks. In contrast, detailed information on the climatic evolution of continental interiors is comparatively rare. This study presents a palynomorph record based on two cores drilled in the Gongpoquan Basin of northwest China located in central Asia during Late Jurassic to Early Cretaceous times. Based on these palynomorph records (G2709 and K705 successions), a total of three stratigraphic sequences with long depositional gaps can be distinguished, consisting of the Lower Jurassic Shazaohe Formation, the Lower Cretaceous (Berriasian to Valanginian) Laoshuwo Group and the Lower Cretaceous (Aptian to Albian) Laoshuwo Group. The palynomorph data provides information on prominent changes of vegetation and climate during the late Mesozoic. During Oxfordian times, spore-producing ferns show a short-lived increase, followed by a long-lasting period of Classopollis dominance during the Late Jurassic, which points to the establishment of continuously dry and warm conditions. In contrast, a more humid and probably warmer climate is indicated by the composition and high diversity of the palynoflora in the Early Cretaceous (Berriasian to Valanginian). Comparison with palynofloras of the same age from other continental basins of northwest China shows a similar vegetation change from Late Jurassic Cheirolepidiaceae-dominated forests to Early Cretaceous mixed forests composed of conifers (including Taxodiaceae and Pinaceae), cycads and pteridophytes. [Copyright &y& Elsevier]

Abstract: The way in which the NE Tibetan Plateau uplifted and its impact on climatic change are crucial to understanding the evolution of the Tibetan Plateau and the development of the present geomorphology and climate of Central and East Asia. This paper is not a comprehensive review of current thinking but instead synthesises our past decades of work together with a number of new findings. The dating of Late Cenozoic basin sediments and the tectonic geomorphology of the NE Tibetan Plateau demonstrates that the rapid persistent rise of this plateau began ~8±1Ma followed by stepwise accelerated rise at ~3.6Ma, 2.6Ma, 1.8–1.7Ma, 1.2–0.6Ma and 0.15Ma. The Yellow River basin developed at ~1.7Ma and evolved to its present pattern through stepwise backward-expansion toward its source area in response to the stepwise uplift of the plateau. High-resolution multi-climatic proxy records from the basins and terrace sediments indicate a persistent stepwise accelerated enhancement of the East Asian winter monsoon and drying of the Asian interior coupled with the episodic tectonic uplift since ~8Ma and later also with the global cooling since ~3.2Ma, suggesting a major role for tectonic forcing of the cooling. [Copyright &y& Elsevier]

Abstract: In northern China, high spatial and temporal instability exists in the southern desert border. Since the region is very sensitive to the changes of global climate and the migration of the southern desert border threatens the survival of surrounding inhabitants, it is very important to strengthen the research about the migration of the southern desert border of northern China. The dust in the downwind of the desert contains relevant information of the desert evolutionary history. In order to investigate the relationship between dustfall grain size and the southern border of northern China desert, we collected 56 eolian surface soil samples from the south of the Tengger Desert, selected two near north–south transects from these samples and used the grain size class-standard deviation method. We finally obtained three sensitive grain size components (ranking by degree of sensitivity from high to low): 61.8–185.4μm, 18.2–61.8μm and 2.3–18.2μm. The values of the three sensitive grain size components from the 56 eolian surface soil samples and the three commonly used grain-size indicators, which are the median grain size, >20μm and >63μm particle content, have been converted to the grain-size contour figures. In the six grain-size contour figures, the contour of the 61.8–185.4μm particle content component has the highest degree of similarity with the southern border of the Tengger Desert, followed by the >63μm particle content component, and then the components of the median grain size, 18.2–61.8μm particle content, >20μm and 2.3–18.2μm particle content in turn. Relative to the >20μm and >63μm particle content indicators, the indicator of 61.8–185.4μm particle content is not only the most sensitive one in theory, but also has the highest degree of similarity between its contour and the southern desert border in practical terms. Moreover, this indicator is further defined as the upper limit of coarse grain size. Since the coarse grains in the eolian deposits are mainly from the near-source desert, the component of 61.8–185.4μm particle content within the loess to the south of the Tengger Desert could be regarded as the indicator of the migration of the southern desert border, which could be used to quantitatively reconstruct the desert palaeo-border in the future. [Copyright &y& Elsevier]

• Nine river terraces have been identified and dated along the lower Taohe River. • The development of the modern river valley in this area began at 1.4–1.14 Ma. • Tectonic uplift and climate change were the main controlling factors. A flight of nine river terraces has been well developed and preserved along the course of the lower Taohe River. Based on optically stimulated luminescence (OSL), electron spin resonance (ESR), paleomagnetic and loess-paleosol stratigraphic analyses, we found that the accumulation ages of the gravel layers of terraces T9–T1 correspond to the loess layers L13, L9, L8, L6, L5, L4, L3-L2, L1-4 and L1-1, respectively. The chronologic results indicate that the formation and development of the modern river valley in this area occurred between 1.4 and 1.14 Ma. The topographic fluctuation caused by the Kunhuang Movement appears to have been the main reason for the reorganization of the river system and valley development in the area. In the context of this tectonic uplift, fluvial processes were coupled with the regional climate on a geomorphic equilibrium scale; i.e., over a glacial-interglacial cycle. That is, river aggradation appears principally to have occurred during glacial periods, while a graded state existed during interglacial periods. In addition, rapid river downcutting in response to climate change occurred during the transition periods from glacial to interglacial climates. [ABSTRACT FROM AUTHOR]