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Runoff and evapotranspiration (ET) are pivotal constituents of the water, energy, and carbon cycles. This research presents a 5-km monthly gridded runoff and ET dataset for 1998–2017, encompassing seven headwaters of Tibetan Plateau rivers (Yellow, Yangtze, Mekong, Salween, Brahmaputra, Ganges, and Indus) (hereinafter TPRED). The dataset was generated using the advanced cryosphere-hydrology model WEB-DHM, yielding a Nash coefficient ranging from 0.77 to 0.93 when compared to the observed discharges. The findings indicate that TPRED's monthly runoff notably outperforms existing datasets in capturing hydrological patterns, as evidenced by robust metrics such as the correlation coefficient (CC) (0.944–0.995), Bias (−0.68-0.53), and Root Mean Square Error (5.50–15.59 mm). Additionally, TPRED's monthly ET estimates closely align with expected seasonal fluctuations, as reflected by a CC ranging from 0.94 to 0.98 when contrasted with alternative ET products. Furthermore, TPRED's annual values exhibit commendable concordance with operational products across multiple dimensions. Ultimately, the TPRED will have great application on hydrometeorology, carbon transport, water management, hydrological modeling, and sustainable development of water resources. [ABSTRACT FROM AUTHOR]

On 1 June 2022, a magnitude 6.1 earthquake struck the southern segment of the Longmenshan fault zone on the eastern edge of the Tibetan Plateau, once again causing casualties and economic losses. Understanding the deep-seated dynamic mechanisms that lead to seismic events in the Lushan earthquake area and assessing the potential hazards in seismic gap areas are of significant importance. In this study, we utilized 118 magnetotelluric datasets collected from the Lushan earthquake area and employed three-dimensional electromagnetic inversion with topographic considerations to characterize the deep-seated three-dimensional resistivity structure of the Lushan earthquake area. The results reveal that the Shuangshi–Dachuan fault in the Lushan earthquake area can be divided into two relatively low-resistivity zones: a western zone dipping southeastward and an eastern zone with a steeper slightly northwestern dip. These two zones intersect at a depth of approximately 20 km, forming an extensional pattern resembling a "Y" shape. The epicenters of both the 2013 and 2022 Lushan earthquakes are primarily located in the upper constricted portion of the pocket-like low-resistivity body at depth. The distribution of seismic aftershocks is confined within the region enclosed by the high-resistivity body, following the pattern of the Y-shaped low-resistivity zone. [ABSTRACT FROM AUTHOR]

An increasing, but spatially inhomogeneous, trend in Tibetan Plateau (TP) precipitation, and especially the precipitation anomalies in southeastern TP (TPSE), has become the subject of major scientific concern. The Indian summer monsoon (ISM) is one of the TPSE's most important moisture sources, and its characteristics are therefore key for precipitation changes. Here we present the ISM activities (ISM onset/retreat date, ISM duration, and ISM intensity) and the percentages of varied moisture sources in TPSE, using OLR datasets and Hysplit modeling with gbl reanalysis. The recent precipitation anomalies in TPSE are analyzed with CMFD reanalysis. Major findings: (1) The ISM in TPSE generally begins later, retreats earlier, is of shorter duration, and weaker in intensity. (2) Uniformly decreasing (increasing) precipitation trends are found in TPSE for periods 1979 − 2018 and 1999 − 2018 (1979 − 1998). (3) Moistures along with the ISM are the primary controls of TPSE precipitation (~ 85% in summer); these are also verified by the generally same linear trends observed in ISM moistures and TPSE precipitation in summer. (4) The precipitation anomalies in TPSE are closely related with the ISM activities: the ISM onset date (retreat date) and its variabilities affect precipitation during May − June (September − October); precipitation during July − August correlates positively with the ISM duration and its intensity. The ISM activities impact the percentages of ISM moistures and finally affect the precipitation amount and their trends. These results will contribute to precipitation-related studies as hydrology, ecology, and paleoclimate reconstructions in TP. [ABSTRACT FROM AUTHOR]

This study reveals a significant subseasonal reversal of precipitation on the western Tibetan Plateau (WTP) from a deficit in December to an increase in January and February (JF). Changes in vertical moisture advection induced by the dynamic effects contribute mostly to the subseasonal precipitation trend reversal. This process involves the reversal of the subseasonal westerly driven uplift, accompanied by the weakened (enhanced) subtropical westerly jet and anticyclonic (cyclonic) anomalies over the WTP in December (JF). Further analysis shows that the North Atlantic Tripolar‐like (NAT) sea surface temperature (SST) modes could regulate the sunseasonal winter precipitation reversal over the WTP. The spatially inconsistent changes in SST can result in subseasonal reversed turbulent heat flux anomalies over Iceland‐Scandinavia in December and JF. In particular, the suppressed turbulent heat flux over the extratropical Northeast Atlantic in December leads to significant descending motion and upper tropospheric convergence. The advection of absolute vorticity induced by convergent winds associated with the NAT favors the generation of Rossby wave sources over Iceland‐Scandinavia, which then enhances the wave activity fluxes propagation. However, there are no significant changes in wave sources over Iceland‐Scandinavia in JF. The discrepancies in wave propagation intensity over Iceland‐Scandinavia determine the changes in the atmospheric pattern over the WTP, with anomalous anticyclone in December and cyclone in JF, and ultimately lead to the precipitation reversal. Furthermore, our results show that the suppressed transient eddies over the Atlantic storm track in JF may also contribute to the weakened wave propagation over Iceland‐Scandinavia. Key Points: A subseasonal reversal of precipitation in winter is evident in precipitation anomalies over the western Tibetan PlateauThe main contributor to the precipitation reversal is the subseasonal reversal of vertical moisture advection due to dynamic effectsThe Atlantic tripolar sea surface temperature anomalies could regulate precipitation reversal through stimulating asymmetric circulation mode over Eurasia [ABSTRACT FROM AUTHOR]

In recent years, there has been growing concern that vegetation changes on the Tibetan Plateau are associated with climate change (temperature and precipitation) and human activities. This study used six types of remote sensing vegetation data, including GIMMS (Global Inventory Modelling and Mapping Studies) NDVI (Normalized Difference Vegetation Index), MODIS (Moderate Resolution Imaging Spectroradiometer) NDVI, MODIS EVI (Enhanced Vegetation Index), SPOT Vegetation (Spot-VGT) NDVI, LAI (Leaf Area Index) and NPP (Net Primary Productivity), and applied the maximum synthesis method, trend analysis, correlation analysis, and multivariate statistical analysis to investigate vegetation change processes since the 1980s. The study showed that the amount of vegetation on the TP had increased significantly since 2000 (p <.01), especially in the northeastern part of the TP. There was no significant change prior to 2000. The different vegetation data sources varied greatly. Four remote sensing indices, MODIS EVI, Spot-VGT NDVI, LAI, and NPP, showed a significant increase in vegetation from 2000, accounting for 16.18%, 44.55%, 30.44% and 8.94% of the total area, respectively (p <.05). Multiple data sources provided a more comprehensive understanding, whereas a single data source had substantial uncertainty. Human activities, such as the implementation of large-scale ecological projects, played a dominant role in increasing vegetation, while climate change played a subsidiary role. The MODIS EVI, Spot-VGT NDVI, LAI, and NPP data showed that the area of increased vegetation caused by human activities accounted for 53.51%, 45.68%, 37.52%, and 31.79% of the total area of the TP, respectively. The relative increase from climate change was 10.28%, 17.49%, 13.15%, and 8.82%, respectively. The current study applied multi-source remotely sensed vegetation data, which effectively reduced the uncertainty caused by individual data sources and provided more rigorous and scientific research conclusions. [ABSTRACT FROM AUTHOR]

Asian dust has significant impacts on atmospheric systems and global biogeochemical cycles. In this study, we applied the U isotopic method to trace sediments based on their comminuting age, analyzing the uranium isotopes of cryoconite samples from various glaciers in western China, including the Tibetan Plateau (TP) and Tianshan Mountains. We aimed to explore the spatial variability of the (234U/238U) activity ratio and residence time, as well as the transport mechanism of the dust cycle in the region. Additionally, we used Nd‐Sr isotopes data from our previous work to jointly determine the provenance. Our results indicate that the average (234U/238U) activity ratios in southern TP glaciers are higher, with mean range of 0.981–0.993, while those in northeastern TP locations are lower, with mean of 0.974. This suggests a decreasing trend from south to north. In the Tianshan region, the (234U/238U) activity ratio is higher in central areas compared to eastern areas, with a mean range of 0.984–0.996, indicating a decreasing trend from west to east. U‐Sr‐Nd isotopes analysis showed that dust provenance is from multiple sources, including long‐range transported and local dust inputs from the glacier basins, mainly originating from the TP surface and central Asian arid regions. Using the end‐member mixing model analysis and meteorological data, we interpret that the cryoconite dust in eastern Tianshan and Qilian Mountains comes from a complex mixture of the southern Gobi, northern TP surface dust, and Taklimakan and Alxa arid deserts. In contrast, the glacial dust in southern TP locations originates mainly from the plateau surface dust. Our findings suggest that the uranium isotopes in high‐altitude glaciers are primarily influenced by the origins of dust, which are affected by related atmospheric circulation. We also developed a conceptual model to illustrate the complete process of U isotopic fragmentation and migration changes during dust production, transport, and deposition in the TP region. Plain Language Summary: In this study, the U isotopic method to trace sediments depending on their production‐transport histories is applied for the first time to dust deposited on glaciers in various locations of Tibetan Plateau (TP) and Tianshan Mountains in western China. The U isotopic variability of dust from glacial sediment is presented and discussed here, providing valuable data for a broader application of uranium isotopes for sedimentology and provenance studies in the future. Results showed that the (234U/238U) activity ratio signature of dust from glaciers is not uniform but exhibits differences depending on the considered geographic sector of the TP and western China. The present study demonstrates the potential of the 234U/238U technique to gather information about the production history of mineral dust deposited on glaciers in complex contexts as the TP and improve the identification of dust sources. Key Points: We measured the (234U/238U) activity ratio of cryoconite dust in large range scale of western China (including the Tibetan Plateau and Tianshan Mountains)The (234U/238U) activity ratio in high‐altitude glaciers is mainly affected by different source regions and transport processA conceptual model shows the complete view of U isotopic fragmentation and migration change during the dust transport and deposition [ABSTRACT FROM AUTHOR]

Unstable hydrological cycles and water resource instability over and around the Tibetan Plateau (TP) are topics of wide concern. The Indian summer monsoon (ISM) is one of the TP's most important moisture sources; as such, its behavior is key to any changes in precipitation and water-related environments. However, there have been relatively few thorough investigations into ISM activities. Here we primarily explore ISM activities using outgoing longwave radiation (OLR) datasets in TP, and precipitation isotopes recorded at Lhasa, for the period 1975–2020. Our major findings are that 1) the ISM onset (retreat date) is between ∼31 May and 19 July (∼8 August–27 September), with ISM duration of ∼40–110 days; 2) significant spatial inhomogeneous patterns are evident in ISM activities, i.e., the western part of our study area experiences earlier ISM onset, delayed retreat, longer duration, and greater intensity and strength, and the inverse is true in the eastern sector of the study area; 3) the ISM activities that dominate the 1975–98 period determine their general patterns over the entire 1975–2020 period, taking into account evident discrepancies in subperiods; and 4) the negative relations between precipitation δ18O and ISM intensity/strength at Lhasa confirm the ISM activities defined using OLR. These results will improve our understanding of hydrological cycles in TP and provide insights into hydrological studies in the "Asian Water Tower" region. Significance Statement: Over the recent decades, the Tibetan Plateau (TP) (Asian Water Tower) has undergone dramatic environmental changes, evinced by the instabilities of hydrological cycles. As one of TP's most important moisture sources, the Indian summer monsoon (ISM) is key to changes in precipitation and water-related environments. To get thorough investigations into ISM activities, we primarily explore ISM activities using outgoing longwave radiation (OLR) datasets in TP and precipitation isotopes at Lhasa. Significant spatial inhomogeneous patterns are evident in ISM activities: the western part experiences earlier ISM onset, delayed retreat, longer duration, and stronger intensity and strength, and the inverse occurs in the eastern sector. These results will improve our understanding of hydrology, meteorology, ecology, and paleoclimate reconstructions in the Asian Water Tower region. [ABSTRACT FROM AUTHOR]

Iron (Fe) as a limiting nutrient has profound impacts on ecosystems and the global biogeochemical cycle. Field observations were made at the atmosphere—snowpack interface in various glaciers of the Tibetan Plateau. The formand chemical properties of the Fe detected were investigated in laboratory using TEM‐EDX measurements, to obtain insights in the content and sources of Fe in aerosol pollutants in glaciers, as well as micro‐structure changes and their environmental effects, as well as interface transformation dynamics. We find that Fe occurs in forms of aggregated and single particulates with diameter d < 5 μm. The Fe particulates collected from different locations show clear spatial heterogeneity, with fly ash and soot constituting the major components of anthropogenic Fe. The concentration of Fe aggregates with pollutants (e.g., sulfate and nitrate) is dominant in regions close to the areas of human activity. Moreover, in the remote areas of the interior plateau, an increased concentration of mineral Fe particles is found in the aggregates. These observations are crucial to elucidate the evolution processes of pollutant‐Fe mixing, from generation or emission through anthropogenic activities to accumulation in remote areas and modification of Fe occurrence form during transportation. Our results also show that, during interface deposition, soluble Fe particle concentration increased by 13.8% on average, as Fe solutes with sulfate‐coating enhances of the dissolution of Fe in fly ash‐soot and minerals—a process that produces large quantities of ultrafine Fe particle under reductive dissolution in snowpack. Overall, these changes significantly contribute to enhancing the bioavailable iron content in the study areas affecting thereby the glacier ecosystem. Plain Language Summary: This study aims at providing an important record of the individual Fe particulates and pollutant mixing states, and to document the variability in the occurrence form and chemical properties over the regions comprising the glacier/snowpack and atmosphere interface. The objective is to determine the Fe‐salt (Sulfate/Nitrate pollutants) mixing state changes from the atmosphere to the glacier/snowpack surface, to elucidate the content and source of Fe‐rich particles in aerosols at the atmosphere‐snowpack interface over the cryosphere of the Tibetan Plateau, and to shed light on the factors influencing the physical and chemical properties of these particles. Key Points: Fe particulate reveal clear spatial heterogeneity with fly ash and soot constituting the major components of anthropogenic FeFe solutes from the sulfate‐coating led to an enhancement of dissolved Fe from fly ash‐soot and mineralsThe interface changes contribute to enhance the bioavailable iron content in the study area significantly [ABSTRACT FROM AUTHOR]

The Tibetan Plateau (TP) affects its surrounding regions through thermal and dynamic processes. Hydrological cycles in TP are experiencing dramatic changes under the warming climate. As one of the most important circulations, the Indian summer monsoon (ISM) affects precipitation changes and therefore has a major effect on TP water resources. In this paper, the widths of ISM are defined as extents perpendicular to the moisture trajectories. They were calculated using ground-based measurements and verified with reanalysis datasets. The directions of maximum summer precipitation decreases (Dirmin) were selected using the cluster proxy of directions of daily maximum winds (Wd) and the slope aspects derived from digital elevation models (DEMs) at various resolutions. The major findings were that (1) similar southwestern Dirmin were found based on the Wd and the slope aspects derived from DEMs with resolutions of 100 and 200 km; (2) Reanalysis data from China Meteorological Forcing Dataset verified that a high percentage (~ 90%) of cells showing precipitation decreases also had slope aspects (derived from 100- and 200-km resolution DEMs) in the range of 112.5°–247.5°; (3) The possible widths of ISM trajectories in TP were approximately 100–200 km. [ABSTRACT FROM AUTHOR]

Qinghai-Tibet Plateau lakes are important carriers of water resources in the 'Asian's Water Tower', and it is of great significance to grasp the spatial distribution of plateau lakes for the climate, ecological environment, and regional water cycle. However, the differences in spatial-spectral characteristics of various types of plateau lakes, and the complex background information of plateau both influence the extraction effect of lakes. Therefore, it is a great challenge to completely and effectively extract plateau lakes. In this study, we proposed a multiscale contextual information aggregation network, termed MSCANet, to automatically extract Plateau lake regions. It consists of three main components: a multiscale lake feature encoder, a feature decoder, and a Multicore Pyramid Pooling Module (MPPM). The multiscale lake feature encoder suppressed noise interference to capture multiscale spatial-spectral information from heterogeneous scenes. The MPPM module aggregated the contextual information of various lakes globally. We applied the MSCANet to the lake extraction of the Qinghai-Tibet Plateau based on Google data; additionally, comparative experiments showed that the MSCANet proposed had obvious improvement in lake detection accuracy and morphological integrity. Finally, we transferred the pre-trained optimal model to the Landsat-8 and Sentinel-2A dataset to verify the generalization of the MSCANet. [ABSTRACT FROM AUTHOR]

Human-perceived thermal comfort (known as human-perceived temperature) measures the combined effects of multiple meteorological factors (e.g., temperature, humidity, and wind speed) and can be aggravated under the influences of global warming and local human activities. With the most rapid urbanization and the largest population, China is being severely threatened by aggravating human thermal stress. However, the variations of thermal stress in China at a fine scale have not been fully understood. This gap is mainly due to the lack of a high-resolution gridded dataset of human thermal indices. Here, we generated the first high spatial resolution (1 km) dataset of monthly human thermal index collection (HiTIC-Monthly) over China during 2003–2020. In this collection, 12 commonly used thermal indices were generated by the Light Gradient Boosting Machine (LightGBM) learning algorithm from multi-source data, including land surface temperature, topography, land cover, population density, and impervious surface fraction. Their accuracies were comprehensively assessed based on the observations at 2419 weather stations across the mainland of China. The results show that our dataset has desirable accuracies, with the mean R2 , root mean square error, and mean absolute error of 0.996, 0.693 ∘ C, and 0.512 ∘ C, respectively, by averaging the 12 indices. Moreover, the data exhibit high agreements with the observations across spatial and temporal dimensions, demonstrating the broad applicability of our dataset. A comparison with two existing datasets also suggests that our high-resolution dataset can describe a more explicit spatial distribution of the thermal information, showing great potentials in fine-scale (e.g., intra-urban) studies. Further investigation reveals that nearly all thermal indices exhibit increasing trends in most parts of China during 2003–2020. The increase is especially significant in North China, Southwest China, the Tibetan Plateau, and parts of Northwest China, during spring and summer. The HiTIC-Monthly dataset is publicly available from Zenodo at 10.5281/zenodo.6895533 (Zhang et al., 2022a). [ABSTRACT FROM AUTHOR]

As one of the most important reservoirs of water in arid regions, lakes experience a series of complicated changes. However, the natural driving mechanisms behind such changes remain unclear. In this study, we collected data from 1333 lakes in the arid region of Central East Asia (CEA) to investigate the underlying natural causes of lake changes over the past five decades. The lakes were located within three different geomorphological zones: (I) Tibetan Plateau zone; (II) high mountain—basin zone; and (III) low mountain zone. Our results show that lakes as a whole in CEA exhibit a unique change trend, with an overall lake area increase of 7099 km2 (41%) and with heterogeneous spatial variations over the past five decades. The lake area increase was 6236 km2 (47%), 935 km2 (31%) and decrease was 72 km2 (~1%) in zones I, II, and III, respectively. The different geomorphological zones have influencing factors. In zones I and II, increased precipitation (including cloud water) and temperature rise (causing glacier, frozen soil, and snow melt) contributed to approximately 66% of the change in lake area; in zone III, changes in precipitation contributed to approximately 87% of the lake changes. Increased atmospheric circulation of water vapor caused by warming of the ocean surface appears to be the main driving factor of these changes; this is supported by future projection scenarios. From 2006 to 2098, temperature and precipitation will increase by 4.0–7.8 °C and 1.07 to 1.29 mm per day, respectively, under both the RCP4.5 and RCP8.5 scenarios. Notably, although the climate appears to have become more optimum for lakes in CEA at the interdecadal timescale, short timescale climatic events such as lake expansion will bring more extreme climate events, such as extreme high-temperature heat waves, which should be considered as a potential threat to lake ecology in the future. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau (TP) significantly affects its surroundings and the global climate through thermal and dynamic processes. Precipitation is a key driver of hydrological, meteorological, and ecological processes. In general, the precipitation over and around the TP displays a wetting trend over the past half century, with large spatial heterogeneity. However, the causes of such spatially variable trends in TP precipitation and the driving forces have not been well quantified. Here we investigate the spatial patterns of precipitation trends and their possible mechanisms, using ground-based observations from 132 CMA (China Meteorological Administration) stations (1970–2016) and CMFD (China Meteorological Forcing Dataset) reanalysis data (1980–2016) over and around the TP. The major findings are: (1) Pronounced spatial patterns of precipitation changes (increasing in inner TP and decreasing for regions around the TP) are observed in both CMA and CMFD data. (2) Maximum precipitation decreases generally occurred in stations that experienced southwestern daily maximum winds. (3) Positive correlations between mean precipitation and temperature (or daily maximum winds) are obtained in clusters with maximum precipitation increase (decrease), which are further verified by the qualitative and quantitative analysis of the CMFD dataset. (4) Therefore, we suggest that intensified local recycling in a intense warming and hydrologically unbalanced environment has led to precipitation increases in central TP, whereas precipitation decreases in areas bordering the TP may be the result of weakening Indian monsoon. [ABSTRACT FROM AUTHOR]

Human thermal comfort measures the combined effects of temperature, humidity, and wind speed, etc., and can be aggravated under the influences of global warming and local human activities. With the most rapid urbanization and the largest population, China is being severely threatened by aggravating human thermal stress. However, the variations of thermal stress in China at a fine scale have not been fully understood. This gap is mainly due to the lack of a high-resolution gridded dataset of human thermal indices. Here, we generate the first high spatial resolution (1 km-1 km) dataset of monthly human thermal index collection (HiTIC-Monthly) over China from 2003 to 2020. In this collection, 12 commonly used thermal indicators are generated by the LGBM machine learning algorithm from multisource gridded data, including MODIS land surface temperature, topography, land cover and land use, population density, and impervious surface fraction. Their accuracies were comprehensively assessed based on observations at 2419 weather stations across the mainland of China. The results show that our dataset has desirable performance, with mean R2, root mean square error, mean absolute error, and bias of 0.996, 0.693°C, 0.512°C, and 0.003°C, respectively, by averaging the 12 indicators. Moreover, the predictions exhibit high agreements with observations across spatial and temporal dimensions, demonstrating the broad applicability of our dataset. The comparison with two existing datasets also suggests that our high-resolution dataset can describe a more explicit spatial distribution of the thermal information, showing great potentials in fine-scale (e.g., intra-urban) study. Further investigation reveals that nearly all indicators exhibit increasing trends in most parts of China during the year 2003~2020. The increase is especially stronger in North China, Southwest China, the Tibetan Plateau, and parts of Northwest China, and in the spring and summer seasons. The HiTIC-Monthly dataset is publicly available via https://zenodo.org/record/6895533 (Zhang et al., 2022a). [ABSTRACT FROM AUTHOR]

Remote sensing precipitation products provide rich data for ungauged basins. Evaluating the accuracy and detection capability of remote sensing precipitation products is crucial before application. In this study, an index system in terms of quantitative differences, capturing capacity and precipitation distribution was constructed to evaluate three precipitation products, TRMM 3B42 V7, GPM IMERGE Final and CMORPH V1.0, at various temporal and spatial scales on the Tibetan Plateau from 2001 to 2016. The results show that the correlations among the three products were larger at the monthly scale than at the annual scale. The lowest correlations between the products and observation data were found in December. GPM performed the best at the monthly and annual scales. Particularly, the GPM product presented the best capability of detection of both precipitation and non-precipitation events among the three products. All three precipitation products overestimated 0.1~1 mm/day precipitation, which occurred most frequently. An underestimation of precipitation at 10~20 mm/day was observed, and this intensity accounted for the majority of the precipitation. All three precipitation products showed an underestimation in terms of the annual maximum daily precipitation. The accuracy of the same product varied in different regions of the Tibetan Plateau, such as the south, the southeast, eastern–central region and the northeast, and there was a certain clustering of the accuracies of neighboring stations. GPM was superior to TRMM and CMORPH in the southern Tibetan Plateau, making it recommended for applications. [ABSTRACT FROM AUTHOR]

The analysis of uranium isotope ratio 235U/238U in environmental media serves as a reliable method to distinguish between natural and anthropogenic sources of uranium, playing a crucial role in assessing the extent of contamination with anthropogenic uranium and disturbances in its biogeochemical cycle. In this study, we focus on the northeastern Tibetan Plateau to examine the atomic ratio of 235U and 238U in riverine suspended particulate matter (SPM) across eight glacial watersheds. Results reveal that the 235U/238U atomic ratio in the suspended load ranges from 0.007247 to 0.007437 (with an average value of 0.00727 ± 0.00003), which closely aligns with the ratio found in natural uranium (0.00725). The highest mean ratio (0.00729 ± 0.00007) is observed in the upper glacial basin of the Ningchan River. Results suggest the negligible influence of isotopically altered in relation to human nuclear activities. When considering different environmental media, such as soil, snow/cryoconite, and riverine suspended particulate matter in the study area, the 235U/238U ratio in surface soil presents the highest values, pointing to a slight enrichment of 235U. This may be attributed to the fact that soil retains the cumulative signals of uranium atmospheric deposition, including the deposition of 235U-enriched airborne particulate matter deposited after atmospheric nuclear tests carried out in the second half of the 20th century. On the contrary, riverine suspended particulate matter and glacial sediments are more influenced by the natural 235U/238U signature under modern environmental conditions. This confirms that the northeastern Tibetan Plateau is still relatively pristine with respect to biogeochemical disturbances related to human activities. [Display omitted] • the 235U/238U of glaciated river systems in the northeastern Tibetan Plateau closely aligns with natural levels. • the NE Tibetan Plateau experienced a mild deposition of enriched 235U during the global nuclear weapon testing. • the NE Tibetan Plateau is currently not significantly contaminated by human nuclear-related activities. [ABSTRACT FROM AUTHOR]

There have long been controversies over the extrusion mechanism of the Sundaland block in the southeastern Tibetan Plateau in response to the tectonic convergence between the Indian and Eurasian plates. In this study, we focus on macro- and micro- structural and kinematic analysis, timing of shearing, and thermal history reconstruction of several typical metamorphic complexes in the southeastern Tibetan Plateau in order to understand the tectonic processes driving the deformation of the complexes and extrusion of the block. It is shown that Cenozoic dome structures are widely distributed in the area. The dome cores comprise high-grade metamorphic rocks with high-temperature deformation fabrics (HMU), while rocks in the mantles are characterized by low-grade metamorphism and low-temperature deformation (LMU). Foliation and lineation in the rocks of different units of the domes are generally parallel to the stratigraphic horizons, implying the dominant role of bedding-parallel shearing in all the domes. Shear discontinuity contacts exist as high strain zones between the HMUs and LMUs that the sheared complexes show kinematically coupled but rheologically decoupled two-layer structures. Kinematic indicators from all the domes show consistent LMU-to-the SE shearing. Thermochronological data reveal that the initiation of doming was coeval with ductile shearing of the middle to lower crustal rocks, but was diachronous at different places. Most of the domes possess two-stage cooling histories. We conclude that the ductile shearing, formation, and exhumation of the dome structures were ascribed to middle and lower crustal flow that accommodated a large amount of deformation during the extrusion of Sundaland block. [ABSTRACT FROM AUTHOR]

Substantial progress has been made in understanding the relationship between summer precipitation in the Tibetan Plateau (TP) and North Atlantic Oscillation (NAO), but impacts of the summer NAO on precipitation spatial pattern remain controversial. Using the long‐term observational and reanalysis datasets, we have identified the intimate relationship between summer NAO and TP precipitation dipole pattern has been weakened since the late 1990s. Changes in regional atmospheric circulation induced by the asymmetrical wave propagation structure along the Eurasian continent are responsible for this weakened linkage. Further analyses revealed that the wave propagation anomalies are mainly induced by interdecadal change of summer NAO, which is attributed to the Atlantic multidecadal oscillation (AMO) variations. Moreover, the model simulations derived from the Geophysical Fluid Dynamics Laboratory (GFDL AM2.1) provide direct evidence to demonstrate that the AMO phase transition contributes to the unstable relationship between the summer NAO and precipitation dipole pattern in the eastern TP. Plain Language Summary: The spatial mode of summer precipitation in the TP is of great significance to the regional climate and ecosystem. Previous studies have indicated the summer NAO exerts great impacts on the generation of precipitation dipole pattern in the eastern TP. However, based on the statistical analysis and dynamic diagnose, we have found the relationship between the summer NAO and TP precipitation dipole pattern is nonstationary and characterized by a significant interdecadal change. In the late 1990s, the enhanced wave activity flux propagation emanating from the North Atlantic can give rise to the change in regional atmospheric circulation on the TP, which results in the anomalous cyclonic circulation on the eastern TP and prejudices the generation of precipitation dipole pattern. Evidence indicates that the interdecadal shift of the summer NAO and the AMO could be responsible for this unstable relationship. The warm AMO is favorable to bring more precipitation in the eastern TP and is not conducive to the occurrence of precipitation dipole pattern. Additionally, the model simulations conducted by the GFDL present evidence to highlight the important role in modulating the relationship between the summer NAO and dipole precipitation pattern in the eastern TP. Key Points: The relationship between the summer North Atlantic Oscillation (NAO) and Tibetan Plateau precipitation dipole pattern has been weakened since the late 1990sThe wave propagation structure induced by the summer NAO anomaly is the major cause of the unstable linkageThe interdecadal shift of Atlantic multidecadal oscillation is partly responsible for the unstable relationship of the summer precipitation pattern with NAO [ABSTRACT FROM AUTHOR]

Toxic and major elements, such as As and Fe, in watersheds can significantly impact the surrounding water environment and ecosystem. Thus, in this study, we conducted an investigation into the origins and spatial distribution of typical toxic trace elements (As and Mn) and crustal major elements (Al, Fe, and Ti) in suspended particulate matter (SPM) across various glacial watersheds located at different elevations in the northeastern Tibetan Plateau (NETP) from June to July in 2017. The results revealed that the mean value of each element followed the order of abundance in the samples, with Al having the highest mean value at 21307 µg/L, followed by Fe at 13366 µg/L, Ti at 1520 µg/L, Mn at 245 µg/L, and As at 66.6 µg/L. Moreover, our study identified high content of these elements from the Dabanshan Snowpack, Laohugou Glacier No.12, and Yuzhufeng Glacier in the upper reaches of the basin, which were found to be 9.9, 10.2, and 19.4 times higher, respectively, than that of the upper reaches of the Heihe River. We found that As and Mn exhibited clear indications of anthropogenic influence on a local and regional scale. The calculated enrichment factor (EF) demonstrated a significant As enrichment (EF>100) in the Qiyi and Lenglongling Glaciers, possibly resulting in the release of upstream glacier melt and anthropogenic-derived As deposition. Our findings suggested that the upstream region was primarily linked to glacier meltwater discharge. In contrast, the middle and lower reaches of the basin exhibited a more pronounced influence from local human activities. Based on the findings, the water environment of the glacier watershed appears to be in good condition overall. However, the presence of elevated levels of As element in the water system can be traced back to both anthropogenic and natural factors. As a result, ensuring the safety of the water supply for nearby residents is a matter of utmost concern. This study provides a comprehensive examination of hydrochemical variations and the overall water environment of high-altitude glacier basins in the NETP, offering valuable insights into the topic. [Display omitted] • Elemental concentration indicated a increasing trend in HG, LG, and QG basins, while in DS, LG12, and YG inverse. • As was significantly enriched, probably affected by regional coal combustion and other anthropogenic sources. • Relationship between elemental composition and various sources in upstream and downstream were very different. [ABSTRACT FROM AUTHOR]

Abstract The Tibetan Plateau's enigmatic collapse, which was indicated based on extensional faulting in the interior of the plateau and large eastward-directed strike-slip faults, has inspired intensive geologic inquiry and debate. Interaction of the subducting Indian plate with the overlying Asian lithosphere is one factor that may be affecting the plateau. A more detailed image of the subducting Indian plate can help constrain its role, but regional high-resolution seismic data have not been widely available at a relevant scale. Here we present an integrated interpretation based on two types of seismic datasets: (1) two N-S oriented deep seismic-reflection profiles that cross the Yarlung-Zangbo suture, and (2) two E -W receiver function profiles that cross the Xainza-Dingjye and Nyima-Tingri rifts, respectively. These images reveal different crustal-scale structures in the dominant collision zone between the western and central regions, as well as distinctly offset Moho discontinuities across the N-S trending rift grabens in southern Tibet. These crustal variations, combined with previous tomographic studies in Tibet, outline an easterly tilt of the subducting Indian slab, along which crust-mantle decoupling occurred. Together with the spatio-temporal distribution of synchronous potassium-rich volcanics exposed within the grabens in southern Tibet, this offset Moho structure beneath the grabens lends support to the hypothesis that eastward steepening of the subducting Indian slab was accompanied by slab tearing beneath each north-south striking rift. This overall crustal geometric variation suggests a stepwise flattening of the torn Indian slab from west to the east, a process that brought easterly migration of gravitational instability to the overriding Tibetan crust that drove collapse of the Tibetan Plateau once gravitational instability reached a critical level to the east. [ABSTRACT FROM AUTHOR]

The proposed study aims to examine the relation between the Tibetan Plateau (TP) thermal condition and El Niño and Southern Oscillation (ENSO). There were significant positive correlations between the snow water equivalent (SWE) over the TP from November to next April and sea surface temperature (SST) in the Eastern Equatorial Pacific (EEP) in November from 1987 to 2005. SST in EEP in November is most significantly correlated with the TP-SWE in next April, which suggests an accumulative effect of the ENSO on the TP snow cover. Although El Niño conditions could bring anomalous snowfall over the TP by generating a wave train entering the North African-Asian jet, it is questionable if this impact could change the thermal condition over the TP. There was almost no significant negative correlation between the SWE and TP surface temperature (representing the TP thermal condition) in winter. This suggests that the TP thermal condition hardly varies with the anomalous snowfall caused by this ENSO impact, despite some cooling effect of snowfall during the El Niño phase. On the contrary, preceding El Niño conditions tended to be associated with increasing TP surface temperature in May and there were significant positive correlations between SWE in April and TP surface temperature in May and June. ENSO might play a part in affecting TP thermal condition in a way that is quite different from the previous research. A plausible mechanism based on the relation of ENSO-TP thermal condition has been proposed. The mechanism explained the direct and indirect effects of ENSO on the TP thermal condition and role that the seasonal progress can play in this relation. The issues about snow cover aging and the impact of global warming, among others, were also included in the mechanism. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau (TP) experienced a rapid warming and wetting in recent decades. The elevation dependence of warming rate has been established, while the question of trend in precipitation against the elevation gradient remains open. By using the in situ observation of precipitation, air temperature, and surface specific humidity from 91 stations over and around the TP, this study investigated how the trends in summer precipitation varied along the elevation gradient over and around the TP during the period 1970-2014. The major findings are as follows: (1) the trends in summer precipitation from 1970 to 2014 displayed an increasing tendency at a rate of 0.83% decade-1 km-1 with the increased elevation, and the rate for 1991–2014 (2.23% decade-1 km-1) is even greater and (2) the temporal trends in surface air temperature, surface specific humidity (surface water vapour) from in situ observations and total column of water vapour from Japanese 55-year reanalysis (JRA-55) data overmost stations consistently display similar elevation dependence, which provides a plausible explanation for the elevation dependence of the summer precipitation trends based on the Clausius–Clapeyron relationship. The large-scale atmospheric circulations are other possible factors influencing the elevation dependence of summer precipitation trends, which needs further investigations. [ABSTRACT FROM AUTHOR]

ABSTRACT The Tibetan Plateau ( TP) experienced a rapid warming and wetting in recent decades. The elevation dependence of warming rate has been established, while the question of trend in precipitation against the elevation gradient remains open. By using the in situ observation of precipitation, air temperature, and surface specific humidity from 91 stations over and around the TP, this study investigated how the trends in summer precipitation varied along the elevation gradient over and around the TP during the period 1970-2014. The major findings are as follows: (1) the trends in summer precipitation from 1970 to 2014 displayed an increasing tendency at a rate of 0.83% decade−1 km−1 with the increased elevation, and the rate for 1991-2014 (2.23% decade−1 km−1) is even greater and (2) the temporal trends in surface air temperature, surface specific humidity (surface water vapour) from in situ observations and total column of water vapour from Japanese 55-year reanalysis ( JRA-55) data over most stations consistently display similar elevation dependence, which provides a plausible explanation for the elevation dependence of the summer precipitation trends based on the Clausius-Clapeyron relationship. The large-scale atmospheric circulations are other possible factors influencing the elevation dependence of summer precipitation trends, which needs further investigations. [ABSTRACT FROM AUTHOR]

The shifting atmospheric circulation between the Indian monsoon and the westerlies on the northwestern Tibetan Plateau (TP) influences precipitation as well as precipitation isotopes. Isotopic records will therefore show historical fluctuations. To understand better the factors controlling present day precipitation δ 18 O values on the northwestern TP, we made continuous observations of precipitation isotopes at Ngari station from 2010 to 2013. The drivers of precipitation δ 18 O were investigated using analyses of their statistical relations with temperature, precipitation amount, relative humidity, and convective activities based on outgoing longwave radiation (OLR) data from NOAA satellites, and downward shortwave radiation (DSR) data collected at the Ngari automatic weather station. Atmospheric circulation patterns from NCAR reanalysis, and moisture transport paths of individual events derived from the HYSPLIT model using NCEP data, were also used to trace moisture sources. The results of our study include: (1) The slope and intercept of the Local Meteoric Water Line (LMWL) at Ngari (δD = 8.51 δ 18 O + 11.57 (R 2 = 0.97, p < 0.01)) were higher than for the Global Meteoric Water Line (GMWL), indicating drier local climatic conditions; (2) Precipitation δ 18 O values showed a weak “temperature effect” and a weak “precipitation amount effect” at Ngari; and (3) Convection (or temperature patterns) integrated over several days (0−20) preceding each event were determined to be the main driver of precipitation isotopic values in monsoon (or non-monsoon) season. The longer (shorter) periods of τ m days when correlation coefficients between precipitation δ 18 O and OLR were at their maxima (minima) indicate deep convective activities (shorter moisture transportation pathways) in August (June, July, and September). [ABSTRACT FROM AUTHOR]

ABSTRACT The Tibetan Plateau ( TP) affects its surroundings significantly through thermal and dynamic processes. Reductions in near-surface wind speed ( Ws) have been observed from ground measurements but how the trends of Ws vary with the elevation is less clear. Trends of Ws with respect to elevation were investigated using long-term daily records taken from 1970 to 2012 of Ws and maximum ( Tmax), minimum ( Tmin), and mean ( Tmean) air temperatures from 139 stations over and around the TP. The major findings are as follows. (1) Pronounced reductions in Ws can be observed in all seasons and annually across the TP. Spring demonstrates the most prominent weakening. The rate of reductions in Ws was amplified with elevation, and higher-elevation environments experienced greater changes in Ws than lower-elevation areas. Elevation-dependent reductions in Ws have intensified from 1970 to 2012. (2) Statistically significant negative correlations between Ws and corresponding near-surface temperatures were detected. We suggested that the elevation-dependent warming and thereby the increased surface roughness at higher-elevation environments may contribute to the elevation-dependent reductions in Ws over and around the TP. More detailed mechanisms causing this pattern are to be further explored. [ABSTRACT FROM AUTHOR]

To better understand the relationship between lightning activity and nitrogen oxides (NO) in the troposphere and to estimate lightning-produced NO (LNO) production in China more precisely, spatial and temporal distributions of vertical column densities of tropospheric nitrogen dioxide (NO VCDs) and lightning activity were analyzed using satellite measurements. The results showed that the spatial distribution of lightning activity is greater in the east than in the west of China, as with NO VCDs. However, the seasonal and annual variation between lightning and NO density show different trends in the east and west. The central Tibetan Plateau is sparsely populated without modern industry, and NO VCDs across the plateau are barely affected by anthropogenic sources. The plateau is an ideal area to study LNO. By analyzing 15 years of satellite data from that region, it was found that lightning density is in strong agreement with annual, spatial and seasonal variations of NO VCDs, with a correlation coefficient of 0.79 from the linear fit. Combining Beirle's method and the linear fit equation, LNO production in the Chinese interior was determined to be 0.07 (0.02-0.27) TgN yr for 1997-2012, within the range of 0.016-0.384 TgN yr from previous estimates. [ABSTRACT FROM AUTHOR]

Atom ratio between 235U and 238U is often used as an indicator of U contamination as the isotopic signature of products generated by the nuclear and military industry significantly vary from the natural isotopic ratio of U. In this study, surface soils and glaciers samples were collected in the Tibetan Plateau (TP) and its surrounding areas and analyzed for U isotopic composition. Results show that the 235U/238U atom ratios in the surface soils of the TP ranges from 0.007122 to 0.007615, with an average value of 0.007378 ± 0.00011; while in the snow/ice dust from high-altitude glaciers it ranges from 0.007254 to 0.007687, with an average value of 0.007345 ± 0.000128. These ratios are slightly higher than the typical crustal value, indicating that the TP was affected by an anthropogenic input of 235U, especially in its northeast and southwest sectors. The variability of our results suggests that the spatial distribution of this contamination is not uniform, pointing to differences in the potential sources and transmission paths of radioactive particles. Combining the knowledge of past tests and activities conducted in the geographic areas around the TP with the knowledge of prevailing winds, we hypothesize that the observed 235U contamination in the TP surface soils and glaciers may have originated mainly from the previous nuclear related activities in surrounding areas (e.g., north Gobi Desert and South Asia). In addition, the horizontal and vertical wind field around the Tibetan Plateau, as well as the atmospheric aerosol optical thickness data also demonstrated the possible transport paths of the radionuclides, that is, originated from in northern Gobi desert and South Asia and reached the TP crossing the Himalayas. Spatial distribution of 235U/238U atomic ratios in soil and snow/cryoconite samples of the Tibetan Plateau, showing a relatively high level of 235U/238U atomic ratios in northern and southwest Tibetan Plateau region. [Display omitted] • 235U/ 238 U in surface soil and glaciers of TP are slightly enriched. • 235U/238U showed highest value in the northeast and southwest TP. • Observed 235U may have originated from previous surrounding nuclear test areas. [ABSTRACT FROM AUTHOR]

GPS measurements indicate rapid lateral extrusion of the NE Tibetan Plateau, which causes active NE-directed crustal shortening and has initiated oblique shearing along the margins of NE Tibet. However, the Tibetan highlands terminate around 103°E longitude and topographic relief disappears to the northeast. The exact reasons for this drop in elevation remain obscure due to widespread Tertiary sediments and Quaternary loess, which obscure details of the lithospheric structure. This study describes a new 310 km-long deep seismic reflection line striking NE-SW across the interior of NE Tibet. Integrating its data with a previously described 165 km-long deep seismic profile of the Tibet–Ordos transition zone together, these datasets provide a complete picture of the crustal architecture of the north-easternmost Tibetan Plateau. Gravity anomaly and previous geological evidence also help constrain complex deformation pattern in the region. Interpretations of these patterns indicate the importance of the large-scale sinistral Haiyuan fault zone and inherited vertical variation in mechanical properties of the lithosphere in the overall tectonic evolution of the NE Tibetan Plateau. The overall crustal architecture obtained in this study provides spatial context for the neotectonic evolution of NE Tibet and helps constrain the interplay of geologic and geodynamic processes affecting NE Tibet and adjacent regions. [ABSTRACT FROM AUTHOR]

The eastern Tibetan plateau has been getting more and more attention because it combines active faults, uplifting, and large earthquakes together in a high-population region. Based on the previous researches, the most of Cenozoic tectonic activities were related to the regional structure of the local blocks within the crustal scale. Thus, a better understanding of the crustal structure of the regional tectonic blocks is an important topic for further study. In this paper, we combined the simple Bouguer gravity anomaly with the Moho depths from previous studies to investigate the crustal structure in this area. To highlight the crustal structures, the gravity anomaly caused by the Moho relief has been reduced by forward modeling calculations. A total horizontal derivative (THD) had been applied on the gravity residuals. The results indicated that the crustal gravity residual is compatible with the topography and the geological settings of the regional blocks, including the Sichuan basin, the Chuxiong basin, the Xiaojiang fault, and the Jinhe fault, as well as the Longmenshan fault zone. The THD emphasized the west margin of Yangtze block, i.e., the Longriba fault zone and the Xiaojiang fault cut through the Yangtze block. The checkboard pattern of the gravity residual in the Songpan-Garze fold belt and Chuandian fragment shows that the crust is undergoing a southward and SE-directed extrusion, which is coincident with the flowing direction indicated from the GPS measurements. By integrating the interpretations, the stepwise extensional mechanism of the eastern Tibetan plateau is supported by the southeastward crustal deformation, and the extrusion of Chuandian fragment is achieved by Xianshuihe fault. [ABSTRACT FROM AUTHOR]

The mechanism for uplift of the eastern Tibetan Plateau is still a matter of debate. There are two main models: extrusion and crustal flow. These models have been tested by surface observations, but questions about the uplift remain. In addition, the devastating 2008 Mw 7.9 Wenchuan earthquake along the Longmen Shan fault zone (LMSFZ) reminds us that the tectonic activity within eastern Tibet is complex and poses a major natural hazard. This activity is accompanied by dramatic uplift along the LMSFZ, but only minor convergence (<4 mm year–1) against the Sichuan basin is observed. In order to investigate the mechanism for uplift of Longmen Shan (LMS) area, we explored the lithospheric structure across the Songpan–Ganzi terrane (SGT), LMS, and western Sichuan basin by undertaking an integrated analysis of a variety of data including new, logistically challenging controlled-source seismic profiling (reflection and refraction) results, receiver function estimates of crustal thickness, gravity and magnetic data, GPS data, and geologic constraints. Our analysis of crustal structure indicates that the crust is not thick enough to support its current elevation and that the crust is essentially composed of three layers of similar thickness. Thus, based on our crustal structure model, 2D numerical modelling was conducted to investigate uplift mechanisms. The modelling results indicate that the middle crust beneath the SGT is the most ductile layer, which is the key factor responsible for the crustal-scale faulting, earthquake behaviour, and periods of uplift. In addition, the modelling results indicate that the strong Sichuan block acts as a backstop for the thrusting along the LMS and crustal thickening to the west. [ABSTRACT FROM AUTHOR]

The Yarlung Zangbo River basin is an important alley to transport moisture from the Indian Ocean to the inner Tibetan Plateau. With a wide range of elevations from 147 m to over 7000 m above sea level (a.s.l.), ecosystems respond differently to climate change at various elevations. However, the pattern of elevation-dependent vegetation change and how it responds to recent warming have been rarely reported. Here, we investigated the pattern of vegetation greening at different elevations in this river basin using SPOT normalized difference vegetation index (NDVI) data during 1999-2013, and examined its relationship with elevation-dependent changes in temperature and precipitation. The annual NDVI has increased by 8.83% from 1999 to 2013. In particular, the NDVI increased more apparently at lower elevations, but remained relatively stable or even decreased at high elevations. It seems that rising temperature has driven the basin-wide vegetation greening, but the greening rate is in contrast to the pattern of elevation-dependent warming (EDW) with more significant temperature increase at higher elevations. It appears that decreasing precipitation does not reverse the overall increasing trend in NDVI, but relatively limited precipitation (<500 mm) may constrain the NDVI increases, causing apparently stable or even decreased NDVI at higher elevations (>4000 m). [ABSTRACT FROM AUTHOR]

On 12 May 2008 and 20 April 2013, respectively, the devastating magnitude 7.9 (Wenchuan) and magnitude 7.0 (Ya’an) earthquakes struck the southwestern Longmen Shan fault zone (LMSFZ), the eastern margin of the Tibetan Plateau. These events were notable because they occurred in a heavily populated area and resulted in severe damage and loss of life. Here we present an integrated analysis of potential field anomalies and a crustal-scale seismic reflection image to investigate the crustal structure and some tectonic relationships associated with these devastating events. Our results show that the western margin of the Yangtze crustal block possesses an irregular margin that extends westward beyond the LMSFZ to the northeast and merges gradually with the LMSFZ to the southwest. We interpret this variation in deep structure to create a lateral heterogeneity in the local stress regime that explains the observed variations in fault geometry and slip distribution, as well as seismicity, of the LMSFZ. This structural complexity results in a differential build-up of stress as the Tibetan Plateau is being extruded eastward. Thus, the results of this research can help identify potential natural hazard zones and focus efforts on hazard mitigation. [ABSTRACT FROM AUTHOR]

Abstract: Competing models have been proposed to account for the unusual uplift of the Longmen Shan fault zone in the eastern Tibetan Plateau and resulting hazards. However, due to the terrain and thick sedimentary cover, the crustal structure of the eastern Tibetan Plateau remains uncertain. Therefore, testing these models has been difficult. In 2011, a 310 km long, SE-trending SinoProbe-02 deep seismic reflection profile was recorded in easternmost Tibet in order to study its regional crustal structure. The resulting image revealed the detailed crustal structure of eastern Tibet, which when combined with geological, GPS (Global Positioning System), and geochemical evidence, strongly suggests that Yangtze sub-continent crust extends beneath the region. The seismic profile also images the tremendously thick Triassic sedimentary cover in the Songpan-Ganzi terrane (SGT). These Triassic sediments vary considerably in thickness across several crustal blocks. In addition, both the Longriba fault zone of the northeastern SGT and the Longmen Shan fault zone show strong intracrustal reflections that terminate at a depth coinciding largely with the crust–mantle boundary (Moho). Accordingly, we propose a new tectonic model based on an integrated analysis of this seismic reflection profile and previous GPS measurements. In this model, crustal-scale deformation is suggested to have participated in the oblique extrusion and uplift of the easternmost edge of the Tibetan Plateau along the Longmen Shan. In a broader context, the lithospheric configuration imaged by the seismic reflection profile will advance our understanding of the tectonic response of the eastern Tibetan Plateau to the ongoing India–Eurasia collision and has new implications for the estimating seismic risk in the region. [Copyright &y& Elsevier]

Aims We aim to quantify the relative importance of various endogenous and exogenous processes influencing the spatial distribution of the individuals of plant species at different temporal and spatial scales in a species-rich and high-cover meadow in the eastern Tibetan Plateau. Methods We calculated Green’s index of dispersion to infer the spatial distribution patterns of 73 herbaceous species at two scales (0.25 and 1.0 m2). We constructed a series of generalized linear models to test the hypotheses that different species traits such as mean plant stem density, per capita dry biomass, maximum plant height and mean seed mass contribute to their spatial distribution. We used the first principal component of soil C, N and P to explain abundance variation across quadrats and sub-plots. Important Findings The individuals of the species studied were highly spatially aggregated. At both spatial scales, biomass and stem density explained the most variation in aggregation, but there was no evidence for an effect of mean seed mass on aggregation intensity. The effects of soil carbon, nitrogen and phosphorus at different depths affected plant abundance mostly at the broader spatial scale. Our results demonstrate that self-thinning and habitat heterogeneity all contribute to determine the spatial aggregation patterns of plant individuals in alpine meadow vegetation in the eastern Tibetan Plateau. [ABSTRACT FROM PUBLISHER]

Although long-lived detachment faulting plays an important role in fluid circulation and in accommodating tectonic extension at slow-spreading oceanic ridges, it is still unclear how the fluid-enriched faults contribute to the observed seismic anisotropy in the lower crust. We investigated sheared and altered gabbros along the detachment fault zones from the Xigaze ophiolite in the southern Tibetan Plateau. Results demonstrate that the positive feedback between fluid circulation and shearing, linked by dissolution-precipitation creep of amphibole, resulted in fluid enrichment during strain localization along the fault zones. Based on this shearing-enhanced fluid circulation model, our calculations of the seismic properties show that amphiboles (de)formed by dissolution-precipitation creep along the fault zones largely contribute to the seismic anisotropy (P and S waves) and S-wave delay time in the lower crust at slow-spreading ridges, with the polarization directions of fast shear waves being subparallel to the ridges. The strength of resulting seismic anisotropy is largely a function of crustal thickness, fault zone attitude, and metasomatism intensity. This study provides a novel explanation for the origin of seismic anisotropy in the lower oceanic crust at slow-spreading ridges. The conclusion may also have implications for the origin of seismic anisotropy at fast-spreading ridges where there are high melt supplies. [ABSTRACT FROM AUTHOR]

[Display omitted] • Interactions of bacteria, fungi, and nematodes were examined in this study. • Grassland degradation changes microbial and nematode community structures. • Changes in metabolic pathways of soil micro-foodwebs with grassland degradation. • A higher number of links was observed in severely degraded grasslands. Resource-transfer connections among bacteria, fungi, and microbivorous nematodes play an integral role in the decomposition pathways of soil micro-foodweb. Exploring the response of soil bacteria, fungi, and nematodes to grassland degradation is crucial for predicting the direction and trajectory of degradation. However, the knowledge about soil bacteria-fungi-nematode interactions in ecosystem function and nutrient cycling must be highlighted properly, especially in the Qinghai-Tibet Plateau. Therefore, this study focuses on four alpine meadows at different degenerate gradients (non-degraded grassland, slightly degraded grassland, moderately degraded grassland, and severely degraded grassland) on the Qinghai-Tibet Plateau. The investigation of soil bacteria-fungi-nematode interactions uses high-throughput sequencing and correlation network analysis. The results demonstrate significant variations in the composition of soil nematode genera, and bacterial and fungal phyla, across different degradation stages. Moreover, the diversity of nematodes, bacteria and fungi declined as grassland degradation worsened. Principal component analysis (PCA) revealed that alpine meadows with varying degradation gradients significantly influenced the community structure of bacteria, fungi, and nematodes. Mantel analysis indicated that soil water content (P < 0.05), total phosphorus (P < 0.05), and total nitrogen (P < 0.05) were the primary soil properties affecting the soil bacterial community. Similarly, available soil potassium (P < 0.05), microbial biomass carbon (P < 0.05), and microbial biomass nitrogen (P < 0.05) were the main soil factors influencing the soil fungal community. In contrast, the correlation between individual soil characteristics and soil nematodes did not reach a significant level, suggesting that a blend of physical and chemical properties regulates the soil nematode community. As grassland degradation intensified, the number of links in the interaction network of bacteria, fungi, and nematodes increased. Particularly, the networks between fungi and nematodes expanded, and the key species within each network varied with the different stages of grassland degradation. Concurrently, soil micro-foodweb decomposition pathways shifted. In the ND treatment, bacteria and fungi jointly dominated the degradation channels of the soil micro-food web, while the LD and MD treatments mainly dominated the degradation channels of fungi. On the other hand, SD treatment was dominated by bacterial degradation channels. This research adds to our theoretical understanding of meadow soil micro-foodwebs and the sustainable use of alpine grasslands in the Qinghai-Tibet Plateau. [ABSTRACT FROM AUTHOR]

The most extreme environments are the most vulnerable to transformation under a rapidly changing climate. These ecosystems harbor some of the most specialized species, which will likely suffer the highest extinction rates. We document the steepest temperature increase (2010–2021) on record at altitudes of above 4,000 m, triggering a decline of the relictual and highly adapted moss Takakia lepidozioides. Its de-novo -sequenced genome with 27,467 protein-coding genes includes distinct adaptations to abiotic stresses and comprises the largest number of fast-evolving genes under positive selection. The uplift of the study site in the last 65 million years has resulted in life-threatening UV-B radiation and drastically reduced temperatures, and we detected several of the molecular adaptations of Takakia to these environmental changes. Surprisingly, specific morphological features likely occurred earlier than 165 mya in much warmer environments. Following nearly 400 million years of evolution and resilience, this species is now facing extinction. [Display omitted] • Steepest temperature increase at 4 km elevation threatens highly adapted moss species • Sequenced genome with highest number of fast-evolving genes under positive selection • Adaptation to severe UV-B radiation and freezing likely evolved at high altitudes • Morphological peculiarities of Takakia plants likely evolved earlier than 165 mya Field observations of Takakia , a highly adapted moss facing extinction in the Tibetan Plateau, integrated with an evolutionary framework provide insights into when its distinct features emerged relative to the geological events that shape this extreme environment. [ABSTRACT FROM AUTHOR]

The extrusion model suggests that the India-Eurasia collision triggered lateral escape of the Tibetan Plateau via strike-slip faults from south to north. However, questions remain as to how the collision resulted in the different geological settings of northern Tibet. The area between the Haiyuan fault and the eastern Kunlun fault is ideal for investigating whether major strike-slip faults contributed to lateral extrusion of the plateau. This study uses a deep seismic profile spanning a 257 km transect, along with regional geologic, gravity, and magnetic data. Examining our results integrated with those of previous studies, we propose that the block between the Elashan and Riyueshan faults extruded southward under the background of a large-scale eastward extrusion of the Tibetan Plateau. According to regional tectonic events, the north-dipping intracrustal seismic reflectors that appear beneath the Western Qinling orogen are the remnants of the Indosinian Mianlue suture zone. The subduction of the Mianlue Ocean led to the underthrusting of South China beneath the Qinling orogen, similar to the process that occurred in the Western Kunlun Range and central Alps. As a result, the Moho was duplicated beneath the Western Qinling orogen. Southward extrusion resulted in the offset of the eastern Kunlun fault from the Diebu-Bailongjiang fault, which transferred part of the Western Qinling orogen to the Ruo'ergai basin and pulled the Ruo'ergai basin as well. Based on interpretations of structures and other evident features, we develop a kinematic model to specifically explain how the northern Tibetan Plateau between the Elashan and Riyueshan faults, located between the Haiyuan and Kunlun faults, accommodates southwesterly compression. [ABSTRACT FROM AUTHOR]

The productivity of the alpine meadows in the central Tibetan Plateau (TP) is usually linked to atmospheric circulation shifts between the westerlies and Indian monsoon. Hence, it is critical to identify the dates of these circulation shifts, i.e., the Indian monsoon onset and retreat. However, the exact timing of the Indian monsoon onset in the central TP is highly uncertain. Here, we diagnose the atmospheric circulation shifts in the central TP during 2016–2018 using hydrogen and oxygen stable isotopes. Our results show that the Indian monsoon onset was marked by sharp decreases of the stable isotopes in both water vapor and precipitation (δ2H v and δ2H p) in mid-late June, which is approximately one month later than previous findings. In the subsequent period, the Indian monsoon replaced the westerlies across the central TP, where water vapor and precipitation were characterized by persistently lower stable isotope values. Substantial increases of the δ2H v and δ2H p values in late September denoted the Indian monsoon retreat. The δ2H v and δ2H p values also record fluctuations of the Indian monsoon intensity and the occasional intrusions of the westerlies even during the monsoon season. Our findings propose that stable isotopes can be used as indicators of atmospheric circulation shifts and may act as potential indices to monitor the vegetation growth in the central TP. • The Indian monsoon onset and retreat in central TP are identified by water isotopes. • Water isotopes record the monsoon intensity fluctuations and westerly intrusions. • It should be cautious to declare the monsoon onset based solely on precipitation. • Moisture for vegetation spring green-up cannot be attributed to the Indian monsoon. [ABSTRACT FROM AUTHOR]

A large number of thermal springs are widely distributed along the deep suture zones and faults in the north section of the Sanjiang Orogenic belt in southeast Tibetan Plateau, connecting the two high-temperature hydrothermal areas in southern Tibet and western Sichuan. Whether the genesis of all geothermal water in the north section of the Sanjiang Orogenic belt is consistent is still an unanswered question. In order to fill the research gap of the high temperature geothermal system in this region, in this study, we classified the geothermal springs into three geothermal fields (Jinsha, Lancang, and Nujiang geothermal fields) and attempted to find clues by comparing the hydrochemical and isotopic characteristics of geothermal fluids in the three geothermal fields. The δ2H and δ18O composition of geothermal springs suggest that all thermal springs are replenished by the meteoric water. Low content of trace elements and low degree of oxygen isotope shift indicate that the partial melting of the crust at a depth of about 20 km mainly provide heat for all thermal springs in the geothermal fields through conduction. But due to the difference of tectonic conditions, there are two formation patterns of geothermal waters in the study area, one was controlled by regional faults, the other was controlled by the folded complex. The geothermal waters controlled by regional faults were heated after deep circulation, and the reservoir temperatures calculated by the Silica-enthalpy mixing model are 175–200 °C and 200–225 °C, respectively. But the geothermal waters controlled by the folded complex were heated after shallow circulation, and the reservoir temperature is only 100–125 °C. Upon rising to the surface, the geothermal waters mixed with cold groundwater to different degrees. The dissolution of Na/K-silicates and carbonate rocks controlled the formation of Na-HCO 3 and Ca·Mg-HCO 3 type water, respectively. But dissolution of halite and gypsum (or anhydrite) in some areas can lead to further diversity of hydrochemical species, resulting in the formation of Na-Cl, Na-HCO 3 ·Cl, Ca·Mg-SO 4 and Na-HCO 3.SO 4 type waters. • The crustal partial melting mainly provides heat for geothermal waters through conduction. • Two formation patterns of geothermal waters are formed due to the difference of tectonic condition. • Geothermal water controlled by regional faults was heated after deep circulation. • Geothermal water controlled by complex fold was heated after shallow circulation. • Reservior temperatures of the two patterns are calculated as 175–225 °C, 100–125 °C respectively. [ABSTRACT FROM AUTHOR]

How middle to lower crust in Southeastern Tibetan Plateau flowed in response to the Indian-Eurasian continental collision remains hotly debated in the last decades. Metamorphic complexes along crustal mobile zones, e.g., the Diancang Shan (DCS) complex along the Ailao Shan-Red River (ASRR) metamorphic belt may provide key knowledge on our understanding of the middle-lower crustal flow during the collision. In this contribution, integrated structural, microstructural, kinematic, and thermo-chronological studies of the DCS complex reveal that the complex constitutes a destructed A-type dome. High-grade metamorphic rocks of Proterozoic protoliths form the core (Unit I) that is covered by low-grade metamorphic rocks of Mesozoic age in the limbs (Unit II). The eastern limb of the DCS dome is cut by a normal shear zone (Unit III). Three phases (D 1 , D 2 and D 3) of Cenozoic deformation structures are recognized in the complex. The D 1 and D 2 structures constitute the dominant structural style of the Units I and II. The D 1 structures consist of penetrative S 1 foliations, mineral lineations (L 1), symmetrical intrafolial folds (F 1) and tectonic lenses of granitic and quartz veins in rocks from the Units I and II. Mylonitic foliations (S 2 //S 1), NNW-SSE plunging subhorizontal stretching lineations (L 2), widespread A-type folds (F 2), asymmetric porphyroclasts and tectonic lenses form the dominant structural styles in the D 2 deformation. D 3 structures are new foliations S 3 and hot striae L 3 in the normal-slipping shear zone (Unit III). The S 2 //S 1 foliations define the domal framework of the DCS complex, which is truncated by the D 3 shear zone. The dome is NW-SE elongated and has a hinge line paralleling to the L 2 //L 1 stretching lineations. Synthetic analysis of structural and microstructural styles, and kinematic vorticity data estimated by rotated rigid porphyroclast method (0.38–0.69) and oblique grain-shape/quartz c-axis-fabric method (0.72–0.98) implies that the D 1 and D 2 deformations formed a progressive process from early pure shear-dominated (D 1) to simple shear-dominated (D 2) shearing. Shear sense indicators from different parts (Units I and II) of the dome are compatible with top-to-the southeast shearing during D 2 deformation. It is shown that the D 1 -D 2 deformation was characterized by a successive process from penetrative flow (D 1) and ductile shearing at middle to lower crustal levels to doming (D 2) that was coeval with exhumation of the DCS complex since 27 Ma or earlier. We conclude that these processes, i.e., the penetrative flow, ductile shearing, doming and exhumation of the DCS complex, were attributed to lateral subhorizontal middle to lower crustal flow along the ASRR metamorphic belt in the Southeastern Tibetan Plateau during the Indian and Eurasian plate collision. Image 1 • The Diancang Shan complex forms an A-type dome at the northern segment of the Ailao Shan-Red River belt. • Top-to-the southeast lateral subhorizontal shearing occurred along the Ailao Shan-Red River belt at ca. 27-21 Ma. • Lateral subhorizontal shearing, doming and exhumation of the Diancang Shan complex are in relation to middle to lower crustal flow. • The above processes occurred during the tectonic extrusion of the Sundaland block in response to Indian-Eurasian collision. [ABSTRACT FROM AUTHOR]