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The spatial heterogeneity and temporal tendency of snow avalanche (hereafter called avalanche) activities are responses to variations in the inducing environment under climate warming and epitomize the repercussions of the global cryosphere on climate warming. This paper focuses on channeled avalanches in the marine snow climate region of the Parlung Tsangpo catchment in southeast Tibet as an example. Through field investigations, we identify the spatial extents of avalanche paths, while historical avalanche flow paths from the past 35 years (1986/1987–2021/2022) within these paths are interpreted using Landsat optical images. Statistical analysis is then employed to derive spatial heterogeneity and temporal tendencies within and between years. The results indicate that the runout altitudes of historical avalanches primarily range from 3468 m to 4051 m, with average flow directions predominantly following the northwest, north and northeast directions. Avalanche activity peaks between February and April, with longer runout distances observed during this period. Regarding interannual regularity, the evolution of the runout distance, runout altitude, and height difference of avalanche flow paths over the past 35 years demonstrates a cyclic evolution akin to a sine function. Additionally, a moderate correlation between the interannual variation in historical avalanche activity intensity and the Southern Oscillation Index was observed. These findings strengthen the understanding of the temporal evolutionary pattern of avalanches in response to climate warming, providing valuable insights into the channeled avalanche occurrences in the maritime snow climate of southeastern Tibet. • Peak avalanche activity occurs between February and April, with March showing the highest activity. • Spring avalanches runout farther and reach lower elevations than do winter avalanches. • The historical evolution of avalanche activity demonstrates a cyclic evolution akin to a sine function. • A moderate correlation was observed between the historical avalanche activity and the Southern Oscillation. [ABSTRACT FROM AUTHOR]

Many granitoids and their eruptive equivalents are substantially derived from the uppermost proportion of continental crust, and so their petrogenesis and source are significant in understanding the evolution and characteristics of continental crust. The Eocene felsic rocks in the Qiangtang block (central Tibet) commonly have enriched Nd isotope compositions and have been considered to be related to the recycling of ancient continental crustal material. In this paper we report new data on early Eocene felsic rocks with positive ε Nd (t) values in the northeastern Qiangtang block, which can be used to help understand Cenozoic evolution and characteristics of continental crust in the Qiangtang block. These rocks consist of rhyolites and occur in the Shanglaxiu and Xialaxiu areas in the north−eastern Qiangtang block. Zircon U−Pb dating yields ages of 47.8 ± 0.6 and 44.2 ± 0.7 Ma for the Shanglaxiu and Xialaxiu rhyolites, respectively, and so they represent the earliest record of Eocene magmatism in the Qiangtang block. The Shanglaxiu−Xialaxiu rhyolites have relatively low calculated zircon saturation temperatures (719–819 °C), along with high SiO 2 (74.8–83.3 wt%) and K 2 O (5.1–7.8 wt%) contents, and low MgO (0.2–0.3 wt%), Cr and Ni contents. They are enriched in light rare earth elements (LREEs), Rb, K, Th, Zr, and Hf, and are depleted in Nb, Ta, Ti, Sr, and P, with moderately negative Eu anomalies. The Shanglaxiu rhyolites have positive whole−rock ε Nd (t) (0.3–0.4) and zircon ε Hf (t) (1.8–10.4), and variable zircon δ18O (6.3–7.3‰). The Xialaxiu rhyolites have slightly different whole−rock ε Nd (t) (−1.5 to −1.6), but similar zircon ε Hf (t) (2.2–7.7) and δ18O (6.7–7.2‰). We propose that the Shanglaxiu−Xialaxiu rhyolites were most probably generated by partial melting of the pre−existing juvenile crust with the addition of minor sedimentary material. This partial melting was possibly triggered by the south−dipping continental subduction of the Songpan−Ganzi block. The pre−existing juvenile crust was probably formed during the subduction of Paleo−Tethyan oceanic slab in Paleozoic−Early Mesozoic. • The Shanglaxiu-Xialaxiu rhyolites were formed at 44–48 Ma. • These rhyolites were generated by partial melting of juvenile crust and sediments. • These rhyolites were formed during continental subduction. • The juvenile crust might be formed during Paleozoic-Early Mesozoic. [ABSTRACT FROM AUTHOR]

The construction of the deep-buried tunnels of the Sichuan-Tibet railway is facing severe rockburst disasters. Pressure relief boreholes and rock bolt support are effective methods for mitigating rockburst in hard rock. However, the mechanisms and differences in control effectiveness of these methods for different types of rockburst have yet to be revealed. This paper presents the results of two true triaxial unloading rockburst tests: Static-driven rockburst (static tests) due to excavation disturbance and dynamic-triggered rockburst (dynamic tests) due to adjacent tunnel excavation. The rockburst samples include intact granite, granite with a borehole (hole-granite), and granite with a negative Poisson's ratio bolt (bolt-granite). The mitigation mechanisms of the borehole and bolt were investigated in terms of rockburst intensity, failure patterns, and acoustic emission precursors. The results show that borehole and bolt inhibit the formation of a shear fracture plane during rockburst, with the bolt's inhibition effect being more pronounced. For static tests, borehole and bolt significantly reduce rockburst intensity, with the reduction being more significant for bolt-granite. The bolt mainly inhibits the propagation and penetration of shear microcracks. In contrast, the borehole promotes the propagation of shear microcracks. However, for dynamic tests, the rockburst intensity of bolt-granite is equivalent to that of intact granite, while the borehole enhances the rockburst intensity. The bolt inhibits the final buckling crack penetration in dynamic tests, while the borehole promotes slabbing. For static and dynamic tests, the borehole has little influence on precursor indicators, while the bolt increases the difficulty of precursor capture. Generally, the pressure relief borehole is more effective in controlling static tests, while bolt-reinforced support has advantages in dynamic test control. • Rockburst mitigation mechanisms using stress relief borehole and rock bolt support were revealed. • Static and dynamic rockburst tests were conducted on intact granite, hole-granite, and bolt-granite. • Pressure relief borehole is more effective in controlling static tests. • Boreholes and NPR bolts inhibit the formation of shear fracture during rockburst. • The borehole does not influence the optimal AE precursor, but the bolt increases the difficulty of capturing it. [ABSTRACT FROM AUTHOR]

Following the brilliant results of the ARGO-YBJ experiment (Tibet, 4300 m asl), this paper intends to investigate how to optimize the potential of Resistive Plate Chambers (RPCs) for detecting cosmic-ray showers. This requires improving parameters like construction simplicity, low cost, and working reliability in hostile environments, rather than high-rate capability and time resolution as required in collider experiments. RPCs are particularly suitable for the detection of very low energy showers, as shown by ARGO-YBJ. An example of RPC detector, conceived for cosmic-ray physics and gamma-ray astronomy, particularly Gamma Ray Burst (GRB) observation, will be shown. This is of great interest in view of a large-size cosmic-shower detector to be installed in the Southern hemisphere. [ABSTRACT FROM AUTHOR]

• Identification of the Suolong Cu-rich porphyry is suggestive of a new mineralization event. • The porphyry was generated from crust-mantle interactions during the roll-back of subducted NTO. • The features of magma promoted the enrichment of Cu, but thinned crust limited the scale of deposit. The Tibetan Plateau hosts the majority of porphyry Cu deposits in China. There are two large metallogenic belts, the Gangdese and Bangong-Nujiang belts, in the Lhasa Terrane, Central Tibet. The Lhasa Terrane experienced multistage magmatic activity from the Mesozoic to Cenozoic, and the subaerial volcanic areas of the western part of the terrane are regarded as favorable targets of porphyry Cu deposits. In this paper, we describe the geology of our newly identified Early Cretaceous Suolong Cu-rich porphyry in the western Lhasa Terrane and present new U–Pb ages, trace element and Hf isotopic compositions of zircon and whole-rock elemental and Sr–Nd isotopic compositions. The Suolong porphyry contains zircon grains with ages ranging from 136 to 135 Ma, ε Hf (t) values ranging from −1.5 ∼ +2.7 and log f O 2 values ranging from −16.27 ∼ −9.92. Geochemically, the porphyry rocks are peraluminous in nature, with whole-rock ε Nd (t) values of −5.7 ∼ −5.4. We infer that the Suolong porphyry originated from a mixture of ∼53 % enriched lithospheric mantle and ∼47 % ancient lower crustal melt, triggered by the roll-back of the northward-subducting Neo-Tethyan Ocean. The conditions of high oxygen fugacity and water content and tectonic transition promoted the formation of the Suolong Cu-rich porphyry, but the condition of a thinned crust may have constrained the mineralization scale of the Cu deposits. This new identification of Early Cretaceous mineralization event provides important clues for identifying new potential exploration targets for porphyry Cu deposits in the western segment of the Lhasa Terrane. [ABSTRACT FROM AUTHOR]

• Sand wedge deposits were identified in the Early Miocene Wuqia Group. • Sand wedges occurred in braided fluvial environment under arid and cold climate. • The northern Tibetan Plateau surpassed 1000 m elevation in the Early Miocene. The uplift of the Tibet Plateau and its climatic effects have long been a hot topic in academic research. However, there is still significant controversy regarding the uplift history and related climate changes along the northern margin of the plateau. In this paper, we present sand wedge deposits from the base of the Wuqia Group (∼20 Ma) on the southwestern Tarim Basin, representing the oldest reported sand wedges in the Tibetan Plateau. A comprehensive study was conducted on lithostratigraphy, sedimentary environment, and macroscopic–microscopic features of the sand wedge deposits. The results indicate that the lithostratigraphic succession preserving the sand wedge deposits consists mainly of lenticular conglomerates and cross-bedded gravelly sandstone interbedded with medium–thin-bedded mudstone, consistent with the braided fluvial environment. The sand wedge deposits commonly exhibit a V-shape geometry and are filled with gravelly sandstone, with the gravels arranged parallel to the walls of the wedge. The clasts of the wedge-filled sandstone are well-rounded and show a unimodal grain size distribution. The quartz surfaces commonly display dish-shaped and crescent-shaped impact features, indicating an eolian origin and an arid climate. Based on the relationship between the formation temperature of modern sand wedges, the atmospheric temperature gradient, and altitude, the reconstructed paleo-elevation of the sand wedge deposits at the base of the Wuqia Group in the southwestern Tarim Basin is approximately ∼ 1000 m. These results indicate that the northern margin of the Tibet Plateau had already reached an elevation of ∼ 1000 m during the Early Miocene, forming a seasonal arid and cold climate. [ABSTRACT FROM AUTHOR]

• The dynamic stiffness matrix method is used for seismograms synthesis of layered transversely isotropic half-space. • The proposed method is suitable for large-scale and high-frequency cases. • The point sources are equated to the external loads of the auxiliary surfaces. • The numerical results show a 10.91% deviation in peaks distribution and 120% of amplitude since ignoring anisotropy. Natural rocks and soils show significant anisotropic behavior owing to sedimentation and weathering, particularly apparent in the crust. However, seismograms synthesis for the anisotropic medium is scarce, especially bottlenecks for large-scale and broadband seismic wave propagation. In this paper, seismogram synthesis for a multi-layered transversely isotropic half-space due to seismic point sources is addressed by using a dynamic stiffness matrix method. The critical step of the proposed method lies in the construction of the global dynamic stiffness matrix in frequency-wavenumber domain, which avoids the accumulation of errors that appeared in the reflection and transmission matrix method. Exponential divergent terms related to wavenumber and layer thickness in dynamic stiffness matrix are extracted for fast simulating large-scale and high-frequency wavefield. The seismic point sources are equated to the external loads imposed at the introduced auxiliary surfaces, through which the dynamic stiffness matrix can be utilized to obtain the solutions. The accuracy is verified by comparing the proposed method results with three examples in the publications, involving different source types and depth scales. Two numerical examples regarding Thomsen parameters are given to illustrate the mechanism of wave propagation and ground motion in an anisotropic media. Numerical results show that the anisotropic characteristics affect the wave propagation time, waveform and wave-front energy distribution, further leading to shear wave splitting phenomena, which remarkably differ from the isotropic case. A case study using a simplified three-layered crustal structure model in Tibet elucidates that peak ground displacement and its distribution difference within the epicenter of 10 km by comparing with the equivalent isotropic model without considering anisotropic properties. The results show a 10.91% deviation in the location of the peaks, with amplitude differences of up to 120% due to a 45° dip-slip source at different frequencies (from 1 Hz to 15 Hz). [ABSTRACT FROM AUTHOR]

Along with habitat destruction and the intensification of climate change, economic and social development is threatening the living of species. In the context of China's domestic economic circulation, the spatial structure of biodiversity loss is complicated by the decentralization of production, with many regions affecting the survival of species in other regions. Based on the environmentally extended MRIO model, this paper calculated the subnational biodiversity loss footprint through structural path analysis and social network analysis, identified the regional linkages and spatial networks of species loss, and traced the conservation responsibility to specific sectors. Our findings indicate that Yunnan, Tibet, Guangdong, and Sichuan possess the most significant biodiversity footprints, comprising over 40% of the total footprint. In terms of threat patterns, Yunnan and Tibet have the largest intra-regional footprints, indicating their important impact on species within the region; Guangdong and Zhejiang have the largest extra-regional footprints, indicating their role in threatening other species through cross-regional trades. The primary industry, tap water and food and tobacco sectors are major biodiversity footprint producers. Overall, some eastern and coastal areas are the final drivers of biodiversity loss in China, driven by increasingly complex trade links. Notably, the directionality of species loss in biodiversity hotspots is evident, with Shandong and Guangdong significantly influencing the biodiversity of Yunnan and Guangxi, respectively. This study systematically analyzed the complete network of biodiversity loss and divided four biodiversity protection communities to promote the realization of trans-regional protection and compensation. Examining the biodiversity loss through the lens of networks, and connecting economic activities to species, serves as a warning to decision-making bodies that a future of increasingly intricate domestic trade could pose a critical threat to biodiversity, necessitating collaborative conservation efforts. [Display omitted] • 1.Inter-provincial trade contributes to the complex structure of biodiversity loss. • The characteristics of biodiversity footprints vary widely among provinces. • Some eastern and coastal provinces are the final drivers of biodiversity loss. • Four protection communities are established through social network analysis. [ABSTRACT FROM AUTHOR]

Mountain glaciers are one of the most sensitive indicators of climate change. Reconstructing past glacier extents provides valuable insights into the climate change for specific regions where instrumental records are not enough and even absent. In the paper we mapped the outlines for 691 Little Ice Age (LIA) glaciers in terms of prominent moraines beyond contemporary glaciers in the Tanggula Mountains, central Tibetan Plateau (TP). Based on these glacier outlines, we reconstructed the ice thicknesses and surfaces for the LIA glaciers in the region. Accordingly, we calculated the equilibrium-line altitudes (ELAs) for contemporary and LIA glaciers. By comparing the ELAs between the contemporary and LIA glaciers, we estimated the LIA summer temperature decreases in different subregions of the Tanggula Mountains. Since the LIA, the ELA have risen by 35.6 ± 18.8 m, 26.1 ± 17.6 m, and 63.1 ± 38.6 m in the respective western, central, and eastern subregions of the Tanggula Mountains. Assuming no change in precipitation, the LIA summer temperature would decrease by 0.22 ± 0.12 °C, 0.14 ± 0.09 °C, and 0.34 ± 0.21 °C in the three subregions, respectively. Moreover, glaciers in the western, central, and eastern subregions have lost 13.3%, 23.9%, and 42.8% of their area, 15.4%, 25.3%, and 39.6% of their length, and 20.8%, 39.0%, and 61.0% of their volume, respectively. By compiling the LIA ELA data from previous studies, we also estimated the LIA summer temperature changes for other regions of the TP. The LIA ELA and summer temperature changes relative to the present showed a decreasing trend from the edges towards the interior on the TP. • LIA glaciers and summer climate were reconstructed at the Tanggula Mountains. • LIA summers were 0.22 ± 0.12 °C, 0.14 ± 0.09 °C, and 0.34 ± 0.21 °C cooler than present in three subregions. • Summer temperature change had a decreasing trend from the edges towards the interior on the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

[Display omitted] • To computationally simulate the ore-forming process in the Luziyuan deposit. • To determine the boundary conditions of the deposit model in a scientific way. • To identify the controlling ore-forming mechanism in the Luziyuan deposit. • To use computational simulations for identifying the location of an ore deposit. The giant Luziyuan Pb-Zn deposit is a typical hydrothermal ore-forming deposit in the southern Baoshan block of SE Tibet. Although extensive studies were conducted to understand the ore-forming system associated with the Luziyuan Pb-Zn deposit through using the traditional geoscience methods, the ore-forming process involved in this deposit has not been justified in a strictly scientific manner to date. In this paper, the hydrothermal ore-forming process of the Luziyuan Pb-Zn deposit is computationally simulated through using the dual length-scale approach associated with the finite element method (FEM). In the dual length-scale approach, the FEM is first used to simulate the regional model of a large length-scale in the geological region where the Luziyuan Pb-Zn deposit is located. Afterward, the FEM is then used to simulate the deposit model of the Luziyuan Pb-Zn deposit. Particularly, the boundary conditions of the deposit model are consistently determined from using the computational simulation results of the regional model. The related numerical results demonstrated that: (1) the pore-fluid convection provides a continuous source of ore-forming fluid and ore-forming material for the Luziyuan Pb-Zn deposit; (2) the convective pore-fluid flow is the main dynamic mechanism, which controls the temperature, pore-fluid velocity and chemical species distribution in the Luziyuan Pb-Zn deposit; (3) the localized structure is the main controlling factor for the localized pore-fluid flow pattern, which further controls the formation and location of the orebody in the Luziyuan Pb-Zn deposit; (4) the dual length-scale approach associated with the FEM is very useful for simulating the hydrothermal ore-forming process of the Luziyuan Pb-Zn deposit. [ABSTRACT FROM AUTHOR]

Due to the collision and lateral compression of the Indian-Asian plate, the Lancangjiang fault has become one of the most active strike-slip faults in the Qiangtang plate. The Qamdo 2013 Ms 6.1 earthquake was induced from the northern section of the fault (the northern Lancangjiang fault). The destruction of the earthquake seriously endangers human activities and the construction of the Sichuan-Tibet Railway. However, there are few high-resolution geophysical data in this area, which limits the understanding of the deep structure, motion mode and seismic activity of the northern Lancangjiang active fault. In this paper, new gravity data were observed at a scale of 1: 200,000, covering an area of 1500km2. Based on wavelet multiscale decomposition, scratch analysis and 3-D inversion of gravity data methods, we obtained gravity anomalies of different scales, faults distribution and density structure. The results show that the overall crustal density change in Qamdo area is obvious and closely related to the distribution of faults. The Qamdo earthquake occurred at the layered interface with steep density change and the result from scratch analysis shows that the stress is concentrated at this position. We believe that the existence of stratigraphic density difference leads to different ability of strata to withstand regional tectonic stress, which is an important cause of the Qamdo earthquake. We analyzed the differences magnitude of earthquake activity between the northern Lancangjiang fault and Kamaduo-Gangtuo fault and believe that the northern Lancangjiang fault is more conducive to the preparation of large earthquakes. Otherwise, this paper provides geophysical evidence for the hypothesis that the northern Lancangjiang fault thrusts to the Qamdo Basin at a high angle. • Crustal density change in the Qamdo is more complex. • Crustal density characteristics are linked to distribution of faults. • The northern Lancangjiang fault thrusts into the Qamdo Basin at a high angle. • The northern Lancangjiang fault is conducive to the preparation of large earthquakes. • The Qamdo earthquake occurred at the layered interface with steep density change. [ABSTRACT FROM AUTHOR]

The Qinghai-Tibet Plateau (QTP) is an area with highly distinctive natural and socio-cultural characteristics. In recent years, the pastoral areas of northern Tibet have undergone a phase transition from nomadic to settled grazing, and the settlement system is in a stage of formation and evolution. Against the backdrop of China's new strategy of rural revitalization, conducting associated research on the evolution of the settlement system and the prospect of rural revitalization is of great significance for improving the living and working conditions of herdsmen in alpine pastoral areas and promoting sustainable development on the QTP. Using settlement patch data obtained by visual interpretation of high-definition remote sensing images, combined with field investigations, this paper explores the temporal and spatial evolution characteristics of the settlement system in Nagqu County, northern Tibet, summarizing its development status and existing problems from the perspective of factor-structure-function, and details the paths for rural revitalization on this basis. The results show the following: (1) Since 2005, the settlement system of Nagqu County has undergone a phase transition from concentrated settlement to functional expansion, with the continuous enrichment of development elements and the enhancement of functions. The density distribution of settlements shows strong adaptability to the natural geographical environment. The pattern of settlement has gradually changed from resource-dependent to facility-dependent. Transportation and public service facilities play an important role in guiding the speed and direction of settlement evolution. (2) There are still various problems in the settlement system of Nagqu County, including a weak industrial foundation; some occupation of important ecological spaces and ecologically fragile areas by settlements; insufficient attention to the cultural aspect of the Tibetan settlement system; a scattered settlement layout, which makes grassroots governance difficult; a large talent gap; and weak spatial support system of settlements. (3) From the perspective of enriching and integrating the development factors of rural settlements, reorganizing the diversified structure of rural settlements, and improving and expanding the functions of rural settlements, this paper explains the correlation mechanism between optimization of the rural settlement system and rural revitalization, and puts forward the implementation paths for rural revitalization in alpine pastoral areas of the QTP. The study expands our understanding of the characteristics of settlements in sparsely populated alpine pastoral areas, and provides valuable, up-to-date policy guidance for the promotion of rural revitalization in alpine pastoral areas on the QTP. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lilong ultramafic igneous rocks are Late Cretaceous sulfide-bearing cumulates. • Mantle sources of Lilong ultramafic igneous rocks had been metasomatized by terrigenous sediment- and altered oceanic crust-derived fluids. • Deeply subducted oceanic crust plays an important role in the formation of sulfide-bearing juvenile mafic lower crust of magmatic arc. Post-collisional porphyry copper deposit (PCD) is a new genetic type of PCDs discovered in the Himalayan–Tibetan orogenic belt. It is believed that the formation of ore-forming magmas results from the re-melting of a sulfide-bearing, thickened, juvenile mafic lower crust in a magmatic arc associated with the oceanic plate subduction. However, the material contribution of subduction processes to the formation of this particular arc magma remains unclear. In this paper, we attempted to present a study that includes petrology, mineral geochemistry, whole rock Sr–Nd–Li isotopes, of Late Cretaceous Lilong ultramafic igneous rocks, south Lhasa sub-terrane, Tibet. The target ultramafic igneous rocks are sulfide-bearing cumulates. They show relative depletion in whole rock Nd isotopic compositions, slightly elevated (87Sr/86Sr) i ratios (0.7043–0.7059), and variable δ7Li values (2.8–9.0‰). Simulation results showed that trace element of melts in equilibrium with cumulus hornblende grains exhibit typical arc-like trace element distribution patterns, indicating that these ultramafic igneous rocks crystallized from arc magma. Additionally, the modeled melts showed enrichment in melt-mobile elements such as Ba, Pb, Sr, Th, and light rare earth elements (LREE), and higher Th/Yb ratios, as compared with normal mid-ocean ridge basalt (MORB). These geochemical properties can be explained by the metasomatism of depleted MORB mantle peridotites by hydrous melts derived from subducted seafloor sediments. Whole rock Sr isotopes show correlations with Ba/Nb and Th/La ratios for the modeled melts, showing that fluids from the basaltic igneous crust, in addition to hydrous melts from the seafloor sediments, contribute to their mantle source. In addition, the heterogeneity of whole rock δ7Li values for ultramafic igneous rocks also indicates that their mantle sources have been metasomatized by terrigenous sediment- and altered oceanic crust-derived fluids. Depleted MORB mantle peridotites react with the mixed fluids at sub-arc depths to produce ultramafic metasomatites, and model calculations for trace element contents and Sr–Nd–Li isotopic compositions further validate that the geochemical compositions of the Lilong ultramafic rocks can be clarified by this process. The results show that the deeply subducted oceanic crust may have played an important role in the formation of sulfide-bearing juvenile mafic lower crust of this magmatic arc. [ABSTRACT FROM AUTHOR]

Schematic representation of Isostatic balance between source and sink distribution of sediments and tectonics. [Display omitted] • The NSCSM evolved and linked with successive uplifts in SE Tibet Plateau. • Deep and surface parameters isostatically influence sediments and control their geometry. • Strengthening of lithosphere at the continental margin isostatically balanced with inland exhumation. Tectonic processes of the SE Tibet Plateau (SETP) and the northern South China Sea margin (NSCSM) strongly affected the surface drainage system for sediment transportation to deposition. It remains challenging to investigate the dominant mechanisms such as tectonics, deep dynamics, and surface processes. This paper aims to examine the influence of the SETP paleogeography on the NSCSM. Twenty-eight seismic profiles were quantified by flexurally interpolated backstripping and significantly correlated with the published paleogeography. A numerical simulation tool (Badlands) is assigned to study the integrated response of surface processes and deep dynamics. This paper inferred that drastic sedimentation changes in our models were linearly correlated mainly with erosion during the SETP uplifts, dynamic topography, and flexural isostasy. Deep dynamics and tectonic processes control basin architectures for sediment depositions, whereas the surface processes contribute isostatically in response to uplifts in the source region. We inferred that Eocene was the stage of extension, thinning of lithosphere (Te = 10 km) that is linked with the low topography (<2000 m) and erodibility (Є) of 5e-7 in the SETP. However, the increase in cumulative thickness is associated with strengthening the lithosphere (Te = 15 km) and tributary rotation with its rise in SETP topography (≥4000 m) during the Oligocene to Early Miocene. The Middle Miocene doesn't have the source-sink linkage for its high SETP topography with low deposition. But a strong connection with paleogeographic evolution in the later stage due to the rise in SETP topography and Taiwan orogeny. [ABSTRACT FROM AUTHOR]

[Display omitted] • The land surface area of the mainland China was calculated based on 30 m resolution DEM. • Absolute difference and relative difference of ESV based on surface area and plane area was conducted at country, provincial and county levels. • The characteristics of temporal-spatial variation of ESV of various ecosystems based on surface area in China were revealed. • The total ESV based on surface area was compared with other studies. • The importance of the surface area in land resource survey, natural asset estimation and ecological protection was emphasized. The assessment of ecological assets is of great significance for protecting and using ecological resources. Traditional methods of ecological assets assessment, which adopt the planar area as the standard, often ignore the impact of the surface area, resulting in a large difference between the evaluation and the actual result. To fill this gap, this paper conducted research on ecological assets assessment based on surface area. Taking mainland China into consideration, this paper constructed a triangulation network based on 30 m resolution DEM data to simulate the real land surface form and calculate its surface area. Then, land use/cover data from 1995, 2000, 2005, 2010, and 2015 were used to estimate the ecosystem service value (ESV) and analyze its spatial variation. This paper found that: (1) The surface area of mainland China is 1.04 × 107 km2, which is 8.2 × 105 km2 larger than the planar area; (2) A huge difference was found between the total ESV based on the surface and planar area, with an absolute difference of ∼$141.66-$144.14 billion and a relative difference of ∼ 10%. For different ecosystem types, the largest difference was found in the forest ecosystem, followed by the grassland ecosystem, while the wetland ecosystem showed the smallest difference; (3) The high value of absolute difference between the ESV based on the surface and planar area was concentrated in Tibet and Northeast China. The high value of relative difference was mainly distributed in Central and Southern China. On the provincial level, the absolute difference in Tibet ranked in the first place. There was a total of 14 provinces showing a relative difference above 10%; (4) The total ESV based on surface area was basically unchanged, while various ecosystems underwent significant changes. The ESV of wetland increased by nearly 50%, while the ESV of grassland decreased by more than 10%; and (5) Change in the ESV based on surface area showed obvious spatial heterogeneity. High-High cluster was located in Tibet and the Northeast China while the Low-Low cluster was distributed in the North China Plain and Xinjiang. This paper emphasized the importance of the surface area in resource survey and asset estimation and gave more effective suggestions for ecological protection. [ABSTRACT FROM AUTHOR]

Measurements of stable water isotopes (oxygen and hydrogen) are commonly used to estimate palaeoelevation and quantify past changes in surface height across Tibet. Isotope palaeoaltimetry is often based on simple Rayleigh fractionation of a "parcel of air", but must make a considerable number of approximations and assumptions. In this paper, we elaborate on the practicability of oxygen water isotopes in palaeoaltimetry, and evaluate a recent challenge to the palaeoaltimetry community. First, we examine the isotopic composition of oxygen (δ 18 O) versus altitude relationship in a set of five topographic realisations of Tibet using an isotope-enabled palaeoclimate model for the mid-Eocene, a period where a variety of topographic 'uplift' models have been proposed, and compare it to modern relationships. Second, we investigate whether isotopic composition is a good predictor of more modest changes in topography, such as the introduction of a valley system or uplift of only part of the Tibetan region. The aim of the paper is not to perform a direct comparison to data, but to use the model to further refine knowledge of the strengths and limitations of using oxygen isotopes in palaeoaltimetry. We find that oxygen isotope palaeoaltimetry works surprisingly well, with the exception that it could not identify low elevation valley systems bounded by high elevations because the isotopic composition of the water in the air becomes depleted at the first high elevation that an air parcel passes over and does not recover when it descends into the valley. Hence, isotope-based elevations are biased towards mountain range peaks. Overall, the application of oxygen isotope palaeoaltimetry does have value, but would be further strengthened when employed together with isotope-enabled models. In conjunction with other techniques such as terrestrial thermal lapse rates and energy conservation approaches, over a wide spatial region, a more accurate and fully three-dimension view of complex palaeo-topography is increasingly possible, which will in turn improve the precision of these palaeoaltimeters. • Isotope enabled paleoclimate models can aide paleoaltimetry studies. • Water isotope paleoaltimetry can accurately reproduce mountain height. • Accurate reconstructions of complex topography are more challenging. • Airmasses modification along the elevation trajectory can bias the height estimate. [ABSTRACT FROM AUTHOR]

The Gangdese arc underwent the most intense magmatic flare-up of southern Tibet in the early Eocene (peaked at ∼50 Ma), generating widespread plutonic and volcanic rocks both along and across the arc. However, the dynamic mechanism for the magmatic flare-up is mysterious. This paper systematically analyzed the petrology, mineralogy, geochronology, and geochemistry of the early Eocene volcanic and intrusive rocks in the Pangduo basin in the eastern Gangdese arc. These rocks yielded identical zircon U Pb ages of ∼50 Ma and similar isotopic compositions. The low-silica (< 60 wt%) rocks, including basalt andesite and trachyandesite, result from low degree (2–3%) partial melting of garnet-bearing lithospheric mantle. Based on textural observations and geochemical studies, coupled with Rhyolite-MELTS modeling and zircon trace elements Rayleigh fractionation models, the following research results were obtained. The high-silica rhyolite, ignimbrite, and granite porphyry are the product of limited melt extraction, while the quartz monzonite belongs to the associated residual silicic cumulates. The quartz monzonitic porphyry and trachydacite show a widespread dissolution structure and high formation temperature of ∼850 °C. Whole-rock geochemical mixing model results indicate that they are generated by mixing products of mafic magma, high-silica melts, and remelting melts of quartz monzonite. The volcanic and intrusive rocks in the Pangduo basin are considered as a volcanic-plutonic complex, resulting from the synergistic effect of melt extraction and cognate magma mixing. Both the complex magmatic processes and the early Eocene magmatic flare-up are attributed to mafic magma injection. • The Pangduo volcanic-plutonic complex with various rock types is well exposed in the Pangduo basin, southern Tibet. • The rhyolitic ignimbrite and the quartz monzonite are extracted melts and corresponding residual cumulates, respectively. • Melt extraction and magma mixing via mafic magma injection promote the large-scale magma formation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lower crustal rocks may be a major contributor of Au in the orogenic gold deposits. • Thermodynamic modeling can reveal the mechanisms by which Au is released. • Chlorite breakdown can be considered the main release mechanism of Au. • Prograde metamorphism can efficiently extract Au from lower crustal rocks. The metamorphic devolatilization model is presently the most widely accepted model for the formation of orogenic gold deposits. According to this model, Au is likely derived from metamorphic rocks that experienced metamorphism from greenschist to amphibolite facies. Nevertheless, in recent years, some researchers have suggested that Au may have originated from different source regions, such as the mantle. As one of China's most significant orogenic gold provinces, the Indus-Yarlung Zangbo suture zone (IYZSZ) in southern Tibet plays a critical role in this discussion. Orogenic gold deposits within the IYZSZ are typically hosted in Triassic metasedimentary rocks called the Langjiexue group. This paper aims to investigate the suitability of metasedimentary rocks of the Langjiexue group as a source region of Au and base metals. Furthermore, we also examine whether the metamorphic devolatilization model is applicable to the IYZSZ. Our study involves reporting the mineral compositions and evolution of metamorphic zones (chlorite to sillimanite zones) in metasedimentary rocks obtained from the IYZSZ and providing detailed petrographic descriptions of these rocks. Thermodynamic modeling based on metamorphic mineral compositions was used to reveal the behaviors of H 2 O, Au, S, Cu, Pb, and Zn within prograde metamorphism. Our modeling results proved that the breakdown of chlorite and muscovite, both of which are the main mechanisms of Au and base metals release in metasedimentary rocks, occurs under different geothermal gradients. Given the observed metamorphic mineral compositions, it is the breakdown of chlorite that is the predominant reaction responsible for releasing Au and base metals under the real geothermal gradient of lower crustal metasedimentary rocks (∼25 °C/km). This gradient is capable of releasing at least 1.5 ppb Au, 5.2 ppm Cu, 4.3 ppm Pb, 5.0 ppm Zn, and 20 ppm S (as part of the bulk rock) into the ore fluids. Through the mass balance calculations, we found that over 4.05 t of Au, 14,040 t of Cu, 11,600 t of Pb, and 13,500 t of Zn can be mobilized from 1 km3 of metasedimentary rocks. Therefore, lower crustal metasedimentary rocks can play a significant role in contributing to Au and base metals in the IYZSZ and other metasediment-hosted orogenic gold deposits worldwide. [ABSTRACT FROM AUTHOR]

In the context of carbon neutrality, renewable energy, especially wind power, solar PV and hydropower, will become the most important power sources in the future low-carbon power system. Since wind power and solar PV are specifically intermittent and space-heterogeneity, an assessment of renewable energy potential considering the variability of wind power and solar PV with high temporal resolution in different regions will facilitate more accurate identification of the decarbonization pathway of power system. In this paper, the complementary output potential of wind-solar-hydro power every 15 min in 31 Chinese provinces is evaluated by developing a multi-objective optimization model based on Nondominated Sorting Genetic Algorithm II. The results show that the total annual complementary power generation potential in China is 17.57 PWh, of which the three components account for 47.8%, 25.3% and 26.9%, respectively. Inner Mongolia and Tibet are the major renewable energy source provinces with annual complementary power generation potential of 5330 TWh and 3907 TWh, accounting for 30.3% and 13.7% of the total power generation potential, respectively. The temporal potential of wind-solar-hydro power varies greatly, with daily potential is more volatile than monthly. Seasonal and spatial heterogeneity of the complemental renewable potential makes some provinces suffer power shortage during long-hours period especially in winter. Our findings will encourage a higher penetration of renewable energy, the promotion of multi-energy complementarity, and the development of inter-provincial power transmission and energy storage infrastructure in China's future power sector. • A multi-objective wind-solar-hydro complementary optimization model is developed. • Electricity supply and demand have gaps at different temporal and spatial scales. • Wind-solar-hydro complementary potential shows great temporal and spatial variation. • Renewable complementarity can improve China's future power system stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Depleted continental mantles occur with different mineral chemistry and occurrence. • Mafic dikes were formed from melts via low-degree melting of asthenosphere mantles. • Orthopyroxenites were formed from reaction between SiO 2 -rich melts and peridotites. • Ophiolites were formed in a continental margin that was related to the Meso-Tethys. Whether the ophiolites in the southeast margin of the Gaoligong tectonic belt are related to subduction or rift is hotly debated. The aim of this paper is to present the geological and geochemical data of these ophiolitic blocks in order to understand the significance of these in the tectonic evolution of the Meso–Tethys. The peridotites in the ophiolites are dominantly harzburgites with high Mg# (88.7–92.2) and low Al 2 O 3 (<0.8 wt%) and CaO (<0.5 wt%) contents, and display U-shape chondrite-normalized rare-earth element patterns. However, they show two different groups of mineral chemistries and occurrences. Group I are with olivine Fo 90.6–92.3, orthopyroxene Mg# 91.0–92.6, clinopyroxene Mg# 91.1–93.3, and spinel Cr# 42.1–67.4 and Mg# 62.8–71.6. They exhumed adiabatically and were intruded by mafic dikes from the melts through low-degree melting of asthenospheric mantles and by orthopyroxenites in the Early Jurassic. Group II are with olivine Fo 89.8–95.3, orthopyroxene Mg# 91.3–94.6, and spinel Cr# 62.4–94.1 and Mg# 19.5–51.0. They underwent brittle deformation and medium- to low-temperature fluid replacement. The two group's peridotites have experienced the similar partial melting degrees and are the fragments of subcontinental lithospheric mantles. Extensive continental affinity tholeiites erupted in the Middle Jurassic, coeval with the primary spreading time of the Bangonghu–Nujiang Ocean in the central Tibet. The peridotites, mafic rocks, and marine-facies sediments represent the opening products of the Meso–Tethys in the Jurassic as ophiolites in a continental margin. [ABSTRACT FROM AUTHOR]

• The ecohydraulic modeling framework is a valuable tool for assessing fish ecology in dammed rivers. • Cascade dam construction could fragment spawning site habitats and reduce fish population abundance in the tailwater zone of the main stream. • Spawning site habitats would improve, leading to an increase in fish population abundance in the backwater zone of tributaries. • The effects of cascade dam construction on endemic fish habitat and population status depend on spawning site location, fish species, and life stages. Cascade dam constructions will alter the habitat of spawning sites and affect fish population in the Lancang River basin. This paper examines the impacts of cascade dam construction on four spawning sites, focusing on two co-distributed and endemic fish species: Schizothorax prenanti and Schizothorax davidi. An ecohydraulic modeling framework that combined hydro-morphodynamic, habitat, and population models was used to investigate changes in habitat quality and fish population under two scenarios: no-dam and with-dam. Fish habitat quality was evaluated using the habitat suitability index, and population fluctuations were assessed by the abundance and density of fish populations at all life stages. The simulation results indicated that cascade dam construction would fragment the spawning site habitat in the tailwater zone of the main stream and result in a decrease in fish population abundance and density. Conversely, spawning site habitats in backwater zone of tributaries would improve, and fish population abundance and density would increase. Additionally, the simulation results showed that the magnitude of fish population variations varied by species and life stages. These results highlight the different responses of spawning site location, fish species, and life stages to dam construction, which can help identify areas of the habitat with higher potential for finer-scale endemic fish conservation and recovery efforts. This study provides a comprehensive framework tool for fish ecological evaluation in dammed rivers, which has the potential to assist decision-makers involved in river ecosystem ecological conservation. [Display omitted] [ABSTRACT FROM AUTHOR]

• Water erosion on the Qinghai-Tibet Plateau decreased from south to north. • Water erosion decreased from 1982 to 2015 but slightly increased since 2007. • Climate variability enhanced erosion and human activity reduced it from 1982 to 2015. Climate variability and human activities cause changes in precipitation and underlying surface conditions, which are the main driving forces of changes in water erosion, especially in the Qinghai-Tibet Plateau (QTP). In this paper, the water erosion on the QTP from 1982 to 2015 was quantified by the Revised Universal Soil Loss Equation (RUSLE), and the response of water erosion changes to climate variability and human activities was investigated. The results indicated that the distribution of water erosion gradually decreased from south to north during 1982–2015. Areas of severe erosion were mainly distributed along the Yarlung Tsangpo River and in the western Hengduan Mountains. The years of the abrupt change in water erosion were 1989 and 2006. Compared to 1982–1989, the amount of water erosion was mitigated in both 1990–2006 and 2007–2015, with a 19.5% and 6.2% decrease, respectively. The contribution of human activities to the decrease in water erosion was 25.4% and 16.7% for each of these periods, respectively, and the contribution of climate variability to the increase in water erosion was 5.9% and 10.5%. However, water erosion increased by 16.5% from 2007 to 2015 compared to 1990–2006. The contribution of climate variability was 4.9% and the contribution of human activities 8.4%. The increase in water erosion due to human activities may be attributed to the construction of the Qinghai-Tibet Railway and associated human activities. It is therefore important to draw attention to the influence of human activities on the QTP on erosion, to prevent potential future risks. This study is the first attempt to research the relative contributions of variation in climate and human activities to changes in water erosion on the QTP. It would be beneficial for carrying out ecological environmental protection work on the QTP. [ABSTRACT FROM AUTHOR]

When impinging on the lithosphere in spreading ridges or intra-plate settings, the asthenospheric mantle can significantly influence plate tectonics. However, the active role of the asthenospheric mantle on subducting slabs remains poorly understood. The main reason for this dispute is the lack of typical geochemical mafic rocks in the subduction zone. In this paper, we first report the Early Jurassic (187 Ma) Yurongguo Nb-enriched basalts in the western segment of the Bangong-Nujiang suture zone. These samples show typical Nb-enriched basaltic features with high Na 2 O, TiO 2 , Nb (>7 ppm), high Nb/Th (average = 11.05), Nb/La (average = 1.37) and Nb/U (average = 72.98) ratios. Unlike the adakite-related Nb-enriched basalts, the Yurongguo Nb-enriched basalts formed from the mixture of magmas derived from upwelling asthenosphere (20–30%) and depleted mantle (70–80%) in the spinel lherzolite region (<70 km). We conclude the Yurongguo Nb-enriched basalts were formed in the fore-arc basin setting with the influence of slab rollback, which occurred under the intra-oceanic subduction. Two southward intra-oceanic subductions may exist in the western part of the Bangong-Nujiang Tethyan Ocean in the Jurassic. The Early Jurassic (200–180 Ma) intra-oceanic subduction formed the fore-arc basin, probably accompanied by asthenospheric mantle activity at the same time, followed closely by flat subduction due to the oceanic plateau. After a period of geological stabilization, the Late Jurassic (170–150 Ma) was the period when the spreading of the little ocean basin ceased, and the second intra-oceanic subduction occurred. We proposed an oceanic plateau-subducted oceanic slab interaction and overriding intra-oceanic subduction model for the Meso-Tethyan subduction in the western Tibetan Plateau. • Yurongguo rocks were formed in 187 Ma, which are the typical Nb-enriched basalts. • OIB (20–30%) and MORB (70–80%) mixed to form the Yurongguo Nb-enriched basalts. • Yurongguo Nb-enriched basalts are the consequence of intra-oceanic subduction. • Oceanic plateau played an important role in the intra-oceanic subduction. [ABSTRACT FROM AUTHOR]

The Late Paleozoic Ice Age is characterized by diverse stratigraphic records with extensive spatial-temporal distribution in the Gondwana. The Lhasa terrane located in northeastern Gondwana during the late Paleozoic developed successive glacial sedimentary records, but the depositional evidence, as well as age constraint for the onset of glaciation, is unknown. This paper provides the first full description of the basal glacial deposits in the Xainza area of Lhasa terrane, southern Tibet. Conodonts present in the carbonate overlying the glacial bed (1 m) dominantly consist of Declinognathodus intermedius , indicating that the initiation of the Late Paleozoic Ice Age in the Lhasa terrane took place in Bashkirian. Three facies associations were recognized: (i) tidal flat association (subtidal channel, bar, intertidal mixed flat), (ii) subglacial association (megaclasts and melt-out diamictite), and (iii) lonestone-bearing heterolithic association (grounding-line fan and iceberg). These facies associations are vertically arranged into a complete transgressive-retrogressive glacial succession. Ice movement direction reconstructed from the imbricated megaclasts, the concordant folds and the lateral distribution of subglacial deposits and glacial marine deposits is consistently from NNE to SSW. These characteristics suggest that the Bashkirian glaciation in the Lhasa terrane is irrelevant to western Australia, implying that these two blocks were separated during the Late Carboniferous. • The initiation of the LPIA in the Lhasa terrane took place in Bashkirian. • The tidal flat, subglacial and lonestone-bearing heterolithic associations were recognized. • The reconstructed ice movement direction is from NNE to SSW. • The Bashkirian glaciation in the Lhasa terrane is irrelevant to western Australia. • The Lhasa terrane was separated from Australia during the Late Carboniferous. [ABSTRACT FROM AUTHOR]

Due to the unclear tectonic setting of the Jurassic ophiolites within the Bangong-Nujiang suture, how and when intra-oceanic subduction initiated within the Bangong Meso-Tethys remain controversial. Based on the new petrological, geochemical, and geochronological data reported in this paper, ∼190–180 Ma MORB-like ophiolites and OIB-like mafic rocks were identified from the Shiquanhe ophiolitic complex in the western Bangong-Nujiang suture. The MORB-like gabbros exhibit strong light rare earth elements (LREEs) and heavy rare earth elements (HFSEs) depletion and were derived from partial melting of a highly refractory depleted mantle source with limited slab-derived fluids. The OIB-like mafic rocks are enriched in LREEs and HFSEs and were originated from the melting of upwelling asthenospheric mantle without subduction additions. The data for the MORB-like ophiolites reported in this paper and previously published data demonstrate the formation of Early Jurassic fore-arc ophiolites in response to the Early Jurassic intra-oceanic subduction initiation within the Bangong-Nujiang suture. The Early Jurassic OIB-like rocks formed in the extensional tectonic setting, together with regional geological evidence, suggest that the Early Jurassic initial subduction event within the Bangong Meso-Tethys resulted in broad upper plate extension. Our study not only reveals the intra-oceanic subduction initiation age of the Bangong Meso-Tethys but also implies that subduction initiation can cause strong extension in a wider region of the upper plate in the Tethys oceanic system, not just in the fore-arc region. • Discovery of MORB-like fore-arc ophiolite (190–185 Ma) in the Shiquanhe area. • Identifying of OIB-like gabbro-monzonite (185–180 Ma) in the Shiquanhe melange. • Confirming Early Jurassic intra-oceanic subduction initiation in Bangong Ocean. [ABSTRACT FROM AUTHOR]

The population of countries with high altitudes accounts for about 20.4% of the world's population, but the annual electricity consumption is still at a low level, which significantly slows down the development of these regions. Wind energy is suggested as the solution, but the progress is very slow due to challenges in operations from the relatively harsh environment. To overcome this challenge while considering Qinghai-Tibet plateau is one of most representative high altitude regions in the world, we recently developed a 22 MW wind farm at an altitude of over 5000 m in Tibet, China, and conducted a one-year field-test campaign using direct-drive permanent-magnet generators (DDPMGs) and doubly fed induction generators (DFIGs) as a case study. In this paper, we report some main results. During resource assessment, it is found that the wind speeds is between 11 m/s and 22 m/s for most winter time with abundant energy production but relatively significant daily fluctuation due to temperature change. From a technology perspective, we found that both DDPMGs and DFIGs can adapt to the ultra-high-altitude environment. Wind turbines with DDPMGs are reliable because of their gearless design, and turbines with DFIGs have a lower cut-in wind speed, which enables them to generate power in regions with low wind speeds. This wind farm generates nearly 60 million kWh of electricity to support 8410 local households per year. It can also eliminate the need to burn 50.24 million kg of cow dung, thereby effectively reducing the local residents' dependence on burning organic matter for energy. This study is expected to provide guidance to technology developers and governmental policymakers to plan future wind farms in the high altitude area. • Field study of the world first wind farm over 5000 m was systematically conducted. • Wind speed is found as 11–22 m/s with significant fluctuation in winter. • Performance and reliability of different turbine designs are extensively discussed. • The 22 MW farm can provide 60 m kWh electricity to support 8410 households. [ABSTRACT FROM AUTHOR]

Studies of geochemical proxies, such as carbonate δ18O and TEX 86 , show that the Earth's climate has changed significantly during the Cretaceous Period. However, knowledge about the sea surface temperature (SST) history of the eastern Tethys is limited. Based on the calcareous nannofossil record of the Nirang section, Tethys Himalayas, this paper attempts to establish the biostratigraphic framework and SST evolution of the Cretaceous Period in the southern Tibet. A total of 131 species were identified from the studied succession. Twelve bioevents were recognized, allowing for early Albian to the early Campanian (CC8 to CC18 biozones) in the section. Meanwhile, a disconformity within 81–71 Ma was also identified. The SST evolution was analysed by the calcareous nannofossils modified temperature index (mTI), and the results reveal that the long-term SST changes in the Tethys Himalayas of southern Tibet experienced progressive warming from the early Albian to the early Turonian and the warm interval persisted until the early Campanian. Short-term warming and cooling events, e.g., rapid warming in the early and late Albian, subsequent cooling in the latest Albian and peak warmth at the Cenomanian–Turonian transition, are also recorded in the study area. The SST history of the Albian-Cenomanian in the eastern Tethys can be well correlated to the western Tethys (central Italy). However, the compilation of TEX 86 data indicates substantial global cooling during the Coniacian to Campanian. This study suggests that the northward drift of the Indian continent towards the equator is likely to be responsible for the sustained warmth in the Tethys Himalayas from the middle Turonian to the early Campanian. • Calcareous nannofossil biozones of Albian-early Campanian in Tethys Himalaya of southern Tibet is defined. • Based on mTI of nannofossils, long term history of Cretaceous palaeoclimate of eastern Tethys is reconstructed. • The SST history in Tethys Himalaya is controlled by changes of global palaeotemperature and regional palaeolatitude. [ABSTRACT FROM AUTHOR]

Granitic rocks derived by sequential partial melting are not well-documented worldwide. This paper provides another new important case in southern Tibet. The Yardoi gneiss dome within the Southern Tibet Rift System (STRS) consists of at least four suites of Miocene high-Sr/Y granites, formed at 20.4 Ma, 18.9 Ma, 17.7 Ma, and 17.1 Ma, respectively. Geochemical data indicate that they are Na-rich and peraluminous granites with high Sr/Y and La/Yb ratios. These granites show relatively radiogenic 87Sr/86Sr(t) (0.7091–0.7149) and unradiogenic ε Nd (t) (−11.1 to −7.7) isotopic signatures. As crystallization ages become younger, they are characterized by decreases in ε Nd (t) and Sr/Y but increases in 87Sr/86Sr(t) and Rb/Sr. Such temporal trends could be explained by sequential partial melting of first the mafic lower crustal rocks and then progressively shallower metasedimentary rocks. These findings together with literature-derived data, suggest that from north to south along the STRS, as extension proceeded with a heat source from the upwelling of asthenospheric mantle, sequential partial melting produced different Miocene magmatic rocks. This provides new insight into the mechanisms for the generation of geochemical and isotopic variations in spatially confined but temporally progressed granitic rocks. • The granites are Na-rich peraluminous ones with high Sr/Y and La/Yb ratios. • The granites have lower 87Sr/86Sr(t) but higher ε Nd (t) than other Miocene ones. • As crystallization ages become younger, ε Nd (t) decreases, 87Sr/86Sr(t) increases. • Data suggest sequential partial melting of first mafic and then metapelite rocks. • The E–W extension was active at ∼20 Ma. [ABSTRACT FROM AUTHOR]

Over the past 50 years, catastrophic rock-ice avalanches have frequently occurred in the Parlung Zangbo Basin, such as those involving the Guxiang and Tianmo gullies, causing serious casualties. The initial slope failures generally occurred in high mountains at an elevation of >4000 m above sea level (asl), which subsequently triggered long run-out geohazard chains, such as debris avalanches, debris flows and outburst floods. In this paper, based on satellite imagery, aerial photography, interferometric synthetic aperture radar (InSAR) technology, and field surveys, the characteristics of these rock-ice avalanches are analyzed. The results indicate that high-risk zones are located in the upstream and downstream sections of the Parlung River, where intense geohazards occurred. Based on the movement characteristics of geohazards, four disaster chain modes were summarized, namely rockslide-river blocking-flood, rock and ice avalanche-glacier lake outburst-flood, rockslide/rock-ice avalanche-debris avalanche/debris flow-river blocking-flood, and debris flow-river blocking-flood. Several factors jointly determined the propagation mode and high mobility observed during rock-ice avalanche events: (i) the pipe-like terrain favoured long-runout propagation; (ii) detached ice and snow quantities can be greatly increased via entrainment, thus reducing friction between the moving mass and basal layer. (iii) The debris-moraine may provide abundant materials easily scraped by debris flows. (iv) Meltwater provided by ice and snow at the base of the flow could lubricate debris to improve mobility after mixing with avalanches' debris. Choosing Tianmo gully as an example, dynamics analysis was conducted in by DAN-3D. In the future, possible increases of failure events in formerly glaciated and permafrost areas are likely because of ongoing changes in climatic conditions. This study provides insight into multi-stage avalanche motion in the glacier regions. The results constitute a reference for hazard zonation in similar mountainous areas. [ABSTRACT FROM AUTHOR]

In this paper, we examine the Early to Middle Holocene evolution of a prominent group of ground-water fed lakes in the southeastern hinterland of the Badain Jaran Desert (BJD) of northwest China. Specifically, we describe a sediment profile record from the Taoerlegetu (TR) palaeolake basin using multiple proxies of total organic carbon (TOC), total nitrogen (TN), C/N ratio, δ13C org , grain size and mineral composition based on a well-dated trench profile. As C/N values suggest that sedimentary organic matter mainly originated from aquatic plants, δ13Corg values can be used as a qualitative proxy for water level because aquatic plants in different biotopes (water depth) have different δ13C values. Our results show that from 10.9 to 9.1 cal kyr B.P., water level rose slowly, and aquatic macrophytes occupied the lake basin. From 9.1 to 5.5 cal kyr B.P., water level reached an even higher level and phytoplankton replaced macrophytes as the major contributor to organic matter. The humid episode of the lakes in the hinterland of the BJD in the early Holocene might be related to the increased groundwater supply from the northeast region of the Tibet Plateau. These findings are consistent with earlier studies of lacustrine and peat sediments found in periphery of the modern lake group, which indicate that their geographic extent may have been larger in the past. A relative drought period recorded in the studied succession from 8.5 to 8.0 cal kyr B.P. marks an interval of reduced ground-water transport from the Tibet Plateau. This interval probably corresponds to the "8.2 ka cold event" and provides evidence that this widespread climate episode influenced groundwater processes across inland Asia. • The δ13C org value could be used as a qualitative indicator for the change of water level. • Lakes in the hinterland of the Badain Jaran Desert shows different evolution progress with these in the edge. • The main water source of lakes in the hinterland of the BJD in the Early Holocene comes from the Tibet Plateau. [ABSTRACT FROM AUTHOR]

Magmatic flare-ups are well recognized as a fundamental feature of continental arc magmatism, but its driven mechanism still remains unresolved. Exploring this behavior is of significance in unraveling the deep dynamic processes related to plate subduction and crustal growth. In central Tibet, arc magmatism within the South Qiangtang terrane (SQT) caused by the northward subduction of the Bangong-Nujiang Ocean (BNO) is featured by a prominent high-flux event during Jurassic, but its details and corresponding geodynamic background are not determined. This paper reports geochronological and geochemical data of the granodiorites near the Rigen Co area in the middle part of SQT. These rocks were generated at ca. 150 Ma and display typical adakitic characters. Their low MgO (1.41–2.39 wt%), initial 87Sr/86Sr ratios (0.7055–0.7059) and slightly low ε Nd (t) values (−1.9 to −1.2), and high zircon ε Hf (t) (+1.9 to +8.4) and δ18O values (+6.6 to +9.2 ‰) suggest the adakitic granodiorites were derived from partial melting of subducted crust involving 10–20% inputs of overlying sediment. Our sample, together with previous reports delineates a distinct slab-window association (adakite and oceanic island basalt (OIB)-type diabase) along the southmost of SQT, which coincided with the magmatic flare-up at ca. 155 Ma as revealed by the age spectra of magmatic rocks and complementary detrital zircons. Furthermore, a trench-ward migration is recognized for the arc magmatism from ca. 170 Ma to 155 Ma, implying a slab-roll back process. Accordingly, this high-flux event with the slab-window formation is best explained by the trigger of ensuing slab break-off. These results, combined with other geological evidence, contribute new constraints on elucidating the Jurassic geodynamic evolution of the BNO subduction. • The Rigen Co granodiorites were generated by oceanic crust melting at ca. 150 Ma. • Jurassic arc magmatism in the South Qiangtang terrane shows a trench-ward migration. • The Late Jurassic magmatic flare-up was triggered by slab break-off. • A oceanic plateau-continent collision was proposed to explain these processes. [ABSTRACT FROM AUTHOR]

Geochemical exploration data plays a vital role in mineral prospectivity mapping (MPM) for discovering unknown mineral deposits. In this study, compositional balance analysis (CoBA), unsupervised and supervised learning are collaboratively used to improve the practice of identification of geochemical anomalies related to mineralization in the Qulong-Jiama mining district of Tibet. For CoBA, five balances of geochemical elements were constructed by the sequential binary partition (SBP) technique, facilitating the interpretation of geochemical/geological processes and contrasting with geochemical anomalies generated by unsupervised and supervised learning. The iterative self-organizing data analysis techniques algorithm (ISODATA) and isolation forest (iForest) are used for preprocessing the geochemical data and therefore optimizing the appropriate training sets (e.g., positive and negative training samples) for supervised learning. Different training datasets including locations of known mineralization, randomly selected positive samples from resulting clusters by ISODATA and outliers by iForest are fed to the support vector machine (SVM) and random forests (RF) algorithm. The results of high AUC values indicate that supervised learning can effectively delineate prospective areas both with SVM and RF, however, the excessive large area of high-prospectivity and a bias toward known mineralization makes the outcomes of MPM unpractical. Nevertheless, a hybrid of the CoBA, unsupervised learning and supervised learning could alleviate such situations and provide insights into MPM using the geochemical data. • Detection of geochemical anomalies related to mineralization using a hybrid method • The effects of training datasets on mineral prospectivity mapping • The paper provides new insights into mineral exploration using geochemical data. [ABSTRACT FROM AUTHOR]

Genetic pattern of a continuous volcanic series of andesites, dacites, and rhyolites from the Ziruco area, northern Tibet was debated in this paper to evaluate the later evolution of A-type granites. We present new zircon U Pb ages, whole-rock geochemical, zircon Hf isotopic, and whole-rock Sr Nd isotopic data for these magmatic rocks. Our analysis shows that the zircon U Pb ages of the andesites, dacites, and rhyolites are ca. 105.4 Ma, ca.105.3 Ma, and ca.106.8 Ma, respectively. The andesites have high Nb contents (16.3–24.9 ppm) and Nb/U ratios (22.7–32.4), and chondrite normalized REE and primitive-mantle normalized trace element patterns similar to Nb-rich basalts. They were most likely derived from the mantle that had been metasomatized by melts derived from subducted slab and sediment, and then underwent fractional crystallization. The dacites and rhyolites have high Ga/Al ratios (3.05–3.70 and 2.93–3.43, respectively), REE (226–256 and 195–285 ppm, respectively), Nb (30.0–34.4 and 20.3–24.4 ppm, respectively) and Zr contents (443–513 and 147–163 ppm, respectively), and zircon saturation temperatures (856–886 °C and 823–837 °C, respectively), which are similar to A-type granites. The dacites were most likely formed by partial melting of underplated basaltic lower crust with ilmenite and zircon, followed by slight fractional crystallization. The rhyolites were most likely formed by fractional crystallization of the dacite magmas. The minerals of fractional crystallization probably include feldspar, apatite, zircon, and titanite. This continuous volcanic series in Ziruco area may be related to break-off of the Meso-Tethyan slab in northern Tibet during the late Early Cretaceous. Our studies indicate that fractional crystallization is important later evolutionary process for A-type granites from the crustal source area, and it mainly controls the geochemical characteristics of significant negative Ba, Sr, P, Ti, and Eu anomalies of A-type granites from the crustal source area. [Display omitted] • Albian A-type granites in northern Tibet were from underplated basaltic crust. • Break-off of the Meso-Tethyan slab occurred during the late Early Cretaceous. • Fractional crystallization is important for A-type granites from lower crust. [ABSTRACT FROM AUTHOR]

This paper reviews the spatial-temporal distribution, geological and geochemical features, and geophysical context of diverse types of Cenozoic ore deposits formed during India-Eurasia continental collision in Tibet, in order to shed new light on their genesis and their control by mantle lithosphere. The parental magmas for porphyry-skarn Cu (± Mo ± Au) deposits were derived from metal-rich pre-Cenozoic juvenile crust, and the high magma oxidation state was controlled by involved mantle-derived basic magmas and thickened crust condition; magma emplacement was controlled by structures related both to tears in the subducting continental slab to deep and to mantle-crust decoupling parts at depth. Orogenic Au deposits mostly formed intermittently from hydrothermal fluids formed by devolatilization of earlier-fertilized mantle lithosphere that was triggered by asthenosphere upwelling; they were largely controlled by lithosphere-scale shear systems that reactivated earlier-formed suture zones. Giant MVT Zn Pb deposits, hosted by ancient oil reservoirs, formed during salt diapirism and infiltration of metal-rich basinal brines related to crustal-scale channel flow. The diverse range of ore deposits was derived predominantly through release of metal and fluid components, introduced into the crust and mantle lithosphere that occurred in the earlier oceanic subduction during anomalous lithosphere-scale deformation. The metallogenic history of collisional orogens contrasts with those of accretionary orogens. • Tibetan mineralization system provides an important global insight into metallogenesis during continental collision. • Lithosphere architecture and fertility formed by oceanic subduction control diverse ore deposits in collision setting. • Diverse types of Tibetan ore deposits have different genesis to those from oceanic subduction settings. • Tibetan ore deposits formed in various geodynamic settings of thrusting, shearing, rotation, and rifting. [ABSTRACT FROM AUTHOR]

Aerosol Optical Depth (AOD) represents the optical attenuation of aerosol, which, to a certain extent, can reflect regional air pollution levels with obvious spatiotemporal characteristics. However, the currently limited monitoring technology cannot provide long-time sequential and detailed AOD information. Therefore, in this paper, Modern Era Retrospective-Analysis for Research and Applications, Version 2 (MERRA-2) data, and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data from 1980 to 2020 were used to analyze the characteristics of both the spatiotemporal distribution of aerosols and dust transportation in the Tibet Plateau and Tarim Basin. Moreover, Random Forest (RF) Model was employed for ranking the importance of multiple natural factors (evaporation, mean surface temperature, daily precipitation, mean air pressure, mean relative humidity, mean temperature and mean wind speed) on AOD, Wavelet Analysis Method was utilized for the scale analysis between key natural factors and AOD, and Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) Model was applied to the simulation of the transportation trajectories of dust aerosols. The results show that high AOD values in the Tibet Plateau and Tarim Basin appeared in spring. Dust aerosols in the northern slope of the Tibet Plateau dispersed and decreased from the north to the middle of Plateau. Dust Aerosol Optical Depth (DAOD) reached its peak in spring and summer with the maximum transportation range of 34° N or so. Besides, Tarim Basin transported dust to the northern slope of the Tibet Plateau significantly, which was then transported to the main body of the Plateau along its northern slope (37°N) with a dust particle proportion of 40%–80%. Moreover, precipitation was the most significant factor (32.18%) influencing the spatiotemporal distribution of AOD. The former lagged behind the latter by 5/12 periods at most and showed a negative correlation with it. [ABSTRACT FROM AUTHOR]

Aiming to realize the long-endurance ecological environmental monitoring and the rapid takeoff and landing mission in Tibet, a hand-launched solar-powered unmanned aerial vehicle (UAV) in flying wing configuration is introduced and analyzed in this paper. The low-Reynolds-number (LRN) flow is quasi-steadily simulated by solving the full three-dimensional Reynolds Averaged Navier-Stokes (RANS) governing equations coupled with the k T - k L - ω transition model while the propeller performance is evaluated using the multiple-rotating reference frame (MRF) method. Both the cruise and the low-speed takeoff aerodynamic analyses which include the aerodynamic force analysis and the propeller/wing integrated flow mechanism analysis are performed in details. The results indicate that the present UAV can meet the high-efficiency cruise requirements quite well, at the same time, has the ability to take off at the low-speed hand-launched state and a rather low Reynolds number by making good use of the energy injected from the propeller rotation into the flow field. [ABSTRACT FROM AUTHOR]

This paper investigated the freezing processes of Qinghai-Tibet silty clay within an added quartz sand layer (QSL) under different one-dimensional freezing temperature gradients by using computed tomography scanning and image acquisition technologies in an open system. The heat transfer, cryostructure formation and water migration processes and mechanisms were discussed. The results reveal that the temperature of the samples was essentially steady within 12 h, and the addition of the QSL has a significant impact on the temperature distribution in the samples. The moisture content of the QSL and the frozen part of the sample increased, while the moisture content of the unfrozen zone decreased significantly after being frozen for 120 h. The QSL was able to effectively limit liquid water migration, however, there was still vapor migration in the samples. Ladder-like and net -like cryostructures formed in the vertical sections of the sample while polygon cracks formed in the horizontal sections, which providing pathways for moisture migration. The saturated vapor pressure difference which calculated by the Antony Equation can be used as the driving force for vapor migration from the unfrozen zone to the frozen zone. From both an experimental and theoretical standpoint, this work is intended to aid research into the physical process and mechanism of sand interbedded stratum and foundation freezing. • The image acquisition and computed tomography scanning method were used to study the cryostructure of freezing soil. • Ladder-like and net-like cryostructures were formed due to the freezing temperature gradient. • The added quartz sand layer was able to effectively limit liquid water migration but there still vapor migration exists. • The polygon cracks formed in the horizontal sections of the soil samples, providing pathways for moisture migration. • The saturated vapor pressure difference provides the driving factor for vapor migration in the freezing soil. [ABSTRACT FROM AUTHOR]

The construction and operation of the Sichuan-Tibet railway require constructing extensive supporting facilities along its route. Sichuan-Tibet transportation corridor features high mountains and deep valleys where land resources suitable for such purposes are very limited. As a result, safe utilization of the torrential fan along the railway becomes essential. Focus on buildings at the torrential fan, this paper aims to develop a vulnerability model that can assess their maximum potential damage and support the planning and development of the torrential fan. The model was developed based on 51 building damage data collected at 11 torrential fans. The hazard intensity was defined by the geometric configuration of torrential fans and the location of assessed buildings. In addition, a physical experiment was carried out to study the shielding effect of building groups. The results show that the shielding effect range is about 25 times the building size, and the maximum reduction in impact force can reach 60%. The advantage of the proposed vulnerability assessment model is that it only requires the spatial information of the site that can be easily derived from the satellite image. In addition, the model can reflect the complex torrential process and the shielding effect of building groups. This study provides an alternative approach to building vulnerability assessment. It supports the planning and development of torrential fans when constructing the supporting facilities for the railway construction and operation. • The intensity of torrential hazards at each building is defined by the fan's geometric configuration and the assessed building's position. • The proposed model is easily adaptable since the required data is widely accessible from the satellite image. • The shielding effect of building groups when subject to torrential hazards is considered in this vulnerability assessment model [ABSTRACT FROM AUTHOR]

Normal faulting in orogens is usually associated with gravitational potential energy (GPE) due to elevation differences and contrasting material rheology between mountains and foreland areas. The 2008–2020 Yutian normal earthquake sequence in the West Kunlun Mountains has been closely studied over the last decade, but the mechanisms of normal faulting in the region are still an open question as both gravitational force and releasing step-overs have been proposed to explain the extension in West Kunlun. We investigated the normal faulting mechanism through (1) co- and postseismic kinematic models constrained by interferometric synthetic aperture radar (InSAR) and (2) analytical force balance modeling with a thin viscous approximation. We used the InSAR time series technique to map the postseismic deformation within 3 years following the 2008 Yutian earthquake. The InSAR-derived afterslip model revealed a clear slip polarity transition from strike-slip to normal faulting, suggesting a tight connection between the normal faulting and bounding strike-slip faults. The global navigation satellite system (GNSS)-constrained thin viscous sheet model gave an estimate of ~1022 Pa∙s for the effective viscosity of the West Kunlun lithosphere, which is generally in line with previous estimates that used a similar methodology. The stress field predicted by the thin viscous model primarily features north–south compression rather than east–west extension, suggesting that normal faulting is caused not by the GPE contrast across the margin of West Kunlun, but instead by the releasing step-overs bounded by strike-slip faults. The main contribution of this paper is therefore identifying the primary causes of normal faulting in West Kunlun and improving our understanding of the active tectonics of the NW Tibetan Plateau. • The postseismic InSAR time series following the 2008 Mw 7.1 Yutian earthquake is presented. • The slip transition from strike-slip to normal faulting was revealed by slip models. • Extension in West Kunlun is due to releasing step-overs rather than gravitational force. [ABSTRACT FROM AUTHOR]

The terrain along the Tibet Railway is primarily steep mountains and valleys with complex geological structures. The occurrence of the Mainling earthquake indicates that the intensity of seismicity in the eastern structural junction area has strengthened, and the potential risk of earthquake-induced disasters such as landslides and debris flows is also increasing. The earthquake engineering community generally recognizes that the prediction of near-field strong ground motion can reduce the disasters caused by future large earthquakes and can guide earthquake prevention, disaster reduction and seismic design along the Sichuan–Tibet railway. The M6.9 Mainling earthquake affected the stability of Sedongpu Glacier near the epicentre. A glacier avalanche occurred under the coupling of multiple factors, including post-earthquake and precipitation events. The waveform and response spectra of a strong earthquake are key input parameters for investigating the seismic triggering mechanisms of landslides and glacier avalanches and accurately reproducing the dynamics of such disasters. In this paper, the concept of the equivalent Green's function is introduced, and various source parameter uncertainties are fully considered. The waveform and response spectra of the Mainling earthquake at Sedongpu Glacier are simulated, and the most likely seismic waveform is comprehensively assessed from multiple perspectives. This work can provide reliable acceleration waveform input for the analysis of ground motion damage and the study of earthquake-induced disaster mechanisms at important locations along the Sichuan–Tibet railway and provide a scientific reference for earthquake prevention and disaster reduction along the railway. • The concept of equivalent Green's function is proposed. • The waveform containing many practical and complex information for seismic damage analysis • It expands the application range of empirical Green function method. • It could help to study the mechanism of earthquake induced geological hazards. [ABSTRACT FROM AUTHOR]

• Estimation of biomass by random forest combined with Monte Carlo simulations. • Using Monte Carlo method to reduce the error caused by residual variability. • Quantifying the effect of different variable combinations on model uncertainty. Estimates of aboveground biomass (AGB) in forests and the associated uncertainty are important pieces of information outlined in the United Nations Framework Convention on Climate Change. Traditional integrated surveying methods require high inputs of manpower and material resources, whereas remote sensing technology can be used to improve the efficiency of forest resources surveying at a lower measurement cost. Previous studies have primarily utilized spectral information and textural features as the main modeling factors for AGB prediction models, however, few studies have examined how different modeling factors affect prediction accuracy in detail. At the same time, uncertainties in AGB are usually determine by a data set producing a single prediction result, ignoring the model uncertainty due by residual variability in the prediction results. To solve the above problems, this study focuses on Milin County of the Tibet Autonomous Region of China as the research area and uses data from the Landsat Operational Land Imager, digital elevation models (DEM), and the national forest inventory (NFI) to extract and analyze spectral information, textural features, and terrain factors. Four regression models based on different combinations of variables were established using a combination of random forest and Monte Carlo simulation methods (RF-MC), and the uncertainties of each model were determined. The purpose of this paper is to study the influence of different types of variable factors on AGB inversion and to measure the model uncertainty resulting from changes in the variable factors. The coefficient of determination (R2), mean absolute error (MAE), and root mean square error (RMSE) were used to evaluate the fit and accuracy of the model, while the relative root mean square error (rRMSE) was used to quantify the uncertainty. The results show that the degree of fitting and accuracy are greatest for the RF-MC model based on three kinds of variables (spectrum and plot data + DEM + texture characteristics) the best (R2 = 0.85, RMSE = 11.76 t /ha, MAE = 8.49 t /ha, rRMSE = 5.97 %), which performed better than the RF-MC model based on two variables (spectrum and plot data + texture characteristics, R2 = 0.78, RMSE = 13.93 t /ha, MAE = 10.01 t /ha, rRMSE = 7.07 % or spectrum and plot data + DEM, R2 = 0.69, RMSE = 16.75 t /ha, MAE = 14.62 t /ha, rRMSE = 8.49 %) and the RF-MC model based on a single variable (spectrum and plot data, R2 = 0.49, RMSE = 21.39 t /ha, MAE = 19.84 t /ha, rRMSE = 10.86 %). The range of the predicted model value is 150.6–227.8 t /ha, which is close to the actual value. The RF-MC method based on multifeature is demonstrated to be effective in the practical application of AGB inversion, and different types of modeling variables have a certain impact on the accuracy of AGB inversion. This study provides a theoretical basis for improving the accuracy of AGB estimates and the selection of modeling variables, while also contributing to continued improvements in remote sensing-based systems for monitoring forest resources. [ABSTRACT FROM AUTHOR]

The uplift of the Tibetan Plateau has been widely associated with India-Asia continental collision during the Cenozoic. However, recent studies have proposed that a proto-Tibetan Plateau in central Tibet was elevated during the late Mesozoic. This paper improves that understanding by focusing on the Cretaceous terrestrial strata in the Gerze area of central Tibet. Our studies suggest that the Qushenla Formation in the Nare area contains alluvial fan conglomerate intercalated with rhyolitic ignimbrite and vesicular rhyolite. Zircon U Pb dating of rhyolitic ignimbrite (103.9 ± 1.4 Ma) and two granitoid boulders of conglomerate (106.0 ± 1.6 and 106.1 ± 1.5) indicate that the Qushenla Formation was deposited during the late Albian. The compositions of the Qushenla Formation conglomerate were dominated by hypabyssal intrusions on the southern Qiangtang terrane, which recorded a rapid uplift and denudation process in the late Albian, accompanied by intense volcanic eruptions. The second set of terrestrial strata is the Upper Cretaceous Jingzhushan Formation alluvial fan-braided river deposits, which can be divided into a lower conglomerate member (Member 1) and a upper sandstone member (Member 2). The large amount of bioclastic limestone fragments in the Member 1 show that they come from the Upper Cretaceous Langshan Formation in the central and northern Lhasa subterranes. While in the Member 2, abundant limestone debris, detrital zircon yielding Jurassic–Cretaceous ages with ε Hf (t) values between −18.6 and + 8.4, and occurrence of volcanic and ancient zircon grains indicate a volcanic-sedimentary source located in the central and northern Lhasa subterranes, with some input from the Bangong-Nujiang suture zone. This suggests that the central and northern Lhasa subterranes experienced rapid crustal uplift in the Late Cretaceous, thus ending the marine sedimentary environment since the Jurassic. Based on the temporal and spatial sedimentary characteristics of the Qushenla and Jingzhushan formations as well as the regional data, our integrated study suggests that the central plateau (Lhasa and southern Qiangtang terranes) experienced a complex uplift history during the Aptian-Turonian, with southwards stepwise growth in time and space. Furthermore, the uplift mechanism of the central plateau is complex, which was controlled by the diachronous closure of the Bangong-Nujiang Tethyan Ocean from east to west during the Early Cretaceous, and by the far-field forces associated with northwards subduction of the Neo-Tethys Ocean during the Late Cretaceous. [Display omitted] • There are two sets of Cretaceous terrestrial strata in the Gerze area. • Gerze area had a residual sea retreat southwards during Aptian-Turonian. • Central Tibet experienced a dual diachronic uplift of E–W and N S in Aptian-Cenomanian • We suggest that the early uplift process of central Tibet was phased. [ABSTRACT FROM AUTHOR]

Exploring magmatic 'flare-up' events can be used to unravel dynamic Earth processes including plate subduction and crustal growth. However, the cause and mechanism of magmatic 'flare-up' remain unresolved. The abundant magmatic records that are preserved in the Lhasa Terrane on the southern Tibetan Plateau make it an important region to study the episodic nature of the secular magmatism. This paper presents geochronological, mineralogical, and geochemical data that describes the Dazhuka diorites in the central-western and Sangri granites in the eastern parts of the southern Lhasa Terrane. Zircon LA–ICP–MS U Pb data indicate that these rocks were generated around ~95–90 Ma. Both are enriched in large ion lithophile elements and depleted in high field strength elements, indicating geochemical affinity with subduction-related magmatic rocks. The Dazhuka diorites have low SiO 2 contents (54.49–56.72 wt%), with moderate Mg# (41.7–42.7) and rare earth element fractionation ((La/Yb) N = 6.9–8.6), and homogeneous whole-rock 87Sr/86Sr i (0.704204–0.704480), ε Nd (t) (+3.5 − +4.1), and zircon ε Hf (t) (+10.2 − +13.3). These features suggest that the Dazhuka diorites originated in the spinel-garnet transition zone within the lithospheric mantle of a mantle wedge environment. The Sangri granites have high SiO 2 (64.36–69.54 wt%), Al 2 O 3 (14.27–15.61 wt%), and (La/Yb) N (4.6–49.6) and Sr/Y (34.7–119.3) ratios, indicating geochemical affinity with adakites. Low MgO (1.3–2.22 wt%) and depleted Sr-Nd-Hf isotopes (whole-rock 87Sr/86Sr i = 0.704099–0.705453, ε Nd (t) = +2.9 − +3.5, zircon ε Hf (t) = +7.1 − +9.3) suggest that the granites were derived from oceanic crust. The types of magmatic rocks that are distributed over the central-western and the eastern parts of the southern Lhasa Terrane differ, with higher magmatic temperatures in the east as compared to the central-west. These results indicate that different areas in the southern Lhasa Terrane may have experienced different geodynamic processes, with oceanic ridge subduction in the eastern part of the southern Lhasa Terrane and normal oceanic plate subduction in the central-western part. These different types of subduction processes are likely to have caused the magmatic 'flare-up' and variation in the magmatism of southern Tibet. [Display omitted] • Both Dazhuka diorites and Sangri granites formed in early Late Cretaceous. • Dazhuka diorites were derived from the lithospheric mantle. • Sangri granites with adakitic affinity were sourced from the oceanic crust. • Multiply Neo-Tethys Ocean plate subduction processes result in magmatic 'flare-up'. [ABSTRACT FROM AUTHOR]

[Display omitted] • Constructed a geochemical big data platform on the Tibetan Plateau. • Using GIS analysis, a filling map of geochemical elements was carried out. • The HF and Nd isotopic packing characteristics were explored. • Multivariate statistics were applied to explore mineralization characteristics. Tibet has received much attention as a pivotal area to explore the genesis of ore deposits. So far, a large number of researchers have conducted a lot of discussions on the geological conditions, genesis, distribution and scale of ore deposits in Tibet, and accumulated a plenty of isotopic test data. Isotopic data can reveal the geological changes of an area and analyze the metallogenic regularity. In this paper, combined with GIS (Geographic Information System) spatiotemporal analysis technology, Hf and Nd isotopic data mapping analysis has been carried out in Tibet. The mapping shows high zircons ε Hf (t) value and high whole rock ε Nd (t) value and low T DM c value on both sides of the Eastern Yarlung Zangbo Suture Zone and the Western Bangong-Nujiang Suture Zone. It indicates that the terranes in these two areas are relatively young and have typical characteristics of Cu and Au mineralization, which are favorable areas for the prospecting of Cu and Au. Combined with the geological fault characteristics of Tibet Plateau, the influence of terrane boundary on the deposit and the relevant characteristics of geochemical elements, three favorable targets for Cu and Au prospecting in Tibet Plateau are delineated by GIS analysis. The results show that the characteristics of isotopic data in Tibet Plateau are quite different in disparate terranes, and the isotopic analysis can quickly delineate the strategic prospecting targets. Therefore, using GIS technology for isotope analysis and metallogenic prediction provides important guiding significance for scientific prospecting. [ABSTRACT FROM AUTHOR]

[Display omitted] • High-temperature springs in the Yadong-Gulu rift are related to the deep circulation of groundwater. • Infiltrating water could reach the middle crust in the case of deep fault activity with high permeability. • Rare-alkali metals contributed from deep magma are enriched along upward pathways of hydrothermal circulation, providing new insight for future exploration. Geothermal water from the hot springs in the Yadong-Gulu rift (YGR) of southern Tibet is extremely enriched in rare-alkali metal (RAM) elements; however, the mechanism of enrichment has long been debated. Much attention has been given to the deep melting magma of the YGR, but no direct evidence indicates whether and how it is connected to the RAM anomaly of hot springs. Determining the mechanism of RAM enrichment and its variations with the time and space of hot springs will contribute to the exploration of the hydrothermal metallogenic systems. This paper presents numerical hydrothermal numerical circulation models constrained by the geological data and the geophysical structure of the YGR. The results illustrate that the depths of boundary faults control the anomalous temperatures of hot springs. High-temperature springs (such as Yangbajing) could be induced by deep faults extending to the middle crust, whereas magma at a depth greater than 10 km has a limited effect on geothermal anomalies. Secondary faults define the extent of hydrothermal circulation and further determine the distribution of thermal anomalies across the rift. We simulate the enrichment and distribution of RAMs from a deep magma source. The pathways of RAMs from the source are consistent with hydrothermal circulation. RAM concentrations are lower in infiltrating groundwater and higher in ascending hot water. In general, deep faults control the hydrothermal circulation of geothermal groundwater. Deep faults and magma further constrain the distribution of RAM anomalies. [ABSTRACT FROM AUTHOR]

The history of crustal thickening is critical for comprehending the evolution process of the Tibetan plateau. The genetic relationship and spatiotemporal distribution of adakitic rocks with high Sr/Y, (La/Yb) N ratios may impose fundamental constraints on specific geodynamic and crustal thickening processes. The Songka intrusive suite consists of adakitic rocks with high-Mg adakite (monzonites), low-Mg adakitic rocks (quartz monzonites), and gabbroic-diorites. Their geochemical characteristics, petrogenesis, and geodynamic implication is discussed in this paper. Songka high-Mg adakites formed when subducting Neo-Tethyan oceanic slab melts were assimilated by mantle peridotite at elevated temperatures (average Ti-in-zircon temperatures of sample SK1319 are 830 °C). Low-Mg adakitic rocks exhibit markedly different geochemical characteristics than those formed in the juvenile thickened lower crust. The least-squares mass balance and trace element simulations indicate that Songka low-Mg adakitic samples were formed at a degree of 60–65% fractional crystallization of melts resembling Songka high-Mg adakites. Songka gabbroic diorites are formed in the metasomatic mantle wedge. The genetic relationship between these rocks indicates that the crust of the southern Tibet did not appear to thicken obviously during the early stage of late Cretaceous (100–90 Ma). The intensive emplacement of late Cretaceous high-Mg adakites (Mg# > 50) and mafic rocks (SiO 2 < 52%) in the southern Lhasa terrane around 95–90 Ma, together with the slow convergence velocity of the Indian-Asian continent, can be explained by the response of rapid crustal thickening and Neo-Tethyan slab rollback at 95–90 Ma. • High-Mg adakitic rocks were formed from partial melting of Neo-Tethyan slab. • Coeval low-Mg adakitic rocks were produced by fractional crystallization. • Rapid crustal growth and Neo-Tethyan slab rollback occurred at 95–90 Ma. [ABSTRACT FROM AUTHOR]

[Display omitted] • The first identified oceanic core complex in the Bangong-Nujiang suture zone. • The mid-ocean ridge of the Meso-Tethys Ocean moved northward since the Late Triassic. • This ridge was slow spreading during the Early Jurassic. In this paper, we report the first identified oceanic core complex (OCC) in the Saibucuo area of the Bangong-Nujiang suture zone, describe the geology and petrology of this OCC, and present new zircon U-Pb ages and Lu-Hf isotopes, and whole-rock major- and trace-elements and Sr-Nd isotopes for the diabase dikes in this OCC. The Saibucuo OCC consists of serpentinites, serpentinized peridotites, diabase dikes, tectonic breccias, sedimentary breccias, and limestones. The serpentinized peridotites cross-cut by carbonate veins, the sedimentary breccias with simple gravel compositions cut by normal faults, together with the limestones in the cover sequence lead to the conclusion that the Saibucuo OCC is similar to the OCCs of mid-ocean ridge settings. This conclusion is consistent with the E-MORB features of diabase dikes, which are formed by the interaction of the mid-ocean ridge and mantle plume, and the abyssal peridotite features of serpentinized peridotites. Zircon U–Pb ages of the diabase dikes indicate that the Saibucuo OCC was formed at the ca. 190 Ma. Based on these data and regional geological records, the early Mesozoic tectonic evolution of the Meso-Tethys Ocean was restored. The Meso-Tethys Ocean was a broad and mature oceanic basin during the Late Triassic-Early Jurassic. Coeval collision of the Northern and Southern Qiangtang terranes during the Late Triassic initiated the northward subduction of the Meso-Tethys Ocean, and the northward migration of the mid-ocean ridge. Continuous northward subduction of the Meso-Tethys Ocean caused the mid-ocean ridge to gradually approach the northward subduction zone, and eventually to subduct and collide with the northern trench during the Early-Middle Jurassic. The mid-ocean ridge within the Meso-Tethys Ocean was slow spreading during the Early Jurassic. [ABSTRACT FROM AUTHOR]

This paper develops an improved three-dimensional sphere discontinuous deformation analysis (SDDA) model and uses UAV-based photogrammetry to enable SDDA to numerically analyze potential long-runout debris flows in Zheduotang area along the Sichuan-Tibet railway. First, the original SDDA is improved by proposing a sphere-sphere bonding algorithm to bond spheres with tetrahedral layout to form four-sphere clusters to approximate non-sphere particles in debris flow. Second, the capacity of the improved SDDA is verified by comparing modelling results with four groups of laboratory tests of granular flow. Third, UAV-based photogrammetry is used to obtain the real morphology of the extremely complex terrain surface of Zheduotang area which is finally transferred into a large number of triangular faces as the fixed boundary faces of SDDA. Then, three potential debris flow scenarios on this terrain surface are numerically studied, and some suggestions for engineering disaster prevention are drawn. Model performance shows that, the improved SDDA is a feasible tool to simulate debris flows. With the help of UAV-based photogrammetry, it shows significantly helpful for geohazard prevention for infrastructures in mountainous areas like the Sichuan-Tibet railway. • An improved sphere discontinuous deformation analysis model is proposed. • The validation of the improved model in debris flow simulation is verified. • UAV-based photogrammetry to parameterize the extremely complex terrain surface of mountainous area is used. • Engineering-scale long-runout debris flow simulations are carried out. [ABSTRACT FROM AUTHOR]

• The influence of curing temperatures on the performances of FRCs were studied. • The curing temperatures and curing ages have positive effects on the compressive strength of concrete. • There is an optimum fiber content for the compressive strength of FRCs cured at low temperatures to resist loads. • The added fibers into concrete improves the ductility of concrete due to the fiber bridging effect. • The negative curing temperatures significantly inhibit the hydration reaction. In cold regions or even permafrost areas, it shows growing interests in engineering infrastructures, and more engineering projects have been constructing, e.g. Sichuan-Tibet railway. Undoubtedly, the concrete needs to be cured at the temperature below the conventional curing temperature (about 20 °C). This paper investigated the effect of curing temperatures (i.e. −6 °C, −2 °C, 2 °C and 6 °C) on the performances (compressive strength, stress–strain relationship, microstructure, and hydration products) of steel fiber-reinforced concrete (SFRC), polypropylene fiber-reinforced concrete (PPFRC), and basalt fiber-reinforced concrete (BFRC). The results show that the curing temperature and curing age have positive effects on the compressive strength of concrete samples, and the compressive strength increases with the curing temperatures and curing ages. Besides, regardless of curing temperatures, the type and dosage of added fibers would greatly affect the compressive strength, and there is an optimum fiber content for the compressive strength of FRCs cured at the low temperature to resist loads, and the optimum fiber contents for the SFRC, PPFRC and BFRC are 2.0%, 2.0‰ and 0.5‰, respectively. Additionally, the axial stress–strain curves can be divided into four-section characteristics, i.e. linear ascending stage, plastic yield stage, descending stage and residual stress stage. The addition of fibers into concrete remarkably improves the ductility of concrete due to the fiber bridging effect. Moreover, the negative curing temperatures drastically inhibit the hydration reaction of concrete. Denser microstructure, more hydration products and good fiber–matrix binding quality can be observed in the concrete samples cured at the higher temperatures. [ABSTRACT FROM AUTHOR]

Reconstructing the evolution of the Sumdo Paleo-Tethyan Ocean (SPTO) is important for understanding the transition from the Paleo-Tethyan system to the Neo-Tethyan system. The existence of the SPTO is inferred from the presence of an (ultra-)high pressure metamorphic belt and dismembered ophiolite bodies that separate the southern Lhasa and northern Lhasa terrane. This paper presents new geochronological and geochemical data for the Luobadui Formation in the Lhasa terrane. The geochemical difference between the Lower Luobadui volcanics and the Upper Luobadui volcanics suggests a source transition from a depleted mantle source to an enriched mantle source, which indicates continental-arc subduction. The integrated geological evidence suggests that the SPTO initially opened during the late Carboniferous (ca. 304 Ma), as verified by the earliest record of oceanic crust. Our new data for the Luobadui volcanic rocks, together with the metamorphic and sedimentary records, support northward subduction of the SPTO lithosphere beneath North Lhasa, most likely starting during the Early Permian (ca. 275 Ma) and lasting until the Middle Permian (ca. 260 Ma). The main closure of the SPTO occurred during Middle–Late Triassic (ca. 240–220 Ma), as recorded by medium-pressure metamorphism and syn -collisional magmatism. The Wilson cycle of the SPTO is hereby reconstructed, providing significant insights into the amalgamation of the Tibetan Plateau. • The arc volcanic rocks from Luobadui Formation formed mainly during 275–260 Ma. • The Luobadui sedimentary detritus was sourced from the Lhasa terrane. • The Wilson cycle of the Sumdo Paleo-Tethys Ocean was reconstructed. [ABSTRACT FROM AUTHOR]