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Chromitites or chromite mineralization of varying degrees has been discovered in the various ophiolites along the east–west trending Yarlung-Zangbo Suture Zone (YZSZ) in Tibet, China. The high-Cr variety dominates the Yarlung-Zangbo chromitites, with rare high-Al chromitites reported in the Zedang, Dongbo, and Purang ophiolites. Using empirical equations, the calculated parental magmas that formed the high-Cr YZSZ chromitites are similar to boninitic melts. 187Os/188Os ratios of chromites from the YZSZ chromitites range from 0.12525 to 0.12933, lower than the proposed present-day 187Os/188Os values for the primitive upper mantle. The TRD age variation of the YZSZ chromitites from late Neo-Proterozoic to early Triassic thus reflects that their parental magmas are derived from depleted mantle sources mixed with diachronous ancient mantle domains. The light Zn isotopic compositions of the YZSZ chromitites indicate that subducted materials (e.g., serpentinites and sediments) have contributed to the parental magma of the YZSZ chromitites. By compiling previously published data on mantle peridotites of the YZSZ ophiolites, we concluded that the YZSZ ophiolites may either have formed initially in an ultraslow-slow mid-ocean ridge environment and were then trapped in a supra-subduction zone environment, or have formed in an ultraslow-slow forearc spreading center in a supra-subduction zone environment. The Luobusa ophiolite hosting the largest chromite deposits is discriminated from the other ophiolites in the YZSZ by a thick dunitic transition zone. Previous theoretical modeling indicates that relative to olivine, only a small amount of cumulus chromites crystallize in cotectic volume ratios of around 100:1 to 100:2 of olivine to chromite, which means that large chromite bodies should always be accompanied by a significantly larger mass of dunites. Therefore, we concluded that a thick dunite transition zone or large masses of dunite of boninitic affinity is an indicator for chromitite prospecting in the future. [ABSTRACT FROM AUTHOR]

Detrital U-bearing minerals (e.g., zircon, apatite) U-Pb ages with specific trace-element geochemistry, are frequently used in provenance analyses. In this study, we focus on the Yarlung River drainage in South Tibet, characterized by two distinct lithologic units: The Gangdese batholith to the north (mainly granitoids) and the Tethyan Himalaya (mainly sedimentary rocks) to the south, which plays a crucial role in the erosion of the Tibetan Plateau. To constrain the provenance of the Yarlung River Basin, we performed trace-element and U-Pb age analyses of detrital apatite from the river sands of the Yarlung River and its tributaries. Our findings indicate that the detrital apatite U-Pb age patterns of the north tributaries exhibit main peaks at approximately 40 and 60 Ma, consistent with the corresponding U-Pb age patterns of detrital zircon published. Further, their trace element casts fall mainly in the Type I granite region, also indicating the Gangdese arc-dominated source. However, those of the south tributaries (∼60–20 Ma) exhibit a different age distribution from the detrital zircon U-Pb groups (∼110–150, ∼500, and 1 100 Ma), suggesting that the detailed apatite U-Pb signals can provide excellent constraints on the provenance of igneous and metamorphic rock sources but less so for sedimentary rock sources. Combined with previous detrital zircon data in the study area, our detrital apatite information can highlight young metamorphic events from a complex background (i.e., Niyang and Nianchu rivers), which offers additional constraints on the provenance of the Yarlung River Basin. Generally, a combination of geochemistry and geochronology of multi-detrital heavy minerals, such as zircon and apatite, can provide powerful tools for provenance analysis. [ABSTRACT FROM AUTHOR]

Seismic anisotropy originating within the continental crust is commonly used to determine the deformation and kinematic flow within active orogens and is attributed to regionally oriented mica or hornblende grains. However, naturally deformed rocks usually contain compositional layers (e. g., parallel compositional banding). It is necessary to understand how both varying mineral contents and differing intensities of compositional layering influence the seismic properties of the deep crust. In this study, we analyzed the seismic response of migmatitic amphibolite with compositional banding structures. We present the microstructures, fabrics, calculated seismic velocities, and seismic anisotropies of mylonitic amphibolite from a horizontal shear layer preserved within the Ailao Shan-Red River shear zone, southwestern Yunnan, China. The investigated sample is characterized by pronounced centimeter-scale compositional banding. The microstructures and fabrics suggest that migmatitic amphibolite rocks within deep crust may delineate regions of deformation-assisted, channelized, reactive, porous melt flow. The origin of compositional banding in the studied migmatitic amphibolite is attributed primarily to partial melting together with some horizontal shearing deformation. The microfabrics and structures investigated in this study are considered to be typical for the base of active horizontal shear layers in the deep crust of southeastern Tibet. Seismic responses are modeled by using crystal preferred orientations for minerals of the migmatitic amphibolite by applying the Voigt-Reuss-Hill homogenization method. Calculated P-wave and S-wave velocities are largely consistent in the various layers of the migmatite. However, seismic anisotropies of P-wave (AVp) and S-wave (AVs) are higher in the melanosomes (AVp = 5.6%, AVs = 6.83%) than those in the leucosomes and the whole rock (AVp = 4.2%–4.6%, AVs = 3.1%–3.2%). In addition, there is pronounced, S-wave splitting oblique to the foliation plane in the migmatitic amphibolite. The multiple parallel compositional layers generate marked variation in the geometry of the seismic anisotropy (Vs1 polarization) in the whole rock. Combined with the macroscale geographical orientation of fabrics in the Ailao Shan-Red River shear zone, these compositional banding effects are inferred to generate significant variations in the magnitude and orientation of seismic anisotropy, especially for shear-wave anisotropy (AVs) in the deep crust. Hence, our data suggest that layering of various origins (e.g., shear layers, partial-melting layers, and compositional layers) represents a new potential source of anisotropy within the deep crust. [ABSTRACT FROM AUTHOR]

The study was to determine the blood physiological indexes and coagulation physiological indexes of Xizang improved dairy cows (Holstein x Xizang cattle) under hypoxia environment to reveal the blood physiological characteristics of hypoxia adaptation, and evaluate the improvement effect of Xizang improved dairy cows by regularly detecting their DHI indexes and tracking their milk yield. Improved cattle raised in a low-oxygen plateau environment (Qiongjie County, Shannan City, Xizang, 3 617 m above sea level) were used as the research objects, and Holstein dairy cows introduced from Australia to Xizang and Xizang cattle (a local yellow cattle in Xizang) were selected as the control. Blood routine index, coagulation index, DHI index, and first fetal lactation yield were measured. The results showed that after long-term adaptation to low oxygen environment, the blood physiological indexes and DHI indexes of Xizang improved dairy cows had significant changes, among which HGB, HCT, and MCV were significantly higher than those of Xizang improved dairy cows and Xizang cattles (P<0.05), and the PLT was significantly lower than that of Xizang improved dairy cows (P<0.05). There were no significant differences in PT, APTT, and TT between Xizang improved dairy cows and Xizang cattles (P>0.05), and the coagulation function was improved compared with that of Holstein cows. Compared with Xizang improved dairy cows, milk fat percentage, milk protein percentage and lactose were significantly increased (P<0.05), while somatic cell count was significantly decreased (P<0.05). The study indicates that the Xizang improved dairy cows have a certain ability to adapt to low oxygen, and can adapt to low oxygen environment better than the imported dairy cows. Compared with the Xizang cattle and the imported Holstein dairy cows, the production performance of the Xizang improved dairy cows was optimized and improved. [ABSTRACT FROM AUTHOR]

Xizang boasts a vast and geographically complex landscape with an average elevation surpassing 4000 m. Understanding the spatiotemporal distribution of surface solar radiation is indispensable for simulating surface processes, studying climate change, and designing photovoltaic power generation and solar heating systems. A multi-dimensional, long-term, spatial, and temporal investigation of solar radiation in Xizang was conducted using three unique datasets, including the difference in surface solar radiation (SSR) between high-resolution satellite and ground station data, the annual and monthly distribution of SSR, and the interannual–monthly–daily variation and the coefficient of hourly variability. Combined with high-resolution elevation data, a strong linear correlation was shown between the radiation and the elevation below 4000 m. Furthermore, analysis reveals greater differences in data between east and west compared to the center, as well as between summer and winter seasons. SSR levels vary in steps, reaching the highest from Ngari to Shigatse and the lowest in a U-shaped area formed by southeastern Shannan and southern Nyingchi. In June, high monthly SSR coverage was the highest of the year. Since 1960, the annual mean SSR has generally exhibited a declining trend, displaying distinctive trends across various seasons and datasets. Owing to intricate meteorological factors, some regions exhibited double peaks in monthly SSR. Finally, we have introduced a solar resource assessment standard, along with a multidimensional evaluation of the resources, and categorized all townships. We offer a thorough analysis of Xizang's solar radiation to provide a comprehensive understanding, which will help to prioritize recommendations for PV construction in Xizang. [ABSTRACT FROM AUTHOR]

Simple Summary: Infection of humans and animals with Fasciola spp. poses a threat to both the health of humans and animals and the animal industry. In the pastoral areas of the Qinghai–Tibet Plateau, yak is the most important economic animal, especially for the herdsmen and their animal products. However, the infection of yaks with Fasciola spp. is often underestimated. In this study, we investigated a total of 1784 yaks in 16 administrative counties in the Qinghai–Tibet Plateau region by fecal examination and autopsy of yaks after slaughter, and the differences in infection rates between different age groups and regions were analyzed. The clustering characteristics of the infection rates in spatial statistics were summarized. This investigation revealed that yaks on the Qinghai–Tibet Plateau had a high Fasciola spp. prevalence (17.32%), age was a risk factor for Fasciola spp. infection, and regional differences were the other risk factor for Fasciola spp. infection. The objective of this investigation was to understand the epidemiology of fascioliasis in yaks in the alpine pastoral areas of the Qinghai–Tibet Plateau, China. The prevalence of Fasciola hepatica infection was estimated by examining eggs in the feces of yaks and by autopsy after the slaughter. Yaks were sampled from a total of 16 representative counties in Qinghai province, and risk factors were assessed based on regional and age characteristics. Fecal samples were obtained from 1542 yaks aged 0–1 (<1 year old), 1–2 (≥1 year old and <3 years old), and over 3 years (≥3 years old). In addition, 242 yaks over 3 years old who had not undergone fecal examinations were randomly selected for autopsy. A total of 267 fecal samples were positive for Fasciola spp. eggs. The average infection rate was 17.32% (0–60.61%), and the average infection intensity was 51.9 eggs per gram (epg) of feces, with intensities ranging from 18 to 112 epg. In Maduo, Dari, Zhiduo, Chengduo, and Datong counties, the Fasciola spp. eggs infection rate was zero. Fasciola spp. adult flukes were detected in 66 out of 242 yaks at autopsy, with a total infection rate of 27.27% and an average infection intensity of 21.2 (adult worms), with intensities ranging from 3 to 46 worms. Logistic regression model analysis showed that age was a significant risk factor for yak infection with Fasciola spp. In addition, the risk varied between regions: Haiyan, Gangcha, Duran, and Wulan were all high-risk areas for yak infection with Fasciola spp. The spatial distribution of the Fasciola spp. infection rate in each region showed a very weak negative correlation (Moran's I = −0.062), Duran formed a spatial distribution of high–low clusters with surrounding areas, and Datong formed a low–high clustering distribution characteristic with the surrounding areas. This investigation revealed that the infection rate of Fasciola spp. in yaks was higher on the Qinghai–Tibet Plateau. Increasing age was a risk factor for infection with Fasciola spp.; different regions also have a different risk of Fasciola spp. infection. Only two regions showed clustering characteristics in the spatial distribution of infection rates. These findings extend the epidemiological information on Fasciola spp. infection in yaks and provide baseline data for the execution of control measures against Fasciola spp. infection. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to explore the influence of high altitude on myopia, macular choroidal thickness (mCT), and macular retinal thickness (mRT) in adolescents. Methods: Two schools, one in Shanghai (at sea level) and one in Shigatse, Tibet (more than 4000 m above sea level), were selected. Refractive error was measured by an autorefractor instrument and subjective refraction, and mCT and mRT were measured at three concentric circles by optical coherence tomography. Student's t-test, Chi-square test, and multiple linear regression analyses were used to analyze the data. Results: A total of 1114 participants (657 and 457 in Shanghai and Tibet, respectively) were enrolled in this cross-sectional study. The average age of the participants was 18.81 ± 1.10 years, and 44.34% were males. The spherical equivalent (SE) of adolescents in Shanghai was significantly lower than that of adolescents in Tibet (-4.14 ± 2.37 D and -2.12 ± 1.87 D, P < 0.01). The prevalence of myopia and high myopia among adolescents in Shanghai (94.52%, 19.48%) was significantly higher than those among adolescents in Tibet (44.74%, 2.41%) (P < 0.01). The mCT of Tibetan adolescents was significantly thicker than that of Shanghai adolescents (295.80 ± 62.46 μm and 218.71 ± 61.42 μm, P < 0.01), especially the central mCT. The mRT of Tibetan adolescents was also thicker than that of Shanghai adolescents (301.42 ± 23.26 μm and 281.04 ± 12.24 μm, P < 0.01). Conclusions: Compared with Shanghai adolescents, the choroid of Tibet adolescents is thicker, and the myopia prevalence is lower. It is speculated that increased altitude is associated with the thickening of mCT and a low myopia prevalence. [ABSTRACT FROM AUTHOR]

The 2021 MW 7.4 Maduo event occurred within the Bayan Har block in eastern Tibet, which provides an opportunity to investigate the stress conditions and rheology of faults within the block. Here, we perform dynamic rupture simulations based on the finite element method to explore the physical conditions underlying this earthquake and the factors that controlled the rupture process. We construct the model with a nonplanar fault inferred from the Interferometric Synthetic Aperture Radar (InSAR) data and aftershocks sequence relocation. Our dynamic model is controlled by slip‐weakening friction law with initial stress on fault resolved from a uniform regional stress field. The preferred model produces an average slip of ∼2.2 m with a maximum slip of ∼4.0 m. There are three asperities distributed along the strike, which have captured the main features of the Maduo event. The simulation results are consistent with the static GPS coseismic surface displacements, InSAR data, and displacement waveforms recorded by high‐rate GNSS stations. By comparing the results with the planar fault model and rotated stress fields, we find that the fault geometry and regional stress field are the primary factors that control the rupture process of the event. Moreover, we infer that the unfavorable orientation and fault bend lead to minor slips on the branch fault. Furthermore, we investigate the potential mechanisms of supershear rupture on the eastern fault segment. Plain Language Summary: The 2021 Maduo event ruptured on an intra‐block fault of the Bayan Har block in the Tibetan Plateau, which has aroused widespread interest among the scientific community. In this study, we perform physics‐based numerical simulations based on a nonplanar fault to reproduce the source process of the event. The surface displacements obtained from our dynamic model are in good agreement with the observations. As the other parameters are relatively simple in our model, the source process of the event is mainly controlled by the geometric fault complexities. Our results also help to constrain the orientation of the regional stress field. We find that the branch fault of the earthquake is unfavorably oriented in the regional stress field as well as the fault bend also impedes the rupture to propagate on it, which leads to a minor slip on the branch fault. Furthermore, we infer that the supershear rupture may be induced by the free surface in the earthquake. Key Points: Our dynamic model reproduced the first‐order rupture characteristics of the Maduo earthquakeThe main factor that controls the multipeak slip pattern of the Maduo event is fault geometryThe orientation of the regional stress field was determined through numerical experiments [ABSTRACT FROM AUTHOR]

Aiming Lv,1,2 Tong Ding,2 DeQiong,2 DaWaZhuoMa,2 Long Cai,2 Yutong Zhang,2 Jinyu Yin,2 SeZhen,2 Qiubo Lv11Department of Obstetrics and Gynecology, Beijing Hospital, National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing, People's Republic of China; 2Women and Children's Hospital of Tibet Autonomous Region, Lhasa, Tibet Autonomous Region, People's Republic of ChinaCorrespondence: Qiubo Lv, Department of Obstetrics and Gynecology, Beijing Hospital, National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, No. 1 DaHua Road, Dong Dan, Beijing, 100730, People's Republic of China, Tel +86 13801192185, Fax +86 10 85136220, Email [email protected] Purpose: Pelvic floor disorder (PFD) seriously affects the everyday life of women. This cross-sectional study aimed to evaluate the prevalence and risk factors for postpartum PFD in women living in the Tibet Autonomous Region (TAR).Methods: Parous women who attended the outpatient gynaecology clinic at our hospital between June 2022 and August 2022 were screened in this study. The demographic and clinical data of these women were collected. Their pelvic floor functions were evaluated via a pelvic organ prolapse (POP) quantification examination, the Pelvic Floor Distress Inventory Questionnaire-20 (PFDI-20) and the Overactive Bladder Symptom Score (OABSS).Results: A total of 201 women were included in this study, of whom 81.09% (163/201) were Tibetan. Twenty-seven women (13.43%) were diagnosed with POP stage ≥ 2 and 27 women (13.43%) with an OABSS score ≥ 3. The median PFDI-20 total score was 4.17 (range 0– 43.75). Han women (n = 38) in the TAR had much lower PFDI-20 total scores, compared with Tibetan women (n = 163) (p < 0.05). The results of the multiple linear regression models showed that the PFDI-20 scores obtained from women living in the TAR were closely related to parity, history of heavy weight lifting, age, history of instrumental deliveries, ethnicity and number of caesarean sections.Conclusion: Pelvic floor disorder is common among parous women living in the TAR. Ethnicity, parity, history of heavy weight lifting, age, history of instrumental deliveries and number of caesarean sections are the factors closely related to the PFDI-20 scores. [ABSTRACT FROM AUTHOR]

“Shengdeng”, a group of Tibetan medicines with diverse biological origins, has long been utilized in Tibet for the treatment of rheumatoid arthritis. It showcases remarkable efficacy in alleviating rheumatism, reducing swelling, and relieving pain. This study aimed to clarify the plant species used as “Shengdeng” and summarize their botanical distribution, traditional uses, phytochemistry, and pharmacology to promote its utilization and development. “Shengdeng” is derived from a remarkable collection of 14 plant species belonging to six distinct families. Extensive phytochemical investigations have led to the identification of 355 chemical constituents within “Shengdeng”. Pharmacological studies conducted on “Shengdeng” have revealed a wide range of beneficial properties, including antioxidant, anticancer, antimicrobial, antiviral, antiparasitic, anti-inflammatory, and anti-arthritic activities. Notably, flavonoids and triterpenoids emerge as the predominant groups among these constituents, contributing to the therapeutic potential and diverse applications of “Shengdeng”. The present review provides a concise summary of the recent advancements in textual research concerning the herbal and botanical distribution, traditional uses, phytochemistry, and pharmacological activities of “Shengdeng”. It is crucial to note that future research on “Shengdeng” should prioritize the analysis of its active ingredients and the establishment of rigorous quality standards. These aspects are essential for ensuring consistency, efficacy, and safety in its clinical application. [ABSTRACT FROM AUTHOR]

The geodynamic processes that occurred beneath the Bangong – Nujiang suture zone during the evolution of the Indus – Yarlung Neo-Tethys and Bangong – Nujiang Meso-Tethys are unclear. We conducted a study of Early Cretaceous andesitic rocks from the Nyima area, north – central Tibet, to investigate these processes. The studied rocks have zircon U – Pb ages of 110–104 Ma and negative to positive εHf(t) values (−12.1 to+10.3). These rocks have affinities with trachytes, and have high total alkali contents and Na2O/K2O ratios (5–125). They also have high Sr (281–1409 ppm), Y (21.0–28.5 ppm), and Yb (2.00–2.65 ppm) contents, and exhibit depletions in Nb, Ta, and Ti. Such features indicate these rocks are not adakites, but are similar to typical arc rocks. The geochemical and isotopic data suggest the studied rocks were formed by partial melting of amphibolite-facies oceanic lithosphere, with the addition of enriched sedimentary materials. Based on the regional crustal evolution, we suggest that the Nyima andesitic rocks formed by melting of Bangong – Nujiang oceanic lithosphere. As such, the Early Cretaceous igneous rocks along the central Bangong – Nujiang suture zone were not associated with northward subduction in the Indus – Yarlung Neo-Tethys. [ABSTRACT FROM AUTHOR]

Under the climate warming, the ice avalanches (IAs) and glacier lake outburst floods (GLOFs) will continue or even intensify in the future. In order to find out the number, spatial distribution, and characteristics of hidden dangers of IA and GLOF-prone lakes on the Tibetan Plateau (TP), the first inventory is presented. (1) The study has identified and analyzed 581 IAs and 369 GLOFs on the TP. IAs and GLOFs are widely distributed in the Tibet Autonomous Region (TAR), concentrating in the Yarlung Zangbo River basin and the Nyainqntanglha and Himalaya Mountain range. (2) Most of the IAs have an area of 0.1 ~ 1 km2. The IAs occur on vulnerable slopes ranging from 35 to 45°, with an elevation between 4500 and 5500 m and a north-friendly aspect. (3) Most of the GLOFs with a lake area of 0.1 ~ 0.3 km2 and a north-facing outburst direction are developed in an elevation range from 4500 to 5500 m. There are about half of the GLOF-prone lakes to be close to the front edge of the mother glaciers. (4) The front elevation of IAs changes regularly with the eastern Himalayan syntaxis region as the boundary. It generally increased from west to east on the west side, while a "V-shaped" trend first decreased and then increased, and decreased from south to north on the east side. (5) The IAs and GLOFs are mainly distributed in the southern and northwestern TP with "clustering" characters due to the topographical and climatic settings. [ABSTRACT FROM AUTHOR]

Five new orchid species from southwestern China's Yunnan Province and the Tibetan Autonomous Region, Neottia lihengiae, Neottia chawalongensis, Papilionanthe motuoensis, Gastrochilus lihengiae, and Gastrochilus bernhardtianus, are described and illustrated. To confirm their identities, and to resolve phylogenetic relationships, we sequenced the complete plastomes of these taxa with their congeneric species, adding new plastomes of three Neottia species, two Papilionanthe species and nine Gastrochilus species. Combined with published plastid sequences, our well-resolved phylogeny supported the alliance of N. lihengiae with the the N. grandiflora + N. pinetorum clade. Neottia chawalongensis is now sister to N. alternifolia, while P. motuoensis is closely related to P. subulata + P. teres. Conversely, phylogenetic analyses based on complete plastomes and plastid sequences showed inconsistent relationships among taxa in the genus Gastrochilus, but the two new species, G. lihengiae and G. bernhardtianus were supported by all datasets. [ABSTRACT FROM AUTHOR]

The Devonian–Carboniferous boundary is one of the most important turning points in geological history, marked by the Late Paleozoic Ice Age and Late Devonian extinction. This study investigates the carbon isotope stratigraphy across the Devonian–Carboniferous boundary in Lhasa block, Tibet, China, which was part of the Gondwana continent during that time. The carbon isotope curves show a significant negative excursion trend, consistent with those of the South China block and other regions on the Laurentia continent. This global negative shift may be attributed to the burial of significant amounts of 12C-rich organic matter in strata, a consequence of the Late Devonian extinction event. Based on the carbon isotope curve and stratigraphic data of the Lhasa block, this study determined, for the first time, the specific horizon of the Devonian–Carboniferous boundary in Tibet, which is located between grayish white bioclastic limestone and yellowish-brown sandy limestone in the upper part of the Chaguoluoma Formation (D1C1ĉ). These findings provide a new reference for the international stratigraphic community to reconsider the position of GSSP on the Devonian–Carboniferous boundary, as well as study the Late Devonian mass extinction and Late Paleozoic glaciation. [ABSTRACT FROM AUTHOR]

High-temperature hydrothermal systems are mainly distributed in the north–south graben systems of southern Tibet as an important part of the Mediterranean–Tethys Himalayan geothermal belt in mainland China. As the largest unit capacity and second stable operating geothermal power station in China, Yangyi is the fracture-controlled type geothermal field in the center of Yadong–Gulu Graben. In this paper, hydrogeological and hydrochemical characteristics, isotope composition (δD and δ18O, 87Sr/86Sr and δ11B) of borehole water, hot springs, and surface river samples were analyzed. From the conservative elements (such as Cl− and Li+) and δD and δ18O values, the geothermal water of the Yangyi high-temperature geothermal field is estimated to be of meteoric origin with the contributions of chemical components of the magmatic fluid, which is provided by partially molten granite as a shallow magmatic heat source. According to logging data, the geothermal gradient and terrestrial heat flow value of the Yangyi high-temperature geothermal field are 6.48 ℃/100 m and 158.37 mW m−2, respectively. Combining the hydrothermal tracer experiment, 87Sr/86Sr and δ11B ratios obtained with gradually decreasing reservoir temperatures from the Bujiemu stream geothermal zone to Qialagai stream geothermal zone, we suggested the deep geothermal waters were mixed with local cold groundwater and then flow northeastward, forming the shallow reservoir within the crushed zone and intersect spot of faults in the Himalayan granitoid. Furthermore, in the process of ascent, the geothermal water is enriched in K+, Na+, and HCO3− during the interaction with underlying Himalayan granitoid and pyroclastic rocks that occur as wall rocks. The detailed description and extensive discussion are of great significance for the further exploitation and utilization of north–south trending geothermal belts in Tibet. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau (TP), once considered a pristine environment, is now facing increased heavy metal pollution due to human activities, causing unprecedented ecological risks to soil organisms. However, little is known about the sensitivity and tolerance of different soil organisms to heavy metal toxicity in the high-altitude areas of the TP under the background of human activity intensity and future risk control priorities. In this study, we conducted an ecological risk assessment and threshold calculation for 10 heavy metals in soil for typical soil organisms, including Cd, Co, Cr, Cu, Ni, Pb, Zn, Mn, Sb, and Sn, using the species sensitivity distribution (SSD) method in the zone between Ranwu town and Renlongba glacier on the TP. The results revealed that most sampling sites had average levels of Cd, Sb and Ni exceeding their regional soil environmental background values and were the major contaminants. Impressively, the hitherto undeveloped Renlungba Glacier showed relatively high contamination levels of Sb and Ni. From the view of sensitivity differences, the toxicity risks of Cd, Cr, Cu, Ni and Pb were higher for terrestrial plants than for soil invertebrates based on the fitted heavy metal SSD curve trends. In terms of the ecological risk level, the average potentially affected fraction values of Zn and Ni reached 18.5% and 17.0%, respectively, with significant ecological risk at a few sampling sites. In terms of ecological risk thresholds, the Cd concentration at the 5% hazard concentration (HC5) control level was 0.05 mg/kg, which was the heavy metal with the highest risk in this study. Comparing the HC5 values of each heavy metal with the limit values in the current Chinese soil environmental quality standards, the existing administrative policies as a whole lack a powerful prevention of the potential ecological risk posed by heavy metals to soil organisms. [ABSTRACT FROM AUTHOR]

Based on magnetotelluric array data and the three‐dimensional (3D) inversion algorithm, we obtain the 3D electrical structure of the 1976 Ms7.8 Tangshan earthquake zone. The seismogenic structure comprised a thick resistive anomaly located east of the Tangshan fault (TSF), a thin resistive belt extending westward, and the TSF zone. A geodynamic model is proposed based on the 3D electrical model and the other research findings. The model indicates that the primary cause of the Tangshan earthquake was the almost EW‐trending horizontal pushing from the west. The local uplift of deep thermal materials on the west side of TSF produces tensile deformation superimposed on the existing shear deformation. The combined effect of these two forces controls the Tangshan earthquake deformation characteristic. Prevailing horizontal pushing from the west and local uplift of hot material may be associated with the Tibet Plateau's eastward escape and the subduction of the Pacific plate. Plain Language Summary: The 1976 Ms7.8 Tangshan earthquake was the greatest in eastern China during the past 300 years, and it was an unusual event that occurred immediately beneath the city. It has caused significant economic and human losses. Even though previous Seismologists have conducted various related studies, there are still several controversies about the Tangshan earthquake's seismogenic structure and driving mechanism. An accurate structure model is required to resolve these problems. The magnetotelluric array data and the 3D inversion technology with topography were used to create a reliable 3D electrical model of the Tangshan earthquake zone. The model demonstrates that the seismogenic structure comprised a thick resistive anomaly located east of the source region, a thin resistive belt extending westward, and the Tangshan fault zone. The horizontal pushing force from the west and local thermal material uplift produced the Tangshan earthquake. Prevailing horizontal pushing from the west and local uplift may be associated with the Tibet Plateau's eastward escape and the subduction of the Pacific plate. The research findings not only improve our understanding of the mechanism of typical strike‐slip and extensional large earthquakes in North China but also provide a scientific basis for predicting comparable destructive strong earthquakes. Key Points: Detailed three‐dimensional crustal structure beneath the Ms7.8 Tangshan earthquake zone is obtainedThe seismotectonics comprised a resistive anomaly located east of the Tangshan fault (TSF), a resistive belt extending westward and the TSFThe Tangshan earthquake was triggered by the prevailing horizontal pushing force from the west and the local uplift of hot material [ABSTRACT FROM AUTHOR]

Mountainous regions are prone to dammed lake disasters due to their rough topography, scant vegetation, and high summer rainfall. By measuring water level variation, monitoring systems can detect dammed lake events when mudslides block rivers or boost water level. Therefore, an automatic monitoring alarm method based on a hybrid segmentation algorithm is proposed. The algorithm uses the k-means clustering algorithm to segment the picture scene in the RGB color space and the region growing algorithm on the image green channel to select the river target from the segmented scene. The pixel water level variation is used to trigger an alarm for the dammed lake event after the water level has been retrieved. In the Yarlung Tsangpo River basin of the Tibet Autonomous Region of China, the proposed automatic lake monitoring system was installed. We pick up data from April to November 2021, during which the river experienced low, high, and low water levels. Unlike conventional region growing algorithms, the algorithm does not rely on engineering knowledge to pick seed point parameters. Using our method, the accuracy rate is 89.29% and the miss rate is 11.76%, which is 29.12% higher and 17.65% lower than the traditional region growing algorithm, respectively. The monitoring results indicate that the proposed method is a highly adaptable and accurate unmanned dammed lake monitoring system. [ABSTRACT FROM AUTHOR]

Objective: To validate the Tibetan version of the International Prostate Symptom Score (IPSS-Tib) in patients with and without urinary symptoms in a Tibetan population. Methods: The validity and reliability of IPSS-Tib were studied in 85 patients with benign prostatic hyperplasia (BPH) and 62 controls without lower urinary tract symptoms (LUTS). Reliability was evaluated using the test−retest method and internal consistency using Cronbach's α, and the construct validity was assessed by the correlation between IPSS-Tib scores and quality of life questions (QoL-Tib). Results: The Cronbach's α coefficient of the IPSS-Tib was 0.80 and of a single IPSS scoring item ranged from 0.77 to 0.86. The IPSS-Tib test−retest reliability was evaluated by the intraclass correlation coefficient, and its average value was 0.79 (P < 0.001). The mean (SEM, 95% CI) area under the ROC curve for the IPSS-Tib was 0.91 (0.87–0.96). The IPSS-Tib had a high correlation with the QoL-Tib (Spearman's rank correlation coefficient 0.84, P < 0.01). The mean IPSS score before transurethral resection of the prostate (TURP) was 21.9 (6.8), and dropped to 6.38 (1.54) after TURP (P < 0.001), and the average difference was 15.52 (6.23), related to the drop from 4.5 (0.9) to 1.46 (0.48) in the QoL (P < 0.001). Conclusion: The IPSS-Tib has good reliability and validity in the diagnosis and symptom severity assessment of patients with BPH in Tibetan areas. It is an ideal assessment tool that can be used in Tibetan-speaking areas for patients with BPH and as a method for evaluating postoperative curative effect assessment of patients with BPH. [ABSTRACT FROM AUTHOR]

Precise earthquake locations and InSAR (Interferometric Synthetic Aperture Radar) deformation observation are the major methods to understand the earthquake occurrence and disaster-causing process. This paper proposes a processing framework for analyzing strong earthquake mechanisms from one-dimensional velocity inversion to precise earthquake locations combined with InSAR deformation observation, and discusses earthquake-generating fault and dynamic mechanisms of tectonic deformation. We analyzed the Menyuan Ms 6.9 earthquake in 2022 and discuss the historical seismic activities and corresponding stress adjustment processes in the research region. To analyze and study the seismogenic structure and mechanism of the earthquake, we investigated the spatial and temporal distribution characteristics of the Menyuan earthquake sequence and analyzed the InSAR coseismic deformation field. We obtained the precise locations of the main shock and aftershocks and the coseismic InSAR deformation field of the main shock. It was confirmed that the Ms 6.9 earthquake was a shallow sinistral strike-slip earthquake, which led to the sequential activation of the Tuolaishan and Lenglongling faults. The main seismogenic fault of the mainshock was the northwestern end of the Lenglongling fault, and the earthquake rupture was segmented. It can be inferred that the earthquake was a stress-adjusted event triggered in the Qilian-Haiyuan tectonic belt caused by the northeasterly push of the Qinghai-Tibet Plateau. The risk of moderate to high earthquakes in the region remains high in the future, requiring enhanced seismic observations. [ABSTRACT FROM AUTHOR]

Accessibility and capacity of medical resources are key for the health care and emergency response, while the efficiency of the medical resources is very much limited by hypoxia in Tibet, China. Through introducing exercise efficiency, this study explores the accessibility of township residence to county-ship medical resources in Tibet using weighted mean travel time (WMT), and evaluates the medical capacity accordingly. The results show that: 1) the average travel time of township residence to county-level hospital is around 2 h by motor vehicle in Tibet. More than half of the population can not reach the county-ship hospital within 1 h, 33.24% of the population can not reach within 2 h, and 3.75% of the population can not reach within 6 h. 2) When considering the catchment of the medical resources and the population size, the WMT of the county-ship medical resources ranges from 0.25 h to 10.92 h. 3) After adjusted by travel time and exercise efficiency, the county-ship medical capacity became more unequal, with 38 out of 74 counties could not meet the national guideline of 1.8 medical beds per 1000. 4) In total, there are 17 counties with good WMT and sufficient medical resources, while 13 counties having very high WMT and low capacity of medical resources in Tibet. In the end, suggestions on medical resources relocation and to improve the capacity are provided. This study provides a method to incorporate exercise efficiency to access the accessibility and evaluate medical capacity that can be applied in high altitude ranges. [ABSTRACT FROM AUTHOR]

The Regional Climate Model Version 4 (RegCM4) with the conventional plane‐parallel radiative transfer scheme severely overestimates the summer precipitation over the Tibetan Plateau (TP) due to the excessive surface heat source, which results from the poor representation of the sub‐grid terrain‐related radiation processes. To realistically describe the surface sub‐grid radiation process in the RegCM4, a 3‐dimensional sub‐grid terrain solar radiative effect (3DSTSRE) parameterization scheme is implemented into the RegCM4 to improve the original plane‐parallel radiative transfer scheme. Results show that adopting the 3DSTSRE scheme in RegCM4 can significantly reduce the summer (June–August) wet bias over the TP produced by the model with the plane‐parallel radiative transfer scheme. Mechanism analysis indicates that the 3DSTSRE scheme largely improves the description of the TP surface energy balance in the RegCM4 by reducing the positive bias of downward surface solar radiation (DSSR). The reduced DSSR leads to the weakened surface heat source and cooler near‐surface air over the TP. Consequently, the local atmospheric circulation adapts to the temperature field as the low‐level anti‐cyclonic (high‐level cyclonic) anomaly over the TP. The adjustment of the temperature and wind field attenuates the water vapor transport, enhances the low‐level atmospheric stability, inhibits the updraft motion, and eventually reduces the rainfall over TP. Although the 3DSTSRE improves the DSSR simulation only during daytime, the precipitation simulation is also improved at nighttime, which is fundamentally attributed to the maintenance of the cooled atmosphere throughout the daytime and nighttime. Key Points: A 3‐dimensional sub‐grid terrain solar radiative effect (3DSTSRE) scheme has been successfully implemented into the RegCM4 modelThe surface solar radiation flux and heat balance over the Tibetan Plateau in summer can be clearly improved by RegCM4 with the 3DSTSREThe wet biases of RegCM4 over the regions with complex terrain in Tibetan Plateau can be largely reduced by adopting the 3DSTSRE scheme [ABSTRACT FROM AUTHOR]

The Shiquanhe–Laguoco–Yongzhu–Jiali ophiolite mélange belt in Tibet includes the Laguoco Tso ophiolite as part of its western segment. Researchers studying the evolution of the Tibetan Plateau and the Tethys have taken a keen interest in the debated relationship between this ophiolite belt and the Bangong–Nujiang ophiolite belt. However, there is little research in this field. This study reports the rock geochemistry, SIMS (the secondary ion mass spectrometry) zircon U-Pb ages, and O isotope compositions of gabbro from the Laguoco ophiolite. Gabbro has substantial depletion in HFSEs (the high field strength elements) such as Th, Nb, Zr, and Hf, as well as exhibits comparatively high Mg# (80.6 on average), and low K, N, P, and Ti contents. Therefore, it was possibly formed in an intra oceanic subduction island arc environment originating from ~30% partial melting of the depleted spinel lherzolite. The SIMS zircon U-Pb ages of the gabbro samples are 187 ± 1.2 Ma and 189 ± 2.1 Ma, and the weighted averages of δ18O are 5.24‰ ± 0.12‰ and 5.34‰ ± 0.13‰, which are close to mantle-derived zircon δ18O (5.3‰ ± 0.3‰). These results suggest that during the Early Jurassic, the Laguoco ophiolite recorded the intra oceanic subduction of the northern branch of the Neo-Tethys. [ABSTRACT FROM AUTHOR]

Based on the mechanism of landslide dam failure caused by overtopping, a simplified mathematical model for simulating dam breach overtopping flow processes was proposed in our previous work. The model is composed of five main modules including hydrodynamic, sediment transport and erosion, headward erosion, breach lateral evolution, and breach side slope stability. However, the breach lateral evolution module is still based on the assumption existing in most available models that breach lateral spreading is linearly related to the undercutting, i.e., the lateral erosion rate is twice as much as the vertical undercutting rate in the process of dam breaking. This assumption is obviously lack of theoretical basis. Through a theoretical analysis of sediment initial motion on the river channel slope, a lateral erosion formula was deduced in this paper. Then the lateral enlargement model was developed to update the breach evolution module in the previously established simulation model. To verify the effectiveness of the modification, A case study was conducted in the same overtopping failure event of Baige landslide dam, which was located at the border of Tibet Autonomous Region and Sichuan province in China, took place on November 3, 2018. A good model performance was achieved with predicted flood volume, peak discharge and occurrence time within 10% margin of error compared with field monitoring data. Furthermore, a comparing with the previous model was carried out and the results obtained by the modified model applying the new lateral enlargement formula proposed in this study indicate that the predicting accuracy of the model can be improved significantly for the simulation of landslide dam overtopping failure. [ABSTRACT FROM AUTHOR]

The plateaus of Tibet have a unique climate that poses a great challenge for local agriculture. To promote sustainable development in Tibet, an elite tea variety has been introduced. However, the modifications of tea flavors in response to the climate of the plateaus are unknown. In this study, volatile organic compounds (VOCs) and other taste substances of tea planted in its original location (OOT) and in Tibet (TOT) were systematically analyzed and compared. The volatile components in TOT and OOT showed a slight difference, and principal component analysis revealed that the characteristic aroma compounds distinguishing tea grown in Tibet from tea grown in Guangdong were hotrienol and benzyl alcohol. In terms of taste substances, TOT exhibited higher levels of water extractable compounds, including polyphenols and amino acids, but lower levels of caffeine than OOT, which implies that TOT may taste better than OOT. To our knowledge, this is the first study to describe the changes in aroma and flavor profiles of tea induced by high altitude systematically, which will provide a basis for reference during the introduction and cultivation of tea crops to the plateaus of Tibet. [ABSTRACT FROM AUTHOR]

• The back-arc and arc-type magmatisms (ca. 838–748 Ma) were newly identified in the Rutong and Shiquanhe region, west of Tibet. • The North Lhasa terrane may separat from the Indian continent, finally constituted the northern segment of the East African Orogen during the Neoproterozoic. • The BNSZ retains geological records of the evolution of the Mozambique Ocean in the Neoproterozoic. Due to limited exposure of the Precambrian rocks in the Tibetan Plateau, their affinities and evolutions are inadequately studied. Here we report the newly identified Neoproterozoic metabasites (including metagabbros and metadolerites) at the western end of the Bangong-Nujiang suture zone (BNSZ) and the west part of the North Lhasa terrane. The Rutong Dong (RTD) metagabbros and Shiquanhe Nan (SQN) metadolerites yield zircon U-Pb ages of 838 Ma and 748 Ma, respectively. The RTD metagabbros are tholeiitic and exhibit both MORB- and arc-like geochemical characteristics, and we consider these to have formed in a back-arc basin setting. Combined with positive zircon ε Hf (t) (+6.3 to +13.8) and whole-rock ε Nd (t) (+4.4 to +5.3) values, the geochemical features of the RTD metagabbros indicate that they originated from a depleted mantle source enriched by subduction-related components (e.g., Th and U). The SQN metadolerites are mainly of transitional character (between tholeiitic and calc-alkaline), as well as representing typical calc-alkaline basalts. Their arc-like geochemical characteristics, as well as low positive whole-rock ε Nd (t) (+1.7 to +3.4), and positive zircon ε Hf (t) (+4.3 to +5.9) values, indicate generation by partial melting of an enriched subduction components modified mantle in an arc-type setting. Based on previous research, we propose that the North Lhasa terrane likely separated from India at ca. 925–860 Ma by the opening of the Mozambique Ocean. As the subduction zones were active at ca. 838–730 Ma in this ocean, a series of subduction-related magmatic events occurred, that is recorded in this study of the Rutong-Shiquanhe region, and other parts of the BNSZ and North Lhasa terrane. Consequently, we suggest that the BNSZ not only preserves information of the Meso-Tethys but also retains geological records of the Neoproterozoic Mozambique Ocean. [ABSTRACT FROM AUTHOR]

In 2000, a high-speed remote landslide occurred in Yigong, Tibet, China, which traveled 10 km within 10 min with a final deposit volume of 300 Mm3, forming a dammed lake and causing huge losses and environmental damage. This study aims to numerically simulate the entire dynamic process of the Yigong landslide under seismic loading, focusing on its initiation and sliding mechanism using a continuous–discontinuous method. This method, which combines the finite element method with the discrete element method, was adopted owing to its overall process capability. Triaxial compression tests on rock specimens extracted from the Yigong region were simulated using this method. The simulation parameters of the landslide were preliminarily determined based on the simulation results that matched the test results in terms of the peak strength and overall trend. A landslide under the action of an earthquake was simulated based on a landslide model established according to the geological data of the Yigong area. The simulation results provided a clear and concrete presentation of five types of cracks in the landslide body, which can explain the initiation mechanism. Moreover, the landslide process was completely presented from initiation to sliding to accumulation, as well as the final material accumulation. It is demonstrated that the continuous–discontinuous method can reproduce the landslide accumulation in terms of the height, material composition, and size with acceptable accuracy compared to field investigations. Furthermore, comparison with previous studies shows good agreement in the velocity of the upper avalanche part and deposition, which further supports the reliability of the method. Based on these results, the initiation and sliding mechanism are discussed in detail. The findings can help in understanding the deformation mechanism of landslides. [ABSTRACT FROM AUTHOR]

Background: Molecular markers are essential to identify Echinococcus species and genotypes in areas with multiple Echinococcus species to understand their epidemiology and pathology. Tibet Autonomous Region (TAR) is one of the areas worst hit by echinococcosis. However, molecular epidemiology is still missing among echinococcosis patients in TAR. This research explored the Echinococcus species and genotypes infecting humans in TAR and the population diversity and the possible origin of G1 in TAR. Methods: Cyst samples were collected in one echinococcosis-designated hospital in TAR. Echinococcus species and genotypes were identified through a maximum-likelihood approach with near-complete/complete mtDNA using IQ-TREE. Phylogenetic networks were built with PopART, and the phylogeographical diffusion pattern was identified using a Bayesian discrete phylogeographic method. Results: Using phylogenetic trees made with near-complete/complete mtDNA obtained from 92 cysts from TAR patients, the Echinococcus species and genotypes infecting humans in TAR were identified as Echinococcus granulosus (s.s.) G1 (81, 88.04%), accounting for the majority, followed by G6 of the E. canadensis cluster (6, 6.52%), E. granulosus (s.s.) G3 (3, 3.26%), and E. multilocularis (2, 2.17%). An expansion trend and a possible recent bottleneck event were confirmed among the G1 samples in TAR. Adding the other near-complete mtDNA of G1 samples globally from the literature, we identified the possible phylogeographic origin of the G1 samples in TAR as Turkey. Conclusions: Using near-complete/complete mtDNA sequences of Echinococcus spp. obtained from echinococcosis patients, a variety of Echinococcus species and genotypes infecting humans throughout TAR were identified. As far as we know, this is the first comprehensive molecular investigation of Echinococcus species and genotypes infecting humans throughout TAR. We identified, for the first time to our knowledge, the possible origin of the G1 in TAR. We also enriched the long mtDNA database of Echinococcus spp. and added two complete E. multilocularis mtDNA sequences from human patients. These findings will improve our knowledge of echinococcosis, help to refine the targeted echinococcosis control measures, and serve as a valuable baseline for monitoring the Echinococcus species and genotypes mutations and trends of the Echinococcus spp. population in TAR. [ABSTRACT FROM AUTHOR]

Topographic development via paraglacial slope failure (PSF) represents a complex interplay between geological structure, climate, and glacial denudation. Southeastern Tibet has experienced amongst the highest rates of ice mass loss in High Mountain Asia in recent decades, but few studies have focused on the implications of this mass loss on the stability of paraglacial slopes. We used repeat satellite- and unpiloted aerial vehicle (UAV)-derived imagery between 1990 and 2020 as the basis for mapping PSFs from slopes adjacent to Hailuogou Glacier (HLG), a 5 km long monsoon temperate valley glacier in the Mt. Gongga region. We observed recent lowering of the glacier tongue surface at rates of up to 0.88 m a -1 in the period 2000 to 2016, whilst overall paraglacial bare ground area (PBGA) on glacier-adjacent slopes increased from 0.31 ± 0.27 km 2 in 1990 to 1.38 ± 0.06 km 2 in 2020. Decadal PBGA expansion rates were ∼ 0.01 km 2 a -1 , 0.02 km 2 a -1 , and 0.08 km 2 in the periods 1990–2000, 2000–2011, and 2011–2020 respectively, indicating an increasing rate of expansion of PBGA. Three types of PSFs, including rockfalls, sediment-mantled slope slides, and headward gully erosion, were mapped, with a total area of 0.75 ± 0.03 km 2 in 2020. South-facing valley slopes (true left of the glacier) exhibited more destabilization (56 % of the total PSF area) than north-facing (true right) valley slopes (44 % of the total PSF area). Deformation of sediment-mantled moraine slopes (mean 1.65–2.63 ± 0.04 cm d -1) and an increase in erosion activity in ice-marginal tributary valleys caused by a drop in local base level (gully headward erosion rates are 0.76–3.39 cm d -1) have occurred in tandem with recent glacier downwasting. We also observe deformation of glacier ice, possibly driven by destabilization of lateral moraine, as has been reported in other deglaciating mountain glacier catchments. The formation, evolution, and future trajectory of PSFs at HLG (as well as other monsoon-dominated deglaciating mountain areas) are related to glacial history, including recent rapid downwasting leading to the exposure of steep, unstable bedrock and moraine slopes, and climatic conditions that promote slope instability, such as very high seasonal precipitation and seasonal temperature fluctuations that are conducive to freeze–thaw and ice segregation processes. [ABSTRACT FROM AUTHOR]

A review of 16 species of Hesperosoma Scheerpeltz from China is presented. Five new species are described: H. (s.str.) chenchangchini sp. nov. from Yunnan, H. (s.str.) languidum sp. nov. from Yunnan, H. (s.str.) motuoense sp. nov. from Xizang, H. (Paramichrotus) parvioculatum sp. nov. from Hubei, Hunan and H. (s.str.) xizangense sp. nov. from Xizang. Two species are new to China: H. (Paramichrotus) brunkei Schillhammer, 2015 from Yunnan and H. (s.str.) kleebergi Schillhammer, 2009 from Xizang. Females of H. (Paramichrotus) alexpuchneri Schillhammer, 2009, H. (Paramichrotus) guizhouense Schillhammer, 2018 and H. (s.str.) flavoterminale Schillhammer, 2004 are described for the first time. Habitus and diagnostic characters of all species are photographed and a key to Chinese species of Hesperosoma is provided. [ABSTRACT FROM AUTHOR]

Cattleyaks are the crossbred offspring between cattle and yaks, exhibiting the prominent adaptability to the harsh environment as yaks and much higher growth performances than yaks around Qinghai-Tibet plateau. Unfortunately, cattleyak cannot be effectively used in yak breeding due to its male infertility resulted from spermatogenic arrest. In this study, we performed RNA sequencing (RNA-seq) and bioinformatics analysis to determine the expression profiles of long noncoding RNA (lncRNA) from cattleyak and yak testis. A total of 604 differentially expressed (DE) lncRNAs (135 upregulated and 469 downregulated) were identified in cattleyak with respect to yak. Through gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, we identified several DE lncRNAs regulating the mitotic cell cycle processes by targeting the genes significantly associated with the mitotic cell cycle checkpoint and DNA damage checkpoint term and also significantly involved in p53 signaling pathway, mismatch repair and homologous recombination pathway (P < 0.05). The reverse transcription PCR (RT-PCR) and quantitative Real-Time PCR (qRT-PCR) analysis of the randomly selected fourteen DE lncRNAs and the seven target genes validated the RNA-seq data and their true expressions during spermatogenesis in vivo. Molecular cloning and sequencing indicated that the testis lncRNAs NONBTAT012170 and NONBTAT010258 presented higher similarity among different cattleyak and yak individuals. The downregulation of these target genes in cattleyak contributed to the abnormal DNA replication and spermatogenic arrest during the S phase of mitotic cell cycle. This study provided a novel insight into lncRNA expression profile changes associated with spermatogenic arrest of cattleyak. [ABSTRACT FROM AUTHOR]

Vaccinium motuoense (Ericaceae), a new species from Motuo County, Xizang Autonomous Region, China is described and illustrated. This new species belongs to Vaccinium sect. Calcicolus and is morphologically most similar to V. dunalianum, but differs in having yellowish-brown tomentose young branches, petioles and inflorescence rachis, leaf blades with 2-3(-4) pairs of secondary veins, usually all basal and with fine veins impressed adaxially and urceolate to spherical corollas. [ABSTRACT FROM AUTHOR]

GNSS/INS integrated navigation and positioning technology is widely used for train operations applications seeking a decrease in dependence on trackside equipment. However, during train operations, environmental factors such as bridges, tunnels, hillsides, and buildings will block the satellite signals. When INS works in a stand-alone mode, the system errors accumulate with time due to the inertial sensor characteristics. To overcome this problem, light detection and ranging (lidar) equipment can be introduced to help control INS divergence. The lidar point cloud data is first processed using the random sample consensus (RANSAC) algorithm to determine the track plane, then the moving average filtering (MAF) algorithm is used to detect and classify the rails. The frogs can be detected based on the changing rail number and the constraint condition for turnout parameters. With the assistance of a previously surveyed turnout database, the geographical positions of the detected frogs can be obtained and integrated with INS data to converge INS sensor errors when GNSS is not available. In this paper a lidar-aided GNSS/INS integrated navigation system is proposed that can ensure continuous positioning in both GNSS-available and GNSS-blocked scenarios. GNSS/INS is applied when the system operates in the GNSS-available scenario, and switches to the INS/lidar mode when the GNSS signals are blocked. To evaluate the performance of the proposed system, an actual train experiment was conducted along the Qinghai-Tibet railway. The results confirm that the proposed lidar-aided navigation system can achieve accurate and continuous positioning. When GNSS is not available, the proposed method can effectively suppress the error of INS with a DRMS of 1.66 m, which is a 70.4% improvement compared with a conventional GNSS/INS integrated system. [ABSTRACT FROM AUTHOR]

Knowledge of the evolution of the Bangong-Nujiang Tethyan Ocean is crucial for reconstructing the paleography of the Tethyan Realm, given its significance as a key component of the eastern Tethys. Nonetheless, there has been uncertainty regarding both the timing and the processes involved in the closure of this ocean. This study focused on a 110-106 Ma igneous complex comprising basalts-basaltic andesites, trachyandesites, and granodiorites from the Sumxi area in the western part of the Qiangtang terrane of west-central Tibet. The basalts-basaltic andesites have SiO2 contents of 52.5-58.7 wt% and MgO contents of 2.89-4.63 wt%, and exhibit some arc-like geochemical signatures. However, these rocks also have elevated Nb contents (>10 ppm) and Nb/La ratios (>0.5), as well as enriched Sr-Nd isotopic composition [eNd(Z) = -7.40 to -6.00], implying that they are products of a mantle source metasomatized by adakitic melts. The trachyandesites are characterized by intermediate compositions (SiO2 = 63.6-65.2 wt%), high Mg number (40-60), and more enriched eNd(t) values (-8.37 to -7.49). Comparing their geochemical composition to that of mélange rocks, it is postulated that these trachyandesites were formed through the partial melting of a mantle source including mélange matrix rocks within a subduction zone. The granodiorites exhibit adakitic geochemical features (Sr = 830.14-1032.70 ppm, Y = 14.8615.37 ppm, Sr/Y = 54-68), indicating that they originated from the partial melting of a thickened lower crust in a continental arc setting. Our results, in combination with a synthesis of tectonomagmatism along the Bangong-Nujiang suture zone, provide con-vincing evidence for subduction of an oceanic plateau and subsequent slab roll-back. The Sumxi igneous complex, with its clear arc affinity, suggests that the Bangong-Nujiang Tethyan Ocean, or at least its western part, remained open until the late Early Cretaceous (ca. 106 Ma). [ABSTRACT FROM AUTHOR]

The observed patterns and underlying mechanisms of elevational beta-diversity have been explored intensively, but multi-dimensional comparative studies remain scarce. Herein, across distinct beta-diversity components, dimensions and species groups, we designed a multi-faceted comparative framework aiming to reveal the general rules in the observed patterns and underlying causes of elevational beta-diversity. We have found that: first, the turnover process dominated altitudinal patterns of species beta-diversity (βsim > βsne), whereas the nestedness process appeared relatively more important for elevational trait dissimilarity (βfuncsim < βfuncsne); second, the taxonomic turnover was relative higher than its phylogenetic and functional analogues (βsim > βphylosim/βfuncsim), conversely, nestedness-resultant trait dissimilarity tended to be higher than the taxonomic and phylogenetic measures (βfuncsne > βsne/βphylosne); and third, as elevational distance increased, the contradicting dynamics of environmental filtering and limiting similarity have jointly led the elevational patterns of beta-diversity, especially at taxonomic dimension. Based on these findings, we infer that the species turnover among phylogenetic relatives sharing similar functional attributes appears to be the main cause of shaping the altitudinal patterns of multi-dimensional beta-diversity. Owing to the methodological limitation in the randomization approach, currently, it remains extremely challenging to distinguish the influence of the neutral process from the offset between opposing niche-based processes. Despite the complexities and uncertainties during species assembling, with a multi-dimensional comparative perspective, this work offers us several important commonalities of elevational beta-diversity dynamics. [ABSTRACT FROM AUTHOR]

Trench basins preserved along the southern margin of the Lhasa Terrane, Tibet, are sedimentologic records of convergent margin processes preceding Cenozoic India-Asia collision. We present new sedimentologic, petrographic and geochronologic data from the Rongmawa Formation and surrounding strata near Dênggar, Tibet, to determine depositional environment, provenance and age. Depositional ages range from ca. 92 to 87 Ma and lithofacies are consistent with deposition by low-and high-density turbidity currents and suspension settling of pelagic detritus in a deepmarine, trench basin setting. Sandstone modal analyses and U-Pb geochronology indicate that trench basin detritus in this region was derived from the Lhasa Terrane. We interpret that the Cretaceous subduction trench received detritus from an axial sediment dispersal system that transported sediment from headwaters in the centralsouthern Lhasa terrane near Lhasa City directly to the trench and then flowed westwards parallel to the trench. The preservation of trench basin strata deposited during Late Cretaceous time compared with the lack of trench deposits prior to ca. 92 Ma and after ca. 80 Ma suggests the margin experienced a period of significant accretion during this interval. In addition, deposition of trench basin strata occurred during Late Cretaceous adakitic magmatism and high-temperature metamorphism, which are hypothesized to be explained by subduction of an oceanic ridge or subduction zone retreat and related upper plate extension along the southern margin of the Lhasa terrane. Subduction of an oceanic ridge may provide a mechanism to potentially erode forearc basin strata and promote increased sediment delivery directly to the trench. [ABSTRACT FROM AUTHOR]

Wild-caught animals must cope with drastic lifestyle and dietary changes after being induced to captivity. How the gut microbiome structure of these animals will change in response receives increasing attention. The plateau zokor (Eospalax baileyi), a typic subterranean rodent endemic to the Qinghai-Tibet plateau, spends almost the whole life underground and is well adapted to the environmental pressures of both plateau and underground. However, how the gut microbiome of the plateau zokor will change in response to captivity has not been reported to date. This study compared the microbial community structure and functions of 22 plateau zokors before (the WS group) and after being kept in captivity for 15 days (the LS group, fed on carrots) using the 16S rRNA gene via high-throughput sequencing technology. The results showed that the LS group retained 973 of the 977 operational taxonomic units (OTUs) in the WS group, and no new OTUs were found in the LS group. The dominant bacterial phyla were Bacteroides and Firmicutes in both groups. In alpha diversity analysis, the Shannon, Sobs, and ACE indexes of the LS group were significantly lower than those of the WS group. A remarkable difference (P < 0.01) between groups was also detected in beta diversity analysis. The UPGMA clustering, NMDS, PCoA, and Anosim results all showed that the intergroup difference was significantly greater than the intragroup difference. And compared with the WS group, the intragroup difference of the gut microbiota in the LS group was much larger, which failed to support the assumption that similar diets should drive convergence of gut microbial communities. PICRUSt revealed that although some functional categories displayed significant differences between groups, the relative abundances of these categories were very close in both groups. Based on all the results, we conclude that as plateau zokors enter captivity for a short time, although the relative abundances of different gut microbiota categories shifted significantly, they can maintain almost all the OTUs and the functions of the gut microbiota in the wild. So, the use of wild-caught plateau zokors in gut microbial studies is acceptable if the time in captivity is short. [ABSTRACT FROM AUTHOR]

Two generations of garnet are recognized in a granite and a pegmatite from the Gangdese orogen in southeastern Tibet on the basis of a combined study of petrography, major and trace element profiles, and garnet O isotopes. Zircon U-Pb dating and Hf-O isotope compositions also help constrain the origin of both granite and pegmatite. The first generation of garnet (Grt-I) occurs as residues in the center of garnet grains, and it represents an early stage of nucleation related to magmatic-hydrothermal fluids. Grt-I is dark in backscattered electron (BSE) images, rich in spessartine, and poor in almandine and grossular. Its chondrite-normalized rare earth element (REE) patterns show obvious negative Eu anomalies and depletion in heavy REE (HREE) relative to middle REE (MREE). The second generation of pegmatite garnet (Grt-II) occurs as rims of euhedral garnets or as patches in Grt-I domains of the pegmatite, and it crystallized after dissolution of the preexisting pegmatite garnet (Grt-I domains) in the presence of the granitic magma. Compared with Grt-I, Grt-II is bright in BSE images, poor in spessartine, and rich in almandine and grossular contents. Its chondrite-normalized REE patterns exhibit obvious negative Eu anomalies but enrichment in HREE relative to MREE. The elevation of grossular and HREE contents for Grt-II relative to Grt-I domains indicate that the granitic magma had higher contents of Ca than the magmatic-hydrothermal fluids. The garnets in the granite, from core to rim, display homogenous profiles in their spessartine, almandine, and pyrope contents but increasing grossular and decreasing REE contents. They are typical of magmatic garnets that crystallized from the granitic magma. Ti-in-zircon temperatures demonstrate that the granite and pegmatite may share the similar temperatures for their crystallization. Grt-II domains in the pegmatite garnet have the same major and trace element compositions as the granite garnet, suggesting that the pegmatite Grt-II domains crystallized from the same granitic magma. Therefore, the pegmatite crystallized at first from early magmatic-hydrothermal fluids, producing small amounts of Grt-I, and the fluids then mixed with the surrounding granitic magma. The U-Pb dating and Hf-O isotope analyses of zircons from the granite and pegmatite yield almost the same U-Pb ages of 77–79 Ma, positive εHf(t) values of 5.6 to 11.9, and δ18O values of 5.2 to 7.1‰. These data indicate that the granite and pegmatite were both derived from reworking of the juvenile crust in the newly accreted continental margin prior to the continental collision in the Cenozoic. [ABSTRACT FROM AUTHOR]

Aiming at the problem of radar base and ground observation stations on the Tibet is sparsely distributed and cannot achieve large-scale precipitation monitoring. UNet, an advanced machine learning (ML) method, is used to develop a robust and rapid algorithm for precipitating cloud detection based on the new-generation geostationary satellite of FengYun-4A (FY-4A). First, in this algorithm, the real-time multi-band infrared brightness temperature from FY-4A combined with the data of Digital Elevation Model (DEM) has been used as predictor variables for our model. Second, the efficiency of the feature was improved by changing the traditional convolution layer serial connection method of U-Net to residual mapping. Then, in order to solve the problem of the network that would produce semantic differences when directly concentrated with low-level and high-level features, we use dense skip pathways to reuse feature maps of different layers as inputs for concatenate neural networks feature layers from different depths. Finally, according to the characteristics of precipitation clouds, the pooling layer of U-Net was replaced by a convolution operation to realize the detection of small precipitation clouds. It was experimentally concluded that the Pixel Accuracy (PA) and Mean Intersection over Union (MIoU) of the improved U-Net on the test set could reach 0.916 and 0.928, the detection of precipitation clouds over Tibet were well actualized. [ABSTRACT FROM AUTHOR]

The Chinese government has provided various forms of assistance to the Tibet Autonomous Region and has substantially improved their facilities, which has had a positive influence on the development of tourism in Tibet. The present study investigated how assistance to Tibet (AT) coordinates with tourism development (TD) by exploring the patterns and influencing factors of AT and TD using statistical data from 74 prefectural units from 1991 to 2015. The findings led to several conclusions: (1) AT displayed strong and constant coupling interactions with TD, and the coupling coordination degree increased from moderately unbalanced development (MUD) to barely balanced development (BBD). However, the coupling coordination degree remains low (MUD) in most prefectural units; (2) in 2015, the degree of coupling coordination displayed a "core-periphery" spatial pattern (i.e., low in center and high in the periphery), which highly coincides with the patterns of AT (x) and TD (y), and should thus be improved further; and (3) both AT factors and TD factors have significant effects on the spatial differentiation of coupling coordination degree but not on the coupling degree. This study expands research on coupling coordination and AT and provides scientific guidance for further coordinating AT and TD. [ABSTRACT FROM AUTHOR]

Paeonia ludlowii is indigenous to Tibet and has an important ecological and economic value in China. In Tibet, P. ludlowii has been used in folk medicine with relative success. Plant microbial endophytes play an important role in plant growth, health and ecological function. The diversity of endophytic bacteria associated with P. ludlowii remains poorly understood. In this study, the structure of the endophytic bacterial communities associated with different tissues, including fruits, flowers, leaves, stems, and roots, and rhizosphere soils was analyzed with Illumina MiSeq sequencing of bacterial 16S rDNA. A total of 426,240 sequences and 4847 operational taxonomic units (OTUs) were obtained. The OTUs abundance of roots was higher than that of other tissues; however, the OTUs abundance was similar among different deep soil samples. In the plant tissues, Cyanobacteria was the most abundant bacterial phylum, followed by Proteobacteria; however, the most abundant phyla were Proteobacteria and Acidobacteria in soil samples from three different layers. In addition, the diversity and richness of the microorganisms in the soil were very similar to those in roots but higher than those in other tissues of P. ludlowii. Predictive metagenome analysis revealed that endophytic bacteria play critical functional roles in P. ludlowii. This conclusion could facilitate the study of the ecological functions of endophytic bacteria and their interactions with P. ludlowii to analyze the reasons why this important medicinal plant is becoming endangered. [ABSTRACT FROM AUTHOR]

Nearly 19% of the world's population lives in China, yet the country contains only 7% of the planet's fresh water. Combining remotely sensed data and ground‐based measurements, we conducted a comprehensive assessment of recent changes in China's water resources. Beginning in the 21st century, glaciers in western China have been melting at very high rates; lakes on the Tibetan Plateau have been expanding rapidly, but lakes in other regions have been severely impacted by humans; and groundwater in the North China Plain is increasingly being depleted. Overall, the nation's water resources have been decreasing at an annual rate of ~9.6 billion cubic meters. Precipitation was the dominant factor controlling the observed changes in water resources, but human activities and rising temperatures have also been major drivers in the decline of water resources in the North China Plain and Tibet, respectively. From a global perspective, the changes in China's water resources are among the most pronounced on Earth, and water policies should be re‐evaluated and revised in light of the findings presented here. [ABSTRACT FROM AUTHOR]

From July to November 2018, 10 Black-necked Crane (Grus nigricollis) juveniles were tracked using GPS-GSM satellite transmitters to study their migration routes and stopover sites in Yanchiwan Nature Reserve, Gansu Province, China. By the end of the autumn migration in November 2018, more than 25,000 GPS locations had been obtained during tracking. Migration routes, migration distances and stopover sites were determined, and the stopover home range was estimated for each individual. Individuals moved away from Yanchiwan during 2-25 October 2018 and migrated through Da Qaidam, Golmud City, Qumarleb County, Zadoi County, Zhidoi County, and Nagqu City. In mid-November 2018, the birds arrived in Linzhou County, Tibet, China to winter. The migration routes of all individuals were the same, and the average migration distance was 1,500 ± 120 km. Da Qaidam Salt Lake was an important stopover site, with an average stopover duration of 27.11 ± 8.43 d, and the average stopover range of the Black-necked Cranes at Da Qaidam was 27.4 ± 6.92 km2. Through field monitoring and satellite maps, the main habitats were determined to be grasslands and wetlands. [ABSTRACT FROM AUTHOR]

This study presents 13 new U-Pb zircon ages obtained by laser ablation-inductively coupled plasma-mass spectrometry (LAICP- MS) together with whole-rock geochemical, Sr-Nd isotopic and zircon Hf isotopic data for a mafic dike swarm in the southern Qiangtang area of Tibet. These data provide the basis for a new model of the late Paleozoic evolution of the Tethys. Combined with the results of previous zircon U-Pb dating, the magmatic zircon grains extracted from mafic dikes yield latest Carboniferous to Early Permian ages (317-279 Ma). The geochemistry of the southern Qiangtang mafic rocks indicates the presence of low-Ti (QLT) and high-Ti (QHT) suites. The magmas that formed the QLT suite underwent higher degrees of partial melting (>5%) and display evidence of crustal contamination, whereas the QHT suite was derived from magmas generated by low-degree (1%-5%) partial melting of a garnet-bearing mantle source, with a greater extent of fractional crystallization than the QLT suite, and no evidence of crustal contamination. We propose that the QHT and QLT suites may have been derived from magmas from different parts of a single mantle plume. The formation of the southern Qiangtang mafic dikes (latest Carboniferous to Early Permian; 317-279 Ma) may have been related to the northward drift of the Cimmerian continent from the northern Gondwana margin, which resulted in the opening of the Meso-Tethys Ocean. [ABSTRACT FROM AUTHOR]

Amphibolite- and granulite-facies metamorphic rocks are common in the eastern Himalayan syntaxis of southeastern Tibet. These rocks are composed mainly of gneiss, amphibolite and schist that underwent various degrees of migmatization to produce leucogranites, pegmatites and felsic veins. Zircon U–Pb dating of biotite gneiss, leucocratic vein and vein granite from the syntaxis yields consistent ages of ∼49 Ma, indicating crustal anatexis during continental collision between India and Asia. Garnets in these rocks are categorized into peritecitc and anatectic varieties based on their mode of occurrence, mineral inclusions and major- and trace-element zoning. The peritectic garnets mainly occur in the biotite gneiss (mesosome layer) and leucocratic veins. They are anhedral and contain abundant mineral inclusions such as high-Ti biotites and quartz, and show almost homogeneous major-element compositions (except Ca) and decreasing HREE contents from core to rim, indicating growth during the P - and T -increasing anatexis. Peak anatectic conditions at 760–800°C and 9–10·5 kbar are well constrained by phase equilibrium calculations, mineral assemblages, and garnet isopleths. In contrast, anatectic garnets only occur in the vein granite. They are round or subhedral, contain quartz inclusions, and exhibit increasing spessartine and trace-element contents from core to rim. The garnet–biotite geothermometry and the garnet–biotite–plagioclase–quartz geobarometry suggest that the anatectic garnets crystallized at ∼620–650°C and 4–5 kbar. Some garnet grains show two-stage zoning in major and trace elements, with the core similar to the peritectic garnet but the rim similar to the anatectic garnet. Mineralogy, whole-rock major- and trace-element compositions and zircon O isotopes indicate that the two types of leucosomes were produced by hydration (water-present) melting and dehydration (water-absent) melting, respectively. The leucocratic veins contain peritectic garnet but no K-feldspar, have lower whole-rock K2O contents and Rb/Sr ratios, higher whole-rock CaO contents and Sr/Ba ratios, and show homogeneous δ18O values that are lower than those of relict zircons, indicating that such veins were produced by the hydration melting. In contrast, the vein granite contains peritectic garnet and K-feldspar, has higher whole-rock K2O contents and Rb/Sr ratios, lower whole-rock CaO contents and Sr/Ba ratios, and shows comparable δ18O values with those of relict zircons, suggesting that this granite were generated by the dehydration melting. Accordingly, both hydration and dehydration melting mechanisms have occurred in the eastern Himalayan syntaxis. [ABSTRACT FROM AUTHOR]

This article presents new zircon U-Pb geochronology, Hf isotopic, and whole-rock major- and trace-element geochemical data that provide insights into the petrogenesis and tectonic history of the Riwanchaka granodiorite porphyries of Central Qiangtang, Tibet. Zircon U-Pb ages of 236-230 Ma indicate an early Late Triassic age of emplacement of the porphyries, and zircon Hf isotopic data yield εHf(t) values of - 7.0 to - 1.5 and ancient zircon Hf crustal model ages (TDMC) of 1524-1220 Ma. The granodiorite porphyries are characterized by low K2O contents, high Mg# values, and relatively high Cr and Ni contents. They are classified as I-type calc-alkaline granite and are considered to have formed through the anatexis of ancient mafic crustal rocks with contributions from mantle-derived components. The geochemistry and isotopic compositions of all samples are similar to those of magmatic rocks that originated in the South Qiangtang crust. However, field observations indicate that the pluton intrudes the North Qiangtang crust, and we propose that the granodiorite porphyries were derived by partial melting of subducted continental crust of the South Qiangtang terrane. These new data have been integrated with data from previous studies to construct a new model of slab rollback during northward subduction of the Southern Qiangtang continental crust at ca. 245-226 Ma, thereby improving our understanding of magmatic processes involved in continental subduction in collision settings. [ABSTRACT FROM AUTHOR]

The Yanqiang Ling fragmented ophiolite (YLFO) crops out within the southern part of the Duolong ore concentration area, ∼20–30 km to the north of the western Bangong Co–Nujiang suture zone in central Tibet. It was tectonically emplaced within a Late Triassic–Jurassic accretionary complex and can be divided into two groups, western and eastern. Both groups consist of sheeted dikes, basalts, and ribbon cherts, and tectonites developed at the contact between the accretionary complex and tectonic lenses. U-Pb dating of zircons separated from the sheeted dikes and basalts suggests that both the eastern and western parts of the YLFO were generated at or after ∼118 Ma. The mafic sheeted dikes and lavas from both parts display normal mid-ocean ridge basalt–like chondrite-normalized rare earth element patterns and show positive Th and negative Nb anomalies on primitive-mantle-normalized multielement variation diagrams. Detailed geochemical analyses indicate that they were derived from partial melting of upwelling asthenospheric mantle, and the geochemical difference between the two parts might be caused by different degrees of partial melting or variations in their source compositions. Geochemical and geochronological evidence of the YLFO and its geological background suggest that it may represent a small rift within the forearc region due to spreading ridge–trench interaction within the Bangong Co–Nujiang Ocean, which also can explain formation of the Early Cretaceous magmatism and Cu-Au deposits within the Duolong ore concentration area. Our new data also support that the Bangong Co–Nujiang Ocean remained open during the Early Cretaceous, as suggested by earlier workers. [ABSTRACT FROM AUTHOR]

In this paper, we present new major and trace element chemical data for the basalts and phonolites of the Nare ocean island fragment (NaOI), as well as zircon U-Pb age data and Hf isotope compositions for the NaOI phonolites in the middle segment of the Bangong-Nujiang Suture Zone, northern Tibet. Our aim is to assess the genesis of these rocks and to reconstruct the Middle Triassic evolution of the Bangong-Nujiang Tethyan Ocean (BNTO). The NaOI retains an ocean island-type double-layered structure comprising a basaltic basement and an oceanic sedimentary cover sequence (conglomerate and limestone, the latter accompanied by layers of erupted phonolite near the top of the sequence). The basalts in the NaOI are enriched in light rare earth elements and high field strength elements (Nb, Ta, Zr, Hf, and Ti), and they exhibit chondrite-normalized REE patterns and primitive mantle-normalized trace element patterns similar to those of ocean island basalts. Taking into consideration their high Dy/Yb, Sm/Yb, and La/Sm ratios, we conclude that the NaOI basalts were derived from the partial melting of garnet peridotite in the mantle. The NaOI phonolites have LREE-enriched chondrite-normalized REE patterns with negative Eu anomalies (Eu/Eu* = 0.41-0.43) and primitive mantle-normalized trace element patterns with enrichments in Nb, Ta, Zr, and Hf, and depletions in Ba, U, Sr, P, and Ti. Given the high contents of Nb (172-256 ppm), Ta (11.8-16.0 ppm), Zr (927-1117 ppm), and Hf (20.8-26.9 ppm), and the very low contents of MgO (0.11-0.25 wt%), the very low Mg# values (5-10), and the near-zero contents of Cr (1.27-7.59 ppm), Ni (0.43-7.19 ppm), and Co (0.11-0.38 ppm), and the small and homogeneously positive εHf(t) values (+ 4.9 to + 9.5), we infer that the NaOI phonolites were formed by the fractional crystallization of an OIB-derived mafic parent magma. The phonolites of the NaOI contain zircons that yielded U-Pb ages of 239 and 242 Ma, indicating that the NaOI formed during the Middle Triassic. These data, combined with data from modern ocean islands (e.g., Canary Islands, Cape Verde, Fernando de Noronha, Tristan da Cunha, and Gough in the Atlantic Ocean, and Society and Austral-Cook in the Pacific Ocean), lead us to infer that the BNTO was open for a long time before the Middle Triassic, and that the ocean had already developed into a mature ocean with a thick oceanic lithosphere by at least the Middle Triassic. [ABSTRACT FROM AUTHOR]

We present our new investigation into the depositional environment and provenance of the Yingshuiquan Formation in the central Qiangtang region of northern Tibet, in order to further our understanding of the environment of the Longmu Co-Shuanghu Palaeo-Tethys during the Early Triassic. The Yingshuiquan Formation is composed of oolitic limestone, calcareous sandstone, calcarenite, thin-bedded ribbon limestone, bioclastic limestone, and coarse oolite limestone that were deposited in a shallow-marine basin and contain abundant Lower Triassic conodont fossils (e.g. Hadrodontina anceps, Pachycladina sp., gen. et sp, Pachyclaina oblique, Hibbardelloides sp). We selected detrital zircons from four calcareous sandstone samples for U-Pb dating, yielding minimum age peaks of 263, 269, 275, and 280 Ma, respectively, and a minimum age of 249 Ma, based on several zircons around the same age. Analysis of the conodont biofacies and zircon LA-ICP-MS dating of calcareous sandstone indicates that the data is consistent with deposition in the Early Triassic. The Yingshuiquan Formation records Early Triassic shallow-water sediment in the Longmu Co-Shuanghu Palaeo-Tethys, and has a Southern Qiangtang and Northern Qiangtang terranes provenance. During the Early Triassic, the carbonate sediments of the Yingshuiquan Formation were deposited in an active environment around the Longmu Co-Shuanghu Palaeo-Tethys, which has became a residual sea basin. [ABSTRACT FROM AUTHOR]

Zircon U-Pb dating of two samples of metagabbro from the Riwanchaka ophiolite yielded early Carboniferous ages of 354.4 ± 2.3 Ma and 356.7 ± 1.9 Ma. Their positive zircon εHf(t) values (+7.9 to +9.9) indicate that these rocks were derived from a relatively depleted mantle. The metagabbros can be considered as two types: R1 and R2. Both types are tholeiitic, with depletion of highfield- strength elements (HFSE) and enrichment of large-ion lithophile elements (LILE) similar to those of typical back-arc basin basalts (BABB), such as Mariana BABB and East Scotia Ridge BABB. Geochemical and isotopic characteristics indicate that the R1 metagabbro originated from a backarc basin spreading ridge with addition of slab-derived fluids, whereas the R2 metagabbro was derived from a back-arc basin mantle source, with involvement of melts and fluids from subducted ocean crust. The Riwanchaka ophiolite exhibits both mid-ocean ridge basalts- and arc-like geochemical affinities, consistent with coeval ophiolites from central Qiangtang. Observations indicate that the Qiangtang ophiolites developed during the Late Devonian-early Carboniferous (D3-C1) in a back-arc spreading ridge above an intra-oceanic subduction zone. Based on our data and previous studies, we propose that an oceanic back-arc basin system existed in the Longmuco-Shuanghu-Lancang Palaeo-Tethys Ocean during the D3-C1 period. [ABSTRACT FROM AUTHOR]