Search

Compositional changes of successively emplaced magmatites can be used to infer changes in their petrogenetic evolution and geodynamic setting. The central-northern Lhasa terrane hosts extensive Late Cretaceous magmatism, however, the mechanism that triggered the magmatism and its relationship to the directly preceding Late Cretaceous tectonic transition in the central Tibetan Plateau is still unresolved. Therefore, we conducted a detailed petrological, geochronological, geochemical, and isotopic study on recently identified Late Cretaceous doleritic and granodioritic rocks in the Xiongmei area, northern Lhasa subterrane. The potassic (K2O/Na2O ratios >1) dolerites (ca. 80 Ma) display a post-collisional basaltic shoshonitic signature with uniform moderately enriched whole-rock Sr–Nd and zircon–Hf isotopic compositions ((87Sr/86Sr)t = 0.7070 to 0.7095, whole-rock εNd(t) = – 2.4 to – 1.3, and zircon εHf(t) = – 5.9 to +1.9), suggesting that they evolved from a similar parental magma and were likely derived by partial melting of an enriched lithospheric mantle metasomatized by hydrous fluids. The granodiorites are geochemically divided into medium-K and high-K calc-alkaline rocks. The medium-K samples (ca. 80 Ma) are generally characterized by low K2O/Na2O ratios <1, whereas the high-K samples (78–76 Ma) display high K2O/Na2O ratios >1. The medium-K samples have positive zircon εHf(t) values from +4.8 to +6.5 and uniform whole-rock ɛNd(t) values from – 2.4 to – 1.3, which significantly differ from those of the high-K samples that have negative to positive zircon εHf(t) values from – 1.9 to +2.8 and negative whole-rock ɛNd(t) values from – 8.4 to – 5.1. The medium-K samples are characterized by high Sr contents and Sr/Y ratios, coupled with low Y and HREE contents, similar to adakitic compositions, and were interpreted to have been derived from deep partial melting of the foundering juvenile garnet-bearing mafic lower crust at relatively low temperatures. Compared to the medium-K samples, the high-K samples have lower Sr/Y and (La/Yb)N ratios, coupled with flat HREE patterns and distinct negative Eu, Sr and Ti anomalies and are most likely derived from shallower partial melting of the K-rich juvenile lower crust at relatively high temperatures. Considering the occurrence of variable magmatism in the central-northern Lhasa subterrane during the Late Cretaceous, the change in magma composition and lower crustal melting conditions (cold-deep vs. hot-shallow) suggest that the lithospheric mantle keel was partially detached by small-scale mantle convection in response to the low-angle Neo-Tethys-associated subduction between 85 and 70 Ma. [ABSTRACT FROM AUTHOR]

Northern Tibet exhibits abundant placer gold deposits, with a longstanding history of mining activities. Despite the widespread placer gold occurrences, the reports on the primary rock gold deposits or occurrences remain scarce. The central Lhasa terrane in northern Tibet hosts well-developed Zenong Group volcanic rocks, indicating great potential for the exploration of porphyry-epithermal copper (gold) deposits. Here, we select the Dangreyongcuo area in this region to investigate its metallogenetic potentiality, through a comprehensive 1:50,000 stream sediment geochemical survey, analyzing 12 elements (Au, As, Sb, Ag, Te, Cu, Pb, Zn, W, Sn, Bi, and Mo), and a detailed geological mapping. We aim to identify gold-related mineralization anomalies and provide clues for further bedrock gold exploration in this region. Based on the stream sediment geochemical data, zones 1–4, have been delineated using single-element indicator Au and element association indicator Au + As + Sb, which was determined through robust principal component analysis (RPCA) and using the exploratory data analysis (EDA) method. Subsequent validation exercises evaluating these four delineated zones reveal that Zone 1, Xinlong-Langmeila area, is the most promising prospect due to its high element concentrations, large size, and marked coincidence of element assemblages (also referred to as high-large-coincidence anomalies; HLCAs) and its characteristics are in line with those of epithermal deposits. Notably, the Xinlong deposit represents the first documented epithermal gold deposit hosted within the Zenong Group volcanic rocks. The identification of this deposit offers valuable insights and strategic directions for the broader understanding of Zenong Group volcanic rocks across the central Lhasa terrane. Additionally, subsequent strategies have been proposed for mineral exploration at both Xinlong camp and regional scales. • Gold anomalies were detected in the western Dangreyongcuo area, Tibet. • Xinlong deposit is a newly discovered high-sulfidation epithermal gold deposit. • Xinlong gold deposit is linked to Zenong Group volcanic rocks. • Promising prospecting potential exists within regional Zenong Group volcanic rocks. [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]

A large amount of distal skarn Pb–Zn deposits without any causative intrusions exposed have been discovered along the eastern Nyainqêntanglha metallogenic belt (NMB) in the Gangdese region, Tibet, China. As a typical distal skarn Pb–Zn deposit in the east of NMB, the Mengya'a deposit is adjacent to the Longmala Pb–Zn ± Cu ± Fe deposit. However, the linkage between these two deposits is not unclear due to the chaotic dating results. In situ Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA‐ICP‐MS) U–Pb dating of reddish‐brown and yellow‐green garnet from Mengya'a yielded lower intersect ages of 53.6 ± 3.1 and 52.4 ± 4.4 Ma, respectively, indicating that Pb–Zn mineralization took place during the main collision stage of the India–Asia plates. The δDSMOW values of garnet, quartz and calcite vary from −148.4‰ to −140.4‰, −123.5‰ to −115.3‰ and −127.9‰ to −121.3‰, with the δ18OH2O values ranging from 5.8‰ to 6.6‰, 0.4‰ to 3.7‰ and 1.0‰ to 1.7‰, respectively. The δ13CV‐PDB and δ18OSMOW values of calcite range from −8.2‰ to −4.7‰ and 9.8‰ to 18.6‰, respectively. These C–H–O isotopic compositions of hydrothermal minerals indicate that the ore‐forming fluids were initially derived from the magmatic water with progressive input of meteoric water from the prograde stage to the retrograde stage. The 87Sr/86Sr(53 Ma) ratios of sphalerite (0.72321–0.73474) are consistent with those of Ando gneiss in the Lhasa‐Golmud area, indicating that the basement gneiss makes a great contribution for the source of ore‐forming materials. The newly obtained garnet U–Pb ages at Mengya'a are consistent with those of mineralization and causative intrusion in the Longmala Pb–Zn ± Fe ± Cu deposit, suggesting that the Mengya'a and Longmala deposits constitute an integrated distal skarn‐type system. This proposed hypothesis suggests that the Fe–Cu ± Pb ± Zn mineralization within the contact zone should focus on the locations beneath the identified Pb–Zn orebodies at Longmala and Pb‐21 orebody at Mengya'a. [ABSTRACT FROM AUTHOR]

Background. The prevalence of chronic kidney disease (CKD) at high altitude is not known. We conducted a population-based survey in Tibet to identify the prevalence and associated risk factors of CKD in subjects living at altitudes of > 3500 m.Methods. One thousand two hundred and eighty-nine Tibetans (≥ 18 years) from four districts of Lhasa city (altitude 3658 m) and eight villages of Dangxiong County (altitude 4200 m) were interviewed and tested for haematuria, albuminuria and estimated glomerular filtration rate (eGFR).Results. The adjusted prevalence of hypertension, albuminuria, haematuria and reduced eGFR were 38.8% (95% CI: 36.2–41.5%), 16.2% (95% CI: 14.1–18.2%), 3.9% (95% CI: 2.8–4.9%) and 2.1% (95% CI: 1.3–2.9%), respectively. Both the presence of hypertension and the presence of albuminuria were strongly and independently associated with hyperuricaemia and elevated haematocrit.Conclusions. This is the first population-based epidemiological study of CKD in the Tibetan population. We found a higher prevalence of CKD and associated high prevalence of albuminuria, hypertension, hyperuricaemia and high haematocrit in the Tibetan population. The present study indicates the urgent need to develop comprehensive strategies targeted at reducing the CKD burden in this area and may lead to a better understanding of CKD in high-altitude populations. [ABSTRACT FROM AUTHOR]

Jurassic continental arc magmatism occurred widely across the southern Qiangtang Terrane, and provides an opportunity to study how continental arc magmas evolve towards intermediate–felsic compositions. We present new LA–ICP–MS zircon U–Pb ages, whole-rock major and trace element compositions, and Sr–Nd and in-situ zircon Hf isotope data for late Jurassic intermediate–felsic intrusive rocks from the Rena Co area of southern Qiangtang, central Tibet. Jurassic intrusive rocks in this area consist mainly of granodiorite, diorite, and related gabbro–diorite mafic enclaves, which have been dated at 153.1–147.6 Ma. Combining our data with previous results shows that continental arc magmatism in the southern Qiangtang Terrane has relatively homogeneous Sr–Nd isotopic compositions, with (87Sr/86Sr) i ratios of 0.7069–0.7092 and ε Nd (t) values of −6.3 to −2.2. Assuming that the hot, hydrous, basaltic melt generated by the subduction of the oceanic slab has a composition similar to island arc basalts, mixing ~50% basaltic magma with ~50% lower crustal material can produce the Sr–Nd isotopic compositions of the Rena Co intrusive rocks. The southern Qiangtang arc magmatism also has similar Hf isotopic compositions, albeit with a large range of ε Hf (t) values (−10 to +3). The different Rena Co intrusive rocks have different geochemical characteristics, including major element and rare earth element (REE) contents, Mg#, and evolutionary trends on Harker diagrams. This suggests that these arc rocks were derived from a common parent magma, but experienced different magmatic processes. The diorites were derived from primitive arc magma through amphibole-dominated low-pressure fractional crystallization, whereas the granodiorites underwent garnet-dominated, high-pressure fractional crystallization in secondary magma chambers. Fractionation of igneous garnet and amphibole played a significant role in the evolution of the continental arc, and was likely an important mechanism in driving the continental arc towards silica-rich compositions. The fractionation of igneous garnet and amphibole possibly changes the Mg# and Nb/Ta ratios of the derivative magmas. • Amphibole-bearing schlieren (MEs) are the direct evidence of the fractional crystallization. • The diorites were derived from initial arc magma through an amphibole dominated LPFC. • The granodiorites were derived from initial magma through an a garnet dominated HPFC. • Igneous garnet and amphibole fractionation play a significant role in continental arc. [ABSTRACT FROM AUTHOR]

The Bangongco–Nujiang metallogenic belt of Tibet is a main suture zone in the Qinghai–Tibet Plateau, which is known as an important porphyry–epithermal–skarn Cu-polymetallic mineralization zone in China. The western part of the Bangongco–Nujiang metallogenic belt exposes several medium high-silica terrestrial alkaline volcanic rocks with strong alteration influenced by collision orogeny. Some research has shown that clues to mineralization such as malachite and gossan are found on the surface. However, volcanic rock areas with varied topography place a huge burden on geological investigation, and the existing research on predicting mineralization is relatively scarce. This paper describes the extraction of alteration mineral information based on medium spatial resolution and hyperspectral resolution images, establishing a spectral library of alteration minerals in this area. By analyzing radar data, digital elevation, and synthesis results of different spectral bands, we combine remote sensing with geographic information technology to establish crater markers. The extraction results from multisource and chemical exploration data are superimposed onto the analysis of mineralization characteristics and geological conditions so as to establish the mineralization signatures for terrestrial volcanic rock areas. Eighteen mineralization prospect areas were identified, which can provide technical support for future mineralization research in this belt. [ABSTRACT FROM AUTHOR]

Abstract: The co-seismic slip sense of the 2008 Wenchuan earthquake (Mw 7.9) has resulted in the present east–west (E–W) crustal shortening and oblique thrusting across Longmen Shan, which are inconsistent with southeast-directed thrusting that occurred during the late Triassic. Although the two major periods of compressional deformations in Longmen Shan have long been recognized, the fault slip rate of the late Cenozoic deformation and the initial E–W crustal shortening remain poorly investigated. This study confirms the fault slip rate in the Dayi Thrust Fault System (DYFS) based on data from the petroleum industry and shallow seismic reflection profiles, and well data. Folded late Pliocene to present strata are analyzed and yield with an average slip rate of 0.2mm/yr on the DYFS. An average fault slip rate of 0.25mm/yr is then obtained from the late Pliocene to present for the range front thrust of Longmen Shan. The E–W crustal shortening is investigated by using 3-D seismic reflection data, interpreting satellite image, and conducting a field investigation in the DYFS to determine stress field changes during the late Cenozoic. Two-period tectonic deformations during the late Cenozoic are found in the DYFS, which correspond to the NE- and NS-trending structures, respectively. The activities of the DYFS may reflect a change in the field direction of the regional stress—from NW–SE during the Oligocene to early Pliocene to E–W during the late Pliocene to Holocene, which is consistent with the present stress measurements. The 120km NS-trending structures in the southern Longmen Shan range front as well as the Wenchuan earthquake co-seismic ruptures are assumed to reflect the active, E–W crustal shortening in Longmen Shan. [Copyright &y& Elsevier]

Abstract: Triassic Paleo-Tethyan subduction-related volcanic rocks are extensively distributed in the Xiangcheng and Changtai regions, northern Yidun Terrane, eastern Tibet. The ~228Ma volcanic rocks in the Xiangcheng region have intermediate-felsic composition (60.1 to 64.7wt.% SiO2) with relatively low Y (14–18ppm) and high Sr (630–1830ppm) yielding high Sr/Y ratios (43–94). They have LREE-enriched and HREE-depleted REE patterns (La/Yb=19–26), typical of adakites. Sr–Nd isotopic compositions of these volcanic rocks are similar to those of the contemporaneous high silica adakitic rocks in the southern Yidun Terrane. The ~231–230Ma volcanic rocks in the Changtai region are composed of basalts, andesites, dacites and rhyolites with SiO2 ranging from 47.7 to 81.0wt.%. Basalts in the Changtai region have initial 87Sr/86Sr ratios from 0.7052 to 0.7058 and εNd(t) from +1.1 to +1.5. They display OIB-like geochemical signatures, and were likely derived from low degrees of partial melting of an OIB-like mantle source with subordinate input of subduction components indicated by increasing Th content. Andesites and dacites show elemental and isotopic compositions that evolved from the basalts, indicative of derivation via crustal contamination and fractional crystallization (AFC) of basaltic magmas. Rhyolites have lower initial 87Sr/86Sr ratios and higher εNd(t) values than andesites/dacites, inconsistent with an AFC process and, are suggested to have been derived from anatexis of crustal materials. Emplacement of volcanic rocks in the Changtai and Xiangcheng regions could be attributed to the subduction of the Ganzi–Litang Ocean, a branch of the Paleo-Tethys Ocean. Volcanic rocks in the Changtai and Xiangchang regions have zircon U–Pb ages about 4–6myr older than that of arc granites in the eastern Yidun Terrane. The spatio-temporal distribution of the volcanic rocks indicates that the subduction was initiated under the southern Yidun Terrane in the Middle Triassic and extended to the northern Yidun Terrane at the beginning of the Late Triassic. [Copyright &y& Elsevier]

Exploring the mechanisms that affect mating pattern with respect to body size has implications for understanding the evolution of sexual selection. Theory predicts that the absence of a relationship between female body size and fecundity, unbiased operational sex ratio, and a short breeding season will lead to random mating by body size in anuran amphibians. We tested these predictions in the Himalayan toad Duttaphrynus himalayanus inhabiting southeastern Tibet. Our study did not detect any correlation between female body size and number of eggs laid, nor was there a significant difference in the sex ratio of toads captured from the breeding site. In addition, the toads were reproductive for only a short period, from late April to early May (typical of an explosively breeding species). As expected, we detected a weak but not significant relationship between body size of amplexing males and females. Our results revealed no apparent size-assortative pairing in the study population of the Himalayan toad and may contribute to an increasing body of literature on mating patterns in relation to body size in animals with indeterminate growth. [ABSTRACT FROM AUTHOR]

Abstract: Eastern Tibet to the west of the Yangtze Block consists of the Yidun and Songpan–Ganzi Terranes, separated by the Ganzi–Litang suture zone. The Yidun Terrane includes the Zhongza Massif to the west, but the eastern part of the Yidun terrane is covered by the Yidun Group extending from the south (Shangri-La region) to the north (Changtai region). The Yidun Group, from the base upward, includes the Lieyi, Qugasi, Tumugou and Lanashan formations, which are mainly composed of volcanic-flysch successions. Based on the ages of volcanic interlayers and plutonic intrusions, depositional ages of the Qugasi and Tumugou formations are considered to be slightly older than 230Ma and ca. 220–230Ma respectively, which are prominently older than the previous estimates. The Yidun Group in the Changtai region has two prominent detrital zircon age peaks at 400–480 and 880–980Ma and a minor peak at 2.45–2.50Ga. This pattern suggests a detritus source from the Zhongza Massif, which was a micro-continent separated from the western Yangtze Block. In contrast, the Yidun Group in the Shangri-La region has various zircon age spectra among different formations. The Qugasi Formation in this region has detrital zircon age patterns similar to the Yidun Group in the Changtai region. However, the overlying Tumugou Formation shows distinct age peaks at Triassic (220–240Ma), Neoproterozoic (~720–880Ma), and Paleoproterozoic (~1.75–1.90Ga). This age pattern is similar to that of the Xikang Group of the Songpan–Ganzi Terrane to the east. The detrital zircon age difference between the Qugasi and Tumugou formations in this region indicates a transition of sedimentary sources from the Zhongza Massif to locally distributed Triassic magmatic rocks at ~230Ma. It is thus suggested that the Songpan–Ganzi Terrane may have been connected to or collided with the southern part of the Yidun Terrane during the Late Triassic, whereas the Songpan–Ganzi Terrane and the northern part of the Yidun Terrane were still separated by the Ganzi–Litang Ocean. [Copyright &y& Elsevier]

Abstract: The 2008 Mw 7.9 Wenchuan earthquake is a consequence of ongoing India-Tibet collision and reflects the growth of the Longmen Shan fold-and-thrust belt. In this paper, we present new constraints on the deformation mechanism of the Longmen Shan fold-and-thrust belt, by comparing the physical models to the example of the Longmen Shan fold-and-thrust belt. The result indicates that the deformation mechanism of the belt is mainly dominated by the pre-Sinian layer, whereas locally is controlled by the Lower Triassic layer, such as the Longquan anticline. In addition, we discuss the deformation style of the Longquan anticline various along strike, based on the seismic reflection data, interpretations of structural cross-sections and field observations, as well as physical modeling. The sandbox modeling suggests that the deformation of the central segment of Longquan anticline is likely controlled by higher displacement rate, higher erosion and lower sedimentation, which is in contrast with the southern and northern segment. Moreover, the structural geometry of the central segment of Longquan anticline is more complex than the end-member models of fault-related folds, which is mainly controlled by pure-shear wedge fault-bend fold and bounded by west-verging thrust fault. Combining the studies of the structural geometry, deformation mechanism, and previous studies, we infer that the Longquan anticline is active and potentially seismogenic. Therefore, a quantitative re-evaluation of seismic hazard in Longquan anticline and adjacent area directly beneath the densely populated Sichuan basin is urgently needed. [Copyright &y& Elsevier]

• The Shesuo deposit is related to the intermediate-felsic magmatism (117–112 Ma). • The Shesuo deposit associated with slab break-off during a postcollisional period. • The addition of reducing materials limited the magma fertility. The Bangong-Nujiang metallogenic belt is a newly discovered copper-polymetallic belt in the Tethyan domain. To date, the Shesuo skarn Cu-polymetallic deposit is the only productive Early Cretaceous Cu deposit in the middle segment of this belt. We conducted zircon U-Pb and molybdenite Re-Os dating of this deposit, and the results show that the Shesuo skarn Cu-polymetallic deposit formed at 117–112 Ma. Within the mining area, granodiorites and monzogranites are the main metallogenic granitic bodies. The petrogeochemical features imply that the granodiorites and monzogranites were derived from the partial melting of juvenile lower crust resulting from mantle-derived magmatic underplating, with the additional involvement of ancient crust in the magma chamber, whereas the monzogranites experienced significant fractional crystallization. The δ34S values of sulfide ores suggest that they were mainly sourced from the magma and slightly contaminated by surrounding strata. The Pb isotope compositions of sulfides and Re contents of molybdenite indicate that the metals were derived from the juvenile lower crust, with a small fraction from ancient crustal materials. Our study suggests that the generation of the Shesuo deposit was most likely triggered by slab breakoff during the southward subduction of the Bangong-Nujiang Ocean lithosphere. The Shesuo and Xiongmei deposits have low zircon Ce4+/Ce3+ and Eu N /Eu* ratios and low whole-rock average V/Sc, Sr/Y and (Eu N /Eu*)/Yb N ratios. We propose that these values are due to the input of reduced components, leading to the generation of metallogenic magmas with relatively low magmatic oxidation states and water contents and rendering the magmas infertile for later porphyry-skarn Cu formation in the Xiongmei area. [ABSTRACT FROM AUTHOR]

We disagree the basic aspects regarding the evolution of the Bangong–Nujiang Meso-Tethyan Ocean (BNMTO) proposed by Li et al. (2019) (Earth-Science Reviews 198, doi: 10.1016/j.earscirev.2019.102907). Extensive Mid-Cretaceous ophiolite fragments and marine sedimentary rocks along the suture zone, along with Mid-Cretaceous magmatic arc (as late as 94 Ma) in the southern Qiangtang margin, indicates the BNMTO did not close until the Late Cretaceous, consistent with paleomagnetic data. Mid-Cretaceous OIB-type mafic rocks, covered by radiolarian-bearing cherts and being cold-emplaced ophiolitic fragments, together with Mid-Cretaceous magmatism of distinct arc affinity along the southern Qiangtang margin, indicate no magmatic evidence for divergent double subduction of the BNMTO. We also stress oceanic plateaus could have played a key role in the subduction evolution of the BNMTO. [ABSTRACT FROM AUTHOR]

The Majiari ophiolite lies in the western Bangong-Nujiang Suture Zone, which separates the Qiangtang and Lhasa blocks in central Tibet. The ophiolite consists of peridotite, gabbro/diabase and basalt. Zircon U-Pb dating yielded an age of 170.5 ± 1.7 Ma for the gabbro, whereas 40 Ar/ 39 Ar dating of plagioclase from the same gabbro yielded ages of 108.4 ± 2.6 Ma (plateau age) and 112 ± 2 Ma (isochron age), indicating that the ophiolite was formed during the Middle Jurassic and was probably emplaced during the Early Cretaceous. Zircons from the gabbro have ε Hf (t) values ranging from +6.9 to +10.6 and f (Lu/Hf) values ranging from −0.92 to −0.98. Mafic lavas plot in the tholeiitic basalt field but are depleted in Nb, Ta and Ti and enriched in Rb, Ba and Th in the N-MORB-normalized trace element spider diagram. These lavas have whole-rock ε Nd ( t ) values of +5.9 to +6.6, suggesting that they were derived from a depleted mantle source, which was probably modified by subducted materials. The Majiari ophiolite probably formed in a typical back-arc basin above a supra-subduction zone (SSZ) mantle wedge. Intra-oceanic subduction occurred during the Middle Jurassic and collision of the Lhasa and South Qiangtang terranes likely occurred in the Early Cretaceous. Thus, closure of the Bangong–Nujiang Tethys Ocean likely occurred before the Early Cretaceous. [ABSTRACT FROM AUTHOR]

Low air pressure and low oxygen partial pressure at high altitude seriously affect the survival and development of human beings and animals. ECE1 is a recently discovered gene that is involved in anti-hypoxia, but the full-length cDNA sequence has not been obtained. For a better understanding of the structure and function of the ECE1 gene and to study its effect in Tibetan pig, the cDNA of the ECE1 gene from the muscle of Tibetan pig was cloned, sequenced and characterized. The ECE1 full-length cDNA sequence consists of 2262 bp coding sequence (CDS) that encodes 753 amino acids with a molecular mass of 85,449 kD, 2 bp 5′UTR and 1507 bp 3′UTR. In addition, the phylogenetic tree analysis revealed that the Tibetan pig ECE1 has a closer genetic relationship and evolution distance with the land mammals ECE1 . Furthermore, analysis by qPCR showed that the ECE1 transcript is constitutively expressed in the 10 tissues tested: the liver, subcutaneous fat, kidney, muscle, stomach, heart, brain, spleen, pancreas, and lung. These results serve as a foundation for further insight into the Tibetan pig ECE1 gene. [ABSTRACT FROM AUTHOR]

The Bangpu porphyry Mo–Cu deposit is a representative Mo-dominated deposit besides the Sharang porphyry Mo deposit in the Gangdese metallogenic belt. The Mo–Cu mineralization has a close relationship with the monzogranite porphyry and diorite porphyrite. We identify three stages during the ore formation: a pre-ore stage, a main-ore stage with Mo–Cu deposited dominantly, and a post-ore stage. In this study, He–Ar, H–O, S and Pb isotopic compositions of the Bangpu deposit were determined. Based on these determinations, integrated isotope geochemistry studies were performed to constrain the possible sources of the ore-forming fluids and metals. The 3 He/ 4 He and 40 Ar/ 36 Ar ratios of fluid inclusions exhibit a range of 0.12209–0.36370 Ra and 275.6–346.1, respectively. The 4 He and 40 Ar concentrations vary from 1.51 to 3.57 (10 −7 cm 3 STP g −1 ) and 0.49 to 9.31 (10 −7 cm 3 STP g −1 ), respectively. He–Ar isotopic compositions suggest dominantly crustal-derived fluid with minor amount of meteoric water in the main ore stage. The δ 18 O fluid and δD fluid values vary from −1.3‰ to 3.9‰ and −140.5‰ to −73.7‰, respectively, indicating that magma fluids mixed with meteoric water. The average δ 34 S value of the sulfides (0.3‰) in the main-ore stage is close to the ore-forming porphyries, indicating a magmatic source. The lead isotopic components of ore sulfides exhibit restricted ranges with 206 Pb/ 204 Pb, 207 Pb/ 204 Pb, and 208 Pb/ 204 Pb ratios of 18.450–18.728, 15.602–5.672, and 38.715–39.211, respectively and μ values in the range of and 9.46–9.58, indicating ore-forming metals of primarily an upper crust source with a small amount of mantle materials. Compared to the Bangpu deposit, the ore metals derived from mantle are even greater in the Jiama and Qulong deposits, which leads to Cu being the dominant mineralization in the Jiama and Qulong deposit. [ABSTRACT FROM AUTHOR]

The coexistence of aqueous fluid inclusions and silicate melt inclusions in quartz phenocrysts from porphyrites at the Bangpu porphyry Mo–Cu deposit, Tibet, China were examined to characterize the immiscibility processes during the magmatic to hydrothermal transition. The physical and chemical environment during crystallization of the magmas has been reconstructed on the basis of microthermometric experiments and trace element microanalysis. Compositions of melt and brine fluid phases are determined using Synchrotron radiation X-ray fluorescence analysis, SEM–EDS and Laser Raman spectroscopy analyses. Brine fluids were directly exsolved by a crystallizing melt, and the simultaneous entrapment of volatile-rich (brine fluid) and volatile-poor immiscible phases (silicate melt) occurred at 670–700 °C and 1.6–1.95 kbar when the magma had H 2 O contents between 5 and 6 wt% and crystal contents of 60–80%. A later low-density fluid with a higher Mo concentration exsolved after about 80–90% crystallization had occurred. This fluid contained significant concentrations of Cl, Na, K, Ca, Fe, Cu, Zn, Rb, and small amounts of Mn, Br and Pb. Immiscibility of magmatic fluids can lead to different metal partitioning behaviors between residual melt and volatile phases, which generate variable metal ratios. Copper was partitioned preferentially into the brine phase, in contrast to the behavior observed in other porphyry Cu deposits. Ore deposition by a dense brine could explain the partially deep Cu mineralization. Condensation of brine from a later low-density parental fluid could be an efficient mechanism to concentrate shallow Cu mineralization and broadly distributed Mo mineralization. The source of the Mo mineralizing fluids probably was a particularly large magma chamber that crystallized and fractionated at depth greater than upper continental crust level. [ABSTRACT FROM AUTHOR]

The Rutog granitic pluton lies in the Gangdese magmatic arc in the westernmost part of the Lhasa Terrane, NW Tibet, and has SHRIMP zircon U-Pb ages of c. 80 Ma. The pluton consists of granodiorite and monzogranite with SiO[sub2] ranging from 62 to 72 wt % and Al2 03 from 15 to 17 wt%. The rocks contain 2.33-4.93 wt% K[sub2]O and 3.42-5.52 wt% Na[sub2]O and have Na[sub2]O/K[sub2]O ratios of 0.74-2.00. Their chondrite-normalized rare earth element (REE) patterns are enriched in LREE ((La/Yb)n = 15 to 26) and do not show significant Eu anomalies (SEu = 0.68-1.15). On a primitive mantle-normalized trace element diagram, the rocks are rich in large ion lithophile elements (LILE) and poor in high field strength elements (HFSE), HREE and Y. Their Sr/Y ratios range from 15 to 78 with an average of 30. The rocks have constant initial [sup87]Sr/[sup86]Sr ratios (0.7045 to 0.7049) and slightly positive ϵ[subNd](t) values (+0.1 to +2.3), similar to I-type granites generated in an arc setting. The geochemistry of the Rutog pluton is best explained by partial melting of a thickened continental crust, triggered by underplating of basaltic magmas in a mantle wedge. The formation of the Rutog pluton suggests fiat subduction of the Neo-Tethyan oceanic lithosphere from the south. Crustal thickening may have occurred in the Late Cretaceous prior to the India-Asia collision. [ABSTRACT FROM AUTHOR]

The processes and related rock types in post-collision setting are important to fully understand the geodynamic evolution of a collision zone. Bangong-Nujiang collision zone is the oldest collision zone in the Tibet Plateau. Slab break-off is one of the primary processes during post-collision, and is considered to have occured in the Bangong-Nujiang collision zone. Here, we report a newly identified rhyolite-biotite monzogranite (A2-type granite)-norite belt from this collision zone, which trend E-W for nearly 1000 km, and formed 115–104 Ma. The felsic rocks include rhyolite and biotite monzogranite, who share whole-rock geochemical similarities with A2-type granites. These felsic rocks were likely generated from a juvenile mafic crust melting at low pressure and high-temperature. The juvenile crust was derived from melting of metasomatized mantle wedge. The norites were generated from low degree (1–5%) melting of remnant enriched lithospheric mantle mixed with upwelling asthenospheric mantle at low pressure (~1.0 GPa) and high melting temperature (up to 1244 °C). A slab break-off beneath the Lhasa Terrane accounts for this post-collisional high-temperature extensional environment. The results provide important implications for the evolution of the Bangong-Nujiang collisional zone, including the subducting polarity, and timing of the Bangong-Nujiang ocean closure. • ~1000 km long rhyolite-A2-granite-norite belt in Bangong-Nujiang collision zone, Tibet • Felsic rocks formed from melting of a juvenile mafic crust. • Norites formed by asthenospheric and metasomatized lithospheric mantle interaction • The belt formed in a low-P/high-T post-collisional setting associated with slab break-off. [ABSTRACT FROM AUTHOR]

To determine the short- (4 weeks) and long-term (6 month) effectiveness of Tibetan medicated bathing therapy in patients with post-stroke limb spasticity. Prospective, blinded, randomized controlled trial. Post-stroke patients with limb spasticity were recruited between December 2013 and February 2017 and randomly assigned 1:1 to a control group that received conventional rehabilitation (n = 222) or an experimental group that received Tibetan medicated bathing therapy in combination with conventional rehabilitation (n = 222). All patients received conventional rehabilitation. In addition, the experimental group received Tibetan medicated bathing therapy. The interventions were conducted 5 times per week for 4 weeks. The primary endpoint was changes from baseline after 4 weeks of therapy in muscle tone in the spastic muscles (elbow flexors, wrist flexors, finger flexors, knee extensors, ankle plantar flexors), as measured by the Modified Ashworth Scale (MAS). The mean change from baseline after 4 weeks of therapy in the MAS score for the elbow flexors (P =.017), wrist flexors (P <.001), and ankle plantar flexors (P <.001) was significantly greater in patients in the experimental group compared to the control group. The benefit was maintained for 3 muscle groups (elbow flexors P <.001, wrist flexors P =.001, and ankle plantar flexors P <.001) and 6 months (elbow flexors P <.001, wrist flexors P =.002, and ankle plantar flexors P <.001) after therapy. All adverse events were mild, and no serious adverse reactions to Tibetan medicated bathing therapy were recorded. Tibetan medicated bathing therapy, in combination with conventional rehabilitation, has potential as a safe, effective treatment for the alleviation of post-stroke upper limb spasticity. Tibetan medicated bathing therapy was most advantageous for patients who had a baseline muscle tone score of 1+ to 2 on the MAS in the affected limb and recent onset of stroke (duration of the disease of 1-3 months). [ABSTRACT FROM AUTHOR]