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South China block contains abundant rare metal resources that have widely been considered to be associated with highly evolved granitic magmatism and related fluid metasomatism. Here we perform detailed geochemical analyses on apatite and bulk rock from the ore-bearing granites (equigranular zinnwaldite granite) and ore-barren granites (porphyritic biotite granite and granitic dyke) at Qianlishan pluton, South China, to decipher the respective roles of magmatic and fluid processes and further understand the petrogenesis of rare metal granite (RMG). Apatites from both granite types are F-rich, displaying heterogeneous textures and large compositional variations in Cl, Sr, rare earth elements (REEs), Ga, Th, and U. Relative to the ore-barren granite, the apatites from ore-bearing granite contain lower Sr but higher ∑REE, Th + U and Ga, reflecting more evolved features. The oscillatory compositional zonation and bimodal O-Nd isotopic compositions in apatite from the ore-barren granite indicate multiple-pulse intrusion instead of other open-system processes such as magma mixing and/or crustal assimilation during magmatic evolution, while the additional occurrence of monazite and lower δ18O (< 8‰) in half of the apatite crystals from the ore-bearing granite require further influence of hydrothermal metasomatism. In combination with their high W + Sn concentrations and La tetrad effect in chondrite-normalized REE patterns, the ore-bearing granite experienced extensive metasomatism, during which the fluids in equilibrium with the metasomatic apatite were likely magmatic in origin. We therefore suggest that multiple-pulse magmatic intrusion and fluid metasomatism are two predominant factors during the formation of highly evolved RMG, such as the Qianlishan pluton in South China. Our results demonstrates that apatite geochemistry can be a potential approach to monitoring the magmatic evolution and fluid metasomatism during rare metal mineralization. • Qianlishan pluton shows large elemental and isotopic variations in apatite. • Multiple-pulse magmatic intrusion is a key to highly evolved rare metal granite. • Fluid metasomatism promotes the rare metal enrichment and mineralization. [ABSTRACT FROM AUTHOR]

Abstract China has the largest thermal power installed capacity worldwide, which has caused severe greenhouse gas emissions. To reduce the emissions and facilitate the development of energy savings and emission abatement, it is imperative to improve power-generating efficiency. In this paper, the nonparametric weighted Russell directional distance method (WRDDM) was used to evaluate the overall efficiency of thermal power plants in 30 provinces in China. The results show that the efficiency of East and North China is higher than that of Northeast and Southwest China. Furthermore, the correlations between scale, ownership and efficiency are discussed. The nonstate-owned plants with large generation capacity have a higher efficiency than the small and state-owned plants. [ABSTRACT FROM AUTHOR]

The Mesozoic tectono-magmatism in SE China has widely been considered to relate to subduction of the Paleo-Pacific Ocean. However, there lacks robust petrologic and geochemical evidence from subduction-related mafic igneous rocks to reconstruct the architecture of the subduction zone. This paper presents a comprehensive geochemical dataset (petrography, mineral chemistry, zircon U-Pb age, in-situ Sr and Pb isotope compositions of plagioclase and whole-rock major, trace element and Sr-Nd-Pb-Hf isotope data) of three early Cretaceous (Pingtan, Daiqianshan and Quanzhou) mafic intrusions from the coastal region in SE China, with aims to understand their petrogenetic link with subduction of the Paleo-Pacific Ocean. The mafic rocks comprise predominantly calcic hornblende and Ca-rich plagioclase and show varying degrees of crystal accumulation. Petrological observations and mass balance calculation indicate their parental magmas are hydrous and calc-alkaline with typical arc-type trace element features. These rocks are also characterized by "crust-like" isotopic signatures, i.e., moderately radiogenic Sr, unradiogenic Nd and highly radiogenic Pb compositions. The narrow variations of in-situ plagioclase Sr and Pb isotope ratios and the nearly identical isotope compositions between the plagioclase and bulk rock in each intrusion indicate a minor role of crustal assimilation during magmatic evolution. Instead, such "crust-like" isotopic signatures were largely resulted from source enrichment through an input of subducted sediment. Further element-isotopic modeling results suggest that the parental magmas were likely produced by melting of a depleted mantle source metasomatized via the subducted sediment-derived melt. Generation of the early Cretaceous mafic intrusions can thus be explained by subduction of a relatively hot oceanic slab, during which melt derived from the subducted sediment acted as a predominant agent to enrich the mantle wedge. Our results provide powerful petrological and geochemical constraints on the early Cretaceous subduction of the Paleo-Pacific Ocean beneath the SE China and suggest that addition of subducted sediment-derived melt may be an important mechanism for mantle enrichment in relatively hot subduction zones. • Early Cretaceous mafic intrusions are subduction-related with "crust-like" isotopic features. • Parental magmas were formed through melting of a depleted mantle wedge enriched by sediment-derived melt. • A relatively hot Paleo-Pacific Ocean subduction zone existed in SE China during early Cretaceous. [ABSTRACT FROM AUTHOR]

Background: The Junggar Basin plague focus was the most recently identified natural plague focus in China. Through extensive field investigations, great gerbils (Rhombomys opimus) have been confirmed as the main host in this focus, and the community structure of their parasitic fleas is associated with the intensity of plague epizootics. The aim of this study is to provide an indicator that can be surveyed to evaluate the risk of plague epizootics. Methods: Between 2005 and 2016, rodents and fleas were collected in the Junggar Basin plague focus. The parasitic fleas on great gerbils were harvested, and anti-F1 antibody in the serum or heart infusion of great gerbils was detected through indirect hemagglutination assay. Yersinia pestis (Y. pestis) was isolated from the liver and spleen of great gerbils and their parasitic fleas using Luria-Bertani plates. Receiver-operating characteristic (ROC) curve was used to evaluate the predictive value of flea index. Results: Between 2005 and 2016, 98 investigations were performed, and 6778 great gerbils and 68,498 fleas were collected. Twenty-seven rodents were positive for Y. pestis isolation with a positivity rate of 0.4%; 674 rodents were positive for anti-F1 antibody with a positivity rate of 9.9%. Among these 98 investigations, plague epizootics were confirmed in 13 instances by Y. pestis-positive rodents and in 59 instances by anti-F1 antibody-positive rodents. We observed a higher flea index among rodents with confirmed plague epizootic compared to the negative ones (P = 0.001, 0.002), with an AUC value of 0.659 (95% CI: 0.524–0.835, P = 0.038) for Y. pestis-positive rodents and an AUC value of 0.718 (95% CI: 0.687–0.784, P < 0.001) for anti-F1 antibody-positive rodents. Conclusions: Significantly higher flea index was associated with confirmed plague epizootic cases among great gerbils and could be used to predict plague epizootics in this focus. [ABSTRACT FROM AUTHOR]

The Mesozoic geology of SE China has been widely considered to relate to subduction of the Paleo-Pacific Plate beneath the Eurasia, accompanied with extensive felsic magmatism. However, the relationship between the origin of the voluminous crust-derived magmatism and the Paleo-Pacific slab subduction remains unclear. Here we present petrology, zircon U-Pb-Hf isotope data, and whole-rock geochemical and isotopic compositions of two episodes of Cretaceous silicic volcanic rocks (~114–113 Ma for Group 1 and ~ 100–93 Ma for Group 2) from southeastern Zhejiang Province in SE China, to provide new constraints on the geodynamic transition of the Paleo-Pacific slab subduction. Both volcanic groups show similarly unradiogenic whole-rock ε Nd (t) and zircon ε Hf (t) values (ε Nd (t) = −8.6 to −6.4 and ε Hf (t) = −8.5 to −0.7 for Group 1, and ε Nd (t) = −7.1 to −6.1 and ε Hf (t) = −7.8 to −2.2 for Group 2). The limited emplacement of coeval mafic magmas and absence of mafic microgranular enclave and intermediate lavas suggest an insignificant role of mantle-derived melt either as a parental magma for differentiation or a mafic component during magma mixing. Instead, the low MgO and high concentrations of SiO 2 and incompatible elements and the evolved Nd and Hf isotopic compositions indicate derivation of these two groups of silicic magmas from similar hybrid crustal sources containing the metasedimentary rocks of Cathaysia basement and the newly accreted arc crust. Group 1 rocks contain a higher proportion of hydrous minerals (e.g., biotite) and Sr/Y and La/Yb CN ratios but lower zircon saturation temperature than Group 2. Such variations in mineral and geochemical compositions could be mainly attributed to the change of melting conditions from a relatively deeper, colder and water-fluxed crust to a shallower, hotter and less hydrous state. By combining our new results and previous studies of the late Mesozoic volcanic rocks in SE China, we propose that a geodynamic transition from subduction to slab rollback of the Paleo-Pacific Plate was responsible for such P-T-H 2 O variations of the crustal source. • 1. Two episodes of Cretaceous felsic volcanic rocks were identified in SE China. • 2. Both of them were formed by crustal melting at different P-T-H 2 O conditions. • 3. Transition from subduction to slab rollback occurred during ca. 110–90 Ma. [ABSTRACT FROM AUTHOR]

Background: The paradigm shift in hepatitis C virus (HCV) treatment options in the last five years has raised the prospect of eliminating the disease as a global health threat. This will require a step-change in the number being treated with the new direct-acting antivirals (DAAs). Given constrained budgets and competing priorities, policy makers need information on how to scale-up access to HCV treatment. To inform such decisions, we examined the cost effectiveness of screening and treatment interventions in Yunnan, China. Methods and findings: We simulated the HCV epidemic using a previously published model of HCV transmission and disease progression, calibrated to Yunnan data, and implemented a range of treatment and screening interventions from 2019. We incorporated treatment, diagnosis, and medical costs (expressed in 2019 US Dollars, USD) to estimate the lifetime benefits and costs of interventions. Using this model, we asked: is introducing DAAs cost effective from a healthcare sector perspective; what is the optimal combination of screening interventions; and what is the societal return on investment of intervention? The incremental cost-effectiveness ratio (ICER) of switching to DAAs with a median cost of 7,400 USD (50,000 Chinese Yuan) per course is 500 USD/disability adjusted life year (DALY) averted; at a threshold of 50% of Yunnan gross domestic product (2,600 USD), switching to DAAs is cost effective 94% of the time. At this threshold, the optimal, cost-effective intervention comprises screening people who inject drugs, those in HIV care, men who have sex with men, and ensuring access to DAAs for all those newly diagnosed with HCV. For each USD invested in this intervention, there is an additional 0·80 USD (95% credible interval: 0·17–1·91) returned through reduced costs of disease or increased productivity. Returns on investment are lower (and potentially negative) if a sufficiently long-term horizon, encompassing the full stream of future benefits, is not adopted. The study had two key limitations: costing data were not always specific to Yunnan province but were taken from China-level studies; and modelled interventions may require more operational research to ensure they can be effectively and efficiently rolled-out to the entire province. Conclusions: Introducing DAAs is cost effective, the optimal package of screening measures is focussed on higher risk groups, and there are likely to be positive returns from investing in such HCV interventions. Our analysis shows that targeted investment in HCV interventions will have net benefits to society; these benefits will only increase as DAA costs fall. [ABSTRACT FROM AUTHOR]

• The Liucheng OIB-type dolerite sill in the coastal region of SE China was formed during early Cretaceous. • Crustal components from both the sediments and mafic oceanic crust have been identified in the mantle source. • Rollback and tearing of the subducting slab may contribute to OIB-type magmatism at an active continental margin. Both early Cretaceous ocean island basalt (OIB)-type and subduction-related arc-type mafic magmatism occurred in coastal region of SE China. However, whether there existed a genetic relationship between the OIB-type magmatism and contemporary subduction of the Paleo-Pacific Ocean remains unclear. Here we present a comprehensive geochemical dataset of the Liucheng dolerite sill (~108 Ma) from coastal SE China, with aims to investigate the possible genetic link between them. The dolerite displays OIB-like trace element features and contains moderately radiogenic Sr-Nd-Pb-Hf and light Ca isotopic compositions. The nearly identical Sr-Pb isotopes between plagioclase and bulk rock indicate a minor role of crustal assimilation during magmatic evolution. The remarkable positive Ba anomalies, similar Sr and Pb isotopic compositions to the contemporary arc-type mafic rocks and light Ca isotopes suggest a source modified by recycled sediments. Additionally, the low La/Nb and Zr/Nb ratios indicate the involvement of an oceanic crust component that experienced dehydration and metamorphism to retain rutile. Further element-isotopic modeling suggests derivation of the parental magma from the asthenospheric mantle source that had been metasomatized by melts from both sediments and mafic oceanic crust. Considering that SE China was mainly influenced by subduction of the Paleo-Pacific Ocean during late Mesozoic, the subducting Paleo-Pacific slab was therefore the most likely candidate for such recycled components. Interaction of the melts from the recycled oceanic slab with the asthenospheric mantle, possibly as a consequence of rollback and tearing of the subducting Paleo-Pacific slab, formed the OIB-type source of the Liucheng dolerite sill. [ABSTRACT FROM AUTHOR]

Both Cretaceous arc-type and intraplate rocks are widely distributed in SE China, in association with subduction of the paleo-Pacific Plate. However, it remains unclear whether there exists a genetic link between the intraplate and subduction-related magmatism. Here we conduct a comprehensive geochemical data compilation, sorting and processing of the Cretaceous mafic igneous rocks from SE China, in combination with a 2-D numerical simulation on slab melting, to further decipher the petrogenetic relationship between the arc-type and intraplate magmatism under a unified tectonic framework invoking subduction and rollback-tearing of the paleo-Pacific Ocean. The Cretaceous arc-type mafic rocks (120–80 Ma) include eruptive and intrusive rocks, distributing along the coastal region in a NE-NNE direction. After parent magma compositional recalculation of the mafic intrusions, the results indicate that both the eruptive and intrusive arc-type mafic rocks are hydrous calc-alkaline basalts, with enrichments in large ion lithophile elements (LILEs) and light rare earth elements (LREEs) but depletions in high field strength elements (HFSEs), crust-like Sr-Nd-Pb-Hf isotopic compositions, and low Lu/Hf ratios. All these features are typical of igneous rocks formed in a continental arc. The combined data suggest their mantle source was mainly metasomatized by melts derived from the subducted terrestrial sediments and reflect a relatively hot subduction zone during Cretaceous. The intraplate mafic rocks (110–70 Ma) distribute in SE China interior and generally show trace element geochemistry similar to oceanic island basalt (OIB, hereafter we term them as OIB-like basalts). They can be further divided into two groups: high-Nb (Nb > 50 ppm) and low-Nb (Nb < 40 ppm) basalts. The high-Nb basalts have depleted asthenospheric mantle-like isotopic compositions. Their mantle source was composed mainly of pyroxenite that was likely formed through interaction between the asthenosphere and melts from the dehydrated subducted slab. Relative to the high-Nb basalts, the low-Nb basalts have lower Nb/REE and Nb/LILE ratios, and more evolved but highly variable isotopic compositions. Their mantle source was also the asthenosphere metasomatized by addition of the slab melts containing a higher proportion of recycled sediment component. From the arc-type to low-Nb and ultimately to high-Nb mafic rocks, increases of Nb, Nb/LILE and Nb/REE ratios are coupled with more depleted Sr-Nd-Pb-Hf isotopic features, reflecting the occurrence of melting from the upper subducted sediment to the lower oceanic mafic crust that had experienced extensive dehydration. Further thermodynamic modelling results show that melting of the dehydrated slab can occur along the torn surface and lower part of the oceanic crust, once the slab is strongly thinned and fractured in response to tearing and fragmentation. In combination with the contemporaneous sedimentary records in SE China, the Cretaceous mafic magmatism provided geochemical records of tectonic transition from early Cretaceous advanced subduction to late Cretaceous rollback of the paleo-Pacific slab, during which slab tearing or fragmentation and the resultant melting of the dehydrated subducted slab acted as a predominant agent for mantle enrichment. • Geochemistry of Cretaceous arc-type magmas indicate an active continental margin in SE China. • Both high-Nb and low-Nb intraplate basalts were derived from the asthenosphere metasomatized by slab melts. • Geodynamic simulation suggests melting of dehydrated oceanic crust only in strongly thinned slab. • Cretaceous mafic magmatism in SE China recorded the subduction and tearing of the paleo-Pacific slab. [ABSTRACT FROM AUTHOR]