Coupled trace element and SIMS sulfur isotope geochemistry of sedimentary pyrite:Implications on pyrite growth of Caixiashan Pb-Zn deposit

Colloform pyrite with core-rim texture is commonly deposited in carbonate platforms associated with the sulfide ores such as the Caixiashan Pb-Zn deposit.However,the genesis of colloform pyrite in Pb-Zn deposits,its growth controls and their geological implication are insufficiently understood.Integration of in-situ trace element and SIMS sulfur isotopes has revealed geochemical variations among these pyrite layers.These colloform pyrite occur as residual phases of core-rim aggregates,the cores are made up of very fine-grained anhedral pyrite particles,with some rims being made up of fine-grained and poorlycrystallized pyrite,while the other rims were featured with euhedral cubic pyrite.which are cemented by fine-grained calcite and/or dolomite with minor quartz.Sulfur isotope analysis shows that some wellpreserved rims have negative δ^34 S values(-28.12‰to-0.49‰),whereas most of the cores and rims have positive δ^34 S values(>0 to+44.28‰;peak at+14.91‰).Integrating with the methane and sulfate were observed in previous fluid inclusion study,we suggest that the 34 S depleted rims were initially formed by bacteria sulfate reduction(BSR),whereas the positive δ^34 S values were resulted from the sulfate reduction driven by anaerobic methane oxidation(AOM).The well-developed authigenic pyrite and calcite may also support the reaction of AOM.Combined with petrographic observations,trace element composition of the colloform pyrite reveals the incorporation and precipitation behavior of those high abundance elements in the pyrite:Pb and Zn were present as mineral inclusion and likely precipitated before Fe,as supported by the time-resolved Pb-Zn signal spikes in most of the analyzed pyrite grains.Other metals,such as Hg,Co and Ni,may have migrated as chloride complexes and entered the pyrite lattice.Arsenic and Sb,generally influenced by complex-forming reactions rather than substitution ones,could also enter the pyrite lattice,or slightly predate the precipitation of colloform pyrite as mineral inclusions,which are controlled by their hydrolysis constant in the ore fluids.The colloform pyrite may have grown inward from the rims.The successive BSR reaction process would enrich H^32/2S in the overlying water column but reduce the metal content,the nucleation of these pyrite rims was featured by strongly negative sulfur isotopes.The following AOM process should be activated by deformation like the turbidity sediment of the mudstone as the sulfide deposition are associated with fault activities that caused the emission of methane migration upward and simultaneously replenishing the metal in the column.The higher AOM reaction rate and the higher metal supply(not only Fe.but with minor other metals such as Pb and Zn) caused by sediment movement enhanced the metal concentration within the pyrite lattice.

What Happened in the Trans-North China Orogen in the Period 2560-1850 Ma?

The Trans-North China Orogen （TNCO） was a Paleoproterozic continent-continent collisional belt along which the Eastern and Western Blocks amalgamated to form a coherent North China Craton （NCC）. Recent geological, structural, geochemical and isotopic data show that the orogen was a continental margin or Japan-type arc along the western margin of the Eastern Block, which was separated from the Western Block by an old ocean, with eastward-directed subduction of the oceanic lithosphere beneath the western margin of the Eastern Block. At 2550-2520 Ma, the deep subduction caused partial melting of the medium-lower crust, producing copious granitoid magma that was intruded into the upper levels of the crust to form granitoid plutons in the low- to medium-grade granite-greeustone terranes. At 2530-2520 Ma, subduction of the oceanic lithosphere caused partial melting of the mantle wedge, which led to underplating of mafic magma in the lower crust and widespread mafic and minor felsic volcanism in the arc, forming part of the greenstone assemblages. Extension driven by widespread mafic to felsic volcanism led to the development of back-arc and/or intra-arc basins in the orogen. At 2520-2475 Ma, the subduction caused further partial melting of the lower crust to form large amounts of tonalitic-trondhjemitic-granodioritic （TTG） magmatism. At this time following further extension of back-arc basins, episodic granitoid magmatism occurred, resulting in the emplacement of 2360 Ma, -2250 Ma 2110-21760 Ma and -2050 Ma granites in the orogen. Contemporary volcano-sedimentary rocks developed in the back-arc or intra-are basins. At 2150-1920 Ma, the orogen underwent several extensional events, possibly due to subduction of an oceanic ridge, leading to emplacement of mafic dykes that were subsequently metamorphosed to amphibolites and medium- to high-pressure mafic granulites. At 1880-1820 Ma, the ocean between the Eastern and Western Blocks was completely consumed by subduction, and the dosing of the ocean led to the continent-arc-continent collision, which caused large-scale thrusting and isoclinal folds and transported some of the rocks into the lower crustal levels or upper mantle to form granulites or eclogites. Peak metamorphism was followed by exhumation/uplift, resulting in widespread development of asymmetric folds and symplectic textures in the rocks.

U-Pb Zircon Dating of the Granitic Conglomerates of the Hutuo Group:Affinities to the Wutai Granitoids and Significance to the Tectonic Evolution of the Trans-North China Orogen

The Wutai Complex associated with the adjacent Fuping and Hengshan Complexes represents the best and dassical cross-section in the middle segment of the Trans-North China Orogen, generally divided into Eastern and Western Blocks. Unconformably overlying the Wutai and Fuping Complexes is the Hutuo Group considered as the youngest lithostratigraphic unit in the region and important both for interpreting Precambrian history as well as the overall evolution of the Trans-North China Orogen. Lack of knowledge about provenance of the sedimentary rocks in this group has hindered understanding of the depositional environments and tectonic significance. LA-ICP-MS was applied to obtain U-Pb zircon ages for the granitic pebbles, the lowest lithostratigraphic rock of the Hutuo Group, which, combined with previous lithostratigraphic, geochronological, structural and metamorphic data, provides new constraints on the sedimentary provenance and tectonic evolution of the region. The sequence of the Hutuo Group ranges upward from lower basal conglomerates and volcaniclastic rocks （Doucun Subgroup）, through clastic sediments, slates, dolomites and marbles （Dongye Subgroup）, to sandstones and conglomerates at the top （Guojiazhai Subgroup）. Zircons from granitic pebbles preserved in the Doucun Subgroup basal conglomerates give weighted mean ^207pb/^206pb ages between 2517 Ma and 2566 Ma, which are the same as those for the late Archean Wutai Granitoids, indicating that the pebbles were derived from the Wutai granitic intrusions （2566-2515 Ma）. Based on the new data and previous studies, combined with an igneous zircon crystallization age of 2087±9 Ma obtained for volcanics in the Hutuo Group, the Hutuo Group was deposited in a subduction-related retro-arc foreland basin environment that developed behind the Wutai arc during the eastward-directed subduction of the Western Block beneath the western margin of the Eastern Block. This basin underwent long-lived sedimentation and finally closed during the -1850 Ma collisional event that resulted in the final amalgamation of the North China Craton.

Geochronological and geochemical constraints on the Cuonadong leucogranite, eastern Himalaya

First comprehensive investigations of the Cuonadong leucogranite exposed in North Himalayan gneiss dome of southern Tibet are presented in this study.The SIMS U–Pb ages of oscillatory zircon rims scatter in a wide range from 34.1 to 16.0 Ma, and the Cuonadong leucogranite probably emplaced at 16.0 Ma. High-precision ^(40)Ar/^(39)Ar dating on a muscovite sample yields an essentially flat age spectrum with consistent plateau and isochron ages, indicating that the Cuonadong leucogranite cooled below 450 °C at 14 Ma. Based on the youngest zircon U–Pb age and muscovite^(40)Ar/^(39)Ar age, the Cuonadong leucogranite experienced rapid cooling with a rate of 119 °C/Myr from 16 to 14 Ma. The geochronological data of this undeformed leucogranite also suggest that the ductile extension of the South Tibetan Detachment System in the eastern Himalaya ceased by ca. 14 Ma. Furthermore,the initial Sr–Nd isotopic compositions and Nd model ages demonstrate that the leucogranite was derived from metapelitic source within the Greater Himalayan Crystalline Complex. The distinct Ba depletion with high Rb/Sr ratios and negative Eu anomalies make it clear that the leucogranite melts were generated by breakdown of muscovite under fluid-absent conditions.

U-Pb Age and Hf Isotope Study of Detrital Zircons from the Wanzi Supracrustals:Constraints on the Tectonic Setting and Evolution of the Fuping Complex,Trans-North China Orogen

Located in the middle segment of the Trans-North China Orogen, the Fuping Complex is considered as a critical area in understanding the evolution history of the North China Craton （NCC）. The complex is composed of various high-grade and multiply deformed rocks, including gray gneiss, basic granulite, amphibolite, fine-grained gneiss and marble, metamorphosed to upper amphibolite or granulite facies. It can be divided into four rock units： the Fuping TTG gneisses, Longquanguan augen gneisses, Wanzi supracrustals, and Nanying granitic gneisses. U-Pb age and Hf isotope compositions of about 200 detrital zircons from the Wanzi supracrustals of the Fuping Complex have been analyzed. The data on metamorphic zircon rims give ages of 1.82-1.84 Ga, corresponding to the final amalgamation event of the NCC, whereas the data for igneous zircon cores yield two age populations at -2.10 and -2.51 Ga, with some inherited ages scattering between 2.5 and 2.9 Ga. These results suggest that the Wanzi supracrustals were derived from the Fuping TTG gneisses （-2.5 Ga） and the Nanying granitic gneisses （2.0-2.1 Ga） and deposited between 2.10 and 1.84 Ga. All zircons with -2.51 Ga age have positive initial εHf values from ＋1.4 to ＋10.9, suggesting an important crustal growth event at -2.5 Ga through the addition of juvenile materials from the mantle. The Hf isotope data for the detrital zircons further imply that the 2.8 Ga rocks are important components in the lower crust, which is consistent with a suggestion from Nd isotope data for the Eastern Block. The zircons of 2.10 Ga population have initial εHf values of-4.9 to ＋6.1, interpreted as mixing of crustal re-melt with minor juvenile material contribution at 2.1 Ga. These results are distinct from that for the Western Block, supporting that the Fuping Complex was emplaced in a tectonic active environment at the western margin of the Eastern Block.

Implications of the melting depth and temperature of the Atlantic mid-ocean ridge basalts

Mid-ocean ridge basalts(MORBs) are characterized by large variations in trace element compositions and isotopic ratios, which are difficult to be interpreted solely by using magmatic process such as partial melting of a peridotitic mantle and subsequently fractional crystallization. Geochemical diversity of MORBs have been attributed to large-scale heterogeneity within the underlying mantle, and the heterogeneity might have been caused by addition of recycled crustal component, subcontinental lithosphere, metasomatized lithosphere and outer core contribution. In this study, we investigated the MORBs along the Mid-Atlantic Ridge(MAR) by estimating the temperature and pressure of partial melting, and comprehensively comparing trace element and isotope ratios. The data for MORBs from areas close to mantle plumes show large variations. Mantle plumes can affect mid-oceanic ridges 1 400 km away, but plume effects did not cover all of the ridge segments, and those segments without plume effects did not have any abnormalities in temperature, trace element or isotope ratios.We ascribed the above phenomena to result from the shapes of the plume flow, which we categorized as "pipelike channels" and "pancake-like channels". The "pancake-like channels" plumes affected the ambient mantle nondirectionally, but the range of the mantle affected by the "pipe-like channels" plumes were selective. Element ratios of MORBs reveal that the mantle source of the MORBs along the MAR is highly heterogeneous. We suggest that most of source heterogeneities of the MORBs may be due to the presence of subducted slab and delaminated lower crust in the source. In addition, the plume that carried materials from the core-mantle boundary may affect some of the segments.

An in vivo Study of Basic Fibroblast Growth Factor on Activation and Proliferation of Retinal Progenitor Cells in RCS Rat

Purpose: To investigate the effect of intravitreal injection of basic fibroblast growth factor(bFGF) on activation and proliferation of endogenous retinal progenitor cells in the Royal College of Surgeons(RCS) rat. Methods: Twenty-four rats were studied after the 30th postnatal day(≥30). Eighteen RCS-p+/LAV rats were divided into 3 groups: bFGF-treated, vehicle-treated and untreated groups randomly, and 6 RCS-ray+p+/Lav respectively rats were used as normal controls. 6 μl of bFGF (5 μg/10 μl) or vehicle was injected into the vitreous on day 31, 33 and 35 after birth (P31, P33, P35) in the bFGF group and vehicle group respectively, and no injections were administered in the untreated and control groups. All the rats were euthanized, and their eyes were enucleated, hemisected and fixed at 50 d ays after birth for immunohistochemistry and measurement of outer nuclear layer thickness. Results:Nestin and Chx10 were positive in all retinal layers, intravitreal injection of bFGF in retina-dystrophic RCS(RCS-p+/Lav) rats induced intense labeling for the retinal progenitor cell markers Chx10 and Nestin, which were highly colocalized. Fluorescence intensity for both labels was somewhat less in the control rats, and much less in the vehicle-injected rats as well as in the untreated RCS rats. The outer nuclear layer(ONL) was significantly thicker in bFGF group than that in vehicle-treated or untreated group(P<0.01), but thinner than that of the control group(P<0.01). No significant difference was observed in the ONL thickness between the vehicle group and untreated group(P>0.05). Conclusion:bFGF may contribute to the activation of retinal progenitor cells in RCS rats,thus counteract degeneration by promoting the proliferation of the progenitor cells.

Electrophoretic Analysis of Isozymes and Proteins in F_1 Hybrids of Ctenopharyngodon idellus ♀ × Elopichthys bambusa ♂

[ Objective] This study aimed to investigate the biochemical and genetic characteristics of F1 hybrids of Ctenopharyngodon idellus ♀× Elopichthys bambusa ♂ - [ Method ] By using vertical polyacrylamide gel electrophoresis technology, three isozymes （LDH, EST, MDH） in nine tissues （heart, brain, eyes, liver, kidney, spleen, fin, muscle, plasma） of F1 hybrids of C. ideUus and parents were compared. [Result] Three isozymes in F1 hybrids of ♀× E. bambusa ♀ were analyzed; differences in isozyme and proteins between F1 hybrids idellus ♀× E. bambusa ♀ exhibited varying degrees of tissue-specificity; isozymes and proteins in F, hybrids were signiticandy different from the parents. [ Conclusion] These nine differences could be used as indicators to identify F1 hybrids and parents.

An investigation of the antinociceptive effects of Riluzole in hyperal gesia models of mice

Objective： To investigate the antinociceptive effects of Riluzole administered intraperitoneally in three hyperalgesia model of mice. Methods： Antinociceptive tests in C57BL mice were investigated with formalin test,acetic acid induced writhing test and tail-immersion test. The effects of intraperitoneally Riluzole 2 mg/kg ,4 mg/kg and 8 mg/kg on the pain threshold were observed. Result： We found that i.p. treatment with Riluzole （4 mg/kg and 8 mg/kg） blocked the second phase flinching behavior compared with vehicle （P 〈 0.05）, but not during the first phase in the formalin test. In addition to the formalin test, Riluzole at different dose （from 2 to 8 mg/kg） attenuated acetic acid induced writhing response when compared to vehicle group （P 〈 0.05）. In the tail-immersion test, Riluzole at the highest dose （8 mg/kg） caused significant increase in tail flick response latency as compared to vehicle animals or compared with Baseline （P 〈 0.05）. Conclusion： Our results suggest that glutamate release inhibitor Riluzole can attenuate nociceptive behavior and has differrent antinociceptive characteristic according to the various pain models.

Mantle contributions to granitoids associated with Sn mineralization:Geochemical and isotopic evidence from the giant Dachang deposit,South China

Major Sn deposits are commonly linked to crust-derived and highly evolved granites,with magma generation aided by mantle heating.However,whether and how the mantle components contribute to Sn polymetallic mineralization remains unclear.In this study,in combination with a compilation of equivalent data in the region,we provide new constraints on this issue based on detailed investigations on the petrogenesis and metallogenic significance of granitoids including the causative batholith and later granodiorite porphyry dike in the giant Dachang Sn deposit from South China.The former has zircon U-Pb ages of 93-91 Ma and belongs to highly evolved S-type biotite granite,which experienced fractionation of massive feldspar.The latter shows zircon U-Pb ages of 90 Ma and displays I-type granite features.The batholith was mainly derived from the dehydration melting of biotite in the metasedimentary sources,as revealed by the relatively low whole-rock Pb contents(<30 ppm)and high Ba/Pb ratios(2.71-17.1)and initial T(ti-zr)of 790℃.Compared with the adjacent crust-derived S-type granites(-24.8--5.1)and I-type granites(-11.0 to-5.2),the Dachang S-type biotite granites present higher zirconεHf(t)values(-9.1 to-2.1).Furthermore,the low magmatic zirconδ18O values(6.2‰)and higher apatite LREE(3277-4114 ppm)and Sr(1137-1357 ppm)contents than of arc-type basic rocks were discerned.These characteristics jointly hint the contributions of mantle components.The higher initial T(ti-zr)(>850℃),whole-rock Mg#(52 to 58),apatiteεNd(t)(-9.2 to-6.5)and zirconεHf(t)(-7.6 to 2.5)values but lower zirconδ18O values(6.33 to 8.30‰)of the later granodiorite porphyry dike than those of the batholith also suggest that mantle material was involved in the generation of the dikes,which is evident by the variational features of zircon and apatite trace elements.In addition,at the zircon Hf<12000 ppm and Eu/Eu*>0.05,the higher zirconΔFMQ values(mostly from-1.8 to 2.0)and H2O contents(100-1100 ppm)of the Dachang granitoids than the pure crust-derived S-type granites(ΔFMQ=mostly from-3.7 to-1.5;H2O<100 ppm)imply that mantle materials involved are relatively rich in water and oxidized.These suggest that the addition of mantle components is conducive to the extraction of Sn from metasedimentary sources,and moderately facilitates the increase of oxygen fugacity which still maintains the incompatibility of Sn in magmas withΔFMQ<2.Also,the involvement of mantle components upgrades the H2O contents in S-type magmas,favoring the migration of ore-forming elements from magmas to hydrothermal fluids.The sediment-derived causative granites displayed higherεHf(t)andεNd(t)values with greater Sn tonnages of their associated world-class Sn polymetallic deposits,supporting the opinion that the contributions of mantle components play an important role in the generation of giant Sn deposits.

Upconversion nanoparticles@AgBiS_(2) core-shell nanoparticles with cancer-cell-specific cytotoxicity for combined photothermal and photodynamic therapy of cancers

UCNPs@AgBiS_(2) core-shell nanoparticles that AgBiS_(2) coated on the surface of upconversion nanoparticles (UCNPs) was successfully prepared through an ion exchange reaction. The photothermal conversion efficiency of AgBiS_(2) can be improved from 14.7% to 45% due to the cross relaxation between Nd ions and AgBiS_(2). The doping concentration of Nd ions played a critical role in the production of reactive oxygen species (ROS) and enhanced the photothermal conversion efficiency. The NaYF4:Yb/Er/Nd@NaYF4:Nd nanoparticles endows strong upcon-version emissions when the doped concentration of Nd ions is 1% in the inner core, which excites the AgBiS_(2) shell to produce ROS for photodynamic therapy (PDT) of cancer cells. As a result, the as-prepared NaYF4:Yb/Er/ Nd@NaYF4:Nd@AgBiS_(2) core-shell nanoparticles showed combined photothermal/photodynamic therapy (PTT/ PDT) against malignant tumors. This work provides an alternative near-infrared light-active multimodal nano-structures for applications such as fighting against cancers.

PM_(2.5)and water-soluble inorganic ion concentrations decreased faster in urban than rural areas in China

We investigated variations of PM_(2.5)and water-soluble inorganic ions chemical characteristics at nine urban and rural sites in China using ground-based observations.From 2015 to 2019,mean PM_(2.5)concentration across all sites decreased by 41.9μg/m~3with a decline of 46%at urban sites and 28%at rural sites,where secondary inorganic aerosol(SIAs)contributed to 21%(urban sites)and 17%(rural sites)of the decreased PM_(2.5).SIAs concentrations underwent a decline at urban locations,while sulfate(SO_(4)^(2–)),nitrate(NO_(3)^(–)),and ammonium(NH_(4)^(+))decreased by 49.5%,31.3%and 31.6%,respectively.However,only SO_(4)^(2–)decreased at rural sites,NO_(3)^(–)increased by 21%and NH_(4)^(+)decreased slightly.Those changes contributed to an overall SIAs increase in 2019.Higher molar ratios of NO_(3)^(–)to SO_(4)^(2–)and NH_(4)^(+)to SO_(4)^(2–)were observed at urban sites than rural sites,being highest in the heavily polluted days.Mean molar ratios of NH_(3)/NH_xwere higher in 2019 than 2015 at both urban and rural sites,implying increasing NH_xremained as free NH_(3).Our observations indicated a slower transition from sulfate-driven to nitrate-driven aerosol pollution and less efficient control of NO_(x)than SO_(2)related aerosol formation in rural regions than urban regions.Moreover,the common factor at urban and rural sites appears to be a combination of lower SO_(4)^(2–)levels and an increasing fraction of NO_(3)^(–)to PM_(2.5)under NH_(4)^(+)-rich conditions.Our findings imply that synchronous reduction in NO_(x)and NH_(3)emissions especially rural areas would be effective to mitigate NO_(3)^(–)-driven aerosol pollution.

A H_(2)O-in-zircon perspective on the heterogeneous water content of crust-derived magmas in southern Tibet

Geophysical and geochemical evidence revealed that certain amounts of water are stored in the Earth’s interior,and its distribution exhibits temporal and spatial differences.Recent studies indicate that the H_(2)O-in-zircon has a potential to reveal magma water content.Using secondary ion mass spectrometry(SIMS),we analyzed the zircon water content and oxygen isotopes in granitoids(two-mica granite,quartz monzonite,diorite,and granodiorite)from southern Tibet.The results are used to explore the diversity of water content in crust-derived magmas,which is also supported by the LA-ICPMS zircon trace element analysis.There are low zircon water contents for two partial melting products of the ancient crust(peak at 85 and300 ppm,respectively).Meanwhile,there are high H_(2)O-in-zircon peaks(435 and 475 ppm,respectively)for two partial melting products of the juvenile crust.The calculated radiation damage accumulation in these zircon grains is below 3×10^(15)αdecay events mg^(–1),suggesting that the zircon grains are well crystalline.There is no correlation between REE+Y and H+P,indicating that the mechanism of charge balance for water uptaking into zircon,in which the excess of REE+Y to P controls Hcontent,is not applicable to the studied samples.The degree of magma fractionation cannot account for the zircon water content variation,because there is no co-variation between zircon Hf and H_(2)O contents.Similarly,the degree of partial melting was unlikely to be responsible for the H_(2)O-in-zircon distinction.We interpret that the H_(2)O-in-zircon variation reflects the influence of melting mode(dehydration vs.water-fluxed)and water content in the crustal source.In the Late Devonian,dehydration melting of the crustal rocks was facilitated at elevated temperatures,which produced magmas with the lowest water contents.Water-fluxed melting of the ancient crust would produce relatively“drier”magma than water-fluxed melting of the juvenile crust.

Systematic co-delivery of dual agonists to enhance cancer immunotherapy

In the tumor immunosuppressive microenvironment(TIME),antigen presenting cells(APCs)usually exhibit a tumor suppressor phenotype.Toll-like receptors(TLRs)agonists could reprogram M2-type macrophages to M1-type and stimulate dendritic cells(DCs)maturation.The combination of TLR7/8 and TLR9 agonists seems to have synergistic therapeutic efficacy.Here,we designed a lipid-coated mesoporous silica nanoparticle(MSNs@Lipo)for the co-delivery of TLR7/8 agonist resiquimod(R848)and TLR9 agonist CpG oligodeoxynucleotides(ODNs)(CpG@MSNs-R@L-M).R848 was firstly conjugated onto the nanoparticle via silane chemistry,which is acidic responsive drug release.Then,CpG was loaded onto the nanoparticle through the positive charge mainly from TLR7/8 agonist R848.Our in vitro experiments further indicated that both drugs have acid-responsive release properties and could be taken up by DCs and located on the endosomes of APCs.More importantly,CpG@MSNs-R@L-M could significantly improve the antitumor efficacy in B16F10 melanoma model.The mechanistic study demonstrated that CpG@MSNsR@L-M could remarkably modulate the TIME by promoting the maturation of DCs and repolarizing macrophages from M2 to M1 phenotype and facilitating the infiltration of tumor cytotoxic T cells.It was concluded that in comparison to single agonist,the codelivery of dual agonists,CpG and R848,can improve anti-tumor immune responses for cancer immunotherapy.