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High-silica granites are significant carriers of highly incompatible elements and are closely associated with mineralization of the rare metal beryllium. Thus, understanding their origin and evolution is of paramount importance for comprehending the evolution of the continental crust and enrichment processes of beryllium. This study presents zircon U-Pb ages, whole-rock major and trace element compositions, and Nd-Hf-O isotopic data for Early Cretaceous high-silica granite porphyries, monazite U-Pb ages and Nd isotopic data for beryllium-rich quartz veins, and whole-rock and apatite Nd isotopic data for Permian tuffs in the Dongshanwan WMo-Be deposit in the southern Great Xing'an Range, northeastern China. Our aim is to elucidate the link between mineralization and magmatism and to further our insight into the processes of crystal-melt separation and the mechanisms driving beryllium enrichment in granitic magmatic systems. Zircon U-Pb dating of the high-silica granite porphyry yields a weighted mean 206Pb/238U age of 141 ± 1 Ma, which is consistent with the age of hydrothermal monazite (ca. 140 Ma) from the beryllium-rich quartz veins. Hydrothermal monazite from the intra-granite porphyry quartz vein has positive eNd(t) values (+0.76 to +1.63) that overlap broadly with whole-rock Nd isotopic compositions of the host granite porphyry [eNd(t) = + 1.24 to +1.61]. These characteristics indicate that the Dongshanwan beryllium mineralization was temporally and genetically associated with magmatic-hydrothermal activity of the Dongshanwan high-silica granite porphyries. Our systematic studies suggest that both the Dongshanwan high-silica granite porphyries and coeval Be-barren high-silica granites in the study area are high-K calc-alkaline I-type granites. They originated from a shared magmatic system and formed by the partial melting of a predominantly juvenile medium- to high-K basaltic crustal source, with a minor addition of old crustal components. Rayleigh fractionation modeling indicates that the granitic magma underwent a two-stage crystal-melt separation process. During the first stage, the fractional crystallization of a large proportion of plagioclase, in which beryllium is compatible, not only effectively inhibited beryllium enrichment in the differentiated melt, but also removed a large amount of Ca. During the second stage, minerals in which beryllium is incompatible dominated the fractionating assemblage owing to the low Ca contents in the magma, resulting in a surge in beryllium concentration in the differentiated melt. Our findings reveal that beryllium cannot be appreciably enriched in calc-alkaline granitic magmatic systems until plagioclase fractionation has substantially removed Ca from the system. [ABSTRACT FROM AUTHOR]

A-type granites typically exhibit enrichment and mineralization of critical metals such as molybdenum and tin, essential for emerging technologies. However, the key factors influencing their mineralization potential remain elusive. The scarcity of studies on barren systems impedes the understanding of this question. Here, a detailed melt and fluid inclusion study was conducted on the barren Wushan pluton to reconstruct its magmatic evolution and magmatic–hydrothermal transition and explore the factors controlling the metallogenic potential of Mo and Sn in A-type granites. The Wushan pluton displays apparent lithological zoning consisting of two major phases, i.e. medium-grained seriate to porphyritic alkali feldspar granite and fine-grained porphyritic granite. Miarolitic cavities are widely developed in each lithofacies. The silicate melt inclusions from two granitic phases are rhyolitic, with moderate F contents (0.06–0.53 wt %) and depleted H2O contents (2.0–3.5 wt %). Melt inclusions show a wide range of incompatible element contents, such as Cs (9–1977 μg/g) and Rb (268–2601 μg/g), suggesting that Wushan has undergone a high degree of magma evolution. Mo behaves incompatibly in the magmatic evolution, and its content is enriched with the increasing degree of fractional crystallization, but remains constant after the Cs content exceeds 50 μg/g. Rayleigh fractionation model suggests that a large amount of Mo is extracted from fluid exsolution, which restrains Mo from further enrichment. In contrast, Sn behaves as a mildly incompatible element during the entire magmatic evolution history. The contents of Sn increase slowly compared to the trend of Mo, and the maximum contents reach ~30 μg/g in the highly evolved melts. The separation and crystallization of Sn-bearing minerals such as biotite, magnetite, and titanite inhibit the enrichment of Sn. Intermediate-density (ID-type) fluid inclusions hosted in the miarolitic quartz, representing the initial fluid exsolving from magma, display high Mo but low Sn concentrations. Constrained from two assemblages of coexisting ID-type fluid and melt inclusions, the fluid/melt partition coefficients of metals are obtained, with D Mo, fluid/melt at 16–19, while D Sn, fluid/melt is only about 1. The comparison between Mo-mineralized and barren intrusions worldwide shows that the metal contents in melts and fluids are not fundamentally different. The mineralized intrusions are characterized by the lower melt viscosity and the development of apophyses, both of which facilitate the extraction of metals and fluids from large magma chambers, followed by their concentration into a small rock volume. Consequently, it appears that physical and structural conditions rather than chemical compositions play a crucial role in the Mo mineralization process. Enrichment of Sn in melts is necessary but not decisive for Sn mineralization, whereas Sn enrichment in the initial exsolving fluid determines the Sn mineralization potential of a given granitic system. Compared to Sn enrichment in source melting and fractional crystallization which commonly enhance final Sn fertility in the highly evolved melts, the efficiency of Sn partitioning between melt and fluid plays a fundamental role in converting melt fertility into Sn-enriched fluids and thereby high mineralization potential of the magmatic–hydrothermal system. Our findings suggest a prospect for Mo exploration in the coastal A-type granite belt in South China, while the potential for Sn mineralization is expected to be limited. [ABSTRACT FROM AUTHOR]

The large Mo isotopic fractionations between diferent geological reservoirs make this isotopic system a potentially useful tool for constraining the origins of magmatism. However, the efect of magmatic diferentiation on Mo isotopes is still controversial. In this study, we obtained Mo isotope data for the Panzhihua gabbroic intrusion (i.e., including mineral separates of clinopyroxene, plagioclase, magnetite, and ilmenite). The whole-rock samples and mineral separates exhibit large Mo isotopic fractionations with δ98/95Mo values as follows: magnetite (–0.73‰ to –0.32‰) < clinopyroxene (–0.32‰ to –0.10‰) < ilmenite (0.06‰ to 0.36‰) < plagioclase (0.33‰ to 0.83‰). Iron-Ti oxides have Mo contents that are one order of magnitude higher than those of clinopyroxene and plagioclase. Mass balance calculations based on Mo isotopes and contents are consistent with an accumulated origin for the Panzhihua intrusion. Rayleigh fractionation modeling shows that the removal of magnetite and ilmenite results in significant Mo isotopic fractionation in the residual magma. Due to the low Mo contents of clinopyroxene and plagioclase, Mo isotopes are not significantly fractionated by the removal of these minerals. Therefore, our study highlights that fractionation of Fe-Ti oxides can cause considerable Mo isotopic fractionation; consequently, caution is needed when using Mo isotopes to infer magma origins. [ABSTRACT FROM AUTHOR]

The paper presents a novel statistical approach for analyzing the daily coronavirus case and fatality statistics. The survival discretization method was used to generate a two-parameter discrete distribution. The resulting distribution is referred to as the "Discrete Marshall–Olkin Length Biased Exponential (DMOLBE) distribution". Because of the varied forms of its probability mass and failure rate functions, the DMOLBE distribution is adaptable. We calculated the mean and variance, skewness, kurtosis, dispersion index, hazard and survival functions, and second failure rate function for the suggested distribution. The DI index demonstrates that the proposed model can represent both over-dispersed and under-dispersed data sets. We estimated the parameters of the DMOLBE distribution. The behavior of ML estimates is checked via a comprehensive simulation study. The behavior of Bayesian estimates is checked by generating 10,000 iterations of Markov chain Monte Carlo techniques, plotting the trace, and checking the proposed distribution. From simulation studies, it was observed that the bias and mean square error decreased with an increase in sample size. To show the importance and flexibility of DMOLBE distribution using two data sets about deaths due to coronavirus in China and Pakistan are analyzed. The DMOLBE distribution provides a better fit than some important discrete models namely the discrete Burr-XII, discrete Bilal, discrete Burr-Hatke, discrete Rayleigh distribution, and Poisson distributions. We conclude that the new proposed distribution works well in analyzing these data sets. The data sets used in the paper was collected from 2020 year. [ABSTRACT FROM AUTHOR]

Iron isotopes are important for tracing the magmatic process. The fractionation of iron isotopes in granite is up to 0.55 ‰. In this study, Wangjiagou (XWJ) granite and Tayueping (XTY) granite in the Xinxian pluton of the Western Dabie orogen were evaluated. Both the XTY and XWJ granite belong to monzogranites, with high SiO2 (74.42–76.82 wt.%) contents. The granites are depleted of Nb and Ti but enriched with Pb and K, and they display negative Eu anomalies (Eu/Eu* = 0.40–0.52) on REE plots that are normalized by chondrite. The δ56Fe values of the XTY granites vary from 0.19 ± 0.03 ‰ to 0.27 ± 0.04‰, and the δ56Fe values of the XWJ granites are 0.34 ± 0.02 ‰ and 0.36 ± 0.01 ‰, respectively. Both the XTY and the XWJ granites belong to highly fractionated granites due to their SI (solidification index), DI (differentiation index), and content of CaO. Evidence from the iron isotopes shows that neither fluid exsolution, alteration, weathering, nor partial melting can explain the enrichment of the heavy iron isotopes. The results modeled using the Rayleigh equation showed that fractional crystallization can produce Δ56Femelt-crystal with the value of 0.08–0.15 ‰. In conclusion, fractional crystallization was the main factor controlling the fractionation of iron isotopes, and the change of melt composition may also lead to the enrichment of heavy iron isotopes in the residual melt. [ABSTRACT FROM AUTHOR]

The stable chromium isotope composition of Earth's mantle has been suggested to be heterogeneous, with mantle-derived chromitites slightly enriched in heavier Cr isotopes than mantle-derived silicate rocks. To better understand such heterogeneity and to search for a potentially complementary light Cr isotope reservoir in the mantle, we analyzed the stable Cr isotope compositions (δ53Cr expressed as deviation of sample 53Cr/52Cr from NIST SRM 979) of whole-rock pyroxenite and peridotite xenoliths from the North China Craton using a double spike technique. The δ53Cr values of the peridotites vary from −0.21‰ to −0.07‰ with an average value of −0.14 ± 0.10‰ (2SD, N = 5), which overlaps with the range of the Bulk Silicate Earth (−0.12 ± 0.10‰). In contrast, pyroxenites in this study yield lower δ53Cr values (−0.30‰ to −0.14‰ with an average value of −0.21 ± 0.08‰, 2SD, N = 20). The variation in the δ53Cr values of the pyroxenites can be explained by a Rayleigh distillation model during partial melting of the primitive mantle. The model provides minimum Cr isotope fractionation factors during partial melting ranging from 0.01‰ to 0.12‰, with light isotopes enriched in the melt. Combined with literature data, our results suggest that both peridotites and basalts are indistinguishable from the Bulk Silicate Earth in terms of δ53Cr. However, pyroxenites and chromitites are isotopically lighter and heavier than the Bulk Silicate Earth, respectively. Future work is needed to investigate the petrogenetic relationship between chromitites and pyroxenites in order to understand why they seem to complement each other in δ53Cr. [ABSTRACT FROM AUTHOR]

The contributions of early potassic and later phyllic alteration stages to Cu endowment of the giant Dexing porphyry Cu–Mo–Au system in South China are determined using changes in the Cu isotope composition of hypogene chalcopyrite from three vein stages. The δ65Cu values of chalcopyrite (δ65Cucpy values) from the potassic (stage 1: -0.05‰ to 0.21‰) to the phyllic alteration stages (stage 2: -0.03‰ to 0.24‰) are relatively invariable, but chalcopyrite in the propylitic alteration stage (stage 3) has notably lower isotopic values (-0.35‰ to 0.02‰). The sharp decrease in δ65Cucpy values in the latest vein stage is likely a result of precipitation of significant amounts of isotopically heavy chalcopyrite in the phyllic alteration environment. The overall isotopic evolution can be simulated, using a Rayleigh fractionation model, with the majority of Cu having precipitated during the phyllic alteration stage. By comparing our data with published Cu isotope results from other porphyry deposits, we demonstrate that the systematics of δ65Cucpy values during different hydrothermal alteration stages could convincingly trace the relative timing and mechanism(s) of Cu precipitation in porphyry Cu systems. Spatial mapping of Cu isotopes at Dexing suggest that sharp decreases of δ65Cucpy values in hypogene zones may be used to delineate the boundary of high-grade ore zones. [ABSTRACT FROM AUTHOR]

To establish Weibull distribution patterns for outdoor wind speed (WS) over an extended time period and determine wind conditions for building energy-efficient design, this study collected daily WS data from 381 cities spanning all thermal design zones in China. Weibull distribution shape and scale parameters were estimated using three methods: Maximum Likelihood Estimation (MLE), Graphical Method (GM), and Method of Moments (MM). A comprehensive goodness-of-fit assessment of these methods revealed that GM and MLM exhibited superior performance, making them suitable for determining Weibull parameters in the summer, winter, and the entire year. Through a rigorous examination and evaluation of the shape and scale parameters within each subzone across the summer, winter, and the entire year periods, the study identified the Rayleigh distribution as the typical pattern for low WS in building energy-efficient design. The determined Weibull distribution patterns can serve as fundamental information for wind inlet in assessing climate potential, WS in Outdoor Climate Design Conditions, and wind information in Typical Meteorological Year. • A comparative analysis was conducted using daily wind speed data from 381 stations using three estimation methods. • Weibull parameter ranges for the summer, winter, and annual were determined and analysed across all subzones. • A consistent Rayleigh distribution pattern was found in all seasons. • The distribution patterns can be used to determine wind conditions in building energy-efficient design. [ABSTRACT FROM AUTHOR]

Dabie-type porphyry Mo deposits have recently been identified as a new subtype of porphyry Mo deposits, but several questions remain about the role of ore-related magmas in the formation of this type of deposit, as well as distinctions in genetic processes with the well-studied Climax-type porphyry Mo deposits. Here, mineral and melt inclusions from the giant Qian'echong deposit, Dabie orogen, central-eastern China, were studied in order to improve our understanding of the nature and the role of ore-related magmas in the genesis of Dabie-type porphyry Mo deposits. The magmatic and hydrothermal evolution of the system was reconstructed based primarily on the analysis of quartz-hosted silicate melt and mineral inclusions, in concert with field and petrographic relations as well as previously published U–Pb and Re-Os geochronology. Ore-related magmas at Qian'echong include, from early to late, quartz porphyry dikes, rhyolite porphyry dikes, granite porphyries (stock and dikes) and a newly discovered, deep-seated monzogranite porphyry stock. Based on TitaniQ thermobarometry, these lithologies were sourced from a ~16–19-km deep (500–600 MPa) magma chamber and underwent nearly isothermal decompression to ~7 km (200 MPa), at temperatures ranging from 720°C to 690°C. According to the trace element composition of melt inclusions, in combination with published whole-rock Nd isotopic compositions, the early magma evolved from quartz porphyry to rhyolite porphyry through fractionation crystallization and thus became a crystal mush. This viscous crystal mush was subsequently re-melted to produce the granite porphyries and was injected with melts from a different source to generate the monzogranite porphyry. At Qian'echong, all melt inclusions have low concentrations of Mo (2–8 ppm), >5 wt. % H2O, and little to no F (≤0.26 wt. %), arguing against the requirement for ore-related magmas to be enriched in Mo to form large porphyry Mo deposits. Rayleigh fractionation modeling shows that the concentration of Mo in the quartz and granite porphyries increased through fractionation of quartz, feldspars, biotite, magnetite, and ilmenite and that Mo was subsequently depleted in the melt through fluid exsolution, exclusively in the rhyolite and monzogranite porphyries, as a result of magma ascent and decompression. This suggests that, in addition to ore-related granite porphyry, both the rhyolite and the monzogranite porphyries also contributed to the hydrothermal mineralization. This study confirms that the formation of porphyry Mo deposits does not rely on abnormally high concentrations of Mo in ore-related magmas but instead requires efficient extraction of Mo from large volumes of magmas, with normal concentrations of Mo. Unlike the Climax-type deposits where multiple pulses of ore-forming fluids are delivered from convecting shallow magma chambers, Mo mineralization in Dabie-type deposits was achieved by the assembling of ore-forming fluids from successively emplaced, relatively deep intrusions. Although the Dabie- and Climax-type Mo deposits are respectively associated with I-type and A-type granitoids in the Dabie orogen, it is suggested that both types of magmas are derived from the partial melting of subducted Yangtze continental crust and that it is the tectonic transition from compressional to extensional settings that controlled the different styles of porphyry Mo mineralization in this orogen. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Jiada pegmatites are produced by magmatic fractionation, not the low degree partial melting. • Aqueous fluid enrichment could account for the accumulation of 6Li in albite-spodumene type pegmatite. • High Li, Cs contents and low δ 7Li values in metasandstones are effective tracers for locating concealed ore bodies The origin and petrogenesis of pegmatite-type lithium deposits within the Songpan-Garze Fold Belt (SGFB) of western China remain subjects of debate. To provide further insight on this subject, this study investigated the whole-rock trace elements and whole-rock Li isotopic compositions of the two-mica monzogranite (TMG) from the Ke'eryin composite pluton, the Jiada albite pegmatite (AP) and albite-spodumene pegmatite (ASP) and their metasedimentary wall rocks within the Ke'eryin ore field in the eastern SGFB. Modeling of muscovite-dehydration melting based on the whole-rock trace elements (e.g., Li, Rb, and Sr) and Rayleigh dehydration modeling related to the whole-rock Li isotopes suggest that the Jiada pegmatites are unlikely to have originated from the low-degree partial melting of metasandstone (MS) of the Zhuwo Formation. Variations in the whole-rock trace elements and Li isotope between the TMG and the Jiada pegmatites are consistent with the evolution trend of magmatic fractionation. However, the whole-rock Li isotopic compositions of the AP and ASP display inverse variation characteristics with the muscovite Li isotopic compositions, with the AP exhibiting lower Li concentrations and higher whole-rock δ 7Li values than ASP. Furthermore, the variation patterns of whole-rock trace elements do not align perfectly with the Rayleigh-type fractional crystallization processes, implying other geological processes would be also involved in the formation of the Jiada pegmatites. Collectively considering the Li isotope behavior during various geological processes, the observed variations in whole-rock Li isotopic compositions between AP and ASP can be explained by aqueous fluid enrichment during the pegmatitic melt evolution. This suggests that fractional crystallization and fluid exsolution jointly contributed to pegmatite formation and Li mineralization in the Jiada deposit. Moreover, the whole-rock δ 7Li values of the wall rock of ASP (MS2) are lower than those of MS and the wall rock of ASP (MS1), primarily due to metasomatism by 6Li-enriched fluids expelled from ASP and the kinetic diffusion of Li isotopes. The high concentrations of highly mobile elements, especially Li and Cs, combined with the low whole-rock δ 7Li value of the metasandstone, could serve as effective tracers for locating concealed orebodies and evaluating the metallogenic potential of Li mineralization. [ABSTRACT FROM AUTHOR]

• Stibnites from a large hydrothermal system reveal a large δ 123Sb range of −0.27 to +0.86‰. • Sulfide separation from the fluid causes significant Sb isotope fractionation, and the best estimated Sb isotope fractionation factor (α fluid-stibnite) is ~0.9994. • Estimated initial Sb isotope composition may constrain potential metal sources. • Sb isotopes can be used to fingerprint hydrothermal fluid flow directionality. In order to characterize antimony (Sb) isotope fractionation in hydrothermal systems, we present Sb isotope compositions of primary stibnite ores from a large Sb deposit in south China. A total number of 39 analyses reveals a large δ 123Sb range of −0.27 to +0.86‰, representing an up to 1.13‰ variation in this hydrothermal system. A gradual increase of Sb isotope ratios from the proximal to the distal parts was observed in stibnite ores. Rayleigh distillation models the systematic variation trend of the Sb isotope values, demonstrating that ore fluids are preferentially enriched in heavier Sb isotopes during the precipitation of isotopically light stibnite. In this way, we consider that separation of stibnite from a Sb-bearing fluid related to reaction kinetics as a cause for Sb isotope fractionation. The modeled data constrain a Sb isotope fractionation factor (α fluid-stibnite) between hydrothermal fluid and stibnite at approximately 0.9994. The model also constrains an initial Sb isotope value of ~0.45‰, which indicates metal sources in the basement rocks of the study area. Given that distal stibnites possess higher Sb isotopic values, Sb isotopes could be used to fingerprint hydrothermal fluid flow and unravel different processes in natural systems. [ABSTRACT FROM AUTHOR]

Anyue gas field is a large gas field located in the central Sichuan Basin, China. Although many studies have been carried out previously, the formation mechanism of this field is unclear and currently under debate. To better understand the accumulation history, the role that groundwater plays in transporting hydrocarbons within sedimentary basins and water-gas interactions, stable and noble gas isotopes were measured in thirteen free gas samples from the Anyue gas field. In addition, nine formation water samples and five reservoir bitumen samples were analyzed for stable carbon isotopes. δ13C(CH 4) values in the gas samples range from −35.0 to −32.6‰, showing evidence of thermogenic origin. δ13C values among three different types of samples (free gases, water-dissolved gases and reservoir bitumen) show a pattern that cannot be explained by oil cracking followed by free gas accumulation. It suggests the occurrence of gas-groundwater interaction in the Anyue field. Free gas samples can be divided into 2 distinct groups by their geographical locations and stratigraphical source formations. 3He/4He ratios (R/R a) in group 1 and group 2 samples range from 0.0118 to 0.0132 and 0.0115 to 0.0256, respectively, indicating He is mainly derived from the crust. 20Ne/22Ne and 21Ne/22Ne ratios suggest a mixing between the air and crust sources. 40Ar/36Ar ratios ranging from 1658 to 2109 and 2168 to 5973 in group 1 and group 2 samples, respectively, are significantly higher than the air value of 298.6. In comparison, heavier noble gas (Kr and Xe) isotopic compositions are predominantly air-like. The relative enrichment of 4He and 21Ne* in group 1 samples can be possibly explained by preferential release of light noble gases in a low temperature environment. Samples in group 2 show a good fit to the solubility-controlled Rayleigh fractionation model, suggesting the presence of an open system degassing of gases from the groundwater. The excess heavy noble gases in natural gas samples can be attributed to the addition of sedimentary components from the source rocks during geological evolution. 4He groundwater ages considering in-situ production and external flux indicate the addition of young groundwater into the Anyue gas field. Low gas-groundwater ratios and high CH 4 /36Ar ratios suggest that only a small portion of the gases in the current Longwangmiao reservoir of Anyue gas field has been in contact with the relatively young groundwater. Based on the noble gas and stable carbon isotope results in all samples, we propose a two-stage gas and groundwater interaction process during the gas preservation and accumulation history in the Anyue gas field in China. [ABSTRACT FROM AUTHOR]

The Zijinshan district, Fujian Province, southeastern China, is a globally renowned Cu Au orefield and hosts a wide variety of ore deposits within the Zijinshan granite complex and surrounding volcano-sedimentary rocks. We performed Fe S isotope analysis on pyrite separates from the Zijinshan high-sulfidation epithermal deposit, Yueyang intermediate-sulfidation epithermal deposit, Wuziqilong transition-type (from high-sulfidation epithermal to porphyry) deposit, and Jintonghu porphyry Cu Mo deposit, aiming to understand the formation process of Fe-sulfides and the evolution of ore-forming fluids in different deposits. Pyrites from the Jintonghu porphyry Cu Mo deposit show variations in δ56Fe and δ34S from −0.15 ‰ to 0. 45 ‰, and from 1.81 ‰ to 2.70 ‰, respectively. In contrast, pyrites from epithermal-type deposits (i.e., Zijinshan, Yueyang, and Wuziqilong) show a negatively shifted Fe isotopic composition from −1.74 ‰ to 0.45 ‰. The combination of Fe isotopic data from the Jintonghu porphyry Cu Mo deposit with published minerals-fluid fractionation factors and the use of a Rayleigh fractionation model allowed us to determine the δ56Fe range of regional ore-forming fluids (−1.00 ‰ to −0.40 ‰), which is consistent with the previous "light fluid" hypothesis, suggesting that pyrite of porphyry Cu Mo deposits has isotopic compositions reflecting the isotopic value of the hydrothermal fluids. For the epithermal deposits, pyrite Fe isotopic composition is the result of a complex interaction of Rayleigh fractionation, rapid precipitation and kinetic fractionation, and δ56Fe values of the initial fluids is difficult to estimate. Integrating the Fe and S isotope data for pyrite of different genesis, we found that porphyry Cu Mo deposits (δ56Fe: −0.9 ‰ to 0.46 ‰; δ34S: −4.06 ‰ to 3.9 ‰) can be distinguished from a non-magmatic/low-temperature region, while the transitional area of which may be a porphyry-related hydrothermal deposit (i.e., epithermal deposit). In general, we suggest that the Fe and S isotopic signatures of pyrite can effectively distinguish porphyry-type deposits from their associated hydrothermal deposits. [ABSTRACT FROM AUTHOR]

Abstract The boron (B) isotope-pH proxy for marine carbonates has been widely used to reconstruct past ocean pH values. Unlike seawater, the apparent dissociation constant of boric acid (K B) and the δ11B values of brines from the terrestrial salt lakes in western China vary. However, relevant studies concerning the B isotope geochemistry of brine-carbonate systems in terrestrial salt lakes are limited. In this study, thirty-nine clastic samples from a sediment core (ISL1A) from the Qarhan Salt Lake in the Qaidam Basin were collected. These carbonates were analyzed for δ11B, B, Mg, Sr and Ca. Using our new data as well as published pH values, total dissolved solids (TDS), element concentrations, and δ11B values of brines in western China, we reached the following conclusions. (1) During evaporation process, salinity increases, the δ11B values of brines in salt lakes increase, and the pK B (−logK B) and pH values simultaneously decrease. (2) The large heterogeneity in the δ11B values of the carbonates (−2.74‰ to +7.64‰) from core ISL1A is mainly due to the δ11B values of the brines, rather than pK B and pH. (3) B isotopic fractionation with a small α carbonate-brine of 0.997 in a brine-carbonate system conforms to the Rayleigh fractionation model. (4) Our comparison of the δ11B values of these carbonates with other records from core ISL1A suggests that the δ11B values of the carbonates in the arid Qaidam Basin can be used as a new proxy for the salinity of paleo-lake water. Highlights • δ11B and B, Mg, Sr, Ca concentrations of carbonates in ISL1A were analyzed. • δ11B of carbonates are influenced by δ11B of brine rather than pH or pK B. • B isotopic fractionation in a brine-carbonate system conforms to Rayleigh model. • High (low) δ11B correspond to high (low) Mg/Ca, Sr/Ca ratios of carbonates. • δ11B of carbonates in salt lakes can indicate salinity of lake water. [ABSTRACT FROM AUTHOR]

Tungsten is a critical and strategic metal used widely in the aerospace, automotive, electronic, and defense industries. Most tungsten deposits are genetically related to granitic rocks and a small number of them are giant deposits that supply much of the World's demand for tungsten. Understanding the genesis of these giant deposits and developing models based on this understanding that can guide exploration for them is, therefore, a matter of considerable interest. China hosts nearly 50% of the global tungsten resource, much of which is contained in a few giant deposits. This makes it an ideal location in which to study the processes that lead to the formation of giant tungsten deposits. Here, we use a compilation of the whole-rock geochemical and zircon Hf O isotopic compositions of granitic rocks associated with tungsten deposits in China and elsewhere, in conjunction with Rayleigh fractionation modeling and Monte Carlo simulations, to quantitatively evaluate the role of the source region, oxygen fugacity, and the degree of magma differentiation in the formation of giant tungsten deposits. The zircon Hf O isotopic compositions are very heterogeneous, indicating that there is no source either in the upper crust, the lower crust, or one representing a mixture of crust and mantle that can explain the existence of giant tungsten deposits. Our modeling also shows that changes in oxygen fugacity have little impact on the formation of giant tungsten deposits. Instead, the modeling demonstrates that a combination of a pre-enriched source and a high degree of magma differentiation are pre-requisites for forming a giant tungsten deposit. • The formation of the giant tungsten deposits is independent of the source region, which either can be upper crust, lower crust, or a mix of crustal magma with mantle materials. • Oxygen fugacity of ore-related magma does not control the formation of giant tungsten deposits. • The combination of pre-enriched sources and a high degree of differentiation is the prerequisite for forming giant tungsten deposits. [ABSTRACT FROM AUTHOR]

High precision detection of the shallow-surface structure is of great significance to geotechnical engineering and archaeological geophysical research. Surface wave Full waveform inversion (FWI) is attracting more and more attention in shallow seismic exploration. The FWI of Love waves is more straightforward and has a higher precision and resolution compared with Rayleigh waves. In the classic gradient-based FWI algorithm, the gradient amplitude does not scale with increasing depth due to the coupling effect and double scattering; thus, the inversion image cannot represent the significant small-scale characteristic structures in archaeogeophysics. To overcome the above limitations, a pre-conditioned FWI approach was presented, and a complete elastic Love waves FWI workflow was developed for archaeogeophysics. The superior performance of the developed method was verified through synthesis tests and a field experiment. The synthetic tests on a tomb model show that the pre-conditioned approach has a better parameter reconstruction capability, can characterize small-scale anomalies, improves the convergence rate, and has a strong anti-noise ability. In the field experiment, the pre-conditioned approach-based Love waves FWI workflow was adopted to invert the recorded Love waves datasets gathered in Xianyang City, China. The target of the survey was to determine the location and approximate size of a buried ancient tomb to provide reliable guidance for further excavation. The obtained FWI image revealed an underground profile with a depth of 9.5 m, and a low-velocity anomaly with a height of about 1.6 m and a length of about 4.7 m was delineated, which we identified as the tomb. The subsequent excavation confirmed this conclusion. The above results show that the complete Love wave FWI workflow developed has the ability to perform accurate imaging under the condition of few shots. • Focus on characterizing high-precision small-scale structures for archaeogeophysics. • Develope a complete workflow of pre-conditioned approach-based 2D Love waves FWI. • Demonstrate the superior performance of our method through synthesis and field tests. • Reveal the structure of an ancient tomb accurately by inverting field data. [ABSTRACT FROM AUTHOR]

To the problem of being lack of transit network hierarchy theory, a research on public transit network hierarchy optimization based on residential transit trip distance is conducted. Firstly, the hierarchy standard of transit network is given, in addition, both simulating electron cloud model and Rayleigh distribution model are used to fit the residential transit trip distance. Secondly, from the view of balance between supply and demand, the hierarchy step of transit network based on residential transit trip distance is proposed. Then, models of transit's supply turnover and demand turnover are developed. Finally, the method and models are applied into transit network optimization of Baoding, Hebei, China. [ABSTRACT FROM AUTHOR]

SUMMARY In this paper, we conduct ambient noise seismic tomography of northwestern China and adjacent regions. The data include 9 months (2009 January to 2009 September) three-component continuous data recorded at 146 seismic stations of newly upgraded China Provincial Digital Seismic Networks and regional Kyrgyzstan and Kazakhstan networks. Empirical Rayleigh and Love wave Green's functions are obtained from interstation cross-correlations. Group velocity dispersion curves for both Rayleigh and Love waves between 7 and 50 s periods were measured for each interstation path by applying the multiple-filter analysis method with phase-matched processing. The group velocity maps show clear lateral variations which correlate well with major geological structures and tectonic units in the study region. Shear wave velocity structures are inverted from Rayleigh wave and love wave dispersion maps. The results show that the Tibetan Plateau has a very thick crust with a low-velocity zone in its mid-lower crust. Along the northern margin of the plateau where a steep topographic gradient is present, the low-velocity zone does not extend to the Tarim basin which may indicate that crustal materials beneath the Tarim basin are colder and stronger than beneath the plateau, therefore inhibit the extension of mid-lower crustal flow and deformation of the Tibetan Plateau, resulting in very sharp topography contrasts. In the northeastern margin with a gentle topographic gradient toward the Ordos platform, the low-velocity zone diminishes around the eastern KunLun fault. Meanwhile, our results reveal obvious lateral velocity changes in the crust beneath the Tarim basin. In the upper crust, the Manjaer depression in the eastern Tarim basin is featured with very low velocities and the Bachu uplift in the western Tarim basin with high velocities; in the mid-lower crust, the northern Tarim basin in general displays lower velocities than the southern part along latitude ∼40° N with an east-west striking, which is consistent with the high magnetic anomaly zone and may be related to the central suture belt connecting the south and north of Tarim basement blocks together in Pre-Sinian. [ABSTRACT FROM AUTHOR]

[Display omitted] • For the first time, Fe and Mg isotope compositions of the Shuangwang gold deposit are investigated. • Fe in the Shuangwang gold deposit was predominantly from a magmatic source. • Mg from wall rocks contributed to the composition of hydrothermal magnesium isotopes during the mineralization. Iron and Magnesium isotopes have been increasingly widely applied to trace mineralization processes of hydrothermal ore systems. In this study, Fe and Mg isotope compositions of whole-rocks, Fe-bearing minerals (pyrite and ankerite) and Mg-bearing mineral (ankerite) from the Shuangwang gold deposits are investigated to evaluate Fe and Mg isotope behaviors in a gold deposit hydrothermal system and provide new constraints on ore-forming processes. The results showed that the magmatic rocks in the Shuangwang gold deposit (mainly granodiorite, monzonitic granite and lamprophyre) yielded δ56Fe values of 0.05–0.10‰ and δ 26Mg values concentrated in a narrow range from −0.23‰ to −0.21‰. The gold orebodies are hosted by a NW-trending breccia belt. The wall rock samples (mainly argillaceous limestone, carbonaceous slate and albitite) have higher δ56Fe values of 0.12–0.29‰ and a wide δ 26Mg range from −2.54‰ to −0.35‰. Pyrite mineral separates show larger δ56Fe variation from −0.44‰ to 0.16‰, whereas ankerite has a small δ56Fe range from −0.15‰ to −0.06 and a δ 26Mg range from −0.66‰ to −0.35‰. The crystallization of magmatic rocks incorporated preferentially heavy Fe isotopes, resulting in enrichment of light Fe isotopes in the residual fluid exsolved from magma. The interactions between the wall rocks and the fluids resulted in increase of δ56Fe value in fluids and resulted in decrease of δ56Fe value in the wall rocks. However, the fluid still had much lighter Fe isotope composition. Thus, Fe in the main ore-forming stages is regarded as derived from the magmatic stock. The opposite enrichment in Fe isotopes between pyrite and ankerite from stages II and III may be explained by equilibrium Fe isotope fractionation in an open system. In addition, the negative δ56Fe value in pyrite from stage IV is indicative of the equilibrium between FeS and dissolved Fe in a closed system. The exsolved fluid from magma has Mg isotope composition similar to magmatic rock, and the water–rock reaction led to the enrichment of heavy Fe isotopes in fluid. The evolutions of Mg isotopes in stages II and III precipitation matched well with the prediction of Rayleigh fractionation model. The Mg from wall rocks contributed to the composition of hydrothermal magnesium isotopes during the formation of the Shuangwang gold deposit. A multi-origin is supposed whereby the main stage ore-forming fluids were derived from metamorphic water and were affected by the influx of magmatic water. [ABSTRACT FROM AUTHOR]

• δ 11 B of paleorainwater (δ 11 B pr) in loess-paleosol deposits from NE China are reconstructed. • Kinetic isotope fractionation explains the linkage of δ 11 B pr to the intensity of summer monsoon. • The δ 11 B pr can be employed as a robust proxy for intensity of East Asian Summer Monsoon. • Increase of ice volume in Northern Hemisphere drove an abrupt EASM weakening in NE China at ca. 430 ka. Based on a study of the boron (B) isotope geochemistry of the loess-paleosol sequence of the Niuyangzigou section (NYZG) in Northeast (NE) China, the boron isotopic composition of paleo-rainwater (δ 11 B pr) is used for the first time as a potential proxy for tracing changes in the East Asian summer monsoon (EASM) since the mid-Pleistocene. The acid-soluble phase of loess in NE China, which is characteristically a sandy loess, has lower boron concentrations (0.26 to 0.89 μg/g) and more positive δ 11 B values, from −12.1‰ to +9.4‰, compared to the loess of the Chinese Loess Plateau (CLP). According to the mass balance of boron accumulation from three distinct sources, a mathematical inversion calculation is used to quantify the proportion of boron from each source and to capture the original δ 11 B pr signature. The resulting δ 11 B pr values range from +6.8 ± 0.95‰ in loess layers to +17.3 ± 3.32‰ in paleosol layers, and the boron accumulated in loess-paleosol layers is shown to be mainly from atmospheric precipitation and silicate weathering. Synchronous variations of reconstructed δ 11 B pr and other loess-based proxies, both in NE China and in the CLP, are observed over a large spatial range and on several temporal scales. The linkage of δ 11 B pr to the intensity of the EASM is attributed to the kinetic boron isotope fractionation associated with vapor-precipitate phase separation along the transport path of moisture-bearing air masses. A Rayleigh fractionation model is proposed to interpret δ 11 B pr in terms of the proportion of water vapor loss after multi-step fractionation processes, which is independent of temperature. The monsoon record based on δ 11 B pr shows a significant shift at ∼430 ka, implying an abrupt weakening of the EASM after the Mid-Brunhes Event (MBE), which provides evidence for regional disparities in monsoon evolution in response to the MBE. The ice volume in Northern Hemisphere is a possible factor controlling changes in the EASM in NE China over the past 800 kyr. [ABSTRACT FROM AUTHOR]

The Jinchuan Ni-Cu deposit is one of the largest magmatic sulfide deposits in the world, but the cause of sulfide saturation remains unclear. It has been suggested that sulfide saturation in the Jinchuan magma was triggered by oxidation through assimilation of fluids related to de‑carbonation of marbles. This study uses Mg and C-O isotopes to evaluate the process of carbonate assimilation. The measured values of δ18O and δ13C for carbonate minerals from country rock marbles range from 13‰ to 22‰ and from −1.7‰ to 1.3‰, respectively. Carbonate minerals from xenoliths and hybrid rocks in the contact zone have lower C-O isotope ratios, with δ18O from 11‰ to 16‰ and δ13C from −4.7‰ to −2.3‰, respectively. The carbonate δ26Mg values of xenoliths and hybrid rocks are from −1.71‰ to −1.36‰, similar to the values of the marbles (−1.74‰ to −1.34‰). The whole-rock δ26Mg values of hybrid rocks samples associated with xenoliths vary from from −1.69‰ to −0.92‰. The δ18O values of pyroxene at the margin and the center of the Jinchuan intrusion vary from 5.1‰ to 7.8‰ and from 5.3‰ to 6.5‰, respectively. Despite varying distances from contacts with country rocks, pyroxene in these samples are characterized by δ26Mg values from −0.32‰ to −0.16‰, which are similar to the typical value of the Earth's mantle (−0.25‰ ± 0.07‰). The C-O isotopic variations are consistent with de‑carbonation. Rayleigh fractionation models suggest from 40% to 80% CO 2 loss from xenoliths and hybrid rocks. The Mg isotopic compositions in the contact zone reflect reactive assimilation between xenoliths and mafic magma. Product olivine and diopside inherited the δ26Mg value of reactant dolomite. The transport of released CO 2 from xenoliths into magma is consistent with increasing oxygen fugacity and potentially triggering sulfide saturation. However, Mg isotope exchange was confined to the contact zone, and appears to have been unrelated to the ore-forming process. [ABSTRACT FROM AUTHOR]

Hexavalent chromium, Cr(VI), is a heavy metal contaminant and the reduction of Cr(VI) is accompanied by large isotopic fractionation. In this study, the sources of Cr were explored using the Cr isotopic composition of sediments from the Xiaoqing River, a heavily polluted river located in the Shandong Province of China, which flows into Laizhou Bay. The results show that δ53Cr values of the sediments are the highest upstream near the pollution source, and gradually decrease along the river toward the range for igneous reservoirs observed near the estuary. Based on the calculation of authigenic Cr isotopic composition (δ53Cr auth) using the detrital index and leaching experiments, we suggest that the authigenic Cr in the sample near the pollution source with the highest δ53Cr auth value mainly comes from the reduction of Cr(VI) discharged by anthropogenic activity, and authigenic Cr in other samples in the midstream with δ53Cr auth values slightly higher than the range of igneous reservoirs may come from natural oxidative Cr weathering products. By introducing a Rayleigh model, we calculate that at least 31%–55% of Cr(VI) in the river water had been reduced to Cr(III) near the pollution source. Due to the self-purification ability of the river, Cr(VI) was reduced; thus, there is no record of high δ53Cr auth values in the downstream of the Xiaoqing River and Laizhou Bay, indicating no obvious Cr pollution in these locations. The limited variation of δ53Cr values for samples from a sediment core in Laizhou Bay is also indicative of no obvious Cr pollution in the history. The Cr isotopic compositions of the river sediments are useful for the identification of Cr sources and can be used to advise environmental remediation on Cr pollution. Image 1 • Variations in the Cr isotopic ratios of sediments from Xiaoqing River reflect different Cr sources. • The leaching experiments contribute to source identification of Cr. • Authigenic Cr in the upstream sample mainly comes from anthropogenic activity. • The limited Cr isotopic fractionations in the sediments of Laizhou Bay indicate no Cr pollution. Using Cr isotopes, we distinguished different Cr sources in sediments from the Xiaoqing River and Laizhou Bay, which further allows us to evaluate Cr pollution. [ABSTRACT FROM AUTHOR]

• Dolostone deposited at 25–50 °C by Mg isotope Rayleigh distillation model. • During the Eocene to Oligocene, the detrital zircon ages of 40–44 Ma was first found. • Volcanic ash provided the Mg2+ and high temperature for dolomite formation. • The Anjihaihe dolostone are typical of naturally occurring primary dolostone. During the Eocene to Oligocene, lacustrine dolostone developed in the Anjihaihe Formation on the northern margin of the Tianshan Mountains in the southern Junggar Basin. Dolostone formation is usually restricted to specific environmental and geochemical conditions; therefore, dolostone contains considerable information on palaeoenvironment and palaeoclimate changes. Furthermore, this dolostone provides more information on the formation process and formation mechanisms of dolostone. The studied dolostone is white to greyish white and consists of dolomite crystals that are 3–10 µm in size, homogeneous, subhedral to euhedral and nearly stoichiometric (with average Mg/Ca molar ratios of 0.97). The high Sr content (average 1996 ppm), relatively high δ18O values (average −1.8‰) and co-occurrence with halite and gypsum reflect evaporative and saline conditions. The δ26Mg values of the dolostone range from −0.81 to −2.44‰, with a mean of −1.78‰. Strong positive correlations exist between the δ26Mg values and depth (r = 0.76) and the Mg isotope Rayleigh distillation model results, which indicates that δ26Mg fractionation occurred in conjunction with evaporation and that most of the Anjihaihe lacustrine dolomite developed in a natural environment at 25–50 °C. Moreover, evidence of microbes can be found covering the surface of the dolostone in the presence of a few framboids of pyrite. Additionally, clay layers in the dolostone are primarily composed of bentonite (40–60%) but also contain small amounts of montmorillonite (0.8–3.5%) and zeolite (0.1–0.5%). Detrital zircon ages of 40–44 Ma are presented for the first time for the Anjihaihe Formation. The results show that understanding the primary lacustrine dolostone is significant and essential to reconstructing the evolution of palaeoenvironments and synsedimentary volcanic activity in the northern Tianshan Mountains during the Eocene to Oligocene. This work also provides a possible model that explains the formation of the studied dolostone in an evaporative saline lacustrine environment. [ABSTRACT FROM AUTHOR]

Felsic intrusive magmatic systems are more complex than volcanic systems as they involve prolonged magmatic processes in addition to potentially multiple phases of magmatic–hydrothermal activity within a single pluton. In particular, the competition between exsolved magmatic fluids and crystallizing minerals for elements and isotopes during the magmatic–hydrothermal stages of evolution of these systems remains unclear despite fluid exsolution being one of the key steps in ore formation. This study focuses on a suite of representative Late Jurassic W–Sn mineralization-related granites within the Nanling Range of southern China and investigates the behavior of Fe isotopes during magmatic differentiation and magmatic–hydrothermal processes recorded within these granites. The granites in the study area have variable δ56Fe values (relative to IRMM-014) ranging from 0.12‰ ± 0.04‰–0.42‰ ± 0.01‰. These values do not correlate with bulk-rock geochemical indicators of fluid exsolution (e.g., Zr/Hf, Nb/Ta, K/Rb, and F/Cl ratios), qualitatively indicating that fluid exsolution has an insignificant effect on Fe isotopic fractionation. We further quantified the relative contributions of fluid exsolution and crystal fractionation on bulk-rock Fe isotopic variability using a Rayleigh fractionation model. This modeling indicates that fluid exsolution can only generate a <0.07‰ increase in bulk-rock δ56Fe values of the Nanling granites even in the most fluid-abundant scenario. This means that Fe isotopic fractionation is controlled mainly by fractional crystallization during the magmatic–hydrothermal stages of the evolution of granitic magmas. This further suggests that Fe isotopes could be used to study the magmatic differentiation of felsic magma chambers, including those within fluid-rich mineralizing magmatic systems. • The effect of fluid exsolution on Fe isotope fractionation remains unclear. • Fluid exsolution contributes little to Fe isotopic fractionation in granites. • Fractional crystallization is the main cause of Fe isotope fractionation. • Iron isotopes can be used to trace magmatic differentiation of felsic magma chamber. [ABSTRACT FROM AUTHOR]