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Zinc and Cd isotopes fractionate strongly within a range of hydrothermal systems; consequently, metal stable isotopes have been used to understand the formation of hydrothermal ore deposits. We investigated the Zn–Cd–S isotopic compositions of sulphides from the Carboniferous-Permian Xiaobaliang Cu–Au deposit, Inner Mongolia, China. This ancient seafloor hydrothermal system is the only known Cyprus-type volcanic-hosted massive sulphide (VHMS) deposit in the Central Asian Orogenic Belt. The S isotopic compositions of sulphide minerals are highly variable with δ34SCDT values ranging from −21.2‰ to 25.2‰. We infer that negative δ34SCDT values reflect mixing of volcanogenic S and S derived from bacterial sulphate reduction (BSR), and that positive δ34SCDT values reflect mixing of volcanogenic S with S derived from thermochemical sulphate reduction (TSR). Zinc isotopic compositions are relatively consistent at the deposit; δ66Zn values range from 0.10‰ to 0.70‰. These values are similar to those reported for modern seafloor sulphides. We infer that consistency of δ66Zn values relates to the Zn species ([ZnCl4]2−) present in the ore-forming fluids during sulphide precipitation. All of the sulphides are enriched in the light Cd isotopes; δ114/110Cd values range from −0.74‰ to −0.08‰. Zinc and Cd can be affected by biological activity, and we infer that biological activity caused the negative δ114/110Cd values at this deposit because: (1) biological processes (e.g., bacterial activity) enrich fluids in the light Cd isotopes, leading to the precipitation of sulphides with negative δ114/110Cd values; and (2) the Cd isotopic composition of ore-forming fluid is readily modified because the concentration of Cd is much lower than that of Zn in ore and basalt. Our results indicate that Cd isotopes might record ancient biological activity, and that organisms might play a more important role than previously thought in the formation of VHMS systems.

Complex coronary heart disease (CHD) has become a hot spot in medicine due to its complex coronary anatomy, variable clinical factors, difficult hemodynamic reconstruction, and limited effect of conservative drug treatment. Identifying complex CHD and selecting optimal treatment methods has become more scientific as revascularization technology has improved, and coronary risk stratification scores have been introduced. SYNTAX and its derivative scores are a decision-making tool that could quantitatively describe the characteristics of coronary lesions in patients based on their complexity and severity, could assist clinicians in rationalizing the selection of hemodynamic reconstruction treatment strategies, and have outstanding value in evaluating the prognosis of patients with complex CHD undergoing revascularization treatment. The authors hope that describing the practical application of SYNTAX and its derivative scores in complex CHD will deepen the understanding of the relationship between the choice of different revascularization strategies and SYNTAX and its derived scores in complex CHD and provide a further reference for clinical treatment of complex CHD.

This study examines the Ga isotopic compositions of sulfides in the Yuhuang and Duanqiao hydrothermal fields on the Southwest Indian Ridge, mid-ocean ridge basalts (MORB), and calcareous sediments around the hydrothermal fields. The δ71/69GaNIST-994 values of the MORB samples vary little (+1.20‰ to +1.23‰, with an average of +1.22‰) and are consistent with the δ71/69GaNIST-994 values of two standard basalt samples (BCR-2 and BHVO-2), indicating that Ga isotopes may either not fractionate or fractionate only slightly under high-temperature geological processes; therefore, the δ71/69GaNIST-994 value of oceanic crust may be +1.22‰. The sediments (+1.28‰ to +1.47‰, with an average of +1.38‰) are rich in heavier Ga isotopes than the basalts, and the Ga present in the sediments may have originated from soluble Ga present in the seawater that was adsorbed by (Mn, Fe) oxides/hydroxides. The Ga contribution of basaltic debris to the sediments was almost negligible. Thus, we speculate that the δ71/69GaNIST-994 value of seawater in the study area fell within a range from +1.92‰ to +2.36‰. The δ71/69GaNIST-994 values of the sulfides in the Yuhuang hydrothermal field range from +0.99‰ to +1.57‰, with an average of +1.25‰, and the δ71/69GaNIST-994 values of the sulfides in the Duanqiao hydrothermal field range from +0.93‰ to +1.55‰, with an average of +1.19‰. The δ71/69GaNIST-994 ranges of the sulfides in the Yuhuang and Duanqiao hydrothermal fields are similar, with the Ga isotopic fractionation reaching 0.58‰ and 0.62‰, respectively. The average δ71/69GaNIST-994 values in the sulfides are close to those in the MORBs. This suggests that Ga within the sulfides in the Yuhuang and Duanqiao hydrothermal fields mainly originated from MORBs, with seawater and sediments making only small contributions. The Ga isotopic fractionation in the sulfides may be related to processes associated with the formation of sulfides, such as rapid precipitation or the admixture of different stages of sulfide. This study is of great significance for understanding the global distribution of Ga isotopes and the Ga cycle in submarine hydrothermal systems.

Mineral-hosted melt inclusions have become an important source of information on magmatic processes. As the number of melt inclusion studies increases, so does the need to establish recommended practice guidelines for collecting and reporting melt inclusion data. These guidelines are intended to ensure certain quality criteria are met and to achieve consistency among published melt inclusion data in order to maximize their utility in the future. Indeed, with the improvement of analytical techniques, new processes affecting melt inclusions are identified. It is thus critical to be able to reprocess any previously published data, such that reporting the raw data is one of the first “recommended practices” for authors and a publication-criteria that reviewers should be sensitive to. Our guidelines start with melt inclusion selection, which is a critical first step, and then continue on to melt inclusion preparation and analysis, covering the entire field of methods applicable to melt inclusions. Dedication In March of 2000, a melt inclusion workshop was held at the Chateau de Sassenage in Grenoble and a companion issue of Chemical Geology entitled “Melt Inclusions at the Millennium” was published. Erik Hauri was heavily involved with the meeting and contributed two landmark papers to the topical issue of Chemical Geology on the use of secondary ion mass spectrometry to analyze volatiles in melt inclusions. When the melt inclusion community re-convened at Woods Hole Oceanographic Institution (WHOI) in August of 2018, we were saddened that Erik was unable to join us due to his failing health. Less than a month later came the devastating news of his passing at only 52 years of age. In recognition of his incredible contributions to science in general and to the in situ analysis of melt inclusions in particular, the participants and organizers of the WHOI melt inclusion workshop dedicate this collegial paper to Erik Hauri, our colleague, mentor and friend. Thank you Erik.

The Sichuan–Yunnan–Guizhou (SYG) metallogenic province, southwestern China, is one of the largest Zn-Pb producers in the world. The Zn-Pb deposits in this area have been studied over many years and are commonly classified as Mississippi Valley Type (MVT) deposits. We investigated geological and mineralogical features of the Wusihe deposit and found that ores formed at the sedimentary metallogenic stage exhibit banded and normal grading textures and have different mineral assemblages from other deposits in this area. These features have not been reported previously, suggesting special formation mechanisms for these sedimentary ores. In this study, we firstly investigate the isotope geochemistry of Zn and S in syngenetic sphalerite from the Wusihe deposit. We elucidate spatial and temporal variations of Zn and S isotopes to provide a better understanding for Zn and S isotope fractionation during the hydrothermal processes. The δ34SCDT values of microdrilled sphalerite range from 9.4‰ to 20.9‰ (mean = 14.3‰), which are ca.15‰ lower than that of sulfate from the Dengying Formation, suggesting that reduced sulfur in sphalerite formed through thermochemical sulfate reduction (TSR) but not microbial sulfate reduction (MSR). At the hand specimen scale, no significant Zn isotopic fractionation was observed from bottom to top of the banded sphalerite ore and we propose a model that Zn isotopes are homogeneous in Zn-bearing hydrothermal fluid, and Zn2+ was rapidly and completely precipitated to form sphalerite. This process results in minor Zn isotopic variations in sphalerite (Δ66Zn = 0.08‰) and initial hydrothermal fluid composition was calculated to be δ66Zn values = 0.37 ± 0.03‰. By contrast, positive linear relationships were observed in the sphalerite ore with normal grading between δ66Zn and δ34SCDT values and between δ34SCDT values and Zn/Cd ratios, which are not reported previously. Combined with previous studies, it is proposed that the variations in fluid temperatures may be the key factor that results in such positive correlations. In addition, this study gives some new insights into geochemical and isotopic behavior of Zn and S in hydrothermal systems, and provides an initial glimpse into the utilization of Zn isotopes as an environmental tracer for reconstruction of Zn isotope compositions in the Ediacaran Ocean.

Zinc (Zn)-Lead (Pb) deposits are generally rich in cadmium (Cd), and the weathering of sulfide minerals in such deposits results in large releases of Cd into the environment. From an environmental and public health standpoint, understanding Cd sources and cycling is critical to identifying potential hazards to humans. In this study, the Cd isotope compositions (expressed as δ114/110Cd) of secondary minerals such as anglesite (-0.57±0.03‰; 2S.D.), granular smithsonite (0.04±0.14‰; 2S.D.), layered smithsonite (0.15±0.40‰; 2S.D.), hydrozincite (0.26±0.01‰; 2S.D.) and clay minerals (-0.01±0.06‰; 2S.D.) from the Fule Zn-Pb-Cd deposit, Southwest China, are investigated to better understand the Cd sources and cycling in this area. Combined with our previous study (Zhu et al., 2017), the work herein elucidates the patterns of Cd isotopic fractionation during the formation processes of such secondary minerals and traces the weathering of these minerals into the ecosystem. The δ114/110Cd values of secondary minerals exhibit the following decreasing trend: hydrozincite>large granular smithsonite>small granular smithsonite>anglesite. Although different amounts of Cd were lost during the formation of equally sized samples, no or minor variations in Cd isotopic composition were observed. However, significant isotopic differences were observed between different size fractions. These results demonstrate that the particle size of secondary minerals and weathering products of sulfide significantly influence Cd isotope composition and fractionation during natural weathering. This systematic fractionation provides an initial foundation for the use of Cd isotopes as environmental tracers in ecosystems and in the global Cd isotope budget.

International audience; The Sichuan–Yunnan–Guizhou (SYG) Zn–Pb metallogenic zone in SW China contains >400 carbonatehostedhydrothermal Zn–Pb deposits. Some of these, such as the Huize, Tianbaoshan, and Daliangzideposits, are super-large deposits with significant reserves of Cd, Ge, and Ag. However, the sources ofthese metals remain controversial. This study investigated the Cd isotopic geochemistry of the Huizedeposit, the largest Zn–Pb deposit in the SYG area. Sphalerites formed at three stages in the deposit havedifferent colors: black or dark brown (Stage I), red (Stage II), and light-yellow (Stage III). The d114/110Cdvalues of the sphalerites are in the order Stage III < Stage I < Stage II. Kinetic isotopic fractionation is likelythe key factor causing the lower d114/110Cd values in the early formed Stage I sphalerites than in laterformedStage II sphalerites, with cooling of ore-forming fluids being responsible for the still lower valuesof the Stage III sphalerites. In galena, the d114/110Cd values are inversely correlated with Cd contents andtend to be higher in high-Zn galena. We speculate that Cd isotopic fractionation was significant duringthe precipitation of sphalerite and galena, with light Cd isotopes being enriched in galena rather thansphalerite. Comparison of the Cd isotopic signatures and Zn/Cd ratios of different endmembers suggeststhat the d114/110Cd values and Zn/Cd ratios of sphalerite from the Huize deposit, as well as other largescaledeposits from the SYG area, are lie in those range of Emeishan basalts and sedimentary rocks andthe mean d114/110Cd values of these deposits show good negative correlation with 1/Cd, suggesting thatthe ore-forming materials of these deposits were derived from the mixing of Emeishan basalts and sedimentaryrocks. This study demonstrates that Cd isotopes can be useful proxies in elucidating ore genesisin large Zn–Pb deposits.

We studied the gallium (Ga) isotopic composition of the Xiaoshanba bauxite deposit in central Guizhou Province, southwest China. Claystone with kaolinite as the main mineral has δ71GaIPGP values of − 0.22‰ to + 0.19‰ (−0.04‰ on average), whereas bauxite with diaspore as the main mineral has δ71GaIPGP values of − 0.60‰ to − 0.15‰ (−0.35‰ on average). Other samples with diaspore and kaolinite as the main minerals have δ71GaIPGP values between those of the claystone and bauxite (−0.20‰ on average). Dolostone from the Loushanguan Group has δ71GaIPGP values of − 0.28‰ to − 0.18‰ (−0.24‰ on average). Samples with kaolinite as the main mineral have higher δ71GaIPGP values than samples with diaspore as the main mineral. However, δ71GaIPGP values in the dolostone are lower than those of the claystone. Based on vertical variations in δ71GaIPGP values and Ga/Al ratios, we speculate that weathered dolostone from the Loushanguan Group may have higher δ71GaIPGP values than unweathered dolostone. In addition, for both of the Jiujialu and Wulongsi ore bodies, samples from the upper part of the profile are relatively enriched in heavier Ga isotopes than samples in the lower part. During the process of bauxite ore formation, supergene weathering and Ga re-precipitation could have led to enrichment in lighter Ga isotopes. This mechanism of isotopic enrichment has the potential to record the material source of the bauxite. The results of leaching experiments show that, during supergene weathering, Ga is more available to the leaching liquid than Al under neutral to weakly alkaline conditions, whereas Al is more soluble than Ga under weakly acidic conditions. In natural deposits, samples with a high degree of weathering show an obvious decoupling between Ga and Al; consequently, in a given sedimentary environment, samples with kaolinite as the main mineral have higher Ga concentrations than samples with diaspore as the main mineral. Clay minerals such as kaolinite can be important resources of Ga.

The end-Permian mass extinction was the most severe biotic crisis of the Phanerozoic. Oceanic anoxia has long been considered one of the main drivers of the biotic crisis. We examined the molybdenum isotope compositions of bulk carbonate samples from two Permian–Triassic boundary sections in southern China: the Meishan Global Stratotype Section and Point and the Dajiang section (an isolated carbonate platform). We also measured the Mo contents of the carbonate phases, oxides, and sulfides of the carbonate samples via sequential extraction to investigate the samples' Mo-bearing minerals. In the Meishan section, from Bed 23 to the middle of Bed 24, the δ98/95Mocorr.Al values decrease slowly from +0.89‰ to +0.35‰, while from the middle of Bed 24 to Bed 25, the δ98/95Mocorr.Al values abruptly increase from +0.35‰ to +1.78‰. In the Dajiang section, samples below the mass extinction boundary have relatively low δ98/95Mocorr.Al values with a narrow variation range (−0.05‰ to +0.46‰; average + 0.19‰); the δ98/95Mocorr.Al values of the five samples directly above the extinction boundary increase abruptly (vary from +1.38‰ to +1.63‰; average of +1.53‰), and the δ98/95Mocorr.Al values of other samples above the mass extinction boundary fluctuate slightly before returning to pre-extinction values. The results of the sequential extraction procedure indicate that carbonate-phase Mo accounts for a small portion of the total Mo (average of 13.6 and 18.4 wt% for the Meishan and Dajiang sections, respectively), oxidized and sulfided Mo are the dominant forms in the carbonate samples. Moreover, the carbonate samples with high δ98/95Mo values tend to have high contents of sulfided Mo. We suggest that marine carbonate sediments record paleo-ocean Mo isotopic signals by a mechanism similar to that of other open-ocean sediments (e.g., shales): higher δ98/95Mo values in the sediments indicate a more reducing sedimentary environment. Based on this assumption, the δ98/95Mo values of the studied sections indicate that during the Permian–Triassic transition, oceanic anoxia coincided with or slightly predated the mass extinction, and the ocean anoxic event lasted for a relatively short time, likely less than 0.061 Myr.

The Sichuan–Yunnan–Guizhou metallogenic province in southwest China is one of the most important low-temperature metallogenic domains in the country, and more than 400 Pb–Zn deposits and/or mineralization points are located in this area. The Fule deposit is better known that the other Pb–Zn deposits in the region because it is extremely highly enriched with dispersed elements, including Ge, Ga, and Cd. Based on information obtained from our previous studies, the contents of Ge and its isotopic compositions in sphalerite are investigated herein. Results show that the Ge content ranges from 60 ppm to 141.5 ppm, and δ74/70Ge values vary from −6.57‰ to 0.97‰. In this respect, −6.57‰ is the most negative Ge isotope composition value reported in any sphalerite or seafloor sulfides to date. The Cd and Ge contents in sphalerite have a good negative relationship, and it is suggested that the mechanisms of Cd and Zn substitution are responsible for the low incorporation of Ge and relate to the high Cd content (up to 3%) of the sphalerite. In addition, there is a good positive correlation between the Ge contents and δ34S values, which was likely triggered by variations of fluid temperature. In the same hand specimen, light Ge isotope is more likely to be enriched in dark sphalerite rather than light sphalerite, similarly to Cd isotope distribution in dark and light-colored sphalerite. In addition, Cd and Ge isotope compositions, measured in an ore profile from SBFL22 to SBFL26, show a good positive relationship, suggesting that the fractionation mechanisms between Cd and Ge isotopes may be similar and they were controlled by kinetic fractionation during sphalerite precipitation. Based upon previous limited studies, we conclude that Ge in the Fule deposit is derived from mixing sources and sediment is likely the dominant one.

Cadmium (Cd) isotopic compositions in seawater are important parameters for tracing the biogeochemical cycling of Cd in modern oceans and may be used as a direct proxy for nutrient utilization by phytoplankton and an indirect proxy for primary productivity. In this study, we measured the stable Cd isotope ratios (δ114Cd) of marine sedimentary carbonates from the Meishan section in Changxing County of Zhejiang Province, South China, the Global Stratotype Section and Point (GSSP) of the Permian-Triassic Boundary (PTB). The results suggest that the inferred marine primary productivity recorded in the marine carbonates from the Late Permian (i.e., before the mass extinction) was high and relatively stable (the δ114/110Cd values of carbonates range from +0.31‰ to +0.60‰; after correction for salinity-controlled fractionation into inorganic calcite, the δ114/110Cd values of palaeo-seawater range from +0.47‰ to +0.79‰). During the mass extinctions, the δ114/110Cd values of carbonates abruptly decreased at the beginning of each episode of mass extinction, suggesting that the primary productivity of the palaeo-ocean declined before each episode of extinction events at the PTB. We suggest that the mass extinction events at the PTB in the Meishan section could be a ripple effect due to the destruction of primary producers at the base of the food chain in the palaeo-ocean ecosystem.

Although molybdenum (Mo) isotopic compositions of carbonatites, phosphorites and siliceous rocks can be used as proxies to reconstruct conditions of marine chemistry throughout geological time, only a few studies have, so far, analysed these low-Mo (ng g−1) geological samples because of analytical limitations. In this study, a low blank, high yield two-column Mo purification procedure was developed for various low-Mo geological samples. The sample-standard bracketing (SSB) and double-spike (DS) methods for mass fractionation correction were used to compare the accuracy of Mo isotope ratio measurements. Six Mo reference materials, NIST SRM 3134 Mo, JMC Mo, SC+1 and SC−1 (eluted fractions of Sigma-Aldrich Mo), CRM GSR-6 limestone and USGS BCR-2 basalt, were used as quality controls. The results showed that the Mo delta values of reference materials and geological samples corrected by the SSB and DS methods were, within error, consistent with each other and the DS method was the method of choice for samples with

High-precision cadmium (Cd) isotope compositions are reported for sphalerite, galena, and smithsonite from the Fule Zn–Pb–Cd deposit, a typical Mississippi Valley-type deposit in Southwest China. Dark sphalerite has lighter δ114/110Cd values (0.06 to 0.46 ‰) than light sphalerite (0.43 to 0.70 ‰), and the Cd in galena is primarily in the form of sphalerite micro-inclusions with δ114/110Cd of −0.35 to 0.39 ‰. From early to late stages, δ114/110Cd values of smithsonite regularly increase from 0.19 to 0.42 ‰, whereas Cd/Zn ratios decrease from 252 to 136; the δ114/110Cd variation pattern of supergene smithsonite reflects kinetic Rayleigh fractionation during low-temperature processes. From the bottom to the top of the orebody, the dark sphalerite has different patterns in δ114/110Cd values, Cd/Zn ratios, δ34S values, and Fe concentrations compared to the light sphalerite, indicating that dark and light sphalerite formed by different processes. The varying patterns of δ144/110Cd values and Cd/Zn ratios within light sphalerite are similar to those of layered smithsonite, and the δ144/110Cd values have a positive correlation with δ34S values, indicating that Cd isotope fractionation in the light sphalerite was due to kinetic Rayleigh fractionation. Instead, in dark sphalerite, the δ144/110Cd values have a negative correlation with δ34S values and a positive correlation with the Cd/Zn ratio. Thus, it can be concluded that dark sphalerite could be modeled in terms of two-component mixing (basement fluid and host-rock fluid), which is in agreement with previous explanations for the negative correlation between δ66Zn and δ34S in some typical Zn–Pb deposits. We propose that the significant variation in Cd isotope composition observed in the Fule Zn–Pb–Cd deposit confirms that Cd isotopes can be used for tracing fluid evolution and ore formation.

The Sichuan–Yunnan–Guizhou (SYG) area is a world-class Zn-Pb metallogenic zone and contains over four hundred of carbonate-hosted hydrothermal Zn-Pb deposits, six of which are super large-scale deposits with significant sources of Cd, Ge, and Ag, including the Huize, Wusihe, Xiaoshifang, Maozu, Tianbaoshan and Daliangzi deposits. Although previous studies focused fully on these deposits, the ore genesis of which are still in controversial. Interestedly, four of those super large scale deposits are hosted in the Ediacaran Dengying Formation, including the Maozu, Wusihe, Tianbaoshan and Daliangzi deposits. Based upon previous studies, we investigate the extent, causes and consequences of Zn and Pb isotope signatures at hand specimen scale and ore genesis of the Daliangzi and Tianbaoshan deposits, associated with published data for the Wusihe deposit. Lead isotope ratios, coupled with published data, demonstrate that Pb in the studied deposits was predominantly derived from two components: basements and sedimentary rocks. Meanwhile, a strong positive linear correlation between δ66Zn and δ34SCDT values was observed in hand specimen D-2084, suggesting the variations may be resulted by fluid mixing. Furthuremore, the Zn isotope and Cd/Zn dataset from the Tianbaoshan, Daliangzi and Wusihe deposits defines a logarithmic curve (R2 = 0.82), which, to our knowledege, is firstly reported and lies between two indentified components: a low Cd/Zn end-member with high δ66Zn values and a high Cd/Zn end-member with low δ66Zn values. Based upon previous studies, we suggest that Zn and Pb in the Wusihe and Tianbaoshan deposits were predominantly derived from basements and Ediacaran sediments; in contrast, Zn and Pb in the Daliangzi deposit were predominantly derived from Ediacaran sediments and upper sedimentary rocks, but we cannot rule out metal contributions of the basements. Furthermore, we suggest that fluid mixing is more propreate to better explain Zn isotope signatures in the studied deposits. In summary, Zn and Pb isotope ratios reflect similar ore genesis and metal sources of the Daliangzi, Tianbaoshan and Wusihe Zn-Pb deposits in the SYG area. The application to the studied deposits with the discovery of Zn, S and Pb isotope compositions for sulfides indicates the potential of Zn isotope, combined with Cd/Zn raito, as new geochemical tracers, which may be useful for distinguishing the metal sources in large hydrothermal systems as suggested previously.

In order to better understand chlorine isotopic variations during brine evolution, experiments were designed to determine the changes in the chlorine isotope composition (δ37Cl value) during evaporations of solutions containing NaCl, KCl and MgCl2⋅6H2O at 28 ± 2 °C. Three evaporation experiments were conducted in a clean environment. The precipitate and brine samples were collected during the evaporation, and the chlorine isotopic ratios of the samples were determined using an improved thermal ionisation mass spectrometry procedure based on Cs2Cl+ ion measurement. The results are as follows: the mean fractionation factors of the three solutions are αNa = 1.00055, αK = 1.00025, and αMg = 1.00012, respectively, where αNa, αK and αMg are the fractionation factors between salts (NaCl, KCl and MgCl2⋅6H2O) and saturated solutions. The results showed that the δ37Cl values of precipitate and coexisting brine samples decrease during the precipitation of single chloride minerals. The residual brine was a 35Cl reservoir for different single chloride solutions. New chlorine isotopic evolution curve during seawater evaporation were also calculated. The results indicated that during the primary precipitation stage of halite, δ37Cl decreased continuously, and the most important thing is that this trend continues during the final stages when Mg–salts begin to precipitate.

The Lanping basin is a significant Pb–Zn–Cu–Ag mineralization belt of the Sanjiang Tethyan metallogenic province in China. Over 100 thrust-controlled, sediment-hosted, Himalayan base metal deposits have been discovered in this basin, including the largest sandstone-hosted Pb–Zn deposit in the world (Jinding), and several Cu ± Ag ± Co deposits (Baiyangping, Baiyangchang and Jinman). These deposits, with total reserves of over 16.0 Mt Pb + Zn, 0.6 Mt Cu, and 7000 t Ag, are mainly hosted in Meso-Cenozoic mottled clastic rocks, and strictly controlled by two Cenozoic thrust systems developed in the western and eastern segments of the Lanping basin. To define the metallogenic history of the study area, we dated nine calcite samples associated with copper sulfides from the Jinman Cu deposit by the Sm–Nd method and five molybdenite samples from the Liancheng Cu–Mo deposit by the Re–Os method. The calcite Sm–Nd age for the Jinman deposit (58 ± 5 Ma) and the molybdenite Re–Os age for the Liancheng deposit (48 ± 2 Ma), together with previously published chronological data, demonstrate (1) the Cu–Ag mineralization in the western Lanping basin mainly occurred in three episodes (i.e., ∼56–54, 51–48, and 31–29 Ma), corresponding to the main- and late-collisional stages of the Indo–Asian orogeny; and (2) the Pb–Zn–Ag (±Cu) mineralization in the eastern Lanping basin lacked precise and direct dating, however, the apatite fission track ages of several representative deposits (21 ± 4 Ma to 32 ± 5 Ma) may offer some constraints on the mineralization age.

National Basic Research Program of China [2009CB421005]; Chinese Academy of Sciences for Key Topics in Innovation Engineering [KZCX2-YW-Q04-01]

Hexagonal boron nitride (h-BN) micromeshes (defined as “BNMM”) of high crystallinity (with diameters of up to 100 μm and pore size of 2.5 μm on average) have been synthesized by using Li2B4O7, Mg and NaN3 in stainless steel autoclaves at 500 °C for 12 h. Through tuning the experimental parameters, BN materials with various morphologies (such as nanospheres or thin films) could also be selectively prepared. The thermal gravimetric analysis (TGA) results of the as-grown BNMM reveal their high thermal stability not only in ambient atmosphere but also in nitrogen atmosphere below 1050 °C. The BNMM were also analyzed by thermomechanical analysis (TMA) in nitrogen atmosphere. The as-obtained BNMM were applied for oxidation of benzyl alcohol and also functionalized by monodispersed Ag particles with potential applications as catalysts for carbon monoxide (CO) oxidation. The results indicate that the BNMM have 37.85% catalytic activity and nearly 100% selectivity in translating benzyl alcohol to benzaldehyde, and the Ag/BNMM composites have catalytic activity for 70.50% of carbon monoxide oxidation.

Lead-zinc deposits are often difficult to classify because clear criteria are lacking. In recent years, new tools, such as Cd and Zn isotopes, have been used to better understand the ore-formation processes and to classify Pb-Zn deposits. Herein, we investigate Cd concentrations, Cd isotope systematics and Zn/Cd ratios in sphalerite from nine Pb-Zn deposits divided into high-temperature systems (e.g., porphyry), low-temperature systems (e.g., Mississippi Valley type [MVT]) and exhalative systems (e.g., sedimentary exhalative [SEDEX]). Our results showed little evidence of fractionation in the high-temperature systems. In the low-temperature systems, Cd concentrations were the highest, but were also highly variable, a result consistent with the higher fractionation of Cd at low temperatures. The δ114/110Cd values in low-temperature systems were enriched in heavier isotopes (mean of 0.32 ± 0.31‰). Exhalative systems had the lowest Cd concentrations, with a mean δ114/110Cd value of 0.12 ± 0.50‰. We thus conclude that different ore-formation systems result in different characteristic Cd concentrations and fraction levels and that low-temperature processes lead to the most significant fractionation of Cd. Therefore, Cd distribution and isotopic studies can support better understanding of the geochemistry of ore-formation processes and the classification of Pb-Zn deposits.

Molybdenum (Mo) isotopic data from early Cambrian formations in southern China demonstrate the importance of non-euxinic sediments as a promising archive for coeval seawater Mo records. For the first time, in analogue to noneuxinic, nonskeletal carbonates, we report that the pristine phosphorites also can preserve the ambient fluid, which make the pristine phosphorites a new potential fingerprinting tool to record the coeval paleoseawater. Pristine phosphorite and dolomite samples of two early Cambrian formations in southern China suggest that early Cambrian seawater may have had δ 97/95 Mo values of at least 1.4‰, similar to modern oceans. Low δ 97/95 Mo (as low as −0.5‰) values were obtained from reworked phosphorite, but evidence suggests that these are reflecting Mo related to Fe oxyhydroxide minerals rather than the coeval seawater. In contrast, late Precambrian dolomite just below the transition to the Cambrian would indicate a δ 97/95 Mo of coeval seawater slightly heavier than that of the Mesoproterozoic (0.9‰–1‰ versus 0.8‰), suggesting that oceanic circulation patterns may have been thoroughly reorganized by that time, and may have triggered biological diversification from the Ediacaran to the early Cambrian.

Magnetic, transport and magnetotransport properties of A-type antiferromagnetic Nd(0.45)Sr(0.55)MnO(3) films with different thicknesses grown on SrTiO(3) (100) have been investigated before and after ex situ annealing processes. In contrast to the bulk system, all as-deposited films exhibit insulating behaviour due to the local Jahn-Teller distortion induced by in-plane tensile strain. The annealing process only induces an insulator-metal transition in ultrathin film with a thickness of 16 nm, resulting in metallically conductive behaviour and the transport properties similar to those of the bulk. This may be ascribed to the cooperative influences of changes in oxygen content and strain-induced d(x2-y2)-type orbital order owing to the annealing process. When a magnetic field of 70 kOe is applied, the metallic behaviour appears in a broad temperature range in the annealed film with 16 nm thickness and, the metallic behaviour is also observed in the annealed film with 32 nm thickness. The different effects of the external magnetic field on the transport properties of as-deposited and annealed Nd(0.45)Sr(0.55)MnO(3) films are discussed. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Over the past decade, as one of nontraditional stable isotopes, Mo isotope has developed rapidly and now become an important geochemical proxy to trace paleo-oceanic and atmospheric evolution through geological history. In this paper, Early Cambrian formations in southern China are investigated. The results indicate that δ97/95Mo values of Early Cambrian seawater may have been larger than 1.4%, values that are close to those of the modern ocean. It was also found that the variations in Mo isotope composition in samples from two sections (Huangjiawan and Gezhongwu in Guizhou) were closely related to changes in redox conditions during sedimentary processes. Combining our results with existing data, a preliminary model for the evolution of seawater Mo isotope composition through geological history was provided. It indicated that Mo isotopic variations were generally consistent with the evolution of atmospheric oxygen.

The magnetic and electrical transport behaviors of Cr3(Se1−xTex)4 compounds are investigated. A transition from antiferromagnetism to ferromagnetism occurs at x = 0.2 in this system and abnormal changes of the lattice parameter a and angle β take place around the magnetic transition point. When Se is partially substituted by Te, a minimum of resistivity (ρmin) is observed in the temperature dependence of resistivity. The temperature Tmin, where the minimum ρmin is, increases with Te concentration. The minimum in resistivity at Tmin is ascribed to the competition between a diminishing resistivity due to domain ordering and a rising resistivity due to disordered frozen spins in each domain. The electrical transport behavior below Tmin is described by hopping conductivity in terms of variable range—hopping. An external magnetic field affects strongly the resistivity of the Cr3(Se1−xTex)4 compounds, which shifts the magnetic ordering temperature TMO to higher temperature and Tmin to lower temperature. Subsequently, a negative magnetoresistance is found in this system.

International audience; In practice, stable Cd isotope ratios are being applied to trace pollution sources in the natural environment. However, Cd isotope fractionation during weathering processes is not yet fully understood. We investigated Cd isotope fractionation of PbZn ore in leaching experiments and in the environment under natural weathering processes. Our leaching experiments demonstrated that the leachate was enriched with heavy Cd isotopes, relative to initial and residual samples (Δ114/110Cdleachate − initial state = 0.40–0.50‰, Δ114/110Cdleachate − residual state = 0.36–0.53‰). For natural samples, δ114/110Cd values of stream sediments were higher than those of the corresponding soil samples collected from the riverbank, Δ114/110Cdstream sediment − soil can be up to 0.50‰. This observation is consistent with our leaching experiments, which indicate significant Cd isotope fractionation during natural weathering processes. Therefore, natural contributions should be considered when using Cd isotopes to trace anthropogenic pollution in water and sediment systems.

Magnetic, electronic transport and magneto-transport behaviours of (Co1-xMnx)(2)P (0.55

Magnetic, magneto-transport properties and electronic specific heat coefficient of the Mn2Sb0.88Ge0.12 compound have been studied. A metamagnetic transition from antiferromagnetic to ferrimagnetic, which is induced by an external field, is accompanied with a large negative magnetoresistance (MR) effect. The MR ratio at room temperature is ?11% at a magnetic field of 5?T. The field dependence of the MR ratio and the magnetization of the Mn2Sb0.88Ge0.12 compound, together with the electronic specific heat coefficients, confirm that the negative MR effect is originated from the reconstruction of Fermi surface, due to the collapse of the super-zone gap after the metamagnetic transition.

The subsolidus phase relations of the ternary system, Li2O–CaO–B2O3, are investigated by the powder X-ray diffraction method. The system can be divided into 19 three-phase regions and three two-phase regions based on the phase identifications of 54 ternary samples. There exist 12 binary compounds and two ternary compounds. Two new compounds with composition close to LiCaBO3 and Li6CaB3O8.5 are identified. They both have an orthorhombic structure with different lattice parameters: a=13.2537(6) A, b=6.1799(3) A, c=6.0746(3) A for LiCaBO3, and a=9.2440(6) A, b=8.0999(4) A, c=3.4839(3) A for Li6CaB3O8.5. Moreover, a compound with a composition close to 0.83LiO0.5·0.005CaO·0.165BO1.5 has been observed or confirmed in this system. We believe it is the high temperature phase of Li3BO3.

International audience; Systematic variations in the Cd and Pb isotope ratios in polluted topsoils surrounding the Jinding Pb–Zn mine in China were measured so that the sources of the metals could be traced. The average δ114/110Cd value and 206Pb/207Pb isotope ratio in background soils from the region were +0.41‰ and 1.1902, respectively, whereas the contaminated soil samples had different values, with the δ114/110Cd values varying between −0.59‰ and +0.33‰ and the 206Pb/207Pb isotope ratios varying between 1.1764 and 1.1896. We also measured the Cd and Pb isotopic compositions in oxide ores, sulfide ores, and slags, and found that binary mixing between ores and background soils could explain almost all of the variations in the Cd and Pb isotope ratios in the contaminated soils. This suggests that Cd and Pb pollution in the soils was mainly caused by the deposition of dust emitted during anthropogenic activities (mining and refining). The Pb and Cd isotope ratios clearly showed that contamination in soils in the northeastern part of the area was caused by surface mines and zinc smelters and their slagheaps, while contamination in soils in the southwestern part of the area also came from tailing ponds and underground mines. The main area of soil polluted by dust from Pb–Zn mining processes roughly extended for up to 5 km from the mine itself.

International audience; The Neoproterozoic–Cambrian transition was a key time interval in the history of the Earth, especially for variations in oceanic and atmospheric chemical composition. However, two conflicting views exist concerning the nature of ocean chemistry across the Precambrian–Cambrian boundary. Abundant geochemical evidence suggests that oceanic basins were fully oxygenated by the late Ediacaran, while other studies provide seemingly conflicting evidence for anoxic deep waters, with ferruginous conditions [Fe(II)-enriched] persisting into the Cambrian. Here, two early Cambrian sedimentary platform and shelf-slope sections in South China were investigated to trace early Cambrian ocean chemistry from Mo isotopes. The results reveal that early Cambrian sediments deposited under oxic to anoxic/euxinic conditions have δ98/95Mo values ranging from −0.28‰ to 2.29‰, which suggests that early Cambrian seawater may have had δ98/95Mo values of at least 2.29‰, similar to modern oceans. The heaviest and relatively homogeneous δ98/95Mo values were recorded in siltstone samples formed under completely oxic conditions, which is considered that Mn oxide-free shuttling was responsible for such heavy δ98/95Mo value. Further, combined with Fe species data and the accumulation extent of Mo and U, the variation of δ98/95Mo values in the two studied sections demonstrate a redox-stratified ocean with completely oxic shallow water and predominantly anoxic (even euxinic) deeper water having developed early on, which eventually became completely oxygenated. This suggests that oceanic circulation at the time became reorganized, and such changes in oceanic chemistry may have been responsible for triggering the “Cambrian Explosion” of biological diversity.

International audience; Selenium (Se) isotopes can yield substantial isotopic fractionation (up to 20‰) confirmed by experiments and field investigations, depending on various biotic or abiotic redox transformations. Therefore, it is expected that redox changes in the ancient oceans would induce significant isotopic fractionation, and the Se isotopic signatures recorded in old sedimentary rocks might provide new insight into how the redox state of the ancient ocean has evolved. However, previous studies have shown that Se is slightly enriched in the lighter isotope relative to the bulk earth values in most deposited conditions (oxic, anoxic, and even sulfidic). Here, our results reveal that ferruginous conditions can result in excessive accumulation of Se in sediments with an elevated Se/S ratio and significant isotope fractionation (about 6‰), which leads us to propose that Se isotopes are an appropriate geochemical proxy to trace unique oceanic conditions over times. Accordingly, Se isotopic variations measured in three Early Cambrian formations in southern China suggest that anoxic waters with ferruginous conditions must have been present in early Cambrian ocean along the eastern margin of the Yangtze platform, and oceanic circulation was stepwise reorganized. This may have triggered biological diversification from the Ediacaran to the Early Cambrian.

The recent discovery of perpendicular magnetic anisotropy (PMA) at the CoFeB/MgO interface has accelerated the development of next generation high-density non-volatile memories by utilizing perpendicular magnetic tunnel junctions (p-MTJs). However, the insufficient interfacial PMA in the typical Ta/CoFeB/MgO system will not only complicate the p-MTJ optimization, but also limit the device density scalability. Moreover, the rapid decreases of PMA in Ta/CoFeB/MgO films with annealing temperature higher than 300°C will make the compatibility with CMOS integrated circuits a big problem. By replacing the Ta buffer layer with a thin Mo film, we have increased the PMA in the Ta/CoFeB/MgO structure by 20%. More importantly, the thermal stability of the perpendicularly magnetized (001)CoFeB/MgO films is greatly increased from 300°C to 425°C, making the Mo/CoFeB/MgO films attractive for a practical p-MTJ application.

The AlxGa1-xN alloy nanocrystalline solids with x=0-1 were successfully synthesized through ammono-thermal routes. The alloys were formed only in the form of nanocrystalline solids, and not in other forms, i.e. of nano-powders or micro-crystals. The Raman scattering spectra of the alloy solids within the whole range of x values were investigated. One-mode-type behavior of A1(LO) phonon and two-mode-type behavior of E2 phonon were clearly demonstrated. The intensity of E2(GaN) mode decreases as x increases up to x=0.8. For A1(TO), A1(LO), and E2(GaN) phonon modes, the linewidth behaviors follow a pattern that exhibits a maximum at composition x=0.5.

We report the isotopic composition of five molybdenum (Mo) standard reference solutions and four fractions from one of these solutions eluted through anion resin column relative to a sixth reference solution. The reference solutions were National Institute of Standards and Technology (NIST) SRM 3134 (lot#891307), Johnson Matthey Specpure (JMC)-Mo Sie (lot #602332B), JMC-Mo Wen (lot#13989C), Merck (lot#170334), Sigma-Aldrich (lot#207306) and Prolabo. Measurements were conducted using Isoprobe multi collector inductively coupled plasma mass spectrometer (MC-ICP-MS) at the Centre de Recherches Petrographiques et Geochimiques (France) and Nu Plasma MC-ICP-MS at either the Ecole Normale Superieure de Lyon (France) or the Laboratory of Isotope Geology in the Ministry of Land and Resources (China). The sample-standard bracketing method was employed to correct the mass bias for Mo isotopes during instrumental measurement. Except for the Merck Mo solution, all the Mo solutions were identical in isotopic composition within error. Although the JMC Mo solution has been used as the internal reference material by various groups, uncertainty may still occur with different lot numbers and availability might be limited. Here, we propose the NIST 3134 Mo solution as a new candidate for delta zero reference material, used for reporting Mo isotopic composition of natural samples. Isotopic compositions for four eluted fractions of the Sigma-Aldrich Mo solution were 2.18‰, 0.98‰, −1.10‰ and −1.95‰ for δ97/95Mo relative to the NIST Mo standard. These values span the range of reported isotopic compositions for natural terrestrial and experimental samples (approximately −0.5‰ to 1.6‰ for δ97/95Mo). We propose these eluted fractions to be used as a secondary reference for Mo isotope measurements. Mo solutions are available at CRPG upon request.

Nanoscale nitrides, borides and carbides are a fascinating type of materials, which have aroused tremendous and continuous research interest for decades owing to their special mechanical, electrical, optical, photoelectronic, catalytic properties and widespread uses. In this feature article, recent developments and breakthroughs in the synthesis, properties and applications of nanometre scale nitrides (BN, Si(3)N(4), GaN, noble nitrides), borides (LnB(6), LnB(2), Fe(3)BO(5), LiMBO(3)) and carbides (carbon, SiC, TiC, NbC, WC) were briefly reviewed in sequence of their different dimensions (1D, 2D and 3D). In particular, our latest advances in the "autoclave route" fabrication of nanoscale nitrides, borides, and carbides were highlighted. The challenges, issues and perspectives of the synthetic methodologies and potential applications concerning the above-mentioned materials were also briefly discussed.

A large magnetoresistance (MR) is observed in a double helical CoMnSi compound over the entire temperature region from 5 K to the maximum measuring temperature of 380 K, with the largest MR ratio of -18.3% at 245 K and the smallest MR ratio of -5.5% at 85 K at 5 T. This phenomenon is ascribed to two different mechanisms in different temperature regions. The suppressed spin fluctuations of the double helical structure are responsible for the MR below 110 K. However, in consideration of the natural multilayer superstructure of CoMnSi, the larger MR above 110 K is ascribed to the decrease in K-space restrictions when the change in magnetic structure from double helical order to fan order occurs.