Elemental analyzer-isotope ratio mass spectrometry (EA-IRMS) is the most popular method for the measurement of sulfur isotopes in various samples including sulfide, sulfate and organosulfur compounds. The precision of similar to +/- 0.3 parts per thousand (1 sigma) can be achieved for samples with similar to 100 mu g S. However, for samples with low sulfur content, or organic matter in particular (e.g. animal bone collagen), the precise and accurate sulfur isotope analysis remains challenging, with typical delta S-34 precision ranging from +/- 0.3 parts per thousand to +/- 1 parts per thousand. In this study, we applied an improved EA-IRMS with a custom-built cryofocus device for the analysis of sulfur isotopes in organic matter. After sample combustion, all the product gases were transferred into a cold trap by a fast helium flow (100 mL/min). SO2 was then separated from other gases through a packed gas chromatographic (GC) column at lower flow rate (10 mL/min). The sample size of this method is similar to 300 nmol S, which is only 1/10 of that required by the conventional method. Lowered sample size allows fully oxygen isotope homogenization of sample SO2 with oxygen buffers during combustion. With this method, the delta S-34 precision from the measurement of organosulfur standards was better than +/- 0.3 parts per thousand.

Zircon U-Pb and Hf-O isotope compositions preserve valuable records of the formation and evolution of geological processes. To obtain accurate and precise zircon geochronology and Hf-O isotope ratios using in situ techniques, matrix-matched reference materials are essential. In this study, we introduce a new potential zircon reference material, the Perilla megacryst, which has homogeneous U-Pb ages and Hf-O isotopic compositions, as demonstrated by multiple analytical techniques. The chemical abrasion isotope dilution thermal ionization mass spectrometry (CA-ID-TIMS) method presents a weighted mean 206Pb/238U age of 42.40 f 0.06 Ma (2 sigma, n = 8). Further examination of the heterogeneity of U-Pb age of the Perilla zircon megacryst was conducted by secondary ion mass spectrometry (SIMS) and laser ablation (multiple collector) inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) among six laboratories. We obtained mean 206Pb/238U ages of 42.6 f 0.3 Ma (2 sigma, n = 23) using SIMS (SHRIMP), 42.6 f 0.3 Ma (2 sigma, n = 20) using SIMS (CAMECA), 42.2 f 0.3 Ma (2 sigma, n = 14) using LA-MC-ICP-MS, and 42.6 f 0.1 Ma (2 sigma, n = 207) using LA-Q-ICP-MS, respectively. The Hf isotopic compositions of Perilla were evaluated using LA-MC-ICP-MS, yielding a uniform mean 176Hf/177Hf ratio of 0.282565 f 0.000040 (2SD, n = 149) among four laboratories. Oxygen isotope analysis using laser fluorination yielded results consistent with SIMS data, providing a recommended mean delta 18O value of 6.53 f 0.34 parts per thousand (2SD, n = 5). The reproducibility of results obtained by multiple analytical techniques across different laboratories demonstrate the homogeneity of U-Pb ages and Hf-O isotopic compositions of the Perilla zircon megacryst. Based on these results, we propose the Perilla zircon megacryst as a potential secondary reference material for external monitoring or analytical validation of Cenozoic U-Pb geochronology and Hf-O isotopic measurements.

Alunite is a common sulphur-rich mineral in high-sulphidation epithermal deposits and can occasionally form independent alunite deposits, demonstrating a close spatial relationship with epithermal mineralization. In situ sulphur isotope analysis of alunite offers valuable insights into detailed mineralization processes. In this study, using LA-MC-ICP-MS, we evaluated matrix effects, spectral interferences and instrumental parameters that influence measurement accuracy, leading to the development of a high-precision microanalytical method for sulphur isotopes in alunite. In order to verify the results of the in situ method, LA-MC-ICP-MS measurements were compared with GS-IRMS analyses on two natural alunite samples: MT-1 and MTS-1. The internal precision of the in situ delta 3 4S measurement was better than 0.22 parts per thousand when the 32S signal exceeded 5 V. The long-term reproducibility for these two samples was better than 0.33 parts per thousand (2SD). These results suggest that either of the two materials can serve as an in situ sulphur isotope standard. Based on GS-IRMS results, recommended delta 3 4S values for MT-1 and MTS-1 are 9.37 parts per thousand +/- 0.13 parts per thousand and 3.42 parts per thousand +/- 0.31 parts per thousand, respectively.

Stibnite is the principal sulfide mineral and the most important ore mineral in antimony deposits worldwide. In situ S and Sb isotope analyses of stibnite are crucial for investigating the genesis of antimony deposits and for deciphering detailed mineralization processes. To obtain reliable in-situ isotopic data, matrix-matched reference materials are essential for correcting instrumental mass fractionation. In this study, two natural stibnite samples (WX34-80 and KKY) were characterized on the basis of their elemental and isotopic compositions. The results demonstrate that both samples are homogeneous in terms of S and Sb contents, as well as their isotopic signatures, and exhibit significantly distinct sulfur isotopic compositions, rendering them highly suitable reference standards for in situ Sb and S isotope analyse using LA-MC-ICP-MS. Based on IRMS measurements, the recommended 834SV-CDT values are-2.17 +/- 0.29 parts per thousand (2SD, n = 18) for WX34-80 and 10.63 +/- 0.38%o (2SD, n = 18) for KKY. Correspondingly, SN-MC-ICP-MS analyses yield recommended delta Sb-123(spex) values of-0.33 +/- 0.07 parts per thousand (2SD, n = 8) for WX34-80 and-0.29 +/- 0.05%o (2SD, n = 8) for KKY.

Iron oxide-apatite (IOA) deposit is an important source of Fe ores, characterized by a huge amount of Fe oxide ores associated with byproducts of considerable critical mineral resources. The Ningwu ore district is a well-defined IOA ore district in eastern China, containing more than 30 IOA deposits. Four volcanic cycles occurred over approximately 10 Ma (134-126 Ma), forming two types of primary intrusive rocks (i.e., diorite porphyry and granitic rocks). The IOA deposit is typically associated with the diorite porphyry that was intruded at the end of the second volcanic cycle. In this study, the trace element abundances of zircon grains from syn-mineralization intrusive rocks and post-mineralization intrusions are distinguishable and record magmatic transitions during multistage volcanic activity. The zircon trace element abundances imply that the syn-mineralization magmas had greater oxygen fugacity (Delta FMQ > +0.5), higher water content (Eu/Eu* > 0.35, Dy/Yb < 0.21), elevated magma evolution (Zr/Hf < 50), and a high proportion of enriched mantle magma sources that are related to oceanic subduction, which significantly differed from those of the post-mineralization intrusions, reflecting a magmatic transition during multistage volcanic activity. They could also be valuable tools for identifying potential fertile magmas of IOA deposits.

Iron skarn deposits represent significant sources of high-grade Fe ores, although the mechanisms underlying their efficient enrichment in Fe are not yet fully understood. To investigate the enrichment processes of Fe in the skarn system, texture and geochemistry of magnetite from the Jinshandian Fe deposit located in eastern China were analyzed. Disseminated, friable, and massive ore types are identified at Jinshandian. The friable ore is characterized by loose structure, with minimal or absent cementation minerals interspersed among subhedral to euhedral magnetite crystals. The magnetite at Jinshandian displays significant textural heterogeneity, highlighted by macro- and nanoscale inclusions. Overgrowth and dissolution-reprecipitation (DRP) textures were locally recorded in magnetite. Magnetite grains contains low concentrations of Ti and V, alongside relatively higher Mg, Si, and (Ca+) Al+Mn. Most magnetite grains fall within the skarn field when plotted on geochemical discriminant diagrams. These findings, in conjunction with robust geological evidence, suggest that the Jinshandian deposit originates from intense water-rock interactions. The trace elements in magnetite from the friable ore exhibit similarities to those in disseminated and massive ores, indicating that the friable ore likely formed through a structural softening process that removed soluble cementing minerals (e.g., anhydrite/gypsum and calcite) from the disseminated or massive ore. A comparative analysis of Fe skarn deposits in the Edong district suggests that multiple mechanisms, including accumulation, structural softening, DRP, and superposition processes, may have significantly contributed to the formation of high-grade Fe ores within the skarn system, despite the primary controlling factors varying from one deposit to another.

The Nong Sua Sn deposit in Thailand is a typical vein-type deposit with three generations of tourmaline (Tur I, II and III). Tur I as disseminations (Tur Ia) or nodules (Tur Ib) in the pegmatite-aplite stock crystallized from the late-magmatic stage. Tur II coexists with quartz in a complex vein system within the stock and is of magmatic-hydrothermal origin. Tur III occurs in cassiterite-tourmaline veins within contact zones between the quartz-tourmaline vein and metasedimentary country rocks (Tur IIIa) or as smaller cassiterite-tourmaline veinlets (Tur IIIb). Both Tur I and Tur II have similar trends in chemical composition with δ11B values from -15.1 ‰ to -11.5 ‰ and from -15.8 ‰ to -11.7 ‰, respectively, which can be explained by a Rayleigh isotope fractionation. The similarity suggests a common magmatic-hydrothermal system from which tourmaline crystallized. Tur III has lower Sn concentrations (22 to 143 ppm) and higher Fe3+/(Fe2+ + Fe3+) ratios than Tur I, Tur II, and thus crystallized under more oxidized conditions. Tur III has relatively high δ11B values from -13.3 ‰ to -10.6 ‰ with corresponding δ11Bfluid values from -9.1‰ to -6.4‰ for Tur III and from -14.0 ‰ to -9.0 ‰ for Tur I and Tur II. Thus, oxidizing modified meteoric water with relatively high δ11B values was added to the magmatic-hydrothermal system from which the deposit formed. Precipitation of cassiterite was likely caused by the change of redox state related to fluid mixing. Our study provides new important insights about the evolution of hydrothermal fluids from the pre-ore stages to ore genesis of Sn deposits. Such an evolution of the magmatic-hydrothermal system may be a common process for Sn deposits in the Southeast Tin Province (SEAT) and elsewhere.

Iron oxide-apatite (IOA) deposits are important for the global supply of iron resources. Currently, there is considerable debate regarding the evolution of their mineralization mechanisms. The Heshangqiao iron deposit is a significant IOA deposit situated within the Ningwu ore district of the Middle-Lower Yangtze River Metallogenic Belt in China. This deposit exhibits distinct characteristics of multi-stage mineralization, forming disseminated ores, brecciated ores, and vein-type ores, from early to late stages. This study undertook a systematic elemental analysis of the magnetite and hematite from three mineralization stages of the Heshangqiao deposit. In the three mineralization stages of the Heshangqiao deposit, the elemental genesis indicators of ore genesis suggest that the hematite and magnetite both have magmatic hydrothermal genesis, characterized by high Ti and low Mg/Al and relatively high Ti and low Ni/Cr, respectively. The Cr and Sn contents of magnetite and hematite exhibit similar variation from the first to third mineralization stage, with an increase followed by a subsequent decrease. Meanwhile, the contents of V, Co, Ni, and Mn in magnetite and hematite exhibited an opposite trend, declining from the first to the second stage but eventually increasing from the second to the third stage. These changes in the genesis indicator also suggest that the multiple mineralization stages of the Heshangqiao deposit are independent of one another. The replacement of magnetite by hematite in each mineralization stage is not caused by the superposition of subsequent fluids, but rather by the residual fluid. It is noted that in the replacement the elements Cr, Co, and Ga were minimally migrated. These elements remained relatively stable and can be considered new potential discriminant indicators for the genesis of iron oxides.

Lamprophyres are rare but important rocks that can provide crucial information about deep mantle source regions and geodynamic settings. The Bangong-Nujiang collision zone was formed by the collision of the Qiangtang and Lhasa terranes and experienced intense post-collisional magmatism. However, the deep mantle processes and mechanisms involved in this magmatism remain controversial. Here, we present the first complete petrological, geochemical, and geochronological characterization of sodic lamprophyres in the northern Lhasa terrane, central Tibet, with the aim of deciphering their relationship with late Early Cretaceous magmatic flare-up events. These lamprophyres were emplaced at similar to 114 Ma. They exhibit sodic alkaline series affinities with high Na2O contents (2.17-3.52 wt%) and Na2O/K2O ratios (1.8-3.8) and are also characterized by variable MgO contents (5.0-7.9 wt%) and Mg# values (52-68); slight enrichment in LREEs ([La/Yb](N) = 4.9-5.9); relatively flat HREE patterns ([Gd/Yb](N) = 1.46-1.53); no Eu anomalies (Eu/Eu* = 0.94-1.04); and Rb, Ba, Th, U, and Pb enrichments as well as Nb and Ta depletions. The samples have relatively low initial Sr-87/Sr-86 ratios (0.70848-0.70886) and epsilon(Nd)(t) values (-3.2 - -2.4) and variable zircon epsilon(Hf)(t) values (-4.4 - +10.4). These geochemical characteristics indicate that these rocks were derived from an enriched lithospheric mantle source. However, relatively depleted Hf isotopic compositions and Ti/V (20.2-32.5) ratios are comparable to those of MORB. The calculated melting temperature ranges from 1159 to 1244 degrees C, with an average of 1183 degrees C, further supporting the involvement of a high-temperature asthenospheric component. The rapid emplacement and relatively low melting pressure (8.0-10.4 kbar) imply that they formed in an extensional setting. Therefore, we propose that the parental magma of the lamprophyres was generated by the interaction of asthenospheric and metasomatized lithospheric mantle due to slab break-off beneath the Bangong-Nujiang collision zone.

The Emeishan Large Igneous Province (ELIP) is one of the largest igneous provinces, containing some of the world’s richest mineral resources. It mainly comprises magmatic Fe-Ti-V deposits and Cu-Ni sulfide deposits, with minor subvolcanic-type Fe deposits related to mafic–ultramafic rocks. The evaporite layer is involved in the metallogenic system, yet its contribution has not been examined in detail. In this study, an integrated geological study, single-mineral S and O isotopic analysis, and in situ S isotope analysis were carried out on pyrite and magnetite from the Kuangshanliangzi (KSLZ) subvolcanic-type Fe deposit to examine the role of evaporite layers in Fe mineralization. The O isotopic values of magnetite and the S isotopic values of pyrite were abnormally high in the KSLZ deposit. This indicates that the ore-forming system of the KSLZ deposit is contaminated by 18O- and 34S-enriched evaporite layers, inferred from the Dengying Formation, which significantly increase the oxygen fugacity, sulfur fugacity, and water content of the metallogenic system via the basic–ultrabasic magma-upwelling process, thus promoting the formation of Fe ores. When the SO42− (from evaporite layers) oxidizes Fe2+ to Fe3+, the SO42− is reduced to S2−, and the ore-forming system can be changed from unsaturated sulfide to supersaturated sulfide, which also benefits the Cu-Ni sulfide deposit formation.

The host mineral forms of beryllium (Be) play an important role in determining its crystallographic characteristics and geochemical properties. The compositional features of beryllium minerals can serve as indicators of the metallogenic environment and the genesis of deposits. The Mahuaping beryllium-tungsten deposit is a typical super-large beryllium-tungsten deposit in the "Sanjiang" region of Yunnan Province. However, the origin of metallogenic materials, the metallogenic environment, and ore deposit genesis of this deposit are poorly understood. This study focuses on the beryl which is hosted in two-types mineralized wall rocks. In this paper, the main and trace compositions of beryl in two-types wall rocks of the deposit were analyzed by electron probe microanalysis (EPMA), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and polycrystalline X-ray diffraction (XRD), which used to understand the chemical composition and substitution mechanism of beryl in the two-types wall rocks, and their implications for the metallogenic environment. The results show that the beryl from both types wall rocks of the Mahuaping beryllium-tungsten deposit belongs to Na-Li beryl. In the beryl from marble, the elemental substitution mechanisms include (Na, Cs)Fe2+square Al--1(-1) and (Na, Cs)Mg2+square Al--1(-1) channel-octahedral substitution. In contrast, beryl from the low-grade metamorphic clastic rock, the elemental substitution mechanisms primarily include (Na, Cs)Li square Be--1(-1) channel-tetrahedral substitution, and (Na, Cs)Fe2+square Al--1(-1) and (Na, Cs)Mg2+square Al--1(-1) channel-octahedral substitution. The XRD analysis results further indicate that the beryl from the marble is classified as "octahedral" dominant "octahedral" beryl, while the beryl from the low-grade metamorphic clastic rock has both tetrahedral and octahedral substitutions occurring, classified it as "normal" beryl. Fe occupies the [AlO6] octahedral site, which is the main chromogenic mechanism of beryl in the beryllium-tungsten deposit in Mahuaping, responsible for the light blue-blue color. The Cs/Na and Mg/Fe values of beryl in both wall rocks indicate that the beryl in the Mahuaping beryllium-tungsten deposit is related to hydrothermal activity. The Rb-Cs content suggests that the beryl belongs to the magmatic-hydrothermal type. Finally, we proposed that the ore-forming fluid of the Mahuaping beryllium-tungsten deposit were derived from magma. The ore-bearing hydrothermal fluid has replaced the wall rock, extracting elements such as Fe, Mg and other elements, resulting in the compositional variations of beryl in different wall rocks. Our study highlights that fluid-rock interaction is one of the key factors controlling beryl precipitation in the beryllium-tungsten deposit in Mahuaping.

A natural stibnite (BJ-Snt) is recommended as a potential reference material for S isotope analysis employing laser ablation multicollector inductively coupled plasma-mass spectrometry (LA-MC-ICP-MS).

The geochemistry of granite is largely controlled by physical and chemical parameters that are closely linked to tectonic processes in evolving orogenic belts. Therefore, temporal changes in the geochemical compositions of granites could be used to infer critical shifts in tectonic processes. The Himalayan leucogranites are crustal anatexis products, providing a case to formulate petrogenetic models for granites and test tectonic models. From west to east, in the High Himalaya and the Tethyan Himalaya, two groups of leucogranites are derived from fluid-absent melting (Group A) and fluid-fluxed melting of muscovite (Group B), respectively. In the Cona and Mount Everest areas, Group B granites crystallized at 26−10 Ma, and Group A granites formed at 19−13 Ma. Group B granites have higher CaO, Sr, Ba, Zr, Hf, Th, Sr/Y, Zr/Hf, and Th/U, and lower Rb, Nb, Ta, U, Rb/Sr, and 87Sr/86Sr than those in Group A granites. These geochemical differences highlight the role of deep-origin fluids and the dissolution control of the accessory phases on the geochemical compositions in silicic magma systems. Field and microstructural observations show that E-W extension occurred synchronously with the granite intrusion derived from fluid-fluxed melting. Elevated heat flow accompanying the E-W extension could dehydrate hydrous minerals and release fluids from deep-seated crust (e.g., Lesser Himalayan Sequence). Such fluids could flux and melt the metasedimentary rocks within the High Himalaya and produce Group B granites. Together with literature data, from the Lhasa terrane to the Himalayan belt, E-W extensions in Tibet may have initiated as early as 26 Ma.

Lithium(Li)isotopes serve as effective geochemical tracers in mantle-crust cycling,planetary evolution,climate change,continental weathering,mineralization mechanisms,and environmental pollution studies.Efficient separation of lithium from natural samples is essential due to potential interference from isobaric isotopes during analysis.Over the past decades,cation exchange resin methods have been developed to enhance lithium separation for TIMS and MC-ICP-MS analysis.Since then,these methods have evolved to reduce blank contamination,simplify procedures,improve efficiency,and expand applicability to various natural samples.This review examines recent advances in Li isotope separation using single-column,double-column,multi-column and in-series column methods.Key factors like resin type,eluent volume,and method efficiency for various samples are discussed.Single-and double-column methods dominate current research,of which some methods just use minimal resin and eluent while controlling process blanks to below 0.1 ‰.However,separation efficiency remains dependent on lithium content and matrix ions in the sample.Further optimization is needed to balance efficiency,cost,and applicability across sample types.As analytical techniques advance,automated elution systems are likely to become central to Li isotope analysis.The BRIEF REPORT is available for this paper at .

Lithium (Li), as an essential element of green new energy technology, is a global strategic resource. Sedimentary Li is primarily associated with bauxite, with a local grade of >1000 ppm, and has a huge utilization prospect. However, fine particles limit the study of the occurrence of Li. The Danping bauxite deposit, located in northern Guizhou, China, which accompanying considerable Li resources. In this study, in situ elemental concentration analyses were conducted by laser ablation-inductively coupled plasma-mass spectrometry. The analysis results show that Li is mainly enriched at the bottom and top of the aluminiferous rock series, and the Li content at the top is higher (615.98-3289.98 ppm). Li content is positively correlated with Mg and Fe content, indicating that chlorite is a potential Li-bearing mineral. K content of <10,000 ppm, K content is positively correlated with Li content, indicating that illite may also be a Li-bearing mineral. Kaolinite, transformed from montmorillonite, may also have a high Li content. Ga content is always positively correlated with Al content, indicating that Ga mainly occurs in diaspores. Bauxite has similar Nb/Ta and Zr/Hf ratios to the underlying Hanjiadian Formation shale, as well as the same positive Ce anomalies (negative anomalies in Huanglong Formation), indicating that the ore-forming material of Danping is primarily derived from the underlying Hanjiadian Formation.

(Meta)sedimentary rock-hosted gold (Au) deposits are globally important Au resources, of which ore genesis and mineral exploration have been attracted considerable attention. However, the precise dating of Au mineralization of those Au deposits remains challenging due to the absence of suitable dating minerals, thus impeding a comprehensive understanding of their genesis. The Kangjiawan Au deposit, situated in the southern Hunan Province, South China, is one of representative (meta)sedimentary rock-hosted Au deposits. Due to the lack of mineralization age, the genesis of Kangjiawan Au deposit is still a matter of debate. Here we report the data of in situ calcite U-Pb dating, in situ trace elements and sulfur isotope analysis of pyrite, to further constrain the mineralization timing and the sources of ore-forming materials of the Kangjiawan Au deposit. Based on the detailed field investigation and petrographic observations, three mineralization stages have been identified: pyrite (Py1) + quartz (Stage I), gold-bearing pyrite (Py2) + polymetallic sulfides + quartz + calcite (Stage II), and gold-bearing pyrite (Py3) + calcite (Stage III). The results of mineralogical and trace elemental analyses indicate that Au are mainly hosted in Py2 (average 14.19 ppm) and Py3 (average 4.80 ppm), primarily as the form of "invisible gold". In situ LA-ICP-MS U-Pb dating on calcite intergrowth with the gold-bearing pyrite (Py3) yields a Tera-Wasserburg lower intercept age of 151.7 +/- 5.4 Ma. This age is well consistent with the published zircon U-Pb age (158.3 +/- 1.2 Ma) of the nearby Shuikoushan granodiorite, the molybdenite Re-Os age (157.8 +/- 1.4 Ma) of the Laoyachao skarn Pb-Zn deposit in the Shuikoushan ore field, and the garnet U-Pb age (159.1 +/- 1.9 Ma) of the skarn Pb-Zn ore in depth of the Kangjiawan Au deposit. These suggested that the Au mineralization of the Kangjiawan deposit is coeval with the emplacement of the Shuikoushan granodiorite and Laoyachao Pb-Zn mineralization, which are important parts of the large-scale Middle-Late Jurassic Cu-Au-Pb-Zn Metallogenic event of the Qin-Hang Metallogenic Belt, South China. In addition, trace elemental contents, such as relative low Co, Ni, and Se (i.e., <0.01 to 100 ppm), and a narrow delta S-34 range of -2.94 parts per thousand similar to +3.03 parts per thousand of pyrite, indicate that ore-forming materials were mainly derived from granitic magmas. Integrated with previous studies, it is suggested that the Au mineralization in the Kangjiawan deposit is genetically associated with the late Jurassic granitic magmatism and is probably as the distal products of the deep-seated concealed granitic intrusions and related proximal skarn Pb-Zn ore.

The Gongchangling iron deposit in North China hosts abundant high-grade (>50 wt% total Fe) magnetite ores and represents one of the largest BIF-hosted magnetite deposits worldwide. These high-grade magnetite ores are generally accepted to be formed by replacement of banded iron formation (BIF) (similar to 30 wt% total Fe), but the mechanism of iron enrichment remains controversial. Here we report new O-S-B isotope data of BIFs, high-grade iron ores, and related altered wall rocks, from the Gongchangling iron deposit, together with the geological and geochronological data to constrain the formation of the high-grade iron ores, and proposed new genetic model. The high-grade iron ores have positive delta Fe-56 and negative delta Si-30 values, similar to the BIFs, whereas the delta O-18 values of the high-grade iron ores and altered wall rocks are significantly lower than those of the BIFs. The delta S-34 values of pyrite from the high-grade iron ores are much higher than those of the BIFs. The delta B-11 values of tourmaline in the altered wall rocks of the high-grade iron ores are anomalously high, which is distinct from those of the BIFs and wall rocks, but similar to those of the evaporites from the Liaohe Group. At ca. 1.85 Ga, intense hydrothermal activity was initiated by post-orogenic extension and uplift with O-18-poor meteoric water circulated along crustal structures. Compositions of Na+, K+, Mg2+, Cl-, CO32-, S-34-rich SO42-, B-11-rich borate, and other soluble salts minerals were leached from the evaporitic rocks of the Liaohe Group, which driving the ore-forming hydrothermal fluids toward slightly alkaline and weakly oxidized as system matures. As the alkaline fluids migrated along the structures and fractures in the BIFs and reacted with the wall rocks, SiO2 was mobilized from the low-grade iron ores and consequently formed chlorite, garnet, and tremolite in the wall rocks due to reactions with clay minerals. These Si-rich hydrothermal fluids was also related to vein type quartz and massive quartz-bearing rocks. Most Fe was retained in situ and resulted in the formation of magnetite-rich iron ores. The SO42- in the hydrothermal fluids was reduced to form pyrite while B in the hydrothermal fluids reacted with the wall rocks to form B-11-rich tourmaline.

RationaleA novel laser ablation‐isotope ratio mass spectrometry (LA‐IRMS) method for in situ analysis of sulfur isotopes in sulfides has been developed. Instead of the in situ reaction applied by the traditional laser microprobe, the analyte gas preparation in this method is separated temporally and spatially from the LA, resulting in improved precision and accuracy.MethodsOur LA‐IRMS system combines an ultraviolet LA system, an elemental analyzer (EA), a custom‐built cryogenic concentration system, a continuous‐flow interface, and an IRMS. The sulfide aerosol particles generated from LA were transferred by a helium carrier gas from the ablation cell into the reaction tube and were then converted into SO2. Subsequently, SO2 was enriched in two cold traps and was finally introduced into the ion source of the IRMS through the continuous‐flow interface.ResultsWe measured three synthetic and four natural sulfide reference materials to test the performance of this method. Precisions of ±0.25‰–±0.48‰ and ±0.32‰–±0.64‰ (1SD, n = 5) for δ34S values of synthetic and natural sulfide standards can be obtained for spot sizes ranging from 64 to 80 μm. Measured values and their recommended values showed a good linear relationship (R2 within 0.998 and 0.9995) with the slope of approaching unity (within 1.0509 and 1.1313).ConclusionsData from the measurement of reference materials showed that the precision and accuracy of our method were satisfactory. This method is a powerful tool for in situ sulfur isotope measurement of sulfides and can be further applied to in situ carbon and oxygen isotope analyses.

A synthesized sphalerite bulk Sph-LD is recommended as a potential reference material for S isotope and trace element analysis employing LA-MC-ICP-MS and LA-ICP-MS.

Tourmaline is a common mineral in rocks. It can record the geological information during its formation and is a geochemical tracer. Its in-situ element and boron isotope tests provide a broader application perspective. Therefore, the chemical and boron isotope characteristics of tourmaline can be used to trace the mineralization of pegmatite-type rare metals. West Kunlun is an important Li-Be metallogenic belt, and many important Li-Be deposits have been developed. Longmenshan is one of the recently discovered pegmatite-type Li-Be deposits in the Dahongliutan area. There are barren and spodumene-bearing pegmatites that all contain tourmaline in Longmenshan. According to the occurrence, crystal form, and chemical composition, the tourmalines in Longmenshan are divided into two types: Tur-I tourmaline in the barren pegmatite close to the granite and Tur-II tourmaline from the spodumene-bearing pegmatite. Compositionally belongs to the alkali group and schorl-dravite solid solution series, with Tur-I being mainly schorl and Tur-II being schorl-dravite. Tur-I tourmalines are rich in Li, Sn, V, Cr, Zn and Mn while Tur-II tourmalines are rich in Be, Sr and Sc. The δ11B of the Tur-I tourmalines hosted in the barren pegmatite and Tur-II from the spodumene-bearing pegmatite ranges from −8.38‰ to −6.81‰ and from −10.00‰ to −6.41‰, respectively. These characteristics indicate that the formation fluid of tourmaline in Longmenshan is mainly derived from magma, and other fluids are rarely involved. The large range of B isotope variation indicates that the Tur-II tourmalines are more obviously affected by fluid activity.