With the development of measurement techniques, K isotope composition (δ41K) has become a sensitive tracer of surface processes. The evolution of K-Li-B in salt lakes remains insufficiently constrained and a single isotope system cannot resolve the behavior of multiple elements. Bangor Co is a typical carbonate-type salt lake on the Qinghai-Tibet Plateau with relatively simple recharge condition and the absence of extensive K-salt mineral precipitation, making it an ideal site to study early-stage salt lake evolution. This study focuses on K isotope compositions in river (−0.12‰), cold springs (−0.72‰ to 0.02‰), and brines (−0.76‰ to − 0.36‰), together with hydrochemistry, Li and B isotopes. These data indicate that K in Bangor Co is mainly sourced from silicate weathering, geothermal inputs, and the redissolution of lacustrine sediments. The δ41K fractionation observed in the brines may reflect the important influence of clay mineral adsorption, with inferred K removal fractions of 0.29–0.55. Comparison of K, Li and B isotopes reveals decoupled geochemical behavior among elements and establishes a conceptual model for carbonate-type salt lakes. This study demonstrates that δ41K is an effective tracer in carbonate-type salt lake catchments. A multi-isotope approach provides a useful framework for understanding solute evolution in carbonate-type salt lakes and similar evaporitic systems.

The newly discovered Hongchuan nickel deposit in the western segment of the North Qilian Orogenic Belt provides an important basis for further exploring the nickel metallogenic patterns and prospecting directions in the Qilian Mountains-Longshoushan region. This study systematically analyzes the mineral chemistry of early-crystallized olivine, pyroxene and chromian spinel from the Hongchuan mafic-ultramafic intrusion and discusses the ore-forming model based on whole-rock boron isotope results. Petrographic observations show that the Hongchuan intrusion consists mainly of peridotite, pyroxenite and biotite-hornblendite, with mineral assemblages including olivine, clinopyroxene, orthopyroxene, amphibole and chromian spinel. Disseminated sulfides, primarily composed of pyrrhotite, chalcopyrite and pentlandite, are observed in the peridotite phase. Mineral chemical analyses reveal that olivine Fo values ranging from 82. 8 to 84.5; chromian spinel contains Cr2O3 of 33.74%similar to 42.93%, MgO of 4.95%similar to 8.08%, and Cr-# values between 42.76 and 64.47; clinopyroxene is classified as augite, with En, Fs and Wo values ranging from 60.26 to 64.44, 7.94 to 11.94, and 27.29 to 28.85, respectively, and TiO2 content ranging from 0.22% to 0.67%. Parental magma composition inversion estimates that the MgO and FeOT contents of the parental magma were approximately 13% and 9.28%, respectively, indicating a high-Mg basaltic magma composition. The degree of partial melting (F) of the mantle source ranged from 14.8% to 17.5%, averaged at 16.7%. The crystallization temperature of the intrusion ranged from 1114 degrees C to 1327 degrees C, with an average value of 1190 degrees C, while pressure estimates based on clinopyroxene barometry yielded crystallization pressures of 0. 649 similar to 1.558GPa, averaged at 1.068GPa. Whole-rock boron isotope results indicate that the Hongchuan intrusion has relatively high boron content, ranging from 7.1 x 10(-6) to 68.9 x 10(-6) Serpentinized peridotite exhibits significantly positive delta(11) B values, ranging from 10. 38% to 14.07%, suggesting the intrusion underwent overprinting by external subduction-related fluids.

The Jinchuan Ni-Cu-platinum-group elements (PGE) deposit is located at the southern edge of the North China Craton within the Longshoushan Terrane, with mineralization accounting for 47% of the intrusion. The deposit contains abundant net-textured ore, primarily olivine-sulfide heteradcumulate, comprising over 50% of the assessed resources. The origin of the deposit is debated, with theories ranging from the formation of olivine-sulfide mush to sulfide segregation in a single intrusion or multiple ore pulses. This study supports a single intrusion model, with platinum-group elements (PGE) distribution patterns indicating ore zones derived from a common magmatic source. The copper Pd-group PGE (Cu-PPGE)-rich ores, characterised by coarse net-textured segregations, occur interstitial to Cu-PPGEs-poor oikocrysts and as fault-localised semi-massive segregations in Ore Bodies 1 and 24 (central and WNW regions), displaying pronounced Cu-PPGE-Au enrichment relative to Fe-Ni-Co- Ir-group PGE (IPGE). Sulfide ores are concentrated near the lower section of the intrusion, often along fault zones, with many showing negative Pt anomalies and platinum deficiencies when normalised to primitive mantle composition. The PGE concentrations in the Jinchuan parental magma were estimated using average ore compositions and published partition coefficients, with variations in R factors and monosulfide solid solution (MSS) fractionation explaining the PGE distribution across different ore types. Hydrothermal modification was minimal (< 5% of samples). Ore Bodies 1 and 24 formed at moderate R factors (500-1000) with 0%-80% MSS fractionation, while ore body 2 (SES section) formed at lower R factors (300-700) with 0%-40% MSS fractionation. The negative Pt anomalies and Pd-Pt fractionation are attributed to early olivine and chromite crystallisation, MSS fractionation (preferentially incorporating Pt over Pd), and limited hydrothermal Pt mobilisation. The varying & sum;PGEs(100) values in massive and disseminated sulfide ores reflect their magmatic origins, collectively explaining the complex PGE patterns in the Jinchuan intrusion.

The Sigou Mo-W deposit is a recently discovered concealed Mo-W deposit in the western area of the Mangling intrusive complex in the Northern Qinling Belt, with its fluid features and ore genesis unclear, which hinders comprehension of genetic model of molybdenum deposits in this belt. Alteration and mineralization at Sigou can be divided into four stages: Prograde alteration stage (Stage I), retrograde alteration stage (Stage II), quartz-polymetallic sulfide stage (Stage III), and quartz-calcite stage (Stage IV). Stage I is characterized by garnet and pyroxene, which are widely crosscut or replaced by later hydrothermal minerals and veins. The representative minerals of Stage II are amphibole, epidote, magnetite, and quartz, associated with biotite and K-feldspar alteration and scheelite mineralization. Stage III represents the main molybdenum mineralization stage, with typical ore-related mineral assemblages including quartz-molybdenite, quartz-calcite-molybdenite, quartz-calcite-sericite-molybdenite, and quartz-molybdenite-pyrite veins. Stage IV is typically featured by quartz, calcite, sericite, and chlorite that crosscut or replace the early minerals or veins. Three types of fluid inclusions were identified in hydrothermal minerals from these stages: Aqueous (W-type), CO2-rich (C-type), and solid-bearing (S-type). Comprehensive analysis shows a systematic decline in temperature and salinity from Stage II (294-464 degrees C and 2.2-63.1 wt% NaCl eqv.), through Stage III (178-364 degrees C and 2.7-43.8 wt% NaCl eqv.), to Stage IV (135-203 degrees C and 0.4-6.0 wt% NaCl eqv.). H-O isotopes of Stage III quartz (delta Dfluid = -88 to-75%o; delta 18Ofluid = 1.6-2.4%o) suggest that Stage III fluids are mainly of a magmatic-hydrothermal origin, with significant mixing of meteoric water during fluid evolution. In-situ sulfur isotopic data of Stage III sulfides (-2.0 to 5.5%o) show fluids of this stage are mostly derived from magmatic-hydrothermal fluids, with participation of strata materials. Integrating fluid inclusion data, isotopic results, and tectonic setting, we conclude that fluid boiling and mixing processes during fluid evolution are the dominant controls on ore precipitation at Sigou, and this deposit is a porphyry-skarn deposit formed in the Late Mesozoic post-collisional setting.

In the Fatira(Abu Zawal) mine area, located in the northern Eastern Desert of Egypt, fieldwork and mineralogical analysis, integrated with machine learning techniques applied to Landsat-8 OLI, ASTER, and Sentinel-2 multi-spectral imagery(MSI) data delineate gold-sulfide mineralization in altered rocks. Gold(Au) anomalies in hydrothermal breccias and quartz veins are associated with NE-oriented felsite dykes and silicified granitic rocks. Two main alteration types are identified: a pyrite-sericite-quartz and a sulfide-chlorite-carbonate assemblage, locally with dispersed free-milling Au specks. Dimensionality reduction techniques, including principal component analysis(PCA) and independent component analysis(ICA), enabled mapping of alteration types. Sentinel-2 PC125 composite images offered efficient lithological differentiation, while supervised classifications, i.e., the support vector machine(SVM) of Landsat-8 yielded an accuracy of 88.55% and a Kappa value of 0.86. ASTER mineral indices contributed to map hydrothermal alteration mineral phases, including sericite, muscovite, kaolinite, and iron oxides. Results indicate that post-magmatic epigenetic hydrothermal activity significantly contributed to the Au-sulfide mineralization in the Fatira area, distinguishing it from the more prevalent orogenic gold deposits in the region.

Constraining exhumation and tectonic processes along an orogenic plateau's boundary provides important insights into the mechanisms leading to plateau expansion and crustal evolution. The Longshou Shan thrust belt (LSSTB) is located in the foreland of the northern Qilian Shan thrust belt, which is commonly regarded as the northeastern margin of the Tibetan Plateau. The LSSTB is thus ideal for decoding the recent expansion of the Tibetan Plateau by tracking deformational pattern at its northeastern margin. In this study, the spatiotemporal characteristics of exhumation and deformation along the LSSTB are investigated by detailed analysis and numerical modeling of published and new thermochronological data. Five Proterozoic basement and intrusion samples yielded Cretaceous apatite fission-track central ages (126-74 Ma, with mean track lengths of 12.6-13.3 mu m), and Late Cretaceous to Eocene apatite (U-Th)/He mean ages (84-51 Ma). Inverse thermal history modeling reveals multi-stage exhumation of the LSSTB in the Permo-Triassic, late Mesozoic, Paleogene, and post middle Miocene. Permo-Triassic exhumation hints at a > 250 Ma-old peneplain surface that may have formed response to the closure of the Paleo-Tethys and Paleo-Asian oceans. Late Mesozoic exhumation likely resulted from intracontinental extensional deformation associated with tectonic processes at the Eurasian continental margin. Exhumation during the Paleogene was likely triggered by the India-Asia collision. Post-middle Miocene periods of uplifts along the reactivated Longshou Shan thrusts (no later than 10 Ma and 5 Ma on the southern and northern Longshou Shan Thrust, respectively) were driven by the northeastward expansion of the Tibetan Plateau. Our results support the LSSTB as a long-lived block boundary since the Permo-Triassic and an emerging plateau boundary that has lately been reactivated by the Tibetan Plateau expansion.

The implementation of the carbon peaking and carbon neutrality strategy has led to a steady increase in the supply of lithium resources. Brine is one of the important sources of lithium, and the extraction of Li from carbonate-type brine is particularly straightforward. Research into the source of materials and hydrological processes of brine is crucial for the sustainable development of lithium in carbonate-type brine. As a fluid-mobile and metallogenic element, lithium has a significant mass difference between its stable isotopes (7Li and 6Li), leading to isotopic fractionation. In this study, we analyzed the hydrochemistry and Li isotope compositions of samples collected from a Li-rich salt lake (Bangor Co) in the Qinghai-Tibetan Plateau. The samples included lake brines, recharge rivers, cold springs, and salt minerals (hydromagnesites). The Li content in the various types of water varied significantly, ranging from 0.06 mg/L to 198.10 mg/L, showing a variation of 4 orders of magnitude. Water samples exhibit a wide range of δ7Li values, varying from 4.89‰ to 16.02‰. Notably, the lowest and highest values are observed in cold springs. Additionally, the concentrations and δ7Li values in hydromagnesite differ across various relative ages. The hydrochemistry indicated that the recharge water is influenced by rock weathering, but the lake brine is influenced by evaporation concentration. The analysis of trace elements and Li isotopic data reveals that rock weathering, geothermal systems, salt minerals, and freshwater, primarily from early geothermal activities and the redissolution of carbonate minerals, contribute to the Li in salt lake brine. Boron isotopes and lithium isotopes of lake brines are found to vary differently. The δ7Li in brine is increased significantly by adsorption of hydromagnesite. And 11B gradually accumulates in hydromagnesite. This study has demonstrated that hydromagnesite plays a crucial role in influencing the characteristics of Li in brine.

The Niancaowan mafic-ultramafic intrusion is located within the Bayan Obo Rift Zone of central Inner Mongolia. Systematic genetic investigations were conducted in this study to clarify the genetic relationship between the Niancaowan mafic-ultramafic intrusion and known Cu-Ni deposits within the rift zone, as well as to assess the comparability of their mineralization potential. Through integrated petrographic observations, high-precision geochronological dating, whole-rock geochemical analyses, and zircon Hf isotope tracing, the research specifically focused on elucidating the magmatic source characteristics, rock-forming timing, and magmatic evolutionary processes of the intrusion. The Niancaowan mafic-ultramafic intrusion is predominantly composed of hornblende gabbro and gabbro-diabase. LA-ICP-MS zircon U-Pb dating reveals that the hornblende gabbro crystallized during the Early Permian (273.2 +/- 3.5 Ma), which demonstrates temporal synchronicity with the emplacement ages of other mafic-ultramafic intrusions within the central-western Inner Mongolia rift system. Geochemical tracers further disclose significant zircon Hf isotopic heterogeneity, indicating that the parental magma was derived from partial melting of a lithospheric mantle source and underwent contamination by lower crustal materials during its ascent. Comparative analysis indicates that the zircon Hf isotopic compositions of the Niancaowan intrusion (epsilon Hf(t) = -17.0 to +1.4) are similar to those of typical regional intrusions such as the Wulantaolegai and Huanghuatan intrusions, revealing that crustal contamination was prevalent during the emplacement of mafic-ultramafic magmatic systems within the Bayan Obo Rift Zone. The incorporation of such crust-derived components may be controlled by the melting or assimilation processes of ancient basement rocks in the extensional setting of the rift zone. The petrological characteristics and quantitative modeling results indicate that the Niancaowan intrusion experienced relatively weak crustal contamination (4 %-8 %). If sulfide mineralization were to occur in this intrusion, it would primarily depend on deep-seated magmatic differentiation. Comparative studies between the Niancaowan intrusion and other intrusive bodies within the Bayan Obo Rift Zone reveal that the mineral exploration potential of mafic-ultramafic intrusions in the Bayan Obo Rift Zone should not be overlooked. Particular attention should be given to highly contaminated mafic-ultramafic intrusion clusters within the rift zone and multi-stage tectonic-magmatic convergence nodes.

The genetic relationship between distal Pb-Zn-Ag vein-type deposits and porphyry molybdenum systems in orogenic belts is ambiguous, especially for ore-forming fluid sources, metal transport mechanisms, and magmatic-hydrothermal process. This study combines field observations, fluid inclusions, and H-O-S isotopic analyses from the Yaozhuang Pb-Zn deposit in the Northern Qinling Belt, Central China, in which a concealed porphyry molybdenum-related granitic intrusion exists, to clarify the genetic link between Pb-Zn mineralization and the deeper porphyry system. The Pb-Zn orebodies are hosted in the Mesoproterozoic metamorphic marine volcanic rocks and clastic rocks. Alteration and mineralization of the Yaozhuang Pb-Zn deposit could be categorized: Quartz-pyrite-arsenopyrite stage (Stage I), quartz-calcite-polymetallic sulfide stage (Stage II), and calcite-quartz stage (Stage III). Stage I is defined by quartz-pyrite-arsenopyrite and quartz-pyrite veins. Pyrite typically exhibits subhedral to euhedral and was commonly altered or filled by later galena and sphalerite along its fractures. Stage II is featured by notable lead and zinc mineralization, with extensive sulfides such as pyrite, galena, sphalerite, chalcopyrite, and pyrrhotite, coexisting with quartz-calcite +/- biotite +/- sericite and generally occurring as veins. Locally, chalcopyrite and pyrrhotite of this stage can occur as droplets in sphalerite, indicating simultaneous formation with Pb-Zn mineralization. Stage III is characterized by calcite-quartz veins that commonly crosscut previous formed sulfide-bearing veins (Stage I and II), indicating they formed later than the main mineralization stage (Stage II). From Stage I to III, four types of fluid inclusions are observed: CH4-rich (LCtype), aqueous (W-type), CO2-rich (C-type), and multi-phase solid-bearing (S-type) fluid inclusions. The microthermometric result from different types of fluid inclusions at Yaozhuang indicates a decline on temperature and salinity from Stage I (peaks at ca. 400-445 degrees C, 7.0-9.0 and 10.5-12.0 wt% NaCl eqv.), through Stage II (peaks at ca. 265-295 degrees C and 5.0-5.5 wt% NaCl eqv.) to Stage III (peaks at ca. 145-175 degrees C and 0.5-1.5 wt% NaCl eqv.). The H-O isotopic compositions of Stage II quartz (delta Dfluid = -96 %o to -80 %o and delta 18Ofluid = 4.9-5.4 %o) indicate that fluids of this stage mostly originate from a magmatic-hydrothermal origin, but it was also injected by meteoric water, leading to fluid mixing. This inference is consistent with fluid evolution by temperature and salinity decreasing from Stage I to II. In-situ sulfur isotopes of sulfides from Stage I and II are comparable (-3.6 %o to 6.4 %o), also suggesting a predominant magmatic-hydrothermal origin. In combination of recent discovery of the concealed porphyry molybdenum-related granitic intrusion under the Yaozhuang area by comprehensive investigation including drill core verification and geophysical survey, we propose that the Yaozhuang Pb-Zn deposit is a hydrothermal vein-type deposit, probably associated with this porphyry molybdenum-related granitic intrusion.

The Northern Qinling Belt (NQB) develops some medium-sized molybdenum deposits, but their mineralization ages are unclear, which hinders to establish the metallogenesis and later mineral prospecting. The newly discovered Sigou Mo-W deposit in the NQB has garnet alteration, but the ages of skarn alteration and mineralization are unknown. Disseminated and veined garnet (Grt I and II) were identified at Sigou, with the former having three sub-types (I-A, I-B, and I-C) based on their texture, and they all show dark and light zones or oscillatory zoning under backscattered electron (BSE) images. These four types of garnet are grossular-andradite-spessartine solid solution series, with dark zones being Si, Ca, and Al enrichment and Fe, Mn, and Ti depletion than light zones. Furthermore, their dark and light zones show similar geochemical features, e.g., LREE depletion, HREE enrichment, positive Eu anomalies (1.12-5.12), and low Th (<0.52 ppm) and U contents (0.01-7.37 ppm). Uranium and REE incorporated into garnet dark and light zones are mainly controlled by crystal chemistry, such as isomorphic substitution of divalent cation (e.g., Mn2+ or Ca2+) in the dodecahedral position, but surface sorption during Grt I-A formation also plays a controlling role. These different types of garnet formed in different pH and oxygen fugacity (fO(2)) conditions, and fO(2) decreased from Grt I to II during their formation. Garnet I-A and II yielded a lower intercept Pb-206/U-238 age of 148.4 +/- 4.2 Ma, consistent with that of Grt II (150.6 +/- 4.6 Ma). These ages are close to the emplacement ages of granite porphyry in the Sigou Mo-W deposit and regional small granitic plutons and formation of associated molybdenum deposits, indicating close relationship between the Sigou deposit and the granite porphyry. High-salinity magmatic fluid derived from granite porphyry interacted with host rocks (e.g., marble) to form different types of garnet at different pH and fO(2) conditions. The continuous fluid-rock interaction probably led to ore-forming fluids evolving to form subsequent scheelite and molybdenite mineralization for the Sigou deposit. In combination of published regional data and this study, small granitic plutons and molybdenum mineralization in the NQB mainly formed at ca. 154-146 Ma and 152-144 Ma, respectively. Regional geology and geochronological evidence suggest that fractionated small granitic intrusions with contemporaneous or older ages than the Manling dioritic rocks may have potential for molybdenum mineralization in the west and southwest of the Mangling intrusive complex.

Gold (e.g., electrum) has been reported in the Paleozoic Heijianshan Fe-Cu (-Au) or iron oxide-copper-gold-like (IOCG-like) deposit in the Eastern Tianshan, but relationships between gold occurrence and sulfides are unclear. The Heijianshan Fe-Cu (-Au) (or IOCG-like) deposit underwent five alteration and mineralization stages: Pre-ore epidote alteration (Stage I), syn-ore magnetite/iron mineralization (Stage II) followed by pyrite alteration (Stage III) and Cu (-Au) mineralization (Stage IV), and post-ore late veins (Stage V). This deposit mainly has two types of pyrite (A and B) based on pyrite-hematite and pyrite-pyrrhotite-chalcopyrite assemblages. They are euhedral to subhedral and mainly homogenous, with the former having porous or inclusion-rich domains. Trace elements incorporating into pyrite at Heijianshan are mainly controlled by compositions (e.g., As, Co, and Cu), temperature (e.g., Ni and Se), and oxygen fugacity (fO2; e.g., As and Se) of hydrothermal fluids, respectively. The timeresolved depth-concentration profiles suggest trace elements in pyrite and chalcopyrite occur as solid solution (e. g., Co, Ni, Zn, As, and Se) and micro- to nano-sized mineral inclusions (e.g., Cu, Bi, and Pb). The gold occurrence at Heijianshan is invisible as solid solution in Stage III pyrite and Stage IV chalcopyrite and visible as micronsized Stage IV electrum. Moreover, incorporation mechanisms of invisible gold are Au3+ substituting iron or copper in pyrite A and chalcopyrite, respectively, and Au+ incorporating into the vacancy or defect positions of pyrite B. Sulfides texture and geochemical compositions when combined with previous in-situ sulfur isotope suggest that pyrite formation was resulted from interaction between external basinal brines and altered host rocks under different temperature and fO2 conditions. Ongoing fluid-rock reaction led to formation of chalcopyrite +/- electrum veins as Cu (-Au) mineralization at Heijianshan. This study suggests that the prolonged interaction contributes to sulfide formation and Cu (-Au) mineralization in these Paleozoic Fe-Cu or IOCG-like deposits formed in basin-related setting, and the Aqishan-Yamansu belt, Eastern Tianshan has gold mineralization potential.

The southern section of the Great Xing'an Range where many tin-polymetallic deposits (including the Weilasituo, Huanggang, Anle, Dajing, Maodeng and Bianjiadayuan) developed is one of the most important tin-polymetallic metallogenic belts in northern China. The Beidashan pluton, the largest and most well-exposed granitic pluton in the tin-polymetallic metallogenic belt, is composed of quartz monzonite porphyry in the north and biotite granites with tourmaline and beryl in the south. This pluton was generally considered as the parent magma of tin-polymetallic deposits in the area due to their similar spatial and temporal relations. However, the petrogenesis and metallogenic potential of the pluton are still controversial. Based on lithological observation and zircon U-Pb dating, we conduct systematic bulk-rock geochemistry, zircon Hf isotope analysis and MELTS thermodynamic simulation calculation upon the pluton to clarify its genetic type, source area characteristics and evolution process, and then discuss its metallogenic potential. Zircon U-Pb dating results show that the quartz monzonite porphyry in the north of the pluton was formed at 143.4 +/- 1.3 Ma, and the biotite granite in the south was formed at 142.6 +/- 1. 3 Ma, which are consistent with the Early Cretaceous tin- polymetallic mineralization peak age in the southern section of the Great Xing'an Range. The Beidashan pluton contains idiomorphic hydrous mineral (e. g., amphibole and biotite), enriched in alkali (K2O + Na2O = 8. 58% similar to 9.34%) with ACNK/CNK = 0.97 similar to 1.02, and depleted in P2O5, content (<0.14%) with a negative correlation between P2O, and SiO2, indicating it belongs to the high- K calc-alkaline I-type granite. The zircon Hf isotopic composition of the pluton is relatively deficient (with an average epsilon(HF)(t) = 6. 81, n = 20), and the whole rock zirconium saturation temperature is high (averaged at 813 degrees C), indicating it is a product of high- temperature melting from new crustal materials. Major elements covariation and MELTS simulation results indicate that the pluton had undergone different degrees of fractional crystallization in magmatic systems, such as the quartz monzonite porphyry underwent a higher degree of fractional crystallization than the biotite granite. The age, characteristics of the magma source and redox conditions (Delta FMQ-2.5) of the Beidashan pluton are similar to those of granites with rare metal mineralization, and thus exhibit a certain degree of tin- polymetallic mineralization potential for this pluton. However, the initial melting temperature, volatile composition (relatively rich B but poor F), differentiation and evolution degree (relatively low degree of crystal differentiation and melt-fluid interaction) of the pluton are obviously different from those of the Weilasito alkali feldspar granite porphyry, demonstrating that it should not be the metallogenic parent rock for the Weilasituo deposit.

The Mangling intrusive complex has different dioritic to granitic phases and is spatially and temporally related to molybdenum deposits in the Qinling Orogen. Zircon U-Pb dating of the Mangling intrusive complex indicates that dioritic rocks (biotite diorite and biotite diorite enclave; ca. 150−147 Ma) formed earlier than granitic rocks (medium- to fine-grained and fine-grained monzogranite and K-feldspar granite; ca. 145−141 Ma). The Mangling dioritic rocks exhibit large ion lithosphere element (e.g., Rb) and light rare earth element enrichment and high field strength element (e.g., Nb, Ta, and Ti) depletion. They have low to moderate SiO2 (51.33−58.16 wt%), high MgO (3.10−4.75 wt%) and Mg# (48−60), and negative zircon εHf(t) values (−11.6 to −6.8), suggesting origination from the continental lithospheric mantle that may have been metasomatized by previous sediment-derived melts and slab-derived fluids constrained by high Nb/Y, Th/Yb, and Rb/Y ratios. The Mangling granitic rocks are I-type granites and have high SiO2 (67.90−81.88 wt%) and low MgO (0.16−0.74 wt%). They have low and negative zircon εHf(t) values (−18.7 to −1.9) and old zircon Hf two-stage model ages (2334−1287 Ma), as well as similar mineral fractionation (e.g., hornblende, biotite, sphene, and apatite) with the Mangling dioritic rocks, indicating that they were derived from the remelting of old crustal rocks (e.g., Xiong’er and Kuanping groups) by the evolved underplated mafic magma. Compared with the Taoguanping mineralized monzogranite in the Northern Qinling Belt, zircon geochemistry (e.g., Ce4+/Ce3+, Eu/Eu*, and ΔFMQ [relative fayalite-magnetite-quartz buffer]) indicates that magma of the Mangling intrusive complex (except the biotite diorite) has high oxygen fugacity and small fractionated granitic intrusions, which are coeval with the biotite diorite enclave or younger than the Mangling granitic rocks, may have potential for generating porphyry molybdenum mineralization. The combination of this study and previous studies corroborates that the Qinling Orogen underwent an intracontinental orogenic evolution in a post-collisional compression to extension transitional setting during the Late Jurassic to Early Cretaceous, affected by far-field Paleo-Pacific slab subduction.

This study aims to reveal the occurrence and origin of typical groundwater with high arsenic and fluoride concentrations in the loess area of the Guanzhong Basin—a Neogene faulted basin. Key findings are as follows:（1） Groundwater samples with high arsenic and fluoride concentrations collected from the loess area and the terraces of the Weihe River accounted for 26% and 30%, respectively, of the total samples,with primary hydrochemical type identified as HCO 3 -Na. The karst and sand areas exhibit relatively high groundwater quality, serving as preferred sources for water supply. It is recommended that local governments fully harness groundwater in these areas;（2） groundwater with high arsenic and fluoride concentrations in the loess area and the alluvial plain of rivers in Dali County is primarily distributed within the Guanzhong Basin, which represents the drainage zone of groundwater;（3） arsenic and fluoride in groundwater originate principally from natural and anthropogenic sources;（4） the human health risk assessments reveal that long-term intake of groundwater with high arsenic and fluoride concentrations pose cancer or non-cancer risks, which are more serious to kids compared to adults. This study provides a theoretical basis for the prevention and treatment of groundwater with high arsenic and fluoride concentrations in loess areas.

Elucidating metal transport agents is the key to understanding the genesis of deposits and tracking the locations of concealed orebodies. Here, we integrate H-O-S-Cu isotopic data from the shear-zone-hosted Lingyun Cu deposit, China, as a means to fingerprint metal transport agents. Sulfide mineralization can be divided into early and late stages, which consist of chalcopyrite + bornite + quartz veins and chalcopyrite + bornite + ankerite veinlets, respectively. Both delta O-18(fluid) and delta D values of fluid inclusions hosted by quartz (delta O-18(fluid): 0.5 parts per thousand to 9.9 parts per thousand, delta D: -103.9 parts per thousand to -60.1 parts per thousand) and delta Cu-65 values of sulfides (-1.85 parts per thousand to +0.39 parts per thousand) from the early stage progressively decrease from the southeastern to northwestern portions of the Lingyun deposit, whereas sulfide delta S-34 simultaneously shifts toward heavier values (-14.4 parts per thousand to 5.0 parts per thousand). The delta S-34 and delta Cu-65 values of sulfides from the late stage have restricted ranges from -11.2 parts per thousand to -9.3 parts per thousand and -0.30 parts per thousand to 0.05 parts per thousand, respectively. The possibilities of meteoric water addition, water-rock interaction, inter-mineral Cu partitioning, diffusion, and oxidation could be ruled out as reasons for having caused systematic H-O-S-Cu isotope variations. Vapor-liquid separation resulted in preferential incorporation of light Cu, H, and O isotopes into the vapor phase. The decrease in oxygen fugacity in the fluids resulted in a shift toward heavier delta S-34 values as fluid flowed outward. Vapor-phases are the dominant transport agents for Cu in the Lingyun deposit, which may be widely applicable to shear-zone-hosted deposits. The direction of progressively increasing delta Cu-65, delta D, and delta O-18 values and decreasing delta S-34 values allows identification of potential locations of concealed orebodies.

The Xiaonanshan–Tunaobao Cu-Ni-PGE deposit is located in the northern margin of the North China Craton (N-NCC) in central Inner Mongolia. However, the age, magma source, petrogenesis, and sulfide mineralization mechanism of the ore-related Xiaonanshan-Tunaobao pluton remain unclear. Zircon U-Pb dating indicates the Tunaobao pluton formed at 275.9 ± 2.8 Ma (Early Permian), similar to the Xiaonanshan pluton (272.7 ± 2.9 Ma). The ore-related gabbro is enriched in LREE and LILE (e.g., Rb) and depleted in HREE and HFSE (e.g., Nb and Ti). It likely originated from enriched mantle metasomatized by subduction fluids, supported by enriched Hf-Nd isotopes (–34.34 to –6.16 for zircon εHf(t) and –7.24 to –5.92 for whole-rock εNd(t) values) and high Ba/La but low Rb/Y ratios. The δ34S values of the Xiaonanshan sulfides range from 4.5‰ to 11.4‰, indicating a mantle origin with contribution from surrounding rocks. Combining previous recognition with this study, we propose that the Xiaonanshan–Tunaobao pluton formed in a post-collision extensional setting.

Constraining exhumation and tectonic process along the boundary of a plateau provides important insights for understanding the mechanism leading to the plateau expansion. The Longshou Shan thrust belt bounds the Tibetan Plateau along its northeast margin from the North China Craton. In this study, the spatiotemporal characteristics of the exhumation and fault deformation along the Longshou Shan thrust belt are investigated by detailed analysis and numerical modeling of published and new thermochronological data. We dated five Proterozoic basement and intrusion samples from the Longshou Shan, which yielded the Cretaceous apatite fission-track central ages (126 ± 7 – 74 ± 5 Ma with mean track lengths of 12.6 ± 1.7 – 13.3 ± 1.9) and Late Cretaceous to Eocene apatite (U-Th)/He central ages (84 ± 3 Ma – 51 ± 5 Ma). Inverse modelling of thermal history based on newly-obtained and published thermochronological datasets reveal multi-stage cooling and exhumation of the Longshou Shan thrust belt in the Permian-Triassic, Late Mesozoic (Middle-Late Jurassic, Early Cretaceous and Late Cretaceous), Eocene and post-middle Miocene. Permian-Triassic exhumation hints for a >250 Ma-old peneplain surface related with the closure of Paleo-Tethys and Paleo Asian Oceans. Late Mesozoic episodic exhumations are the result of intracontinental deformations as far-field tectonic events responding to tectonic processes at the Eurasian continental margins. Eocene exhumation is simultaneous with and best interpreted by the initial India-Asia collision. Post-middle Miocene uplift along the reactivated southern and northern Longshou Shan thrusts are driven by the northeastward expansion of the Tibetan Plateau. We suggest that the late Cenozoic Tibetan expansion had reached the Longshou Shan thrust belt by at least ~5 Ma. Our results support the Longshou Shan as a long-lived block boundary since the Permotriassic which now represents the active boundary of the northeastern Tibetan Plateau.

兴地镁铁—超镁铁质岩带位于塔里木克拉通北缘的库鲁克塔格地块,由兴地Ⅰ号、Ⅱ号、Ⅲ号和Ⅳ号等岩体组成.其中,兴地Ⅰ号和Ⅳ号岩体以辉长岩相为主;而兴地Ⅱ号和Ⅲ号岩体从橄榄岩相、辉石岩相到辉长岩相均有产出,岩相分带清楚.兴地Ⅱ号和Ⅲ号岩体二辉橄榄岩和二辉岩中均赋存有铜镍硫化物矿(化)体,常见矿石构造有星点状、斑点状、稀疏浸染状和稠密浸染状等,金属硫化物以磁黄铁矿、镍黄铁矿和黄铜矿为主.兴地Ⅱ号和Ⅲ号岩体岩石的铂族元素(PGE)含量(质量分数,下同)((0.41～4.54)× 10-9)低,钯组铂族元素(PPGE)含量总体高于铱组铂族元素(IPGE),IPGE/PPGE值为0.08～0.48,原始地幔标准化铂族元素蛛网图呈左倾型.岩石中铂族元素相对于Ni和Cu明显亏损,Pd/Ir值为3.28～23.33,Ni/Cu值为3.67～10.00,表明其母岩浆为高镁玄武质岩浆,这与橄榄石-熔体平衡估算的母岩浆性质一致.全岩Cu/Pd值((6.58～83.33)×104)以及Cu/Zr值与Ni含量的相关性特征表明,在岩浆源区和侵位过程中均发生了硫化物的熔离作用,导致残余岩浆中显著亏损铂族元素.综合分析认为,兴地Ⅱ号和Ⅲ号岩体具有良好的找矿前景.