The Dadonggou Mo deposit in Western Hebei, within the Yanshan-Liaoning Mo metallogenic belt, is a newly recognized medium-sized porphyry Mo system. Exploration has delineated 126 orebodies, most of which are blind, with identified resources of similar to 22,000 t Mo at an average grade of 0.071% Mo. Integrated lithogeochemistry, zircon U-Pb chronology, molybdenite Re-Os geochronology, quartz fluid-inclusion microthermometry, and H-O-S isotope analyses constrain the mineralization age, ore-fluid evolution, and sources of ore-forming materials. The zircon U-Pb dating of the ore-bearing granite porphyry and quartz porphyry from the Dadonggou molybdenum deposit yields ages ranging from 135.8 Ma to 141.5 Ma. The low Ti content in zircons indicates that they are super-wet magmatic rocks. The magmatic evolution experienced a change in oxygen fugacity from oxidizing to reducing conditions, which facilitated the initial enrichment of molybdenum. Molybdenite yields a Re-Os isochron age of 135.9 +/- 4.0 Ma and a weighted mean model age of 134.2 +/- 1.6 Ma, indicating Early Cretaceous mineralization. Ore fluids evolved from an early CO2-H2O-NaCl system with relatively high temperature and salinity to a later H2O-NaCl system with lower temperature and salinity. Isotopic data indicate progressive meteoric-water incorporation into dominantly magmatic fluids. Sulfur isotopes and high Re contents in molybdenite indicate a mixture of mantle magma mixed with some seawater. Lower late-stage trapping pressures record post-ore depressurization and hydrothermal-system shallowing.

The Mesozoic dykes in the Xingcheng area of western Liaoning Province in China were investigated through an integrated study involving zircon U-Pb geochronology, whole-rock geochemistry, and zircon Hf isotopic compositions to elucidate their emplacement phases, petrogenesis, and tectonic setting. The dykes are classified into two groups: felsic (granite porphyry, granite aplite) and mafic (diabase, lamprophyre). Emplacement occurred in four discrete phases: Late Triassic (229-212 Ma), Early Jurassic (ca. 179 Ma), Late Jurassic (162-152 Ma), and Early Cretaceous (133-102 Ma). The felsic dykes are characterized by high SiO2 and alkali contents, low TFeO and MgO abundances, and belong to the high-K calc-alkaline I-type granite series. The mafic dykes exhibit low SiO2, elevated MgO, and high Na2O contents, displaying both alkaline and calc-alkaline affinities. Both dyke suites are consistently enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs), and depleted in heavy rare earth elements (HREEs) and high field-strength elements (HFSEs). Zircon epsilon Hf(t) values for the felsic dykes range from -22.3 to -7.4, corresponding to two-stage model ages (TDM2) of 2613-1729 Ma, indicating derivation from partial melting of Neoarchean to Paleoproterozoic crustal material. Late Jurassic mafic dykes yield epsilon Hf(t) values between -27.8 and -20.2, consistent with an origin from partial melting of enriched lithospheric mantle. In contrast, Early Cretaceous mafic dykes display a bimodal epsilon Hf(t) distribution (-12.9 to -9.5 and +4.3 to +8.4), suggesting a predominant enriched mantle source with variable inputs from depleted mantle components. Integrated with regional tectonic reconstructions, the data indicate that the Xingcheng area evolved within a post-collisional extensional regime following the amalgamation of the North China Craton and the Central Asian Orogenic Belt during the Late Triassic. The Jurassic magmatic pulses are attributed to an active continental margin setting associated with subduction of the Paleo-Pacific Plate, whereas the Early Cretaceous phase reflects regional extension triggered by rollback of the subducting Paleo-Pacific slab.

Molybdenum (Mo) isotopes are powerful tracers of subduction-zone material cycling, yet their fractionation mechanisms and transport pathways during slab dehydration remain poorly constrained. This study integrates Mo concentrations and isotopic compositions from multiple global reservoirs with thermodynamics and numerical simulations, aiming to clarify Mo isotopic fractionation behavior and develop a Mo cycling model for subduction zones. Mass-balance calculations yield mean S98Mo values of 0.22 +/- 0.04%o (2 sigma) for sediments, -0.15 +/- 0.04%o (2 sigma) for the underlying altered mafic oceanic crust (AMOC), and 0.15 +/- 0.04%o (2 sigma) for the bulk altered oceanic crust (AOC). Isotope fractionation modeling indicates that upon complete dehydration, residual sediment S98Mo can be reduced to -1.79%o (alpha = 1.0015) and -1.88%o (alpha = 1.002), while AMOC may decrease to -0.32%o (alpha = 1.0015) and -0.38%o (alpha = 1.002). The contribution from residual slabs after dehydration can explain pronounced negative S98Mo observed in some arc lavas. Monte Carlo simulations demonstrate that slab residues retain substantial Mo after extreme subduction dehydration, with 33.9 % retention in sediments and 85.3 % in AMOC, highlighting their important contribution to Mo enrichment in deep subduction settings. Magmatic mixing models further indicate that subduction-modified, high-S98Mo mid-upper mantle can yield enriched mid-ocean ridge basalts (MORBs), while the deeper mantle metasomatized by low-S98Mo dehydrated slabs can source ocean island basalts (OIBs). High-S98Mo arc magmas in hot arcs form through fluid- or AOCmelt-dominated metasomatism, while cold subduction zones favor fluid-dominated metasomatism. Conversely, low-S98Mo back-arc magmas mainly originate from dehydrated AOC melts. These results demonstrate that premelting slab dehydration controls Mo isotope fractionation and recycling in subduction systems.

Granite-type rare metal and rare earth element deposits (GRMEDs) have garnered significant attention from both academia and industry owing to their strategic importance in supplying critical metal resources. Nevertheless, the critical factors controlling the formation of GRMEDs remain empirically ambiguous. In the No. 782 REE-Nb-Zr deposit, NE China, three distinct periods of granites have been recognized: pre-mineralization monzogranite, syn-mineralization granitic complex comprising biotite granite-muscovitized granite-albitized granite, and post-mineralization syenogranite. Systematic petro-genetic investigations of these intrusive phases provide crucial insights into element super-enrichment mechanisms inherent to GRMEDs systems. Zircon U-Pb geochronological constraints reveal successive emplacement ages of 488 +/- 4 Ma for monzogranite, 458 +/- 4 Ma for the mineralized complex, and 451 +/- 4 Ma for syenogranite. These granites exhibit diagnostic A-type affinities manifested by elevated Zr + Ce + Nb + Y concentrations (330-544 ppm), enhanced 10,000 x Ga/Al ratios (2.93-3.40), and pronounced negative Eu anomalies (Eu/Eu* = 0.15-0.29), consistent with magmatic rocks formed under extensional tectonics. Zircon grains from the monzogranite, biotite granite and syenogranite show positive epsilon Hf(t) values of 4.2 +/- 0.93 %o (1 sigma, n = 19), 3.6 +/- 0.63 %o (1 sigma, n = 10) and 5.4 +/- 0.82 %o (1 sigma, n = 10), respectively, coupled with elevated delta 18O values of 7.72 +/- 0.80 %o (1 sigma, n = 15), 7.45 +/- 1.23 %o (1 sigma, n = 10) and 7.06 +/- 0.74 %o (1 sigma, n = 20), respectively, indicative of derivation from juvenile lower crustal sources. Our geochemical data reveal distinct variations in ore-forming elements: the monzogranite shows significant depletion, contrasting with pronounced enrichment in the biotite granite and syenogranite. This result suggests that the monzogranite was likely derived from a crustal source depleted in ore-forming elements, while the enrichment of ore-forming elements in the granitic complex and syenogranite may be attributed to the incorporation of fluorine-rich volatile components from mantle sources. Furthermore, the granitic complex displays distinct HREE and HFSE distribution patterns, where biotite granite shows moderate HREE-Nb enrichment, albitized granite demonstrates significant enrichment (FREE up to 2850 ppm), while muscovitized granite exhibits relative depletion. This differential distribution implies that element remobilization during muscovitization and subsequent precipitation through albitization constituted the dominant mechanism for rare earth super-enrichment. We therefore propose that the formation of GRMEDs requires two essential and interdependent conditions: (1) the generation of fertile magma through lower crustal metasomatism by mantle-derived volatiles, and (2) subsequent metal extraction and reconcentration via hydrothermal activity during the late magmatic evolutionary stages.

The northern margin of the North China Craton (NCC) hosts large numbers of hydrothermal gold deposits, with mineralization ages ranging from the Paleozoic to Mesozoic eras. The genesis of these deposits has been primarily ascribed to magmatic‐hydrothermal or crustal‐metamorphic fluid models. The Hadamengou gold deposit (>170 t Au), the largest gold deposit in this region in terms of gold reserve, is still unclear on either the mineralization age or the source of metals. In this work, in situ apatite (hydrothermal) U‐Pb dating and Hg isotope tracing were employed to address the two key issues. In situ apatite U‐Pb dating revealed a mineralization age of 335 ± 10 Ma (2SD), coinciding with the period of Paleo‐Asian Ocean subduction. Mercury isotope analyses yielded near‐zero Δ 199 Hg values (−0.01 ± 0.06‰, SD) in ores and sulfides, consistent with results for the nearby ∼360 to ∼330 Ma Dahuabei granitic pluton (−0.09 ± 0.03‰, SD), suggesting a close genetic connection between them. The results of this study support that the Hadamengou belongs to a Late Paleozoic hydrothermal gold mineralization system, which was formed closely related to subduction of the Paleo‐Asian Ocean. This study demonstrates a Late Paleozoic gold mineralization event and a good potential for exploration of gold around Late Paleozoic granitic plutons in the northern margin of the NCC.

Identifying the origin and evolution of silicic magma is crucial for elucidating the transcrustal magmatic system and the evolution of continental crust. The Early Cretaceous volcanic-intrusive complex in the Kulongshan area provides an important insight into the evolution of silicic magma. Zircon U-Pb dating indicates that these spatially associated rocks formed between 140 and 131 Ma. The volcanic and subvolcanic rocks and alkali feldspar-alkaline granites are high silica (SiO2 = 75.79-77.89 wt%) and alkali-rich and demonstrate strong negative Eu anomalies (Eu/Eu* = 0.02-0.06), as is typical of A-type rocks. Significant geochemical discontinuities were found between the potassium (K)-feldspar granite porphyry (SiO2 = 67.86-70.80 wt%, Eu/Eu* = 0.20-0.44) and the high-silica rocks. These rocks exhibit epsilon Hf(t) and TDM2 values ranging from -18.1 to -9.2 and 2.34 to 1.84 Ga, respectively, indicating that the magmas originated from partial melting of the Paleoproterozoic continental crust. The geochemical characteristics show that the high-silica volcanic and subvolcanic rocks, along with the alkali-feldspar-alkaline granites, display a distinct trend of fractional crystallization. The Kfeldspar granite porphyry exhibits distinct characteristics of feldspar accumulation. The consistent material source of the Kulongshan volcanic-intrusive complex suggests that the magma may have ascended from the source area, leading to magma interaction in the deep magma reservoir, followed by fractional crystallization in the shallow magma reservoir. The results indicate that Early Cretaceous high-silica rocks were formed via the extraction and coalescence of interstitial melts within the magma reservoir, with the K-feldspar granite porphyry representing residual crystal accumulation.

The Xiarihamu magmatic Ni-Co sulfide deposit in the Paleozoic East Kunlun orogenic belt, western China, is the largest magmatic sulfide deposit in an orogenic setting (157 Mt at 0.65% Ni, 0.013% Co, and 0.14% Cu). In this study, mercury isotope analyses of ores and sulfide separates from the Xiarihamu deposit reveal negative Δ199Hg values (–0.11 ±0.08‰ standard deviation [SD]). These values are distinct from the near-zero Δ199Hg values for the primitive mantle (0.00 ±0.05‰ SD) and positive Δ199Hg values for the subcontinental lithospheric mantle modified by oceanic subduction (0.16 ±0.17‰ SD) but within the range of terrestrial materials (–0.23 ±0.19‰ SD). Primitive harzburgite cumulates display negative Δ199Hg values of –0.09 ± 0.06‰ (SD), suggesting that the mantle source was modified by subducted continental materials via continental subduction after the closure of the Proto-Tethys Ocean. Olivine orthopyroxenites, orthopyroxenites, websterites, and gabbronorites also display negative Δ199Hg values (–0.12 ± 0.09‰, SD), suggesting assimilation of terrestrial material into the parental magma at the crustal level. The results demonstrate that mantle metasomatism and crustal assimilation are both critical factors for the metallogenesis of magmatic sulfide deposits in orogenic belts.

The Mohe Basin is a famous placer gold (Au) field in Northeast (NE) China, and has garnered more attention due to the discovery of several sediment-hosted Au deposits. However, the genesis of these deposits remains poorly constrained. This study investigates the pyrite geochemical and S-Hg isotopic data from the sediment-hosted Sanshierzhan Au deposit to provide a critical insight into the metallogenic mechanism of the sediment-hosted Au mineralization in NE China. At Sanshierzhan, pyrite predominantly occurs as disseminated grains in altered sandstones, with minor occurrences in quartz veins. Three pyrite generations (Py I, Py II, and Py III) were identified from four mineralization stages. These include: coarse-grained pyrite (Py I) disseminated in altered sandstones, which shows dissolution textures; fine grained zonal pyrite (Py II) disseminated in polymetallic sulfide quartz vein with dissolution surface in its core (Py II-1) and relatively clean rim (Py II-2); medium grained pyrite (Py III) disseminated in calcite-quartz veins. These textural features, particularly zoned structures and inhomogeneous element distributions, record a dynamic change of fluid composition during the Au precipitation. The delta S-34 values of the pyrite generations Py I, Py II, and Py III range from 3.07 parts per thousand to 4.27 parts per thousand, 4.41 parts per thousand to 6.15 parts per thousand, 6.27 parts per thousand to 9.96 parts per thousand, respectively. Most of these values exceed the magmatic delta S-34 values (-5.00 parts per thousand to + 5.00 parts per thousand), indicating the involvement of the crustal sulfur (S) during the Au mineralization. Furthermore, Hg isotopic data from ore (pyritized and silicified rocks) and altered rock samples at Sanshierzhan show slightly negative to positive delta Hg-202 values (-0.28 parts per thousand to 0.76 parts per thousand) and negative to near zero Delta Hg-199 values (-0.11 parts per thousand to 0.04 parts per thousand). Their positive delta Hg-202 values suggest preferential leaching of heavy Hg isotopes from source area. Significantly, the slightly negative Delta Hg-199 values are similar with those of the terrestrial reservoirs, further indicating that some Hg as well as Au was likely derived from the upper continental crust. Therefore, our findings demonstrate that the Sanshierzhan mineralization is likely the result of strong water-rock reaction triggered by the magmatic-hydrothermal fluids. This hydrothermal system facilitated the remobilization of elements from the upper continental crust, together with the ore-forming metals carried by the magmatic fluids, causing the enrichment of Au in the hydrothermal system.

The Kulongshan granite and its associated volcanic rocks, located in the central section of the northern margin of the North China Craton, represent an exemplary series of magmatic evolution. Several beryllium-niobium-uranium-lead-zine deposits occurred within the most evolved granite; however, the mineralization age and genetic mechanism associated with beryllium and niobium remain poorly understood. The Be-Nb mineralized alteration zone is clearly influenced by faults trending in the NNE and NEE directions. The processes of silicification, chloritization and fluoritization are closely associated with Be-Nb mineralization. This study utilizes U-Pb dating of cassiterite and columbite, micro-temperature measurements of fluid inclusions, H-O isotope analysis of quartz, and S isotope analysis of whole rock and sulfides to reveal these processes. The U-Pb ages of columbite and cassiterite, which coexist with helvine, range from 134Ma to 132Ma. This finding is consistent with the U-Pb age of zircon (134Ma) extracted from the ore-bearing granite, suggesting that the mineralization is a product of the same magma-hydrothermal series at different evolutionary stages. There exist gas-liquid two-phase (VL) primary inclusions within hydrothermal quartz, which are closely related to the mineralization processes. The temperature of the ore-forming fluid ranges from 220 degrees C to 430 degrees C, while the salinity varies between 2.56% and 13.44% eqv. This fluid is classified all part of the H2O-NaCl hydrothermal system, characterized by medium to high temperatures and medium to low salinity. The H-O isotope analysis of quartz suggests that the ore-forming fluid is a mixed hydrothermal solution derived from both magmatic water and atmosphere precipitation. The whole rock delta S-34 values of measured samples vary greatly from 2. 85 parts per thousand to 13. 46 parts per thousand. while the delta S-34 values of sphalerite and pyrite range from 8. 33 parts per thousand to 9.06 parts per thousand and from 6. 77 parts per thousand to 8.07 parts per thousand, respectively, indicating the sulfur source of the samples closely associated with Mesozoic magmaticativity The Kulongshan grawitic magma.experienced significant fractional crystallization, which facilitated the initial concentration of niobium and beryllium. During the magma-hydrothermal stage, the crystallization of fluorite reduced the solubility of these elements, leading to the formation of columbite, helvine and genthelvite. External fluids during the hydrothermal stage led to the coexistence of beryllium minerals with sulfide minerals. The magmatic and mineralization activities in the study area during the Early Cretaceous were influenced by an extensional tectonic regime associated with the retreat of the Paleo-Pacific plate.

Mid - Mesozoic gold deposits, whose metallogeny was coincident with subduction of the Paleo-Pacific plate, are widely distributed in the northern margin of the North China Craton (NCC). The genesis of these deposits is currently debated with magmatic- and metamorphic-hydrothermal models. In -situ analyses of sulfur isotopes and trace elements provide an opportunity to clarify such a debate. Here, the two techniques were used to determine the trace elements and sulfur isotopes of sulfides from three mid -Mesozoic gold deposits (Jiapigou, Jinchangyu, and Jinchanggouliang) in the northern margin of NCC. The Co/Ni ratios of pyrites suggest that Jiapigou and Jinchanggouliang deposits are of magmatic-hydrothermal origin, whereas the Jinchangyu deposits receive oreforming materials mainly from crustal-hydrothermal fluids. In addition, gold -bearing sulfides display positive (5.60 +/- 1.87 %o, SD), near -zero (-0.31 +/- 1.27 %o, SD) and negative delta 34 S V-CDT values (-3.84 +/- 2.97 %o, SD) in the Jiapigou, Jinchangyu, and Jinchanggouliang, respectively. The results suggest that mid -Mesozoic gold deposits in the northern margin of NCC have variable sources of sulfur and metals. The Jiapigou deposit, representative of the arc settings, received sulfur and metals mainly from the subducting ocean crust. The Jinchanggouliang deposit, representative of cratonic destruction settings, received sulfur and metals mainly from the metasomastized mantle. The Jinchangyu deposit, representative of the back -arc settings, received sulfur and metals mainly from the metamorphic basement. We infer that subduction of the Paleo-Pacific plate in the mid -Mesozoic not only led to direct metallogeny of magmatic-hydrothermal gold deposits at arc settings and cratonic destruction settings, but also triggered the release of ore -forming fluids from the basement at back -arc, favoring metallogeny of crustal-hydrothermal gold deposits. Thus, mid -Mesozoic gold deposits in the northern margin of NCC cannot be exclusively explained by a single model.

The Early-Middle Jurassic period represented a crucial juncture for the Northeast Asian continent, marked by significant geological transformations. These included the initial thinning of the North China Craton (NCC), the closure of the Mongol-Okhotsk Ocean (MOO), and the subduction of the Izanagi Plate. Despite the acknowledged significance of these events, the specific temporal and spatial extents of the two tectonic regimes influencing the Northeast Asian continent remain uncertain. This study aims to elucidate these ambiguities, focusing on the spatiotemporal extents of magmatic activity and deformation driven by these distinct tectonic regimes. To achieve this, our research integrates comprehensive analyses of magmatism, stratigraphy, and deformation across the Northeast Asian continent. Our findings highlight the spatially non-uniform intensity of magmatism in Northeast China and the NCC during the Early-Middle Jurassic, pointing to a heterogeneous influence of the tectonic regimes over time and space. This early stage of the orogeny was also signed by local extensional tectonics within the NCC's eastern parts, as opposed to the compressional deformation in the western part, within the Songliao basin. However, the overall extension intensity over the entire region may not have been very pronounced. During the middle to late Middle Jurassic, there was a shift in the scenario, with compressiondominated deformation expanding across the Northeast Asian continent, indicating a significant change in tectonic dynamics. Further analysis reveals the distinct impacts of the Izanagi Plate's subduction beneath the Jiamusi-Khanka Block and the Yanshan fold-and-thrust belt, as well as the MOO tectonic regime's influence on the western Songliao basin, extending to the northern Ordos basin. Interestingly, a substantial portion of the craton remained relatively unaffected during the initial stages of Izanagi Plate's subduction and MOO's closure. However, these events laid the groundwork for the extensive destruction of the craton witnessed during the Late Jurassic-Early Cretaceous period. This study significantly contributes to our understanding of the geological processes in the Northeast Asian continent during the Mesozoic, offering valuable insights into the dynamic interplay of tectonic regimes that shaped this region. By delineating the spatial and temporal extents of magmatic activity and deformation, we provide a clearer picture of the geological evolution of the Northeast Asian continent, highlighting the complexity and variability of tectonic influences during the Early-Middle Jurassic.

The Jinqingding gold deposit, characterized as an extra-large quartz-vein-type deposit, is located in the middle of the Mouping–Rushan metallogenic belt in the Jiaodong Peninsula, and there is still controversy over its sources of ore-forming materials and fluids. This paper divides the mineralization of Jinqinding gold deposits into four stages, based on a field geological investigation and indoor petrographic observations: (1) coarse-grained pyrite–quartz stage, (2) quartz–fine-grained pyrite stage, (3) quartz–polymetallic sulfide stage, and (4) quartz–carbonate stage. The quartz fluid inclusions showed δD values of −96.0 to −81.8‰ and δOV-SMOW values of 0.70 to 6.32‰, indicating that the ore-forming fluids were mainly magmatic water, with some metamorphic water and atmospheric precipitation. The in situ δ34S values in different subzones of the pyrites of the Jinqingding gold deposit range from 6.69 to 10.86‰. The δ34S value range of the Jinqingding gold deposit is basically consistent with the contemporaneous intermediate–basic dikes in the region, suggesting a shared material source. In situ LA-ICP-MS geochemical analyses of the pyrites show large variations of Co/Ni ratios (0.21 to 99.5), which suggest a hydrothermal origin for the gold deposit. We infer that the ore-forming fluid of the Jinqingding gold deposit originated from the magma from the upper mantle and the mantle–crust transition zone.

The generation and evolution of crustal-scale magmatic systems are important in revealing the continental crust differentiation. In the Bayangeer-Aliwula area of Inner Mongolia, metaluminous-peraluminous- peralkaline rock assemblages provide a rare opportunity to evaluate Early Cretaceous magmatic systems. This study presents new geochemical data, including whole-rock and zircon geochemistry, zircon U-Pb dating, and Hf-O isotopic analysis of rocks formed between 132 and 121 Ma. The metaluminous rocks exhibit low SiO2 (55.35-65.65 wt%), low Rb/Sr (0.08-0.24) and (La/Yb)(N) (4.88-7.58) ratios, and positive E-Hf(t) values (+4.9 to +8.7). These features, along with enrichment in large-ion lithophile elements and depletion in Nb and Ta, suggest formation via partial melting of fluid-metasomatised lithospheric mantle. By contrast, peraluminous rocks have high SiO2 (69.37-80.58 wt%), a high differentiation index (DI = 88- 95), and Fe-index (0.84-0.95), resembling highly fractionated I-type granites. They show high Rb/Sr (0.77-3.35) and (La/Yb)(N) (5.79-22.75) ratios, and positive E-Hf(t) values (+6.7 to +10.8), combined with the modelling results, indicating origin from partial melting of K-rich mafic lower crust followed by magma fractionation. Peralkaline rocks display typical ferroan A-type granite characteristics (Zr + Nb + Ce + Y = 906-4292 ppm; Fe-index = 0.96-0.99), with high SiO2 (74.02-77.50 wt%), high Rb/Sr (6.17- 121.38), and (La/Yb)N N ratios (2.19-17.72), and positive E-Hf(t) values (+3.1 to +9.6). Zircon geochemistry characteristics suggest that peralkaline and peraluminous felsic melts are different batches extracted from the same magma reservoir. Further analysis, including hyperbola diagrams and zircon oxygen isotope compositions, suggests peralkaline magma formation through the mixing of altered oceanic crust fluids and peraluminous melts after melt extraction. During Early Cretaceous, the transcrustal magmatic system provides a reasonable explanation for the petrogenesis of various contemporaneous rocks in the study area in southern Great Xing'an Range. (c) 2024 International Association for Gondwana Research. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

The Solonker-Xar Moron-Changchun-Yanji Suture Zone is the result of the final closure of the Paleo-Asian Ocean (PAO). However, the closure time of the PAO in Northeast China remains controversial. The Hunchun area is located in the easternmost part of the Solonker-Xar Moron-Changchun-Yanji Suture Zone. Tectonism and magmatism in the Hunchun area can provide important information for understanding the late-stage evolution of the PAO. In this study, our zircon U-Pb ages show that the granodiorites and diorites in the Hunchun were formed at 282.3–251.4 Ma. This geochronological evidence suggests prolonged Permian magmatism in the Hunchun area. Whole-rock geochemistry, zircon trace, and Lu-Hf isotope data show that all the intrusive rocks are mainly calc-alkaline series to arc tholeiite series. Granodiorites are I-type granites formed by the partial melting of juvenile lower crust derived from the mantle. Diorites show similar characteristics to the sanukitic high-Mg diorite and are formed by the partial melting of the depleted mantle metasomatized by subduction sediments and/or slab-derived fluids. These results indicate that the Permian diorites and granodiorites in the Hunchun area formed in an active continental margin setting related to the subduction of the PAO plate. Significantly, sudden changes in the whole-rock Sr/Y and (La/Yb)N ratios and zircon εHf(t) values are observed in the Late Permian-Early Triassic igneous rocks in the eastern Central Asian Orogenic Belt (CAOB). This indicates that the final closure of the PAO in Northeast China likely occurred in the Late Permian-Early Triassic.

The Kunduleng granite hosts one of several significant uranium anomalies within the southern Great Xing’an Range, NE China. Whole-rock geochemistry and mineral chemistry data, along with the zircon U-Pb-Hf isotope have been used to constrain the petrogenesis of this granitic intrusion and the origin of the uranium anomaly. Microscopically, quartz, alkali-feldspar, and plagioclase are the essential mineral constituents of the granite, with minor biotite, while monazite, apatite, xenotime, and zircon are accessory minerals. Geochemically, the silica- and alkali-rich granites show a highly fractionated character with “seagull-shaped” REE patterns and significant negative anomalies of Ba and Sr, along with low Zr/Hf and Nb/Ta ratios. The granite has positive zircon εHf(t) values ranging from +12.7 to +14.5 and crustal model ages (TDM2) of 259–376 Ma, indicating a Paleozoic juvenile crustal source. Uraninite and brannerite are the main radioactive minerals responsible for the uranium anomaly within the Kunduleng granite. Uraninite presents well-developed cubic crystals and occurs as tiny inclusions in quartz and K-feldspar with magmatic characteristics (e.g., elevated ThO2, Y2O3, and REE2O3 contents and low CaO, FeO, and SiO2 concentrations). The calculated U-Th-Pb chemical ages (135.4 Ma) are contemporaneous with the U-Pb zircon age (135.4–135.6 Ma) of the granite, indicating a magmatic genesis for uraninite. The granites are highly differentiated, and extreme magmatic fractionation might be the main mechanism for the initial uranium enrichment. Brannerite is relatively less abundant and typically forms crusts on ilmenite and rutile or it cements them, representing the local redistribution and accumulation of uranium.

The Waxing Mo polymetallic deposit is located in the central part of the Lesser Xing’an–Zhangguangcai Range (LXZR), NE China. The Mo (Cu) mineralization in the deposit is dominantly hosted by quartz veinlets and stockworks and is closely related to silicification and potassic alteration, while the W mineralization is most closely related to greisenization. Zircon samples from granodiorite, biotite monzogranite, granodiorite porphyry, and syenogranite in the Waxing deposit yielded U-Pb ages of 172.3 Ma, 172.8 Ma, 173.0 Ma, and 171.4 Ma, respectively. Six molybdenite samples from porphyry Mo ores yielded a Re-Os isochron age of 172.0 ± 1.1 Ma. The granitoids in the ore district are relatively high in total alkali (Na2O + K2O), are metaluminous to weakly peraluminous, and are classified as I-type granitoids. The zircon samples from all granitoids showed a relatively consistent Hf isotopic composition, as shown by positive εHf(t) values (3.1–8.3) and young TDM2 ages (0.69–1.25 Ga). These results, combined with the whole-rock geochemistry, suggest that the magma source of these rocks most likely derived from partial melting of a juvenile middle-lower continental crust, with a minor contribution from the mantle. These granitoids have compositional characteristics of adakites such as relatively high Sr contents (e.g., >400 ppm) and Sr/Y ratios (e.g., >33), as well as weak Eu anomalies (e.g., Eu/Eu* = 0.8–1.1), indicating extensive fractionation crystallization of a hydrous magma. The apatite geochemistry indicates that the ore-related magma in Waxing is F-rich and has a relatively low content of sulfur. The zircon geochemistry reveals that the granodiorite, biotite monzogranite, and granodiorite porphyry have relatively high oxygen fugacity (i.e., ΔFMQ = +1.1~1.3), whereas the fO2 values of the granite porphyry and syenogranite are relatively low (i.e., ΔFMQ = +0.1~0.5). The whole-rock and mineral geochemistry suggest that the Mo mineralization in Waxing is probably genetically related to granitoids (i.e., granodiorite, biotite monzogranite, and granodiorite porphyry), with higher oxygen fugacity and a high water content, whereas the magmatic S concentration is not the key factor controlling the mineralization. A comparison of the geochemical compositions of ore-forming and barren stocks for porphyry Mo deposits in the LXZR showed that geochemical ratios, including Eu/Eu* (>0.8), 10,000*(Eu/Eu*)/Y (>600), Sr/Y (>33), and V/Sc (>8), could be effective indicators in discriminating fertile granitoids for porphyry Mo deposits from barren ones in the region.

Mercury (Hg) isotopes, which display mass-dependent fractionation and mass-independent fractionation, provide a multidimensional tracer to decipher the source of metals in mineral deposits. However, mineral ore samples usually contain abundant interfering elements (e.g., Te) that can cause inaccurate Hg isotopic analysis. Available acid digestion and combustion methods failed to remove these interfering elements, hindering the application of Hg isotopes for metallogenetic tracing. Here, we developed a new dual-stage tube furnace system employing a Mn-containing catalyst tube to pretreat mineral ore samples. This method yielded good Hg recoveries (100.5 ± 3.8%, 1SD, n = 15) and low levels of interfering elements in sample solutions, allowing for accurate analysis of a series of ore standard reference materials (GBW-11108v: coal; GSO-3: Cu-Ag sulfide ore; GBW 07859: Au-Te sulfide ore). The new method was also successfully applied to measure the Hg isotopic composition of magmatic and hydrothermal ore deposits, which yielded a large range in Δ199Hg value (-0.19 to 0.22‰) for ore deposits formed in different geological settings, highlighting the future applications of this method for metallogenic tracing, especially tracing the source of metals in mineral ore deposits.

The chemical composition of eastern North China Craton (NCC)'s alkaline basaltes likely influenced by subducting Pacific Plate. Nonetheless, the influence of these processes on the western craton remains uncertain due to the lack of geochemical evidence. The recent discovery of Ulanqab maar volcanic cluster (UMVC) in the western NCC has become significant research windows. However, their petrogenesis and magmatic processes remain poorly understood. In the present study, 40Ar/39Ar, whole rock and mineral geochemistry, and Sr-Nd-Mg isotope data for the UMVC in the western NCC are reported. These data reveal that the UMVC was formed during the Neogene (7.60 +/- 0.04 Ma), diverging from Quaternary basalts or as part of the Hannuoba basalts (eastern Ulanqab). The UMVC rocks, featuring typical oceanic island basalts traits with moderate (87Sr/86Sr)i values (0.70487-0.70524) and eNd(t) values from-4.95 to + 0.82, likely originated from an enriched EMI-type mantle source during the mid-Proterozoic. This involved mixing melts from 30 to 50 % partial melting of garnet lherzolite and 5-15 % partial melting of garnet pyroxenite in a deep magma chamber. Crystallization of clinopyroxene and garnet in this chamber created high-Ti alkaline lavas, with limited presence in erupted lavas due to sluggish magma ascent in the profound lithospheric mantle. In shallower lithospheric mantle regions, interactions between alkaline magma and orthopyroxenite improved transport kinetics, enabling clinopyroxene and olivine crystallization under lower pressure. These magmas integrated mafic crystal mushes from accumulation chambers. The study also identified a low Mg isotope composition (d26Mg = -0.56 parts per thousand to -0.42 parts per thousand) in samples, suggesting a hybrid source influenced by early decarbonation in Precambrian subduction zones. This finding indicates the incorporation of Mg-rich carbonate minerals from marine sediments into the magma source, contributing to the observed variations in eastern China's alkaline basalts.(c) 2023 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.