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A wide variety of deposit types formed in the late Palaeozoic-Mesozoic of eastern NE China and adjacent Russian Far East of the eastern Central Asian Orogenic Belt (CAOB). However, outstanding questions remain on the (1) number of magmatic and metallogenic phases, and their respective space–time distribution; (2) geochemical (incl. isotopic) signature and fertility of each magmatic phase; and (3) tectonic link with these magmato-metallogenic events. We present new data (zircon U-Pb dating, geochemistry, and Sr-Nd isotopes) on the Yangjingou W and Xiaoxi'nancha Au-Cu deposits, and compile published data from major ore deposits in the region. We have newly summarized four magmato-mineralization phases: (1) Middle Permian (ca. 273–259 Ma) Cu-Au-Pb-Zn, (2) Latest Permian-Early Triassic (ca. 253–247 Ma) W-Cu-Mo-Au, (3) Earliest-Middle Jurassic (ca. 201–162 Ma) Mo-Au-Fe-W-Pb-Zn, and (4) Cretaceous (ca. 129–83 Ma) W-Sn-Mo-Cu-Au mineralization. Cretaceous ore-causative granitoids are mainly I-type arc-related, whereas those for the three older mineralization phases are largely adakite-like or adakite-normal arc transitional. These granitoids were mostly derived from partial melting of juvenile crust, and to a lesser extent from a mixture of juvenile and ancient crust. We propose that the Middle Permian subduction of the Paleo-Asian and Panthalassa oceans formed the Au/Cu-Pb-Zn skarn and cryptoexplosive breccia-hosted Pb-Zn ± Ag deposits. Subsequently, the latest Permian-Early Triassic Paleo-Asian Ocean closure likely formed the porphyry-skarn Cu-Mo, orogenic Au, and vein-type W deposits in the Songliao and eastern Liaoyuan terranes. In the Early-Middle Jurassic, Paleo-Pacific subduction may have formed the Jiapigou orogenic Au belt and the Fe-polymetallic skarn deposits in the northern Songliao terrane, as well as porphyry Mo deposits along the Mudanjiang fault. Subsequently, Cretaceous W-Sn-Au-Cu metallogeny was controlled by Paleo-Pacific subduction rollback, and in the Russia Far East by partial melting of redox accretionary complexes. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The Bianbianshan deposit is a typical Cu-polymetallic deposit of the CMB. • Ore-forming fluids are attributed to a moderate T, ρ and moderate-low S NaCl system. • Cu mineralization occured in the deposit during the Early Cretaceous. • Fluid boiling and local mixing with meteoric water drove Cu precipitation. Abstract The Bianbianshan Cu-polymetallic deposit is located in the Xilamulun Cu-Mo belt of Inner Mongolia, NE China, and occurs within Late Jurassic andesite, rhyolite and tuff. Cu mineralization is observed in various types of hydrothermal disseminated veins exhibiting siliciification, sericitization and chloritization. The ore-forming process occurred in four stages: (1) chalcopyrite-pyrite-quartz, (2) pyrite-chalcopyrite-quartz-vein, (3) sphalerite-galena-quartz-vein, (4) and quartz-calcite-vein. Three types of fluid inclusions were identified in the deposit, including C-type (CO 2 -NaCl-H 2 O) as well as V- and L-type (NaCl-H 2 O) inclusions, where only L-type inclusions are observed in the fourth stage. Homogenization temperature of fluid inclusions in the four stages are 325–365 °C, 282–335 °C, 268–312 °C, and 195–259 °C, respectively, all of which exhibit salinities lower than ∼ 13 wt% NaCl equiv. Trapping pressure estimated from C, V- and L-fluid inclusions are between 550 and 900 bars, corresponding to minimum depths of 2.5–3.7 km. Hydrogen and oxygen isotopic compositions of quartz from different stages (δD = −109.7 ~ –107.6‰, δ18O = 7.6–9.6‰, V-SMOW) suggest that the mineralizing fluid gradually evolved from a magmatic to a meteoric origin. Sulfur (δ34S V-CDT = −0.7 to 0.4‰) and lead isotopes (208Pb/204Pb = 37.746–38.137‰; 208Pb/204Pb = 15.52–15.56%; 206Pb/204Pb = 17.75–18.36%) indicate that ore-forming materials were derived from mantle with minor additional participation of crustal reservoirs. Our data suggests the ore-forming fluids of the Bianbianshan Cu-polymetallic deposit are attributed to a moderate temperature, moderate-low salinity, and moderate density system, where decreases in pressure, phase separation and local mixing with meteoric water drove precipitation of metals. [ABSTRACT FROM AUTHOR]

The Xilingol complex is one of the maximal outcropped metamorphic terranes in the eastern segment of the Central Asian Orogenic Belt. Detailed petrological and geochronological study of the Xilingol complex will provide valuable insights into the orogenic process and closure of the Paleo-Asian Ocean. We present a comprehensive study of petrology, pseudosection modelling, and zircon U-Pb geochronology of representative rocks collected in Daqing Pasture, including two-mica quartz schist, epidote amphibolite, biotite plagioclase gneiss and quartzite. The Xilingol complex in Daqing Pasture can be preliminarily divided into the north and south segments based on field and petrological observations. The north segment comprises two-mica quartz schist, biotite quartz schist, amphibolite and minor epidote amphibolite, whereas the south segment consists mainly of biotite gneiss, amphibolite and quartzite, with varying degrees of migmatization developed. Combined pseudosection modelling and composition isopleths of garnet and biotite constrain a peak P–T condition of ~660 °C, ~5.5 kbar for the garnet-bearing two-mica quartz schist in the north segment, corresponding to low amphibolite facies metamorphism. The garnet-bearing biotite plagioclase gneisses in the south segment are interpreted to experience high amphibolite facies metamorphism at a peak condition of ~750–790 °C, ~5.5–8.0 kbar, followed by nearly isobaric cooling. The variations of peak P–T estimates within Daqing Pasture, coupled with the spatial heterogeneities of lithological associations between different outcropped terranes, reveal an overall northward decreasing metamorphic grade for the Xilingol complex. Metamorphic zircons from three biotite plagioclase gneisses in the south segment yield apparent 206Pb/238U age spreads of 397–348 Ma, 363–294 Ma and 341–301 Ma, respectively. These partially overlapping zircon ages are an indication of discrete metamorphic events involving localized thermal metamorphism at depth in the Middle Devonian and long-lasting Buchan-type metamorphism in the Carboniferous, with intermediate data probably related to a mixture of multiple growth domains. Five metamorphic zircons with low Th/U ratios from the epidote amphibolite in the north segment yield a concordia age of 284.8 ± 1.9 Ma, reflecting the diachronism of the Late Paleozoic Buchan-type metamorphism. Summarizing all U-Pb data of inherited magmatic zircons and metamorphic zircons, a distinct U-Pb age continuum is retrieved to elucidate a successive process from sedimentary diagenesis of forearc sedimentary formations to deep burial in the Early Devonian, and then to subsequent multi-stage metamorphic overprinting from the Middle Devonian to the Permian. The isograd patterns, P–T–t paths (clockwise paths and long-term duration) and spatial distribution of metamorphic terranes of the Xilingol complex are more compatible with an active continent rift setting rather than paired metamorphic belts in the arc-basin system, revealing post-collisional extension of the Early-Middle Paleozoic orogenic lithosphere of eastern CAOB in the Late Paleozoic. [Display omitted] • The Xilingol complex underwent long-lasting Buchan-type metamorphism in the Carboniferous to Permian. • Metamorphic patterns of the Xilingol complex are compatible with continent rift setting. • Zircon U-Pb age continuum reveals a successive process from diagenesis to deep burial to multiple metamorphic episodes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Superimposing mineralization (480 Ma for Cu and 246 Ma for Au-Zn) occurred at Zhengguang. • Ore fluids of both events were magmatic-sourced with meteoric water input. • Metal source for the two events was magma and magma-wallrock mixed, respectively. The Duobaoshan orefield is located in the eastern part of the Central Asian Orogenic Belt (CAOB) and underwent multiphase magmatism and mineralization. The Zhengguang deposit in the orefield is characterized by porphyry copper mineralization and intermediate-sulfidation (IS) epithermal gold mineralization. The porphyry-type veinlet-disseminated sulfide mineralization (~480 Ma) is hosted in granodiorite/tonalite porphyries and hydrothermal breccias, and is associated with widespread potassic (K-feldspar and biotite) alteration. Three porphyry-type mineralization stages have been identified: (I-1) quartz + medium-fine grained pyrite, (I-2) quartz + pyrite + chalcopyrite, and (I-3) quartz + calcite + minor pyrite. The IS epithermal vein/veinlet-disseminated mineralization occurs in andesite porphyry and fractures of the Duobaoshan Formation volcanic rocks, and is associated with extensive silicic, sericitic, and pyrite-sericitic-silicic alterations and minor propylitic alteration. Three IS epithermal-type mineralization stages are identified: (II-1) quartz + coarse-grained pyrite, (II-2) quartz + polymetallic sulfides, and (II-3) quartz + calcite + barren sulfides. Five stage II-2 pyrite samples yielded a Re-Os isochron age of 246.0 ± 6.4 Ma (MSWD = 0.85), suggesting a Triassic Au mineralization event after the Ordovician Cu mineralization. Stage I-1 fluid inclusions (FIs) are predominantly of VL- and LV-type and minor SL-type, with homogenization temperatures (T h) of 283–359 ℃ and salinities of 0.3–35.1 wt%. Stage I-2 is characteristically composed of VL- and LV-type inclusions with T h of 193–296 ℃ and salinities of 0.8–14.2 wt%. Only VL-type inclusions occur in stage I-3, II-1, II-2, and II-3 with T h of 149–216 ℃, 213–285 ℃, 169–236 ℃, and 125–176 ℃, and salinities of 2.4–7.9 wt%, 6.5–12.2 wt%, 3.4–8.8 wt%, and 2.1–6.3 wt%, respectively. H-O isotopic compositions for the mineralization (Ordovician: δ18O H2O = -9.9 to −0.5‰, δD = -86 to −75.6‰; Triassic: δ18O H2O = -8.4 to −2‰, δD = −134.1 to −88.5‰) indicate two different evolving fluid systems, both with an initial magmatic source and a later meteoric water incursion. Sulfur and lead isotope (Ordovician: δ34S (−3.1 to −0.7‰), 206Pb/204Pb (17.570–17.613), 207Pb/204Pb (15.427–15.441), 208Pb/204Pb (37.258–37.294); Triassic: δ34S (-5.4 to −2.5‰), 206Pb/204Pb (17.627–17.965), 207Pb/204Pb (15.466–15.534), 208Pb/204Pb (37.468–37.703)) values suggest a dominantly magmatic and a mixed magmatic-sedimentary source for the Ordovician and Triassic mineralization, respectively. [ABSTRACT FROM AUTHOR]

The Chaobuleng skarn deposit, located in the Erlian–East Ujimqin region, Northeast China, is a medium-sized Fe Zn polymetallic deposit. Iron-polymetallic mineralization occurs mainly as stratiform, lenticular, and vein types hosted in the contact zone between the Chaobuleng syenogranite and the Devonian Taerbagete Formation. The Chaobuleng deposit is a calcic skarn deposit dominated by a grossular-rhodonite-allanite-epidote assemblage. The ore minerals mainly consist of magnetite, pyrite, sphalerite, chalcopyrite, and bismuthinite, with lesser amounts of molybdenite, arsenopyrite, and pyrrhotine. Four mineralization stages have been identified: (I) a prograde skarn stage; (II) a retrograde skarn stage; (III) a quartz-minor calcite-polymetallic sulfide stage; and (IV) a quartz-calcite-minor pyrite stage. Three types of fluid inclusions (FIs) in garnet, quartz and calcite were classified: vapor-rich two-phase FIs (V-type), liquid-rich two-phase FIs (L-type), and daughter mineral-bearing three-phase FIs (S-type). The homogenization temperatures of FIs from stages I, II, III, and IV are 446–547, 411–519, 279–415, and 147–217 °C, respectively, with corresponding salinities of 0.87–59.47, 0.52–51.52, 0.70–13.25, and 3.05–7.85 wt% NaCl equiv., respectively. The results suggest that mineralization in the Chaobuleng deposit occurred at a depth of 1.0–2.8 km, with fluid boiling and mixing with meteoric water likely being responsible for ore precipitation. The C O isotope data suggest the early ore-forming fluids were mainly related to felsic rocks and were accompanied by intense water/rock reactions during the fluid migration. The S Pb isotopic compositions indicate that ore materials were derived from the mixing between magma and wall rocks. Zircon U Pb dating yields a weighted mean 206Pb/238U age of 135.9 ± 0.8 Ma (MSWD = 1.03), which represents the crystallization time of the syenogranite. Together, these data suggest that the Chaobuleng deposit is a skarn ore system that is spatially, temporally, and genetically related to syenogranite and formed in an extensional environment resulted from the roll back of the subducted Paleo-Pacific Plate. [Display omitted] • The Chaobuleng deposit is a typical skarn Fe Zn deposit, formed in the Early Cretaceous. • The fluids evolved from a high-temperature, intermediate-salinity NaCl–H 2 O system of magmatic water. • Ore-forming materials had a mixed source of the granitic pluton and Taerbagete Formation. [ABSTRACT FROM AUTHOR]

The Qibaoshan polymetallic ore field is located in the Wulian area, Shandong Province, China. Four ore deposits occur in this ore field: the Jinxiantou Au–Cu, Changgou Cu–Pb–Zn, Xingshanyu Pb–Zn, and Hongshigang Pb–Zn deposits. In the Jinxiantou deposit, three paragenetic stages were identified: quartz–pyrite–specularite–gold (Stage 1), quartz–pyrite–chalcopyrite (Stage 2), and quartz–calcite–pyrite (Stage 3). Liquid-rich aqueous (LV type), vapor-rich aqueous (V type), and halite-bearing (S type) fluid inclusions (FIs) are present in the quartz from stages 1–3. Microthermometry indicates that the initial ore-forming fluids had temperatures of 351–397 °C and salinities of 42.9–45.8 mas. % NaCl equivalent. The measured hydrogen and calculated oxygen isotopic data for fluid inclusion water (δ18OFI = 11.1 to 12.3‰; δDFI = −106.3 to −88.6‰) indicates that the ore-forming fluids were derived from magmatic water; then, they were mixed with meteoric water. In the Changgou deposit, three paragenetic stages were identified: quartz–pyrite–specularite (Stage 1), quartz–pyrite–chalcopyrite (Stage 2), and quartz–galena–sphalerite (Stage 3). LV, V, and S-type FIs are present in the quartz from stages 1–3. Microthermometry indicates that the initial ore-forming fluids had temperatures of 286–328 °C and salinities of 36.7–40.2 mas. % NaCl equivalent. The measured hydrogen and calculated oxygen isotopic data for fluid inclusion water (δDFI = −115.6 to −101.2‰; δ18OFI = 12.2 to 13.4‰) indicates that the ore-forming fluids were derived from magmatic water mixed with meteoric water. The characteristics of the Xingshanyu and Hongshigang deposits are similar. Two paragenetic stages were identified in these two deposits: quartz–galena–sphalerite (Stage 1) and quartz–calcite–poor sulfide (Stage 2). Only LV-type FIs are present in the quartz in stages 1–2. The ore-forming fluids had temperatures of 155–289 °C and salinities of 5.6–10.5 mas. % NaCl equivalent. The measured hydrogen and calculated oxygen isotopic data for fluid inclusion water (δDFI = −109.8 to −100.2‰; δ18OFI = 10.2 to 12.1‰) indicates that the ore-forming fluids were derived from circulating meteoric waters. The sulfur isotopes (δ34Ssulfide = 0.6 to 4.3‰) of the four deposits are similar, indicating a magmatic source for the sulfur with minor contributions from the wall rocks. The ore field underwent at least two phases of mineralization according to the chronology results of previous studies. Based on the mineral assemblage and fluid characteristics, we suggest that the late Pb–Zn mineralization was superimposed on the early Cu (–Au) mineralizaton in the Changgou deposit. [ABSTRACT FROM AUTHOR]