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[Display omitted] • Higher silica, K, and lower Al contents of musovites prove the involvement of shallow magmatic fluids. • High Mg-Ti contents of muscovites and core-rim variations of muscovites-beryls show the existence of deep magmatic fluids. • Be mineralization was achieved under the co-contribution of shallow magmatic fluids and deep magmatic fluids. Vein-type and greisen-type beryllium (Be) mineralization is closely associated with the magmatic-hydrothermal evolution in highly fractionated granites. However, the source of ore-forming fluids and their role in the migration and enrichment of Be is poorly understood. Although whole rock Ba-Rb isotope researches highlight that even deep magmatic fluids beneath the shallow magmatic-hydrothermal systems could provide rare metals and promote mineralization, it is still challenging to determine the influences of such fluids via using conventional geochemical indicators. Here we present zircon-monazite-xenotime-wolframite U-Pb ages, whole-rock geochemistry, monazite Nd isotopes, as well as muscovite and beryl geochemistry for the Zhujiayingzi quartz vein-type Be mineralization in the southern Great Xing'an Range (SGXR), Northeast (NE) China, and introduce the neighboring Nasigatu gresien-type Be mineralization for comparison. Geochronological results reveal that the Zhujiayingzi beryl-wolframite-bearing quartz veins formed in the Early Cretaceous (149–147 Ma), much younger than the host Permian (270–267 Ma) crystal tuffs, but coeval with the Nasigatu highly fractionated alkali-feldspar granite (144–139 Ma). Similar muscovite-beryl compositions and monazite Nd isotopes, combining with their close temporal-spatial relationships indicate that the Zhujiayingzi and Nasigatu Be mineralization have consistent hydrothermal assemblages and enrichment processes. Higher silica, K, and lower Al contents of muscovites from Be-rich veins (M2) and greisens (M4) than those recorded in barren crystal tuffs (M1) and alkali-feldspar granite samples (M3) at both Zhujiayingzi and Nasigatu are consistent with the evolution of the Early Cretaceous granitic magma, proving the involvement of shallow magmatic fluids exsolved from the Nasigatu-like highly evolved granitic melts. However, ore-related M2 and M4 samples have higher Mg (>1 wt%) and Ti contents than those of M1 and M3 samples, which violates the conventional hydrothermal evolution trend. Trace element compositions as well as K/Rb, K/Cs, and Rb/Sr ratios of four-type muscovites, together with the core-rim geochemical variations of muscovites at Zhujiayingzi and beryls at Nasigatu, indicate the existence of deep magmatic fluids rather than fluid-rock interaction to account for the anomalous mineralogical evidence. Such deep magmatic fluids were exsolved from large silicic magmatic reservoirs beneath the shallow magmatic-hydrothermal system, and thus likely display low evolution degrees and high Mg-Ti contents. They can not only provide heat and promote fluid-mineral interactions, but also can efficiently extract and transport Be enriched in deep crystal mushes at different depths. Thus we invoke that the Early Cretaceous Be mineralization in the SGXR was achieved under the combined action of both shallow and deep magmatic fluids derived from the crystal mush-dominated transcrustal magmatic system. [ABSTRACT FROM AUTHOR]

There is a broad consensus that subduction of the Paleo-Pacific oceanic plate has caused extensive magmatism, lithospheric deformation, and metal mineralization in the eastern margin of the Eurasian continent during the Late Mesozoic. However, the onset and extent of subduction of the Paleo-Pacific Ocean, especially the timing of the transition in tectonic regime from the Paleo-Asian Ocean to Paleo-Pacific, and extent of the subduction of the Paleo-Pacific Ocean remain poorly constrained. To address these key issues, we present regional geological observations, zircon U–Pb dating, whole-rock geochemistry, and Hf isotopic compositions of the Jurassic intrusions at the northern margin of the North China Craton, with the aim of constraining their petrogenesis and the tectono-magmatic events related to subduction of the Paleo-Pacific Ocean. The geochronological and geochemical results indicate that these intrusions were emplaced between 177 and 155 Ma, with distinct geochemical features. The Huajianggou pluton (HJG), Tongjiatun pluton (TJT), and Haoguantun pluton (HGT) are characterized by high Al2O3 and Sr contents, and low MgO, TFe2O3, Y, Yb, and heavy rare earth elements (HREEs) contents, coupled with high Sr/Y values (34.10–94.36), showing adakitic affinities. Based on these geochemical characteristics, we suggest that these adakitic magmas (i.e. the HJG, TJT, and HGT plutons) were produced by partial melting of thickened lower crust in response to earlier subduction of the Paleo-Pacific oceanic plate beneath the northern margin of the North China Craton. In contrast, the Baijiagou pluton (BJG) and Sheshangou pluton (SSG) are high-K calc-alkaline rocks with low Sr/Y ratios (0.80–17.77), and they exhibit petrological and geochemical characteristics of I-type granites, indicating an origin from the lower crust, with variable degrees of fractional crystallization. In addition, the Bakeshu pluton (BKS) is mainly comprised of diorite that displays high SiO2, low MgO, Cr, and Ni contents, with Mg# of 39.8–42.9, indicating a lower crustal origin. Despite the range in ages of these intrusions, all the Jurassic calc-alkaline intrusions show typical geochemical characteristics of active continental margins, such as enrichment in large ion lithophile elements (LILEs) and light rare earth elements (LREEs), and depletion in high field strength elements (HFSEs). Combined with spatial-temporal variations of coeval magmatic rocks along the northern margin of the North China Craton, we suggest that the transition in tectonic regime from the Paleo-Asian Ocean to Paleo-Pacific Ocean was initiated in the Early Jurassic. These Jurassic intrusions formed in an active continental margin setting, related to westward subduction of the Paleo-Pacific oceanic plate. Importantly, the Early Jurassic subduction-related calc-alkaline magmatic rocks in northeast (NE) China constitute a NE-trending magmatic arc belt, which is best explained as continental magmatism triggered by the westward subduction of the Paleo-Pacific oceanic plate. [ABSTRACT FROM AUTHOR]

The discoveries of oil and gas reservoirs in the volcanic rocks of the Songliao Basin (SB) have attracted the attention of many researchers. However, the lack of studies on the genesis of the volcanic rocks has led to different opinions being presented for the genesis of the SB. In order to solve this problem, this study selected the volcanic rocks of the Yingcheng Formation in the Southern Songliao Basin (SSB) as the research object, and determined the genesis and tectonic setting of the volcanic rocks by using LA‐ICP‐MS zircon U‐Pb dating and a geochemical analysis method (major elements, trace elements, and Hf isotopes). The volcanic rocks of the Yingcheng Formation are mainly composed of rhyolites with minor dacites and pyroclastic rocks. Our new zircon U‐Pb dating results show that these volcanic rocks were erupted in the Early Cretaceous (113–118 Ma). The primary zircons from the rhyolites have ∊Hf (t) values of +4.70 to +12.46 and two‐stage model age (TDM2) of 876–374 Ma. The geochemical data presented in this study allow these rhyolites to be divided into I‐type rhyolites and A‐type rhyolites, both of which were formed by the partial melting of the crust. They have SiO2 contents of 71.62 wt.%–75.76 wt.% and Al2O3 contentsof 10.88 wt.% to 12.92 wt.%. The rhyolites have distinctively higher REE contents than those of ordinary granites, with obvious negative Eu anomalies. The light to heavy REE fractionation is not obvious, and the LaN/YbN (average value = 9.78) is less than 10. The A‐type rhyolites depleted in Ba, Sr, P, and Ti, with relatively low Nb/Ta, indicating that the rocks belong A2 subtype granites formed in an extensional environment. The adakitic dacites are characterized by high Sr contents (624 to 1,082 ppm), low Y contents (10.6 to 12.6 ppm), high Sr/Y and Sr/Yb ratios, and low Mg# values (14.77 to 36.46), indicating that they belong to "C" type adakites. The adakitic dacite with high Sr and low Yb were likely generated by partial melting of the lower crust under high pressure conditions at least 40 km depth. The I‐type rhyolites with low Sr and high Yb, and the A‐type rhyolites with very low Sr and high Yb, were formed in the middle and upper crust under low pressure conditions, respectively. In addition, the formation depths of the former were approximately 30 km, whereas those of the latter were less than 30 km. The geochemical characteristics reveal that the volcanic rocks of Yingcheng Formation were formed in an extensional environment which was related to the retreat of subducted Paleo‐Pacific Plate. At the late Early Cretaceous Period, the upwelling of the asthenosphere mantle and the lithosphere delamination caused by the retreat of the subducted Paleo‐Pacific Plate, had resulted in lithosheric extension in the eastern part of China. Subsequently, a large area of volcanic rocks had formed. The SB has also been confirmed to be a product of the tectonic stress field in that region. [ABSTRACT FROM AUTHOR]

In this study, we present zircon U‐Pb ages, whole‐rock geochemical data and Hf isotopic compositions for the Meiguifeng and Arxan plutons in Xing'an Massif, Great Xing'an Range, which can provide important information in deciphering both Mesozoic magmatism and tectonic evolution of NE China. The zircon U‐Pb dating results indicate that alkali feldspar granite from Meiguifeng pluton was emplaced at ∼145 to 137 Ma, and granite porphyry of Arxan pluton was formed at ∼129 Ma. The Meiguifeng and Arxan plutons have similar geochemical features, which are characterized by high silica, total alkalis, differentiation index, with low P2O5, CaO, MgO, TFe2O3 contents. They belong to high‐K calc‐alkaline series, and show weakly peraluminous characteristics. The Meiguifeng and Arxan plutons are both enriched in LREEs and LILEs (e.g., Rb, Th, U and K), and depleted in HREEs and HFSEs (e.g., Nb, Ta and Ti). Combined with the petrological and geochemical features, the Meiguifeng and Arxan plutons show highly fractionated I‐type granite affinity. Moreover, the Meiguifeng and Arxan plutons may share a common or similar magma source, and they were probably generated by partial melting of Neoproterozoic high‐K basaltic crust. Meanwhile, plagioclase, K‐feldspar, biotite, apatite, monazite, allanite and Ti‐bearing phases fractionated from the magma during formation of Meiguifeng and Arxan plutons. Combined with spatial distribution and temporal evolution, we assume that the generation of Early Cretaceous Meiguifeng and Arxan plutons in Great Xing'an Range was closely related to the break‐off of Mudanjiang oceanic plate. Furthermore, the Mudanjiang Ocean was probably a branch of Paleo‐Pacific Ocean. [ABSTRACT FROM AUTHOR]

The early Mesozoic marked an important transition from collisional orogeny to post‐orogenic extension at the northern margin of the North China Craton (NCC). In this study, we undertook zircon U‐Pb dating and whole‐rock major‐ and trace‐element geochemical analyses of early Mesozoic granitic rocks in the Chifeng area to establish their geochronological framework, petrogenesis, and implications for the tectonic evolution of the eastern Central Asia Orogenic Belt (CAOB). Zircon U‐Pb dating results show that these rocks were emplaced in three stages during the Triassic: (1) syenogranites during 250–248 Ma, (2) granodiorites during 244–243 Ma, and (3) monzogranites and granodiorites during 232–230 Ma. These Triassic granitoids belong to the high‐K calc‐alkaline series and are evolved I‐type granites. They have high SiO2 and low MgO contents with enrichments in light rare‐earth elements, Zr, Hf, Rb, Th, and U, and depletions in Ba, Nb, Ta, Sr, and Eu. These geochemical data indicate that the granitoids were derived from partial melting of a lower‐crustal source under relatively low‐pressure conditions and subsequently underwent extensive fractional crystallization. Considering both the geochemical data and regional geological information, we propose that the 250–248 Ma syenogranites were emplaced in an extensional environment linked to slab break‐off after closure of the Paleo‐Asian Ocean (PAO) along the Solonker‐Xra Moron‐Changchun suture zone. The 244–243 Ma granodiorites were formed in a compressional orogenic setting during collision between the Erguna‐Xing'an‐Songliao composite block and the NCC. The 232–230 Ma granodiorites and monzogranites were emplaced during the transition from compressional orogeny to post‐orogenic extension. Overall, the early Mesozoic tectonic evolution of the Chifeng area can be divided into three main stages: (1) closure of the Paleo‐Asian Ocean and extension related to slab break‐off during the Early Triassic; (2) continuous collisional compression during the Middle Triassic after closure of the PAO; and (3) post‐orogenic extension during the Late Triassic, most probably due to lithospheric delamination after amalgamation of the Erguna‐Xing'an‐Songliao composite block and the NCC. [ABSTRACT FROM AUTHOR]

This paper presents new zircon U Pb ages and Hf isotope data, and whole-rock geochemical and Sr Nd isotopic data, for lamprophyres in the western Shandong area of China. These data provide new insights into the nature of the lithospheric mantle beneath the eastern North China Craton (NCC) during the Early Cretaceous. The lamprophyres are divided into low-Ti (TiO 2 < 1.1 wt%; Ti/Y < 270) and high-Ti (TiO 2 > 2 wt%; Ti/Y > 370) suites, where the Xiaya and Jingziyu minettes are defined as low-Ti lamprophyres and the Jingziyu pyroxene lamprophyres are defined as high-Ti lamprophyres. The igneous zircons yield weighted-mean ages of 126, 132, and 130 Ma for the low- and high-Ti lamprophyres, respectively, indicating these units formed during the Early Cretaceous. The inherited zircons within the Xiaya and Jingziyu minettes define six (2517, 1852, 725, 375, 276, and 236 Ma) and two (2523 and 462 Ma) main age populations, respectively. In comparison, the inherited zircons from the Jingziyu pyroxene lamprophyres yield two main age populations (2523 and 1848 Ma). The low-Ti lamprophyres are enriched in the light rare earth elements (LREE) and large-ion lithophile elements (LILE), depleted in the heavy REE (HREE) and high-field-strength elements (HFSE), and have small negative Eu anomalies. In comparison, the high-Ti lamprophyres are enriched in the LREE but are slightly depleted in the HFSE. The low-Ti lamprophyres also have high 87Sr/86Sr(t) ratios (0.7121–0.7123), low ε Nd (t) values (−18.81 to −18.62), and contain igneous zircons with relatively high ε Hf (t) values (generally between −9.94 and −3.36). In comparison, the high-Ti lamprophyres have 87Sr/86Sr(t) ratios of 0.7066–0.7068, ε Nd (t) values from −5.01 to −4.64, and contain igneous zircons with ε Hf (t) values from −11.77 to −8.50. These data indicate the low-Ti lamprophyres formed from primary magmas generated by the partial melting of an enriched region of the lithospheric mantle that was previously strongly modified jointly by subduction breakoff of the downgoing Yangtze Craton basement material and delamination of the lower continental crust within the NCC. In comparison, the magmas that formed the high-Ti lamprophyres were generated by the partial melting of an enriched region of the lithospheric mantle that was weakly modified by interaction with the lower continental crust of the NCC. Both the low- and high-Ti lamprophyres formed in an extensional tectonic environment during lithospheric thinning, and the presence of these two suites of lamprophyres indicates that lithospheric thinning of the eastern NCC peaked during the Early Cretaceous. • Low- and high-Ti lamprophyres in the western Shandong area formed during the Early Cretaceous. • These lamprophyres indicate that peak lithospheric thinning of the eastern NCC occurred during the Early Cretaceous. • Delamination was an important process during the destruction of the NCC. [ABSTRACT FROM AUTHOR]

Controversy has long surrounded the tectonic framework and evolution of the Mudanjiang Ocean between the Bureya-Jiamusi-Khanka Massif and Songnen-Zhangguangcai Range Massif, which are located in the easternmost segment of the Central Asian Orogenic Belt. To address these issues, we present zircon U-Pb ages, geochemical data, and zircon Hf isotopic compositions of the Taipinggou amphibolite and metagabbro exposed along the boundary area of Bureya-Jiamusi Massif and Songnen-Zhangguangcai Range Massif. Magmatic zircons from the amphibolite and metagabbro yield 206Pb/238U ages of 267 ± 2 Ma and 264 ± 2 Ma, respectively, which are interpreted as protolith ages. The geochemical data of the amphibolite samples show transitional characteristics of calcalkaline to tholeiitic series, with high MgO concentrations (9.44-10.48 wt.%) and Mg-numbers (73-75). These samples are enriched in large ion lithophile elements (e.g. Rb, Ba, and K) and light rare earth elements and are depleted in high-field-strength elements (e.g. Nb, Ta, and Ti) and heavy rare earth elements, with εHf(t) values of −6.63 to −3.26. It is inferred that the parental magma originated from an enriched lithospheric mantle that had been metasomatized by fluids derived from subducted oceanic slab. During magma evolution, the magma that formed the amphibolite mainly experienced accumulation with a shallow-level evolutionary process involving fractional crystallization. The Taipinggou metagabbro samples are subalkaline series and also characterized by enrichment in large ion lithophile elements (e.g. Rb, Ba, and K) and light rare earth elements and by depletion in Nb-Ta-P-Ti, with εHf(t) values of −3.09 to +1.16. The Taipinggou metagabbro and amphibolite have similar geochemical and Hf isotopic compositions, indicating a common parental magma source but with different degrees of magmatic differentiation. Based on the new geochronological and geochemical data presented in this study, we propose that both the Taipinggou metagabbro and amphibolite formed in a Middle Permian continental arc setting, closely related to eastward subduction beneath the Bureya-Jiamusi Massif. Combined with previous studies and regional geological observations, we suggest that a double-side subduction model is favoured for the Late Palaeozoic-Early Mesozoic geodynamic processes along the boundary area of Bureya-Jiamusi-Khanka Massif and Songnen-Zhangguangcai Range Massif. [ABSTRACT FROM AUTHOR]

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In this paper we present geochemical, zircon U–Pb and Hf isotopic data on the late Paleozoic volcanic rocks of the Dashizhai Formation, which are exposed along the northwestern margin of the Songnen terrane in eastern Inner Mongolia. Our aim is to constrain the petrogenesis and tectonic setting of the volcanic rocks and to unravel the late Paleozoic tectonic evolution of the northwestern part of the Songnen terrane, along the eastern segment of the Central Asian Orogenic Belt. Lithologically, the Dashizhai Formation is composed mainly of rhyolitic tuff, rhyolite, dacite, andesite, basaltic andesite and basalt, with minor basaltic trachyandesite. The zircons separated from these rocks are euhedral–subhedral, have high Th/U ratios (0.2–1.6), and display broad oscillatory growth zoning, indicating a magmatic origin. The results of zircon U–Pb dating indicate the volcanic rocks formed during the early Permian (295–283 Ma). Geochemically, these volcanic rocks belong to the mid-K to high-K calc-alkaline series and are characterized by an enrichment in large ion lithophile elements (LILEs) and a depletion in high field strength elements (HFSEs, such as Nb, Ta, and Ti), similar to igneous rocks that form in active continental margin settings. Most magmatic zircons of the rhyolites show positive ε Hf (t) values (+ 3.65 to + 13.0) and two-stage model ages (T DM2 ) of 1396–551 Ma. These geochemical characteristics indicate that the acidic volcanic rocks of the Dashizhai Formation were most likely derived from the partial melting of dominantly juvenile crustal components with a possible addition of “old” materials. In contrast, the basic to intermediate volcanic rocks were derived from the partial melting of a depleted lithospheric mantle that had been metasomatized by fluids derived from a subducted slab. These data, together with regional geological investigations, suggest that the generation of the early Permian volcanic rocks of the Dashizhai Formation was related to the southward subduction of the Paleo–Asian oceanic plate beneath the Songnen terrane. This also implies that the terminal collision between the Songnen and Xing'an terranes did not occur before the early Permian. [ABSTRACT FROM AUTHOR]

The Jiamusi–Khanka Block, located in the easternmost segment of the Central Asian Orogenic Belt (CAOB), is one of the least understood blocks in northeastern China. The age of its basement, the timing of the high-grade metamorphism, and the tectonic affinity of this block have all been subjects of controversy. Here we describe newly discovered Neoproterozoic orthogneisses from the Mishan region in the central Jiamusi–Khanka Block. SIMS and LA–ICP–MS U–Pb dating of the magmatic cores of zircons from three of these high-grade orthogneisses yielded weighted mean ages that range from 898 ± 4 to 891 ± 13 Ma, indicating that early Neoproterozoic magmatism did occur in the Jiamusi–Khanka Block. Twenty-two analyses of metamorphic zircons (rims as well as some grains) gave two groups of concordant ages, one at ca. 563 Ma, interpreted as the timing of the high-grade metamorphism, and the other around 518–496 Ma, interpreted as representing a subsequent retrograde metamorphism. The orthogneisses represent metamorphosed peraluminous syn-collisional syenogranites with SiO 2 = 71.29–78.08 wt%, A/CNK = 1.06–1.99, and Na 2 O/K 2 O = 0.03–1.49, and they belong chemically to the high-potassium calc-alkaline series. They have low Sr (32–134 ppm) contents and Sr/Y ratios (1.6–16.9), and display strongly fractionated to nearly flat REE patterns with negative Eu anomalies (δEu = 0.22–0.95) and depletions in Nb–Ta. These geochemical characteristics suggest that the syenogranitic rocks were derived under low pressures from a crustal source with a high proportion of sedimentary rocks, perhaps in a subduction-related setting that was undergoing transition from compression to extension. In the context of the reconstruction of Gondwana, the ca. 898–891 Ma magmatic activity and the ca. 563 Ma high-grade metamorphism in the Mishan region provide constraints on the possible linkages between the Jiamusi–Khanka Block and East Gondwana during the Neoproterozoic to early Paleozoic. [ABSTRACT FROM AUTHOR]

We report zircon U–Pb age data, Hf isotopes, and bulk-rock geochemical data for the Middle to Late Triassic granitoids in the Taerqi-Chabaqi-Kutihe region within the Xing’an Block of the central Great Xing’an Range, northeast China. Euhedral to subhedral zircon grains were extracted from the nine representative granitoids. These zircons exhibit oscillatory zoning typical of a magmatic origin. The zircon U–Pb determinations on the monzogranite, syenogranite and quartz diorite samples yielded ages between 244 Ma and 206 Ma, which essentially suggests that the magmatism in the Xing’an Block occurred during the Middle to Late Triassic period. Geochemically, these granitoids have SiO 2 = 62.97–76.31 wt%, A/CNK = 1.03–1.51, and K 2 O/Na 2 O = 0.40–2.39, we infer that they belong to high-K calc-alkaline series and are peraluminous I-type granites in nature. The major and trace element systematics indicate that these granitoids have different origins. Among them, the 244 Ma syenogranite of Taerqi and the 230–206 Ma monzogranite and syenogranite of Kutihe were probably generated from partial melting of pre-existing juvenile arc-type rocks in a relatively shallow crustal level. The 210 Ma quartz diorite of Chabaqi likely originated from the hybridization between a depleted mantle component and the juvenile subducted oceanic crustal materials that were buried to depths of the middle to lower continental crust. The 212 Ma monzogranite and syenogranite of Kutihe were probably generated from the partial melting of miscellaneous lower crustal materials at high pressure conditions. By combining these new data with regional geological data, we conclude that the early Mesozoic evolution of the central Great Xing’an Range was governed by two superimposed tectonic regimes, i.e., (1) post-orogenic extension due to slab break-off after the closure of the Paleo-Asian oceanic basin along the Hegenshan-Heihe suture belt, and (2) back-arc extension associated with the southward subduction of Mongol-Okhotsk oceanic plate. [ABSTRACT FROM AUTHOR]

This study presents new whole-rock major and trace element geochemistry, zircon U–Pb ages, and Hf-isotope compositions for volcanic rocks from the Manketouebo Formation of the central Great Xing’an Range, NE China. These data provide precise ages and information on the petrogenesis and source of the magmas that formed this formation, furthering our understanding of the geodynamic setting of the large-scale late Mesozoic magmatism in the Great Xing’an Range and other areas in NE China. The Manketouebo Formation in the study area is dominated by rhyolites and rhyolitic tuffs with minor trachydacites. The LA-ICP-MS zircon U–Pb dating indicates that these volcanic rocks formed between 143 and 139 Ma. The volcanic rocks contain high silica (66.70–79.91 wt.%) and total alkali (5.93–9.72 wt.%) concentrations, and low concentrations of MgO (0.08–1.15 wt.%), total FeO (0.68–4.50 wt.%), and CaO (0.10–2.56 wt.%). They are enriched in large-ion lithophile elements (LILEs; e.g. Rb, Th, and U) and light rare earth elements (LREEs), and depleted in high field strength elements (HFSEs; e.g. Nb, Ta, Ti, and P) and heavy rare earth elements (HREEs), indicating that they are similar to highly fractionated I-type igneous rocks. All of the magmatic zircons from the analysed samples have high initial176Hf/177Hf ratios (0.282900–0.283093), positiveεHf(t) values (7.48–14.19), and young Hf two-stage model ages (954–344 Ma) that suggest the primary magma that formed the volcanic rocks of the Manketouebo Formation was derived from the partial melting of Neoproterozoic to Phanerozoic juvenile crustal material, indicating in turn that significant crustal growth occurred at this time within the Xing’an Terrane. These data, combined with previous research into the spatial–temporal distribution of Mesozoic volcanic rocks in NE China, suggest that the Early Cretaceous magmatism in the Great Xing’an Range was influenced by both the subduction of the Palaeo-Pacific Plate and the closure of the Mongol–Okhotsk Ocean. This was a crucial period in the transformation from the Mongol–Okhotsk Ocean to the Palaeo-Pacific tectonic regimes. In summary, the early stages of Early Cretaceous magmatism in this area were related to the closure of the Mongol–Okhotsk Ocean, whereas the later stages of magmatism in this area and elsewhere in NE China were related to the subduction of the Palaeo-Pacific Plate. [ABSTRACT FROM PUBLISHER]

Whole-rock major and trace element geochemistry together with zircon U–Pb ages and Lu–Hf isotope compositions are reported for a Late Triassic intrusive complex in the Jidong region, Jiamusi–Khanka Block, NE China. Zircon U–Pb dating yields ages between 211 and 208 Ma for enclaves of microgranular diorite and quartz diorite, and between 211 and 209 Ma for the host granitoids. These ages correlate with a previously established intensive Late Triassic magmatic event along the eastern Asian margin. Field observations, together with petrographic features, geochemistry, and zircon Hf isotope data, preclude simple crystal fractionation or restite unmixing as a genetic link for the various rock types within the intrusive complex. The syenogranite suite has high SiO 2 (75.5–76.3 wt.%) and low MgO (0.15–0.19 wt.%), and yields enriched LILE and LREE patterns. Most of the zircons in the syenogranites have two-stage model ages of 766 and 1461 Ma, together with positive ε Hf (t) values of + 0.6 to + 9.1. These results indicate that the granitoid magmas were generated by partial melting of Meso- to Neoproterozoic lower crust. The gabbro suite has a restricted range of SiO 2 (46.1–51.9 wt.%) together with high Mg# values (49–70) and high concentrations of Ni, Co, and Cr. Zircons from two diorite samples have single-stage Hf model ages of 557–787 Ma and ε Hf (t) values of + 1.9 to + 8.3 that are consistent with the coeval gabbros previously studied in the Jidong region. These features, together with the observation that all the gabbros are enriched in LREE and LILE, suggest that the mafic magmas were derived from melting of depleted Neoproterozoic lithospheric mantle that had been metasomatized by slab-derived fluids. It is concluded that the dominant igneous suites within the Late Triassic intrusive complex formed by mingling/mixing of felsic and mafic magmas. The geochemical data, combined with regional geological investigations, indicate that the Late Triassic intrusive complex formed during lithospheric extension caused by slab break-off of the Yuejinshan oceanic plate that was subducting westward beneath the Jiamusi–Khanka Block. [ABSTRACT FROM AUTHOR]

The Mingshui–Jilasitai–Suolun area, located in the central part of the Great Xing’an Range, is characterized by large volumes of alkali feldspar granites. However, the formation time and tectonic setting of these rocks remains controversial owing to a lack of precise geochronological and detailed geochemical data. In this paper, we report new SIMS U–Pb zircon ages and mineralogical, petrographical and geochemical data for Lower Cretaceous alkali feldspar granites from the Mingshui–Jilasitai–Suolun area. The SIMS zircon dating results indicate that these granites formed at 133.6–135.9 Ma. The mineralogical, petrographical and geochemical data show that these granitic rocks belong to highly fractionated I-type granites. Combined with the regional geology data, we propose that the formation of the Lower Cretaceous alkali feldspar granitic rocks was related to an extension induced by delamination of the lithosphere that arose from subduction of the Palaeo-Pacific plate. [ABSTRACT FROM AUTHOR]

Humans have had a significant impact on the terrestrial pedosphere through activities such as agriculture and urbanization. The effects of human activities on land use and the related environmental changes were investigated through point and areal studies surrounding Meiliang Bay, which is an open area of extreme eutrophication in Taihu Lake, China. This study used remote sensing and environmental-tracer profiles [total nitrogen (TN), total phosphorus (TP), total organic carbon (TOC), grain size, and geochemical parameters] to determine the causes of changes in land use and the associated environmental parameters. The results of LUCCs (Land use/cover changes) indicate that over the past three decades, total farmland decreased by 862.49 km2, with an annual decrement rate of 28.75 km2/year, and total urbanized land increased by 859.71 km2, with an annual growth rate of 28.66 km2/year. The geochemical results indicate that the trophic state of Taihu Lake was persistently intensifying and that the TN, TP, and TOC concentrations increased twofold, threefold, and twofold, respectively, from 1949 to 2010. The sources of TN, TP, and TOC were highly similar after 1975. However, before 1974, TN and TP originated from different sources than TOC. The grassland and woodland around the lake retain nutrients and sand from the land of study area. The increase in urbanized land and tertiary industries significantly increased the sediment concentrations of TN, TP, and TOC after 1980. [ABSTRACT FROM AUTHOR]

To constrain the early Paleozoic tectonic evolution of the Jiamusi–Khanka Block and its relationship to the Late Pan-African event in Gondwana, we undertook zircon U–Pb dating and geochemical analyses (major and trace elements, and Hf isotopic compositions) of early Paleozoic intrusive rocks in the Jiamusi–Khanka Block, NE China. LA-ICP-MS zircon U–Pb age data demonstrate that these intrusive rocks were emplaced at three stages during the Late Pan-African event, represented by ~ 540 Ma syenogranite, ~ 515 Ma quartz syenite, and ~ 500 Ma monzogranite and gabbro. Geochemically, the ~ 500 Ma gabbros in the Jiamusi–Khanka Block have low SiO 2 (50.26–51.21 wt.%), relatively high MgO (4.08–5.67 wt.%), Ni (13.1–14.1 ppm) and Cr (28.4–56.0 ppm), and are slightly enriched in LILEs (e.g., Ba, K) and LREEs, and depleted in Zr, Hf, Nb, Ta and P. The ε Hf (t) values of zircons in the gabbro range from + 2.6 to + 6.4. All these geochemical features indicate that the gabbros were likely produced by the partial melting of a depleted mantle that had been metasomatized by fluids derived from a subducted slab. In contrast, the ca.540–500 Ma granites and quartz syenites contain high SiO 2 (64.49–72.20 wt.%) and low MgO (0.40–0.75 wt.%), Cr (1.69–6.88 ppm) and Ni (1.26–3.26 ppm). They have relatively low 176 Hf/ 177 Hf ratios of 0.282247–0.282599 with Hf two-stage model ages of 1173–2280 Ma, and most of the magmatic zircons have positive ε Hf (t) values varying from + 0.2 − + 4.8, indicating that these granites and quartz syenites were probably derived from a dominantly Paleo–Mesoproterozoic “old” crustal source with possible different degrees of addition of juvenile materials. According to the geochemical data and global geological investigations, we propose that the 541–498 Ma intrusive rocks in the Jiamusi–Khanka Block formed in a post-collisional or post-orogenic extensional setting linked to the collapse of a Late Pan-African orogen associated within the Gondwana. [ABSTRACT FROM AUTHOR]

Diabase swarms widely intrude the late Paleoproterozoic to Mesoproterozoic sedimentary rocks in the northern margin of the North China Craton (NCC). In this paper, we present new baddeleyite SIMS Pb–Pb ages and whole-rock geochemical data for representative samples of the diabase swarms intruding the Mesoproterozoic Wumishan and Xiamaling formations in the western Liaoning region. Our aim is to elucidate the age and origin of the diabase swarms and their relationship to the fragmentation of the Columbia supercontinent. The baddeleyite SIMS Pb–Pb dating results show emplacement ages varying from 1325.9 ± 4.1 Ma to 1318.6 ± 3.7 Ma, indicating voluminous basic magmatism leading to the generation of the diabase swarms during the Mid-Mesoproterozoic time. Geochemically, the Mesoproterozoic diabasic rocks have relatively low REEs contents and show weak positive Eu anomalies. Moreover, these diabase samples are characterized by enrichment in light rare earth elements (LREEs), large ion lithophile elements (LILEs; e.g., Rb and Pb) and some high field strength elements (HFSEs; e.g., Th, U, Zr, Ti and Hf), and depletion in heavy rare earth elements (HREEs) and several high field strength elements (HFSEs; e.g., Nb, Sm, Gd and P), with affinities to basalts belonging to within-plate tholeiite series. Taken together, these geochemical characteristics suggest that the primary magmas of the diabases in the western Liaoning region could have been derived by partial melting of a transitional mantle or slightly enriched mantle in a continental extensional setting. In the context of assembly, growth and breakup of the Columbia supercontinent, together with the recognition of large volumes of ∼1.32 Ga diabase swarms in the northern NCC as well as the nearly coeval rift-related anorogenic magmatism recorded elsewhere on the globe, such as Africa, Baltica, Siberia, North America and Greenland, we conclude that the northern margin of NCC experienced the global-scale Mid-Mesoproterozoic rifting events, corresponding to the final breakup of the Columbia supercontinent, probably at around 1.32 Ga. [ABSTRACT FROM AUTHOR]

• 937–933 Ma and 896–891 Ma magmatism occurred in the Bureya Block. • 937–891 Ma magmatic rocks formed in a continent arc setting. • The Bureya Block has an affinity to the northwestern margin of Rodinia. The Bureya Block, located in the easternmost segment of the Central Asian Orogenic Belt (CAOB), is one of the least understood blocks in Russian Far East. Here we describe newly discovered Neoproterozoic magmatic rocks along the Bureya River in the northern Bureya Block. LA–ICP–MS zircon U–Pb dating demonstrates that these rocks were emplaced in two stages during the early Neoproterozoic: (1) 937–933 Ma, forming an intrusive rock association of gabbros, granodiorites, and monzogranites; and (2) 896–891 Ma, representing by a suite of syenogranites. The good correlation on the Neoproterozoic to Late Triassic geological events between the Jiamusi and Bureya blocks suggests the two blocks formed a contiguous crustal unit. Field observations, together with petrographic and geochemical features, and zircon Hf isotopic data, indicate a magma mixing/mingling origin for the 937–933 Ma gneissic granitoids and amphibolites, with the felsic melts generated by partial melting of a dominantly Mesoproterozoic lower crustal source with possible little addition of ancient crustal materials, whereas the mafic melts were derived from partial melting of a depleted lithospheric mantle wedge metasomatized by fluids dehydrated from the subducted oceanic slab. In addition, the 896–891 Ma syenogranites share a common crust source with the 937–933 Ma granitoids but experienced extensive assimilation and fractional crystallization during magma ascent and evolution. In the context of assembly, growth and breakup of the Rodinia supercontinent, together with the recognition of Neoproterozoic continental arc-type magmatic rocks in the Bureya–Jiamusi Block as well as the nearly coeval subduction-related magmatism recorded elsewhere on the globe, such as Seychelles, Madagascar, India, Lhasa, South China, and Australia, we conclude that the 937–891 Ma magmatism in the Bureya Block resulted from the Andean-type orogeny that formed along the northwestern margin of the Rodinia supercontinent. [ABSTRACT FROM AUTHOR]

Abstract This study presents new zircon U-Pb geochronological, whole-rock geochemical, and zircon Hf isotopic data along with regional geological observations for five late Paleozoic granitic plutons within the Xing'an Block of northeastern China. These data provide insights into the petrogenesis of these granitoids and the late Paleozoic tectonic evolution of the region. The geochronological and geochemical data indicate that the intrusions were emplaced during two separate periods, with the resulting granites having distinct geochemical features. The early Late Carboniferous (321–310 Ma) granitic Lizishan (LZS), Xiaonangou (XNG), and Dabeigou (DBG) plutons have high Sr/Y values (33.15–126.73), with low concentrations of Y and heavy rare earth elements (HREE), indicating adakitic affinities. However, the XNG granodiorites contain higher concentrations of MgO, Cr, and Ni, and have higher Mg# values (57–59) than the other plutons. The latest Carboniferous–Early Permian (301–296 Ma) granitic Weilegesi (WLGS) and Wuyi (WY) plutons are high-K calc-alkaline, with low Sr/Y ratios (0.18–24.15), and show petrological and geochemical characteristics of I-type granites. In addition, the magmatic zircon crystals within these plutons yield positive ε Hf (t) values (+4.1 to +12.9) and juvenile two-stage model (T DM2) ages (1056–499 Ma). The timing of emplacement and geochemical and isotopic compositions of the LZS and DBG granitoids are indicative of derivation from magmas generated by the partial melting of thickened lower crustal material, whereas the XNG granitoids were most likely formed from magmas generated by the partial melting of delaminated lower crustal material that subsequently interacted with mantle material during ascent. The latest Carboniferous–Early Permian low-Sr/Y granitoids may have formed from magmas generated by the partial melting of a dominantly juvenile amphibolite-facies crustal source under relatively low-pressure conditions, with these magmas subsequently undergoing variable degrees of fractional crystallization. Combining these new data with the results of previous research indicates that the terminal collision between the Xing'an and Songliao blocks occurred between the late Early and early Late Carboniferous, and the voluminous Late Carboniferous to Early Permian granitoids in the Xing'an Block are most likely related to post-collisional delamination. Graphical abstract Unlabelled Image Highlights • Late Paleozoic high- and low-Sr/Y granitoids are identified in the Xing'an Block. • The collision between the Xing'an and Songliao blocks occurred during ~330–310 Ma. • Late Carboniferous–Early Permian magmatisms formed by post-collisional delamination. [ABSTRACT FROM AUTHOR]

We report zircon U–Pb ages and geochemistry (major and trace elements, mineral compositions, and Hf isotopic compositions) for the Hailin pluton in the southeastern Songnen–Zhangguangcai Range Massif, northeastern China, to constrain the role of magma mixing in its petrogenesis and to reconstruct the tectonic evolution of the Mudanjiang Ocean. Zircon U–Pb dating yields ages of 215 ± 1 Ma, 217 ± 1 Ma, and 219 ± 1 Ma for the host granitoids of the Hailin pluton, and 221 ± 1 Ma for mafic microgranular enclaves (MMEs) within the granitoids, indicating they were emplaced coevally. The host granitoids are characterized by 63.18–70.44 wt% SiO 2 and 0.69–1.94 wt% MgO, and are depleted in high field strength elements (HFSEs; e.g., Nb, Ta, and Ti) and heavy rare earth elements (HREEs), and enriched in large ion lithophile elements (LILEs; e.g., Rb, Sr, and Ba) and light rare earth elements (LREEs). The zircons in the host granitoids yield two-stage model ages of 1058 Ma to 1770 Ma, together with ε Hf (t) values of −6.6 to +3.1. These results indicate that the host granitoid magmas were generated by partial melting of Mesoproterozoic lower crust contaminated by ancient crustal material. The MMEs have a restricted SiO 2 range (47.61–57.4 wt%), high contents of Ni, Co, and Cr, and high Mg # values (42–54). They have higher Fe 2 O 3 T , MgO, Cr and Co contents than the host granitoids, as well as higher total rare earth element (REE) concentrations. Their REE patterns are sub-parallel to those of the host granitoids, characterized by enrichments in LILEs and LREEs, and depletions in HFSEs and HREEs. Zircons from two samples of the MMEs yield single-stage Hf model ages of 666–1077 Ma and ε Hf (t) values of −5.4 to +5.2. The geochemical characteristics of the MMEs are similar to those of the host granitoids, indicating crust-mantle interaction during their formation. The mafic magmas were derived from melting of depleted lithospheric mantle that had been metasomatized by slab-derived fluids. MMEs are common in the host granitoids and are characterized by irregular spheroidal shapes, with sharp, rounded, or irregular transitional contacts, acicular apatites, and plagioclase reverse zoning, suggesting the importance of magma mixing during petrogenesis. Our geochemical and isotopic data suggest that the Late Triassic Hailin pluton formed by the mixing of felsic and mafic magmas in an active continental margin setting, closely related to the westward subduction of the Mudanjiang oceanic plate beneath the Songnen–Zhangguangcai Range Massif. [ABSTRACT FROM AUTHOR]

We report geochronological, whole-rock geochemical, and zircon Hf isotopic data for Late Jurassic rhyolites in the central Great Xing’an Range of northeastern China, to determine their petrogenesis, source, and tectonic setting. Laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) zircon U–Pb ages indicate that the rhyolites previously mapped as the lower Permian Dashizhai Formation in the Wuchagou region formed during the Late Jurassic (162–154 Ma). Geochemically, these rhyolites belong to the mid- to high-K calc-alkaline series and show peraluminous characteristics and consistent correlations between major elements and SiO 2 . They are characterized by enrichments in large ion lithophile elements (LILEs; e.g., Rb and K) and light rare earth elements (LREEs), and depletions in high field strength elements (HFSEs; e.g., Nb, Ta, and Ti) and heavy rare earth elements (HREEs). In situ Hf isotopic analyses of zircons from the rhyolites reveal relatively homogeneous Hf isotopic compositions, with ε Hf (t) values of +4.84 to +9.44, and two-stage model ages of 606–895 Ma. Based on their eruption ages, geochemical characteristics, and Hf isotopic compositions, we conclude that the magmas that formed the Late Jurassic rhyolites were produced during partial melting of a Neoproterozoic quartz-bearing amphibolite-facies mafic crust. These magmas subsequently underwent extensive fractional crystallization of plagioclase, hornblende, Ti-bearing phases, monazite, and apatite. Combined with previous data, our results demonstrate that the Late Jurassic volcanic rocks in the Great Xing’an Range were formed in a post-collisional extensional setting. The gravitational collapse of the orogenically thickened crust was caused by break-off of the subducted oceanic slab and upwelling of asthenosphere after closure of the Mongol–Okhotsk Ocean. [ABSTRACT FROM AUTHOR]

The Yuejinshan Complex, a remnant of the late Paleozoic western Paleo-Pacific Ocean, is located between the Jiamusi Massif and the Nadanhada Terrane in NE China. The complex consists of strongly deformed metaclastic rocks, marbles and metabasaltic lavas. The basalts have undergone hydrothermal alteration, greenschist facies regional metamorphism, and surface oxidation. These rocks can be divided into two broad rock groups based on whole-rock geochemical and Sr–Nd isotopic characteristics: (1) mid-ocean ridge basalt (MORB-type) tholeiites that range in composition from light rare earth element (LREE)-depleted varieties (N-MORB; (La/Sm) N < 1), showing highly positive ε Nd (t) ratios (+10.2 to +10.5), to LREE-enriched tholeiites (E-MORB; (La/Sm) N > 1); and (2) ocean island basalt (OIB-type) alkaline lavas, characterized by less positive ε Nd (t) ratios (+6.20 to +8.61), with significant enrichments in LILE, HFSE, LREE, and MREE, and slight depletions in HREE, relative to average N-MORB. Trace element and isotope systematics indicate that the tholeiitic basaltic rocks were derived from partial melting of a depleted MORB source in the spinel facies mantle, whereas the source of the E-MORB was a depleted MORB mantle (DMM) source significantly enriched by OIB-type components. In contrast, the alkaline basalts were generated from an enriched OIB-type mantle source in the garnet facies and continued melting to spinel facies mantle depths. Therefore, the mafic volcanic rocks of the Yuejinshan Complex, located above the oceanic plate of the Paleo-Pacific Ocean, were most likely derived from chemically heterogeneous mantle sources during back-arc basin spreading and plume-related volcanism. The westwards subduction of the Paleo-Pacific Ocean lithosphere during the late Carboniferous to middle Permian resulted in the back-arc lavas, seamounts, and other oceanic fragments accreting onto the eastern Jiamusi Massif, forming the Yuejinshan Complex. [ABSTRACT FROM AUTHOR]

We present new in situ zircon U–Pb and Hf isotope, whole-rock geochemical, and Sr–Nd isotopic data for volcanic rocks from the Jiejinkou and Baoqing areas in the eastern Jiamusi Massif. These volcanic rocks are bimodal and consist of basalts, basaltic andesites, rhyolites, and rhyolitic tuffs that can be subdivided into mafic and silicic groups. Zircon U–Pb dating by LA-ICP-MS indicates that these volcanic rocks were erupted between the Early and Middle Permian (290–267 Ma). The mafic rocks in this area have positive ε Nd (t) (+0.07 to +6.43) values, and are enriched in light rare earth elements (LREEs) and depleted in heavy REE, Nb, and Ta. From these rocks, the meta-basalt of Jinlu and basaltic andesite of Taipinggou and Haojiatun were derived from parental magmas generated by the partial melting of depleted mantle wedge material that was metasomatized by subduction-related melts. These magmas then underwent variable degrees of fractional crystallization and assimilated insignificant amounts of crustal material. The meta-basalt of Liming likely originated from the metasomatized mantle-derived melts hybridized by the convective asthenosphere during the evolution of the magmas. In comparison, the silicic rocks have negative ε Nd (t) and variable zircon ε Hf (t) values, are enriched in the large-ion lithophile elements (LILEs) and LREE, and are depleted in high-field-strength elements (e.g., Nb, Ta, and Ti), yielding arc-like geochemical signatures. The geochemical and zircon ε Hf (t) characteristics of Jiangfeng and Longtouqiao rhyolites are indicative of formation from magmas generated by the partial melting of mafic lower crustal material, whereas the Liming meta-rhyolite was probably produced from a source involving some depleted mantle components. The bimodal volcanic rocks provide convincing evidence that the Early–Middle Permian volcanism in the Jiamusi Massif occurred in an extensional environment probably associated with slab break-off during the westward subduction of the Paleo-Pacific oceanic plate. [ABSTRACT FROM AUTHOR]

This paper presents zircon U-Pb ages, whole-rock major and trace element data, and Hf isotope data for the metagabbros from the Zhushan pluton and gabbros from the Taiping pluton along the boundary area of Jiamusi and Songnen-Zhangguangcai Range massifs and adjacent regions, which will not only place important constraints on the rock-forming ages, source characteristics and tectonic setting of these gabbros, but will also provide insights into understanding the Permian tectonic evolution between the Jiamusi Massif and the Songnen-Zhangguangcai Range Massif. Zircon U-Pb dating, determined using laser ablation-inductively coupled plasma-mass spectrometry and secondary-ion mass spectrometry, indicates that the magmatic zircons from the Zhushan and Taiping plutons yield 206 Pb/ 238 U ages of 256 ± 2 Ma and 259 ± 3 Ma, respectively, interpreted as the emplacement ages of the intrusions. The metagabbros from the Zhushan pluton display the geochemical characteristics of calc-alkaline series rocks, and are enriched in light rare earth and large ion lithophile elements, and depleted in Nb, Ta, P, Zr and Hf. The ε Hf (t) values of magmatic zircons in these metagabbros vary from − 5.47 to + 0.74. All these geochemical features indicate that the primary magma of the Zhushan pluton was derived from an enriched lithospheric mantle source that was metasomatized by subducted slab-derived fluids. The gabbros from the Taiping pluton are also enriched in large ion lithophile elements (e.g., Rb, Ba and U) relative to high field strength elements, and have negative Nb-Ta-P anomalies, with ε Hf (t) values of − 4.02 to − 1.70. It is inferred that they also formed from a primary magma generated by the partial melting of enriched lithospheric mantle that was metasomatized by subducted slab-derived fluids. The rocks from the Zhushan and Taiping plutons have similar petrogenetic processes, but their primary magmas are likely to be derived from two distinct magma sources based on geochemical and isotopic compositions. According to zircon U-Pb ages, geochemical data, Hf isotope data and regional geological investigations, we conclude that the generation of the metagabbros in the Zhushan pluton was most likely related to westward subduction of the Mudanjiang oceanic plate beneath the Songnen-Zhangguangcai Range Massif, and the gabbros from the Taiping pluton were the result of eastward subduction of the Mudanjiang oceanic plate beneath the Jiamusi Massif. Hence, we suggest that the Jiamusi Massif and Songnen-Zhangguangcai Range Massif were not amalgamated before the Late Permian. [ABSTRACT FROM AUTHOR]

Late Carboniferous–middle Permian magmatism in the Jiamusi Massif of northeast China, in the eastern segment of the Central Asian Orogenic Belt (CAOB), provides critical evidence regarding the tectonic history and geodynamic processes in the region. The gabbro–diorites of the Longtouqiao pluton and two groups of coeval granite in the study area comprise a bimodal magmatic suite. Precise LA-ICP-MS U–Pb zircon ages indicate that the granitoids and gabbro–diorites were emplaced in the late Carboniferous–middle Permian (302–267 Ma). Group I granites have high SiO 2 (70.75–77.04 wt.%) and K 2 O (3.65–5.89 wt.%) contents, are enriched in LILEs (e.g., Rb, Th, and U) relative to HFSEs and LREEs, and have negative Nb, Ta, P, and Ti anomalies, which collectively indicate affinities with subduction-related magmas. Group II granites are weakly peraluminous (A/CNK = 1.03–1.07) and are characterized by enrichment in alkalis (Na 2 O + K 2 O = 8.22–8.90 wt.%), low MgO (0.04–0.09 wt.%) and P 2 O 5 (0.01–0.04 wt.%) contents, high Zr and Nb contents, high 10,000 × Ga/Al ratios, and they are geochemically similar to aluminous A-type granites. All the magmatic zircons in these granitoids have great variations of ε Hf (t) (+ 7.89 to − 5.60) and two-stage Hf model ages ( T DM2 ) of 0.8–1.7 Ga, which suggest that the precursor magmas originated from a heterogeneous source that involved juvenile components derived from a depleted mantle source during magma generation. The aluminous A-type granite magmas were probably derived by high-temperature partial melting of a felsic crustal source, whereas the other granite magmas probably resulted from partial melting of a mafic lower crust. The gabbro–diorites of the Longtouqiao pluton are depleted in Nb, Ta, P, and Ti, and show flat distributions of most LILEs and HFSEs, except for large positive anomalies in Ba, K, and Pb. These features reflect a limited degree of crustal contamination associated with the subduction-related magmatic processes. These data, together with previously reported data and the nature of various rock types along the eastern part of the Jiamusi Massif, suggest that the intrusive rocks were formed in a geodynamic regime that changed from compression to extension during the westwards subduction of the Paleo-Pacific oceanic lithosphere, probably as a result of slab break-off of the subducting plate. [ABSTRACT FROM AUTHOR]

• 1813–1789 Ma A-type granites were identified in southern NCC. • A-type granites originated from partial melting of TTG of Taihua Complex. • The A-type magmatism was in respond to the breakup of Columbia supercontinent in post-collisional setting. A-type granites are produced commonly in extensional settings and they are important proxies to track breakup of continent. Here we report systematic studies on geochronology and geochemical features of A-type granites in Songxian–Ruyang region, southern margin of the North China Craton (NCC), in order to constrain their petrogenesis and tectonic implications. Zircons from these granites show oscillatory zoning and high Th/U ratios (0.12 to 1.26), indicating a magmatic origin. LA–ICP–MS zircon U–Pb dating shows that they were emplaced at 1813 to 1789 Ma, indicating that they were formed in late Paleoproterozoic. Geochemically, these rocks are high in SiO 2 (67.51–74.42 wt%) and total alkalis (Na 2 O + K 2 O = 7.76–10.19 wt%), and low in MgO (0.09–1.31 wt%), CaO (0.09–1.11 wt%) and P 2 O 5 (0.12–0.26 wt%) contents, with negative Nb, Ta, Sr, P and Ti anomalies. They are characterized by high FeOT/(MgO + FeOT), 10000 Ga/Al ratios (1.57–3.15) and Zr + Nb + Ce + Y contents (566–835 ppm). They are also characterized by high calculated Zr saturation temperatures (892–918 °C), high Ti-in-zircon temperatures (693–912 °C) and metaluminous to weakly peraluminous natures, which are typical features of aluminous A-type granites, further belonging to the A 2 granites. The low zircon ε Hf (t) values (–13.8 to –8.6), along with the low whole rock ε Nd (t) values (–8.62 to –6.10) and low apatite ε Nd (t) values (–8.31 to –6.56), indicate that the Songxian–Ruyang A-type granites were derived from partial melting of the calc-alkaline tonalitic–trondhjemitic–granodioritic gneisses in Taihua Complex, and they were formed in post-collisional extensional setting. Combined with coeval regional granitoids, the south margin of the NCC is in a continuous extensional setting during 1.8–1.6 Ga, and the Songxian–Ruyang A-type granites can represent a response of the breakup of Columbia supercontinent. [ABSTRACT FROM AUTHOR]

Zircon U–Pb dating, whole-rock geochemistry, Hf isotopic compositions, and regional geological observations of Jurassic intermediate-acidic intrusions in the Xing’an Block, northeastern China, are presented to constrain their petrogenesis and the tectonic evolution of the Paleo-Pacific Ocean. Zircon U–Pb age dating indicates that the intrusions were emplaced in three stages: during the Early Jurassic (180–177 Ma), Middle Jurassic (171–170 Ma), and Late Jurassic (∼151 Ma). Despite the wide range in ages of the intrusions, the magmas of Jurassic acidic intrusions were likely derived from a similar or common source and experienced different degrees of magmatic differentiation, as inferred from their geochemical and Hf isotopic characteristics. The Jurassic acidic intrusions are characterized by high SiO 2 and total Na 2 O + K 2 O, low MgO, and I-type affinities, suggesting that the primary magmas were derived from partial melting of lower crustal material. These findings, combined with their ε Hf ( t ) values and two-stage model ages, indicate the primary magmas originated from partial melting of juvenile crustal material accreted during the Neoproterozoic to Phanerozoic. The Middle Jurassic intermediate-acidic rocks (diorites and granodiorites of the TJ pluton) have SiO 2 contents of 57.96–69.10 wt.%, MgO contents of 4.48–1.81 wt.%, and high Mg numbers (45–54). They are enriched in large ion lithophile elements (e.g., Rb, Ba, Th, U, and K) and light rare earth elements, depleted in high field strength elements (e.g., Nb, Ta, Zr, Hf, and Ti) and heavy rare earth elements, and have ε Hf ( t ) values of +6.5 to +9.1. These data suggest that the magma was derived from partial melting of a depleted mantle wedge that had been metasomatized by subduction-related fluids. According to these findings and previous studies that focused on contemporaneous magmatic–tectonic activity in northeastern China, we conclude that the generation of Jurassic intermediate-acidic intrusions in the Xing’an Block was related to subduction of the Paleo-Pacific oceanic plate. [ABSTRACT FROM AUTHOR]

This paper reports LA–ICP–MS zircon U–Pb ages, geochemical data and zircon Hf isotope compositions of gabbroic rocks, plagiogranites, and granite porphyries exposed at the eastern margin of the Jiamusi Massif in the easternmost segment of the Central Asian Orogenic Belt (CAOB). LA–ICP–MS zircon U–Pb age data indicate that these rocks were emplaced at 290–274, 277, and 110 Ma, respectively. The gabbroic rocks have low- and medium-K tholeiitic compositions, with variable MgO (3.92–12.59%) and low K 2 O (0.12–0.77%) and TiO 2 (0.59–1.37%) contents. They are enriched in large ion lithophile elements (e.g., Rb, Sr), depleted in high field-strength elements (e.g., Nb, Ta), and exhibit positive zircon ε Hf (t) values (3.1–13.8). It is inferred that the primary magmas of these rocks were derived from a depleted lithospheric mantle source that was metasomatized by subducted-slab-derived fluids shortly before their generation. In addition, the Dongfanghong gabbroic rocks have low Sr/Y (7.32–26.2) and (La/Yb) N (0.99–3.02) ratios, and high HREEs, Y, and Sc contents, indicating that the partial melting of lithospheric mantle occurred under relatively low-pressure conditions. The Early Cretaceous granite porphyries are metaluminous medium-K calc-alkaline I-type granites, where the primary magma originated from the partial melting of crustal material. Based on the new geochemical data and regional geological investigations, we propose that the Dongfanghong gabbroic complex and granite porphyry were both formed in an active continental margin setting, the former most likely related to westward subduction of the paleo-oceanic plate beneath the Jiamusi Massif, and the latter associated with westward subduction of the Paleo-Pacific plate beneath the Eurasian continent. The gabbros and the granite porphyries clearly represent two subduction-related crustal accretion events in the eastern part of the Jiamusi Massif since the late Paleozoic. [ABSTRACT FROM AUTHOR]

This paper reports geochronological, whole-rock geochemical and zircon Hf-isotopic data for the early Paleozoic granitic rocks in the Jiamusi Massif in the eastern segment of the Central Asian Orogenic Belt (CAOB), in order to investigate their precise geochronological framework, petrogenesis, sources and tectonic setting. LA-ICP-MS zircon U–Pb age data indicate that the syenogranite, monzogranite and granodiorite were emplaced during the period of 530–484 Ma. Geochemically, these granitoids have high SiO 2 (64.66–79.17%) and K 2 O (3.08–7.33%), low MgO (0.14–2.63%) and CaO (0.37–3.87%), with A/CNK and δEu values of 0.89–1.10 and 0.16–1.77, respectively. These rocks are characterized by enrichment in Rb and Nd, and depletion in Nb, Ta, P and Ti. In addition, in-situ Hf isotopic analyses of zircons from the granitic rocks reveal that they have ε Hf ( t ) = −5.8 to +2.3, with two-stage Hf model ages ( T DM2 ) varying from 1.3 Ga to 2.4 Ga, indicating that they probably originated from the partial melting of a dominantly “old” Paleo-Mesoproterozoic crustal source. Additionally, these granites have variable major and trace element concentrations. Magmatic zircons from these rocks record consistent homogeneous U–Pb ages but have heterogeneous ε Hf ( t ) values, reflecting that they resulted from fractional crystallization and crustal assimilation. Based on these geochemical data combined with regional geological investigations, we propose that the early Paleozoic granitic magmatism in the study area occurred in a post-collisional extensional setting, which was probably related to the collapse of a thickened crust. [ABSTRACT FROM AUTHOR]

This paper reports new whole–rock major– and trace–element and zircon U Pb and Hf O isotopic data for Early Cretaceous granitic rocks on Liaodong Peninsula, NE China, with the aim of constraining continental reworking in the northeastern North China Craton. On the basis of SiO 2 , MgO, and Sr contents and Sr/Y values, the rocks can be divided into three groups. The low–Mg adakitic rocks show zircon U Pb ages of (134–120 Ma), and high SiO 2 (67.11–71.14 wt%) and low MgO (0.53–0.62 wt%) contents, and high Sr (531–1108 ppm) contents, Sr/Y (29.3–132) ratios, with enriched Sr–Nd–Hf–O isotopic compositions, indicating an origin of thickened lower mafic crust. The high–Mg adakitic rocks show ages of (126–114 Ma) and are characterized by low SiO 2 (53.11–63.88 wt%) and high MgO (2.07–8.93 wt%) contents, and high Sr (391–1041 ppm) contents, Sr/Y (23.9–64.1) ratios, with relatively depleted Sr–Nd–Hf–O isotopic compositions, suggesting that they were derived from partial melting of delaminated lower mafic crust. The normal granitic rocks show ages of (127–121 Ma) and high SiO 2 (71.65–77.22 wt%) and low MgO (0.10–0.51 wt%) and Sr (12.1–309 ppm) contents, Sr/Y (0.89–24.5) ratios, with relatively depleted Sr–Nd–Hf–O isotopic compositions, suggesting an origin from lower mafic crust with normal crustal thickness. These constraints, combined with the regional occurrence of A–type granites, bimodal igneous rocks, and metamorphic core complexes, as well as the regional distribution of Mesozoic granitic rocks displaying a younging trend from southeast to northwest for the Jurassic rocks but a reverse trend for the Cretaceous rocks, recorded the roll–back of the Paleo–Pacific plate towards the Eurasian continental margin. [Display omitted] • Discovery of Early Cretaceous low– and high–Mg adakitic and normal granitic rocks on Liaodong Peninsula. • Reworking of lower crust with different properties occurred in Liaodong Peninsula. • The subducted Paleo–Pacific plate rolled back during Early Cretaceous. [ABSTRACT FROM AUTHOR]

Abstract: We present geochronological, geochemical, whole-rock Sr–Nd and zircon Hf–isotopic data for late Paleozoic volcanic rocks from the Daheshen Formation in central Jilin Province, northeastern China, and constrain the petrogenesis of the volcanic rocks and late Paleozoic tectonic evolution of the northern margin of the Northern China Craton, which is regarded as the eastern segment of the Central Asian Orogenic Belt (CAOB). Lithologically, the Daheshen Formation is composed mainly of rhyolite, rhyolitic tuff, dacite and andesite, with minor basalt. The zircons from three rhyolites, two dacites, one rhyolitic tuff and one basalt are euhedral–subhedral, display oscillatory zoning and have high Th/U ratios (0.50–2.28), implying a magmatic origin. LA–ICP-MS zircon U–Pb age data indicate that the volcanic rocks from the Daheshen Formation formed during Late Carboniferous–Early Permian time (302–299Ma). Geochemically, late Paleozoic volcanic rocks have SiO2 =52.13–81.77wt.% and K2O=0.86–6.88wt.%, belonging to mid-K to high-K calc-alkaline series. These rocks are characterized by enrichment in large ion lithophile elements (LILEs) and light rare earth elements (LREEs), and depletion in high field strength elements (HFSEs, such as Nb, Ta, and Ti) and heavy rare earth elements (HREEs), with affinities to igneous rocks forming in an active continental margin setting. All volcanic rocks have depleted Nd isotopic compositions (ε Nd(t)=+2.4 to +2.5 for the basalts and +5.8 to +7.1 for the andesites and dacites, respectively). In situ Hf isotopic results of zircon from the rhyolites show that they have ε Hf(t)=−1.1 to +10.6. All these geochemical features indicate that the andesites, dacites, and rhyolites likely originated from the partial melting of Meso-Neoproterozoic accreted lower crust (Hf and Nd model ages (TDM2) of 1384–662Ma and 1061–800Ma, respectively). In contrast, the basalts were derived from the partial fusion of a depleted lithospheric mantle that had subsequently been metasomatized by subducted slab-derived fluids. These data, along with the regional geological investigations, suggest that the generation of late Paleozoic volcanic rocks from the Daheshen Formation was related to southward subduction of the Paleo-Asian oceanic plate beneath the northern margin of the North China Craton. This also indicates that the Paleo-Asian Ocean may have not closed before the Early Permian. [Copyright &y& Elsevier]

The late Paleozoic–early Mesozoic tectonic nature of the eastern Central Asian Orogenic Belt (CAOB) has been subject to debate, and the late Paleozoic–early Mesozoic magmatism in the Bureya Massif provides an opportunity to address this issue. We report new zircon U Pb ages, Hf isotope data, and whole-rock major and trace element data for late Paleozoic–early Mesozoic igneous rocks from the south of the Bureya Massif. These data provide insight into the petrogenesis of the igneous rocks, and constrain the late Paleozoic–early Mesozoic tectonic nature of the eastern CAOB. Zircon U Pb ages indicate that the late Permian (ca. 255 Ma) and Middle–Late Triassic (ca. 216 Ma) magmatic events are identified in the south of the Bureya Massif. The late Permian igneous rocks consist mainly of bimodal rock suites, which include quartz monzodiorites, gneissic monzogranites, and A-type gneissic syenogranites. The Middle–Late Triassic igneous rocks are dominated by porphyritic syenogranites, and A-type granite porphyries, syenogranites, and gneissic macroporphyritic quartz syenites. The quartz monzodiorites have low SiO 2 contents (53.9–56.1 wt%), high Mg# (56–57), and Cr (160–175 ppm), Co (25.2–27.8 ppm), and Ni (61.2–72.3 ppm) contents, and are enriched in light rare earth elements (LREE) and large-ion lithophile elements (LILE; e.g., K, Rb, Sr, and Ba). These characteristics, along with enriched zircon Hf compositions [ε Hf (t) = −8.31 to −0.44], suggest that their primary magma was derived from the partial melting of lithospheric mantle that had been metasomatized by fluids released from a fossil subducted slab. The granitoids have high SiO 2 , and low MgO contents, and are enriched in LILE, depleted in high field strength elements (HFSE), and yield ε Hf (t) values of −11.5 to +2.87 and two-stage model ages (T DM2) ages of 1968–1024 Ma. These characteristics suggest that they were derived from the partial melting of Paleoproterozoic–Mesoproterozoic accreted crustal material; however, these granitoids have distinct, heterogeneous geochemical compositions, precluding simple fractional crystallization of a single parental melt, and strongly suggesting that they were originated from distinct petrogenetic processes. The late Permian–Triassic bimodal igneous rock suites and A-type granites imply an extensional environment in the eastern CAOB. • P 3 –T 3 magmatic events are identified in the southern Bureya Massif. • P 3 –T 3 magmatism consists of bimodal rock suites and A-type granitoids. • An extensional environment occurred in the eastern CAOB during the P 3 –T 3. [ABSTRACT FROM AUTHOR]

In this paper, we present zircon U Pb dating, elemental geochemistry, and Sr–Nd–Hf isotopic compositions for Late Carboniferous intrusive rocks in the northern Great Xing'an Range, northeast China. We decipher the mechanisms which triggered lithospheric thinning under microblock-microblock collision and provide a new perspective on the Late Paleozoic evolution of the eastern Central Asian Orogenic Belt. Zircon U Pb dating indicates that Jifeng gabbroic diorites and Xinlin granites were formed during a short time interval at 322–321 Ma, whereas the Xinlin gabbros were crystallized at 300 ± 2 Ma. The Jifeng gabbroic diorites exhibit typical arc characteristics, depleted in HFSEs and enriched in Pb and have positive ε Nd (t) (+1.88 to +2.00) and ε Hf (t) (+6.6 to +10.7) values, suggesting they originated from the partial melting of depleted lithospheric mantle modified by slab fluids. The Xinlin gabbros belong to alkaline series and are characterized by the enrichment in HFSEs with positive Nb and Ta anomalies and depleted Nd Hf isotopic compositions (zircon ε Hf (t) = +12.5 to +18.9, whole rock ε Nd (t) = +8.0 to +8.1). High Nb concentrations and low La/Nb (0.81–0.83) and La/Ta (12.50–14.61) ratios of the Xinlin gabbros indicate an origin from a depleted asthenospheric mantle. The Xinlin granites have high-K calc-alkaline compositions, belonging to I-type granites. These granites have positive ε Hf (t) values (+0.2 to +15.1) and juvenile two-stage model ages (1314–506 Ma) with low Sr and high Yb contents, indicating they were formed by the partial melting of a juvenile lower crust under low-pressure conditions. These data, together with the temporal and spatial distribution and the geochemistry characteristics of the Carboniferous igneous rocks in the Great Xing'an Range, suggest that the amalgamation between the Erguna–Xing'an and Songnen blocks occurred before the Late Carboniferous. The occurrence of asthenospheric mantle-derived mafic rocks indicates localized thinning process of lithosphere. Late Carboniferous magmatism on the Erguna–Xing'an Block attributed to dripping or piece removal of the lithosphere due to asthenospheric fluctuation triggered by slab break-off. • Lithospheric and asthenospheric sources of mafic rocks represent the different stage of post-collisional magmatism. • The amalgamation of the Xing'an and Songnen blocks occurred before late Early Carboniferous. • Lithospheric dripping triggered by slab break-off generated the planar Late Carboniferous post-collisional magmatism. [ABSTRACT FROM AUTHOR]

Apatite is widely utilized to reflect the character and petrogenesis of the parental felsic magma. The compositional variation of apatite from mafic rocks and its applicability to the record of whole-rock are still not well understood. In this study, we present the in situ geochemical analysis of apatite from two types of mafic rocks in the northeastern North China Craton (amphibole-rich mafic rocks for group 1, and pyroxene-rich mafic rocks for group 2). All apatite samples display typically right-sloping rare earth element (REE) patterns, with enrichment in light REE relative to heavy REE, and homogeneous Nd isotopic compositions, suggesting a magmatic origin. Higher apatite REE contents in mafic rocks of group 2 than those of group 1 show a different crystallization sequence in apatite. Extensive apatite crystallization in amphibole-rich mafic rocks, occurs earlier than in pyroxene-rich mafic rocks. The magma differentiation is responsible for the low apatite REE concentrations in group 1 mafic rocks. Combined with previous apatite data, both apatite REE patterns and compositional variations in mafic rocks are mainly controlled by the composition of the original melt. The crystallization of titanite before apatite impoverishes melts in the apatite-compatible trace elements (e.g., middle REE), whereas the crystallization of plagioclase concurrently with apatite can cause some subtle compositional variations of Sr and light REE. Apatite in mafic rocks exhibits higher Sr concentrations than in felsic rocks, which is most likely attributed to the weakening extent of the plagioclase crystallization. [Display omitted] • Apatite compositions in mafic rocks mainly depend on the parental melt. • Apatite grains from appinite crystallize earlier than those from gabbro. • The crystallization of mineral phases can cause apatite compositional variations. [ABSTRACT FROM AUTHOR]

Plagioclase has been widely used to reflect the magmatic evolution and the crust-mantle interaction based on its compositional zoning. However, the abilities in recording the adakitic characteristics and the reworking of continental crust are not understood. This paper reports new in-situ plagioclase geochemistry and Pb isotopic compositions of eight Mesozoic granitoid plutons in the northeastern North China Block (NCB). Based on our previous whole-rock and in-situ apatite geochemistry, we divided them into two groups as adakitic rocks and non-adakitic rocks. Comparison and analysis of plagioclase geochemistry in this paper and previous data between these two groups show that plagioclase crystallized from adakitic rocks possesses higher Sr (735–1588 ppm, generally >1000 ppm) concentrations, δEu (δEu = 2Eu N / (Sm N + Gd N ; N represents after primitive mantle normalize) and Sr/Y (1159–81,344, generally >5000) values than those from non-adakitic rocks. Therefore, we believe that the geochemical index of plagioclase Sr–Y–δEu could reserve the adakitic characteristics and then propose two plagioclase geochemical diagrams (Sr/Y versus Y and δEu versus Sr/Y) to identify the adakitic characteristics. Furthermore, the in-situ plagioclase Pb isotopic compositions (206Pb/204Pb ranging from 16.948 to 18.146, 207Pb/204Pb ranging from 15.403 to 15.656 and 208Pb/204Pb ranging from 37.250 to 39.088), together with the rock-assemblages and spatial-temporal distributions of Mesozoic rocks as well as the variations of whole-rock Sr–Nd–Pb and zircon Hf O isotopic compositions reveal the variation of crustal properties during Mesozoic. Late Triassic magmatism originated from reworking of juvenile lower crust in normal thickness. Early Jurassic magmatism were formed by partial melting of ancient thickened lower crust. Late Jurassic magmatism were derived from remelting of ancient lower crust in normal thickness. Early Cretaceous magmatism were derived from reworking of ancient lower crust in different depth. [Display omitted] • The Mesozoic granitoids in northeastern NCB have varied plagioclase trace elements and Pb isotopes. • Plagioclase Sr–Y–δEu provide a new tool in discriminating adakitic characteristics. • In-situ plagioclase Pb isotopic compositions provide new insights in reworking of continental crust. [ABSTRACT FROM AUTHOR]

To determine the petrogenesis and tectonic setting of the Late Paleozoic Xing’an complex in the northern Great Xing’an Range (GXR), northeastern China, we undertook zircon U–Pb dating and geochemical analyses (major and trace elements, and Hf isotopic compositions) on samples obtained from the complex. The Xing’an complex is composed mainly of the Xinshali (XSL), Ershihao (ESH), Xinnangou (XNG) and Xing’an Station (XAS) plutons. The U–Pb zircon ages measured by secondary ion mass spectrometry (SIMS) and laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) indicate that the Xing’an complex was emplaced in three stages, represented by the ∼358 Ma XSL, ∼308 Ma XNG/XAS, and ∼294 Ma ESH plutons. The XSL pluton is composed mainly of gabbro diorites (SiO 2 = 53.49–56.81 wt.%; MgO = 4.60–5.52 wt.%) of the mid-K calc-alkaline series. These rocks are weakly enriched in large ion lithophile elements (LILEs) and light rare earth elements (HREEs), and depleted in high field strength elements (HFSEs, e.g., Nb, Ta, and Ti) and heavy rare earth elements (HREEs), with ε Hf(t) values of +4.07 to +7.59. Based on these geochemical and isotopic features, we propose that the magma of the XSL pluton was derived from partial melting of depleted lithospheric mantle that was metasomatized by subducted slab-derived fluids. The ESH and XSL plutons have similar geochemical compositions and zircon Hf isotopic values, thereby indicating a common petrogenesis. In contrast, the XNG and XAS plutons comprise syenogranites and monzogranites that are geochemically similar to I-type granites based on their high SiO 2 (67.93–74.98 wt.%) and Na 2 O + K 2 O (7.12–9.20 wt.%) contents, low MgO (0.33–1.14 wt.%) content, enrichment in LILEs (e.g., Rb, Th, U, K) and LREEs, and depletion in Nb, Ta, Ti and P. The positive ε Hf(t) values (+6.34 to +12.72) of the XNG and XAS plutons and their corresponding Hf two-stage model ages of 1149 Ma to 484 Ma indicate that the parental magma was derived from partial melting of juvenile crustal material. According to the geochemical data and regional geological observations, we propose that the formation of the Late Paleozoic Xing’an complex in the northern GXR was related to the subduction of the Paleo-Asian oceanic plate beneath the Xing’an terrane. Hence, we suggest that the Xing’an and Songnen terranes were not amalgamated before the Early Permian. [ABSTRACT FROM AUTHOR]

To constrain the processes of mantle–crust interactions during magma generation and reconstruct the tectonic evolution of the Paleo-Asian Ocean, we present an integrated study involving detailed geological field work, petrological observations, zircon U–Pb–Hf isotope analyses, whole-rock geochemistry, and mineral chemistry for the Tayuan Complex in the northern Great Xing'an Range, NE China. The Tayuan Complex is composed mainly of monzogranites (host granitoids) and gabbros with minor amounts of quartz monzonites, and microgranular enclaves (MMEs) are unevenly distributed within the host granitoids. Our new zircon U-Pb dating results show that the host granitoids were emplaced during the late Carboniferous (318 ± 4 Ma and 319 ± 2 Ma). The MMEs yield similar zircon U-Pb ages of 320 ± 2 Ma and 322 ± 5 Ma, within error of the emplacement ages of the host granitoids. In this study, the petrological and geochemical features of the Tayuan Complex indicate disequilibrium conditions, and we favor a magma mixing model to explain the genesis of various rock types within the complex. Combined with the petrological and geochemical observations, we suggest that the host granitoids can be ascribed to felsic end-member and they originated from the partial melting of the Meso–Neoproterozoic medium- to high-K basaltic lower crust. According to the petrological and geochemical features, the gabbros in Tayuan complex are closely related to the mafic end-member, and we conclude that they were derived from the partial melting of depleted mantle that was metasomatized by subducted slab-derived fluids, and that clinopyroxene, hornblende and Fe-Ti oxides were fractionated during magma generation. The MMEs and coeval quartz monzonites in Tayuan complex represent the mixing of felsic and mafic end-member magmas. Our new data, combined with the spatial distribution and temporal evolution of the Carboniferous magmatism in the Great Xing'an Range, indicate the generation of the late Carboniferous Tayuan complex was related to the northwestward subduction of the Paleo-Asian oceanic plate. Unlabelled Image • The host granitoids and associated MMEs were formed almost simultaneously. • The magma mixing model is favored to explain the generation of Tayuan complex. • Tayuan complex was formed in an active continental margin setting. • The Xing'an-Erguna Massif was in a continuous subduction environment in the Carboniferous. [ABSTRACT FROM AUTHOR]

The northern margin of the North China Craton (NCC) resulted from complicated subduction-accretion process of the eastern Paleo-Asian Ocean (PAO), thus late Paleozoic magmatic records in this region could place conclusive constraints on the final-stage subduction processes of the eastern PAO. Here we present petrological, geochronological, geochemical, and in situ zircon Hf isotopic data of the late Paleozoic intermediate-acidic volcanic rocks, and compiled age and geochemical data of the Permian magmatic rocks along the northern margin of the NCC, with the aim of elucidating their ages, petrogenesis and tectonic implications. Zircon U Pb ages indicate that these rocks formed in the early–middle Permian (275–267 Ma). Lithologically, these volcanic rocks are composed mainly of andesites, with minor rhyolites and dacites. The studied andesites contain 53.94–64.87 wt% SiO 2 , 1.86–3.05 wt% MgO and 0.47–3.56 wt% K 2 O, and belong to low-K calc-alkaline to shoshonite series. Coupled with variable zircon ε Hf (t) values of −14.57 to +12.57, we propose that the parental magma was derived from partial melting of heterogeneous lithospheric mantle resulted from metasomatism of subduction-related fluids. In contrast, the rhyolite-dacite suites are distinguished by higher SiO 2 (65.94–74.77 wt%) and lower MgO (0.15–1.60 wt%) contents, indicating an affinity with highly fractionated I-type granite originated by partial melting of lower crust. These intermediate-acidic rocks are characterized by enrichment in large-ion lithophile elements (LILEs; e.g., Rb, Th, and K) and depletion in high-field-strength elements (HFSEs; e.g., Nb, Ta, P, and Ti), suggesting that they formed in an active continental margin setting. These geochemical features and lithological assemblage, together with the East-West-trending Permian magmatic belt with arc affinities, indicate that their generation was related to southward subduction of the Paleo-Asian oceanic lithosphere beneath the NCC. Synthesized data from this and previous studies lead us to favor a double-sided, early–middle Permian subduction model, with the PAO not closed prior to the middle Permian. Unlabelled Image • Early–middle Permian intermediate-acidic volcanic rocks are calc-alkaline with arc-type affinity. • These volcanic rocks formed in an active continental margin. • The E-W-trending magmatic belt was identified in northern margin of the NCC. • A double-sided, early–middle Permian subduction model was favored. [ABSTRACT FROM AUTHOR]

This paper reports new whole-rock major and trace element, Sr Nd isotopic, and zircon U Pb and Hf O isotopic data for Late Triassic intrusive rocks on Liaodong Peninsula, NE China, aiming to constrain the petrogenesis of these rocks in terms of lithospheric thinning in the northeastern North China Craton (NCC). New zircon U Pb data indicate that the rocks were emplaced during the Late Triassic (220–211 Ma). Based on petrology, petrography and geochemistry, we divided these rocks into three groups. The Group 1 rocks, including hornblende gabbro, hornblende diorite and mafic vein, show low SiO 2 , Na 2 O + K 2 O and high MgO contents, with (87Sr/86Sr) i (0.7066–0.7071), ε Nd (t) (−10.6 to −5.7), ε Hf (t) (−16.6 to +1.5), and δ18O (7.06‰–7.82‰) values, indicating that they were formed by partial melting of lithospheric mantle with addition of lower continent crust materials. The Group 2 rocks, including syenites, display high SiO 2 , Na 2 O + K 2 O and low MgO contents, with (87Sr/86Sr) i (0.7064–0.7073), ε Nd (t) (−14.8 to −14.5), ε Hf (t) (−11.7 to −5.7), and δ18O (5.49‰–6.37‰) values, indicating they were originated through partial melting of lithospheric mantle with continent crust materials added, coupled by fractional crystallization of mafic minerals. The Group 3 rocks, including monzogranite and syenogranite, show high SiO 2, Na 2 O + K 2 O and low MgO contents, with different isotopic signatures: the former shows (87Sr/86Sr) i (0.7085–0.7087), ε Nd (t) (−17.0 to −16.8), ε Hf (t) (−17.9 to −4.4) and δ18O (6.10‰–6.95‰) values. The latter shows higher ε Nd (t) (−9.0 to −8.1), ε Hf (t) (−3.4 to +1.2) and lower δ18O (5.52‰–7.29‰) values. Combined with the adakitic features of monzogranite and different two model ages, we believe they were derived from partial melting of ancient thickened lower crust and juvenile crust, respectively. Together with the spatial and temporal distribution of the Late Triassic rocks, we believe that these rocks were related to the collision between NCC and Yangtze Craton, and the initiation of lithospheric thinning of NCC in eastern segment began in Late Triassic. Unlabelled Image • Late Triassic intrusive rocks on Liaodong Peninsula were formed between 220 and 211 Ma. • These rocks were formed after the collision between NCC and YC. • Lithospheric thinning of northeastern NCC began at ~220 Ma. [ABSTRACT FROM AUTHOR]

• Liaohe Group and related Liaoji granitoid have protolith ages of 2170–2137 Ma, with metamorphic ages of ∼1866 and ∼1883 Ma. • An arc-continent collision model is favored for Paleoproterozoic tectonic evolution of Jiao-Liao-Ji Belt. • The significant arc-continental collision was probably at ca. 1.9 Ga. Zircon U-Pb geochronological, whole-rock geochemical, and Hf isotopic studies were carried out on Liaohe Group and Liaoji granitoid within the central part of the Liaodong peninsula, NE China, to understand the Paleoproterozoic evolutionary history of Jiao-Liao-Ji Belt, North China Craton. Zircon U-Pb dating indicates the studied metavolcanic rocks from Dashiqiao Formation in South Liaohe Group had protolith ages of 2170 ± 29 Ma, 2170 ± 11 Ma, 2166 ± 17 Ma, and 2137 ± 9 Ma, with one showing a metamorphic age of 1866 ± 9 Ma. These metavolcanic rocks are dacite-andesite in compositions, belonging to calc-alkaline series. They are characterized by light rare earth elements (LREEs)-enriched patterns, and enriched in large ion lithophile elements (LILEs) relative to high field strength elements (HFSEs), with significant negative Nb-Ta-Ti-P anomalies, showing arc affinities. Combined with their ε Hf (t) values (–4.36 to +8.38), we suggest that the intermediate-acidic magma were derived from partial melting of Meso-Neoarchean juvenile lower continental crust, with a possible contribution of ancient materials. In addition, the studied monzonitic gneiss from Liaoji granitoid had a protolith age of 2167 ± 26 Ma, with a metamorphic age of 1883 ± 10 Ma. Based on previous studies of Liaohe Group and related meta-mafic rocks, as well as Liaoji granitoid, these Paleoproterozoic rocks not only share statistically indistinguishable Paleoproterozoic magmatic and metamorphic history for the Jiao-Liao-Ji Belt, but also collectively formed in an active continental margin or volcanic arc. These data, combined with previous studies within the Jiao-Liao-Ji Belt, suggest that an arc-continent collision model was favored for the Paleoproterozoic tectonic evolution of the Jiao-Liao-Ji Belt, and the significant arc-continental collision was probably at ca. 1.9 Ga. [ABSTRACT FROM AUTHOR]