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Late Palaeozoic igneous rock associations in response to subduction, accretion, and final closure of the eastern Palaeo-Asian Ocean play a significant role in understanding the geodynamic evolution of the southeastern Central Asian Orogenic Belt. Previous studies have identified a Permian arc magmatic belt associated with the southward-dipping subduction of the eastern Palaeo-Asian Ocean along the Solonker–Changchun suture zone. The genetic mechanism and associated geodynamic settings are of great importance in deciphering the evolution of the eastern Palaeo-Asian Ocean. This paper presents zircon U–Pb–Hf isotope and whole-rock geochemical analyses for a suite of magmatic rocks including the early Permian diorite porphyrites (ca. 281.0 Ma), andesites (ca. 276 Ma) and rhyolites (ca. 275 Ma) in the Kulun region. The diorite porphyrites and andesites have high SiO2 and total alkali contents, and low MgO contents and Mg no. values, with enrichments in large ion lithophile elements and depletions in high-field-strength elements. These geochemical characteristics, together with low-Sr and high-Yb contents, a weak concave-upward shape of middle rare earth elements and negative Eu anomalies, suggest that these intermediate igneous rocks were generated by partial melting of amphibolitic lower crust at a crustal depth of 30–40 km. The rhyolites have heterogeneous isotopic compositions, with ϵHf(t) values and TDM2 ages of –20.8 to +0.5 and 3578∼1494 Ma, implying that they were likely derived from partial melting of a mixed source dominated by recycled ancient crust with minor juvenile crustal materials. The rhyolites show potassic affinity with relatively high K2O and very low Na2O, which was attributed to liquid immiscibility of felsic magma and subsequent limited fractional crystallization of plagioclase. The regional igneous associations, metamorphic events, and coeval sedimentary rocks along the Solonker–Changchun suture zone indicate that the early Permian igneous rocks were formed in an active continental arc environment in response to southward subduction of the eastern Palaeo-Asian Ocean.

In this study, we undertook zircon U–Pb dating and Hf isotopic and whole-rock geochemical analysis of Mesozoic granites from the Zhalantun and Arxan areas of the Great Xing’an Range, northeastern China. Zircon U–Pb dating of four samples indicates they formed in the Early Cretaceous (ca. 140.7–130.0 Ma). Geochemically, the samples have high silica (74.00–77.29 wt.%) and total alkali (8.52–8.90 wt.%) and low CaO (0.21–0.71 wt.%), MgO (0.06–0.48 wt.%), and P2O5 (0.01–0.06 wt.%) contents and exhibit the weakly peraluminous (A/CNK = 0.98–1.06) and high-K calc-alkaline characteristics, with highly differentiated I-type granite affinities (differentiation index = 93.19–96.93). The studied granites are enriched in light rare earth and large ion lithophile elements and depleted in heavy rare earth and high field strength elements. Their zircon εHf(t) values are mainly positive (+2.49 to +11.64) and yield two-stage Hf model ages of 1023–445 Ma. The geochemical and isotopic data indicate they might have been derived from the partial melting of medium- to high-K basaltic crust material during the Mesoproterozoic to Phanerozoic. They underwent fractional crystallization in the magma evolution process, and K-feldspar and plagioclase were the major crystallization phases. Combined with the temporal–spatial migration of the Mesozoic magmatic events in the whole northeastern China, we propose that the generation of Early Cretaceous highly differentiated I-type granites in the central Great Xing’an Range was associated with the delamination effect caused by the roll-back of the Paleo-Pacific plate.

Figure S1: Photographs (A) and photomicrographs (B) of Weilasituo ZK granites. Figure S2: Photographs of Weilasituo ZK granites. Figure S3: Photomicrographs of Weilasituo (A–C) BD granites and (D–I) ZK granites. Figure S4: Photomicrographs of (A) Damuchu quartz monzonite porphyry and (B) Baocun granodiorites. Figure S5: Photomicrographs of Zalute (A) quartz diorite and (B) monzogranite. Table S1: LA-ICP-MS U-Pb zircon data of the Cretaceous HSGs from the SGXRMB. Table S2: Major (wt%) and trace (ppm) elements of the Cretaceous HSGs from the SGXRMB. Table S3: Whole-rock Sr-Nd-Hf isotopic compositions of the Cretaceous HSGs from the SGXRMB. Table S4: Zircon Hf-O isotopic compositions of the Cretaceous HSGs from the SGXRMB.

Intra-oceanic arcs are potential candidates that generate Earth’s continental crust, and serve as active sites for the mixing of juvenile arc and mature continental material. However, whether continental fragments occur beneath intra-oceanic arcs, and how continental materials are involved in island arc magmas remain equivocal. Here we report zircon U-Pb-Hf-O isotopes and whole-rock elemental and Sr-Nd isotopic data on the Silurian island arc gabbro from the southeastern Jiamusi Block in NE China. The gabbro was emplaced at ca. 435–429 Ma associated with the northward intra-oceanic subduction of the Paleo-Asian Ocean, and belongs to the eastern extension of the Bainaimiao arc system. Elevated zircon δ18O (+5.5‰ to +7.9‰) and variable eHf(t) (-2.1 to +4.0) values, and negative whole rock eNd(t) (-1.1 to −1.6) values, suggest an enriched mantle component generated by pelagic and terrigenous sediments input into the mantle wedge. The contribution of terrigenous sediments, together with the recognition of Paleoproterozoic crustal rocks, proves for the first time that continental fragments existed beneath the intra-oceanic arc. In conjunction with published data, we propose that that Tarim Craton-type scattered continental fragments occurred within the Bainaimiao arc system, and that they not only facilitated the initiation of oceanic-oceanic subduction through increasing buoyancy, but also account for the old continental zircon and enriched isotopic variations of the young arc rocks. Our study highlights a fossil example that could help better quantify the scale and role of continental fragments in the origin and evolution of intra-oceanic arcs.

There is a broad consensus that the Solonker suture zone marked the final closure of the eastern Paleo-Asian Ocean, which led to the formation of the eastern segment of the Central Asian Orogenic Belt (CAOB). However, when and how the final closure occurred still remained controversial. Located in a key position in the southeastern CAOB, the Early Mesozoic magmatic rocks along the northern margin of the North China Craton provide a crucial window to evaluate the subduction and final closure processes of the eastern Paleo-Asian Ocean. To address these issues, data on geochronological, whole-rock geochemical, whole-rock Sr-Nd and in situ zircon Hf isotopic study of the Early Mesozoic granites, as well as major-trace elements compositions of the apatites are reported here. Zircon U-Pb dating results showed that our studied granites were emplaced in the Middle Triassic (243.1–242.6 Ma). These granites have high Sr (250–652 ppm) contents, low heavy rare earth elements (HREEs), Yb (0.46–0.77 ppm) and Y (4.48–8.15 ppm) contents, and show high Sr/Y and (La/Yb)N signatures (36–108 and 21–35, respectively), with negligibly negative to moderately positive Eu anomalies (δEu=0.80–1.36), indicating adakite-like features. Most of these granite samples are characterized by relatively high K2O contents (3. 30–4.83 wt.%), and belong to the high-K calc-alkaline and shoshonitic series, with peraluminous affinities (A/CNK=1.02–1.28). Besides, their low MgO (0.10–0.34 wt.%) , Cr (0.99–3.50 ppm), and Ni (0.96–2.40 ppm) contents indicate a thickened continent crustal origin, rather than subducting slab-derived or delaminated lower crust-derived melts. Analyzed granite samples yielded in situ zircon eHf (t) values (–8.3 to +5.8) and whole-rock eNd (t) values (–4.38 to –5.69), with predominately negative values, indicating mixture sources of major recycled old components and limited juvenile crustal materials. Their parental magma was originated by partial melting of thickened lower crust, under garnet amphibolite facies conditions. Thickened crust in the southeastern CAOB yielded crustal thickness of ∼54–64 km estimated from (La/Yb)N ratios of these crust-derived granites. These constraints, in conjunction with the E-W trending collision-related adakitic granitoids (250–243 Ma) in the southeastern CAOB, and other geological evidence, recorded a tectonic transition from this prolonged subduction to final closure of the eastern Paleo-Asian Ocean.

Text: Methods. Figure S1: Diagrams showing chondrite-normalized REEs patterns for zircons from the high-Mg igneous associations in the Qinghe region. Figure S2: Diagrams showing variation of selected elements vs. LOI to check for element mobility during post-magmatic alteration. Figure S3: (A) SiO2 vs. Th/La and (B) MgO vs. Nb/La diagrams of the high-Mg igneous rocks in the Qinghe region. Figure S4: (A) MgO vs. CaO; (B) MgO vs. Cr; (C) MgO vs. Ni; (D) MgO vs. TiO2; (E) Sr vs. Ba; and (F) TiO2 versus V diagrams of the high-Mg igneous rocks in the Qinghe region. Mineral abbreviations: Ol—olivine; Hbl—hornblende; Cpx—clinopyroxene; Pl—plagioclase; Kf—potassium feldspar; Bi—biotite. Figure S5: Diagrams of (A) Nb/Yb vs. Th/Yb; (B) Th/Yb vs. La/Yb of the high-Mg igneous rocks in the Qinghe region. Tables S1–S5.

Late Mesozoic igneous rocks are important for deciphering the Mesozoic tectonic setting of NE China. In this paper, we present whole-rock geochemical data, zircon U–Pb ages and Lu–Hf isotope data for Early Cretaceous volcanic rocks from the Tulihe area of the northern Great Xing’an Range (GXR), with the aim of evaluating the petrogenesis and genetic relationships of these rocks, inferring crust–mantle interactions and better constraining extension-related geodynamic processes in the GXR. Zircon U–Pb ages indicate that the rhyolites and trachytic volcanic rocks formed during late Early Cretaceous time (c. 130–126 Ma). Geochemically, the highly fractionated I-type rhyolites exhibit high-K calc-alkaline, metaluminous to weakly peraluminous characteristics. They are enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs) but depleted in high-field-strength elements (HFSEs), with their magmatic zircons ϵHf(t) values ranging from +4.1 to +9.0. These features suggest that the rhyolites were derived from the partial melting of a dominantly juvenile, K-rich basaltic lower crust. The trachytic volcanic rocks are high-K calc-alkaline series and exhibit metaluminous characteristics. They have a wide range of zircon ϵHf(t) values (−17.8 to +12.9), indicating that these trachytic volcanic rocks originated from a dominantly lithospheric-mantle source with the involvement of asthenospheric mantle materials, and subsequently underwent extensive assimilation and fractional crystallization processes. Combining our results and the spatiotemporal migration of the late Early Cretaceous magmatic events, we propose that intense Early Cretaceous crust–mantle interaction took place within the northern GXR, and possibly the whole of NE China, and that it was related to the upwelling of asthenospheric mantle induced by rollback of the Palaeo-Pacific flat-subducting slab.

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 Eurasia...

An integrated study of the petrology, zircon U–Pb geochronology, whole–rock geochemistry, and in situ zircon Hf isotopic compositions of middle–late Permian granitoids from the Diaobingshan region ...

We performed zircon U–Pb age dating and geochemical analyses of late Mesozoic felsic volcanic rocks in the Hailar Basin, NE China, with the aim of eclucidating their emplacement ages, origin and geodynamic significance. The volcanic rocks consist of dacites, rhyolites and rhyolitic tuffs. Laser ablation–inductively coupled plasma–mass spectrometry zircon U–Pb dating results suggest that the rocks were erupted during the Late Jurassic–Early Cretaceous (161–117 Ma). They belong to the high-K calc-alkaline series and can be divided into two groups. Group I rocks are metaluminous to weakly peraluminous, contain low concentrations of heavy rare earth elements (HREEs) and high field strength elements (HFSEs), and have low zircon saturation temperatures (average 786 °C), all of which indicate an I-type affinity. In contrast, Group II rocks have higher HREE and HFSE concentrations and zircon saturation temperatures (average 918 °C), suggesting an A-type affinity. All the felsic volcanic rocks have positive εHf(t) values of 1.43–12.32 with two-stage model ages of 1110–401 Ma. Our data indicate that the I-type felsic volcanic rocks formed from magmas generated by partial melting of a dominantly juvenile mica-bearing K-rich basaltic lower crust, whereas the A-type felsic volcanic rocks originated from the partial melting of a dry mafic–intermediate middle–lower crust that was dehydrated but not melt depleted. Based on the present results and previous research, we propose that the Late Jurassic I- and A-type felsic volcanic rocks in the Hailar Basin were formed in a post-collisional environment related to break-off of the subducted oceanic slab of the Mongol–Okhotsk Ocean and the subsequent gravitational collapse of the orogenically-thickened crust after closure of the ocean. In contrast, the Early Cretaceous I- and A-type felsic volcanic rocks were erupted in an extensional setting related to rollback of the subducted Paleo-Pacific Plate.

There is a broad consensus that the extensive late Mesozoic igneous rocks in NE China were generated in an extensional setting. However, the timing and mechanism of the lithospheric extension remain controversial. To address this, we carried out an integrated study involving LA–ICP–MS zircon U–Pb dating and geochemical analyses (major elements, trace elements, and Hf isotopes) for the Early Cretaceous adakitic lavas and A-type rhyolites of the Songliao Basin. The adakitic lavas are andesites and dacites. The U–Pb dating of zircons from the adakitic lavas and A-type rhyolites yielded ages between 115 and 102 Ma. Geochemically, the adakitic lavas are characterized by high Sr contents (515–1610 ppm) and low Y (0.98–17.58 ppm) and heavy rare earth element (HREE) contents, and they therefore have high Sr/Y (51–112) ratios. They also exhibit high Mg# values (36–57) and high contents of MgO (0.56–3.53 wt%), Cr (15.7–87.3 ppm), and Ni (6.7–44.7 ppm) that are comparable with those of high-Mg adakitic rocks. The A-type rhyolites show an affinity with aluminous A-type magmatic rocks, and they are metaluminous to peraluminous (A/CNK = 0.98–1.35), enriched in alkalis, Ga, Zr, Nb, and Y, depleted in Sr and P, and exhibit fractionated REE patterns with negative Eu anomalies (Eu/Eu* = 0.05–0.77). All the primary zircons from the adakitic lavas and A-type rhyolites have positive eHf(t) values of +3.6 to +12.1 and juvenile two-stage model (TDM2) ages of 934–392 Ma. The adakitic lavas probably resulted from the partial melting of a delaminated region of the lower continental crust, with the magmas subsequently interacting with mantle materials upon ascent, while the A-type rhyolites were probably generated by the partial melting of a dehydrated charnockitic middle–lower crust. The data suggest that the adakitic lavas and the A-type rhyolites formed in an extensional environment related to the rollback of the subducting Paleo-Pacific Plate. The upwelling of asthenospheric mantle and local delamination of the lithosphere, which were induced by rollback of the subducting Paleo-Pacific Plate, extended from the Great Xing'an Range southeastward through the Songliao Basin to eastern Heilongjiang and Jilin provinces, giving rise to the southeastward migration of lithospheric extension and extension-related volcanism after ca. 140 Ma.

This study presents new secondary-ion mass spectrometry (SIMS) rutile and laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) zircon U-Pb geochronological and whole-rock geochemical data for amphibolites of the Heilongjiang Complex, located within the Yilan area of NE China, to constrain the tectonic evolution of the Mudanjiang Ocean between the Songnen–Zhangguangcai Range and Jiamusi massifs. Magmatic zircon from amphibolites collected from the Yilan Marble Quarry yields a weighted mean 206Pb/238U age of 274 ± 2 Ma, which is interpreted as the protolithic age. Amphibolites from the Longlangang and Tuanshanzi areas yield rutile U-Pb ages of 177 ± 11 Ma and 172 ± 5 Ma, respectively, which are interpreted to reflect the cooling of these rocks below the closure temperature of Pb diffusion in rutile. Amphibolites from the Yilan Marble Quarry are enriched in light rare earth elements (LREEs) and depleted in high field strength elements (HFSEs; e.g., Nb, Ta and P) relative to large ion lithophile elements (LILEs). Amphibolites from the Longlangang and Tuanshanzi areas have relatively flat chondrite-normalized rare earth element (REE) patterns, and remarkable negative Nb and Ta anomalies. Moreover, all of the amphibolites from the Heilongjiang Complex in the Yilan area have tholeiitic and arc-type geochemical affinities. These amphibolites formed by similar petrogenetic processes, but from distinct mantle sources. The magmas that formed these units were generated by the partial melting of mantle sources metasomatized by subducted slab fluids, and the magma that formed the amphibolites within the Yilan Marble Quarry may have also incorporated sedimentary material. Mantle peridotite from the garnet-spinel transition zone is a possible source for the protolith of amphibolites in the Yilan Marble Quarry, and spinel-peridotites may have been the magma sources for the protoliths of amphibolites in the Longlangang and Tuanshanzi areas. Combining our data for amphibolites from the Heilongjiang Complex in the Yilan area with the results of previous research on Late Paleozoic–Early Mesozoic arc magmatism and metamorphism, we infer that the Late Paleozoic–Early Mesozoic tectonic evolution of the Mudanjiang Ocean was characterized by double-sided subduction. These data indicate that the Mudanjiang Ocean closed during the Jurassic (180–160 Ma).

The late Paleozoic tectonic evolution of eastern northeast China and, in particular, the Jiamusi Block and its relationship with the Paleo-Pacific (Panthalassic) Ocean are controversial. Here we present petrological, zircon U-Pb age, whole-rock major and trace elements, and zircon Hf isotopic data for Permian (273–260 Ma) subduction-related mafic intrusions from the Luobei region along the western margin of the Jiamusi Block. These intrusions have mineral assemblages of pyroxene, Ca-rich plagioclase, and hornblende, indicating their crystallization from a water-saturated parental magma. The Luobei mafic rocks are calc-alkaline, enriched in large-ion lithophile and light rare earth elements, depleted in high-field-strength elements, and have variable zircon eHf(t) values (−7.7 to +5.0). These geochemical features suggest that their parental magma was probably derived by

We present major- and trace-element concentrations, Sr–Nd–Hf isotopic compositions, Re Os isotopes, and highly siderophile element (HSE) abundances of 17 xenolithic mantle peridotites from the Nuomin volcanic field to constrain the assembly and evolution of the Xing'an–Mongolia Orogenic Belt (XMOB), Northeast China. The Nuomin peridotites are divided into five groups (harzburgite groups Haz-1, Haz-2, and Haz-3, and lherzolite groups Lhz-1 and Lhz-2). The Haz-1 peridotites are characterized by refractory chemical compositions (Al2O3 contents of 1.03–2.30 wt% and olivine forsterite (Fo) numbers of 90.7–92.5) that are best interpreted as residues after high degrees of mantle partial melting. The Haz-2 and Haz-3 peridotites exhibit slightly more fertile compositions (Al2O3 of 1.72–1.80 wt% and Fo of 89.0–89.9 for the Haz-2, and Al2O3 of 2.86 wt% and Fo of 91.2 for the Haz-3), resulting from refertilization by silicate melts. The Lhz-1 samples are more fertile (Al2O3 of 2.90–3.64 wt% and Fo of 89.1–90.3) than the Lhz-2 samples (Al2O3 of 1.64–2.16 wt% and Fo of 90.9–91.3). The combination of trace-element data (Ti/Eu ratio) and Sr–Nd–Hf isotopic compositions indicates the presence of at least three peridotite end-members (Haz-1, Haz-2, and Lhz-1–Lhz-2) beneath the Nuomin area, which can be explained by the infiltration of two distinct metasomatic agents (MA1: composition similar to potassic basaltic rocks in the Wudalianchi–Erkeshan–Keluo area, and MA2: Fe–Ti-enriched melt). HSE abundances and Os isotopic data show that the Os isotopic compositions of the Haz-1, Lhz-1, and Lhz-2 peridotites were not significantly affected by lithophile-element-dominated metasomatism and can be used to constrain the melt extraction ages of these peridotites. The lower 187Os/188Os ratios of Haz-1 peridotites define a prominent rhenium depletion age (TRD) of ~1.6 Ga and represent fragments of the Paleo–Mesoproterozoic lithospheric mantle rather than reflecting the heterogeneous characteristics of the asthenosphere or extraneous emplacement. In contrast, the Lhz-1 and Lhz-2 lherzolite groups together have a narrow range of 187Os/188Os ratios that give younger TRD ages (~0.5 to 1.0 Ga). Our data demonstrate that both the Paleo–Mesoproterozoic and Neoproterozoic subcontinental lithospheric mantle coexist beneath the XMOB and that they correspond respectively to the bimodal age peaks of crustal growth of ~1.6 Ga and ~0.8 Ga defined by the XMOB granitoids. The XMOB was assembled primarily during the Phanerozoic by multiple blocks that had formed from the Paleoproterozoic to Neoproterozoic. The similar chemical and Sr–Nd–Hf isotopic signatures of both young and old lithospheric mantle indicate that the large-scale metasomatism event involving potassic melts most likely occurred during the evolution of the Paleo–Asian Ocean. The crustal materials carried to the mantle by multiple subduction events could be an effective source of potassium for the origin of potassic basaltic rocks.

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 eHf(t) values (+4.1 to +12.9) and juvenile two-stage model (TDM2) 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.

Central Inner Mongolia is located in the southeastern segment of the Central Asian Orogenic Belt (CAOB), and controversy has long surrounded its late Paleozoic tectonic evolution. Here, we present an integrated study of zircon U-Pb ages, whole rock major and trace elements, and zircon Hf isotopes for five less studied alkali feldspar granitic plutons in the Dongwuqi area to the north of the Erenhot-Hegenshan-Heihe suture zone. Zircon U–Pb dating by laser ablation-inductively coupled plasma–mass spectrometry (LA–ICP–MS) indicates that these granitic plutons were emplaced in the Late Carboniferous (315–300 Ma). The Late Carboniferous alkali feldspar granites belong to high-K calc-alkaline series and are evolved I-type granites. They are high in SiO2 (73.22–77.36%), and low in MgO (0.07–0.49%) with enrichments in light rare earth elements (LREEs), Zr, Hf, Rb, Th, and U, and depletions in Ba, Nb, Ta, Sr, and Eu. The Dongwuqi granitic rocks are characterized by high positive zircon eHf(t) values (+7.6 to +15.1), and relatively young two-stage Hf model (TDM2) ages (364–835 Ma). These geochemical data, together the common miarolitic texture, indicate that they were derived from partial melting of juvenile arc-related mafic to intermediate rocks in the lower crust, and eventually emplaced in low-pressure conditions or at shallow crustal levels, with involvement of extensive fractional crystallization during magma evolution. Our new results, along with the published regional data, delineate a NE-trending Carboniferous continental arc belt (more than 1700 km) in the northern accretionary zone of the Erenhot-Hegenshan-Heihe suture. Accordingly, we invoke that the Dongwuqi Late Carboniferous high-K granites were emplaced in an active continental margin setting, which was probably related to the northwestward subduction of the Hegenshan oceanic plate beneath the Xing'an-Uliastai-Nuhetdavaa block.

Whole-rock major and trace element geochemistry, along with zircon U–Pb ages and Lu–Hf isotope data, are reported for Palaeoproterozoic meta-rhyolites and meta-dacites of the Liaohe Group in the northern segment of the Jiao-Liao-Ji Belt, North China Craton. These data are used to constrain the petrogenesis of the rocks and the Palaeoproterozoic tectonic evolution of the Jiao-Liao-Ji Belt. Zircons from these rocks are euhedral–subhedral, display oscillatory growth zoning, and have high Th/U ratios (0.26–1.21), implying a magmatic origin. LA–ICP–MS zircon U–Pb age data indicate that the silicic metavolcanic rocks formed during the Palaeoproterozoic (2184–2127 Ma). The zircons yield eHf(t) values of −9.7 to +8.9 and TDM2 model ages of 2205–3313 Ma. Geochemically, the silicic metavolcanic rocks are metaluminous to weakly peraluminous and belong to the calc-alkaline I-type series. The rocks are characterized by enrichment in large-ion lithophile elements and depletion in high-field-strength elements (e.g., Nb, Ta, P, and Ti), and have affinities with igneous rocks that form in an active continental margin setting. The geochemical and isotopic data suggest that the rocks were derived mainly from partial melting of Meso-Neoarchaean juvenile lower crust, with a possible contribution from older materials. The present results, combined with the regional geology, further demonstrate that an oceanic plate was subducted northward beneath the Longgang Block during the Palaeoproterozoic.

Ascertaining how high-silica granites form is important for understanding why Earth has a high-silica continental crust and how the composition of the continental crust has evolved through time. This study presents a systematic dataset for the petrology, mineralogy, geochronology, and geochemistry of the granite porphyries and related microgranular enclaves and diabases from the Early Cretaceous Guanmenshan Complex (126–123 Ma) in Liaodong Peninsula, North China Craton, to reveal the complex, multi-stage, magmatic evolution in a shallow silicic magma system prior to and during emplacement of high-silica granites. Zircons from the granite porphyries and microgranular enclaves can be classified into two groups: those with dark-CL cores surrounded by light-CL rims, and those comprising entirely light-CL domains, without dark-CL cores. Our results indicate that dark-CL zircon domains with high Th (46–579 ppm), U (120–1274 ppm), and Hf (6709–12,493 ppm) contents and low Ti contents (1.52–7.85 ppm) and Ti-in-zircon temperatures (TTiZ = 622–751 °C) formed from highly evolved magmas, whereas light-CL zircon domains with low Th (14–157 ppm), U (24–236 ppm), and Hf (4749–10,474 ppm) contents and high Ti contents (7.59–29.36 ppm) and Ti-in-zircon temperatures (TTiZ = 748–885 °C) formed from low evolved magmas. These characteristics, combined with the similar U Pb ages and Hf isotopic compositions of the dark-CL zircon cores and light-CL zircon domains and insignificant intra- or inter-grain (87Sr/86Sr)i variations of plagioclase from the granite porphyries and microgranular enclaves, reflect mixing between two cognate magma batches with contrasting evolved signatures. This study presents a model in which the highly evolved magmas were derived from initial interstitial melts that were extracted from a crystal mush leaving behind residual cumulates, whereas the less evolved magmas were the products of re-melting of the cognate cumulates. The diabases likely represent the mafic recharge magma that contributed necessary heat but limited mass to remobilize the cumulate mush, inducing the internal self-mixing and formation of the hybrid high-silica magmas. Feeder-dyke related emplacement of the hybrid magma generated more mafic rocks that became incorporated and dispersed into the high-silica granite porphyries as cognate microgranular enclaves. Our results lend new insights into the important role of cognate magma mixing induced by mafic recharge in generation of high-silica granites.

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% SiO2 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 eHf(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 SiO2 range (47.61–57.4 wt%), high contents of Ni, Co, and Cr, and high Mg# values (42–54). They have higher Fe2O3T, 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 eHf(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.

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 SiO2. 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 eHf(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.

This study presents new geochronological, whole-rock geochemical, and zircon Hf isotopic evidence for the age, petrogenesis, and source of Mesozoic granitic rocks of the Xing’an Block, Northeast China. This evidence reveals the Late Mesozoic tectonic evolution of the eastern section of the Central Asian Orogenic Belt. Laser-ablation inductively coupled plasma – mass spectrometryzircon U–Pb age data indicate that the syenogranite, monzogranite, and alkali feldspar granite units, as well as their associated diorite microgranular enclaves, were emplaced between 150–142 Ma, providing evidence of Late Jurassic to Early Cretaceous magmatic events within the Xing’an Block. The granites contain high concentrations of SiO2 (65.24%–75.73 wt.%) and K2O (3.94%–5.30 wt.%), low concentrations of MgO (0.10%–1.30 wt.%), and A/CNK values of 0.92–1.06. In addition, Hf isotopic analysis of zircons from the 150–142 Ma granites yields εHf(t) values of +4.54 to +12.16 and two-stage Hf model aged from 906 to 423 Ma, indicating that they formed from magmas generated by partial melting of a juvenile Neoproterozoic–Phanerozoic accreted crustal source. The basic magma source for the diorite microgranular enclaves most likely formed from partial melting of a depleted mantle that had been metasomatized by subduction-related fluids. Combining these new geochemical data with the geology of this region, Late Jurassic to Early Cretaceous magmatism in the Xing’an Block most likely occurred in an extensional environment associated with closure of the Mongol–Okhotsk Ocean.

The Heilongjiang Complex, located between the Jiamusi and Songnen-Zhangguangcai Range massifs, has become a focus of tectonic research in recent years. Here we document new U-Pb detrital zircon age data for metasedimentary rocks from the Heilongjiang Complex in Yilan-Huanan counties. These data not only provide important constraints on the depositional timing and provenance, but also give further insights into the complicated convergence history of the Jiamusi and Songnen-Zhangguangcai Range massifs. Most zircons from the Heilongjiang Complex show “magmatic-like” zircon rare earth element patterns, with enrichment in heavy rare earth elements and positive Ce and negative Eu anomalies, suggesting a magmatic origin. Laser ablation-inductively coupled plasma-mass spectrometry zircon U-Pb analysis indicates that the youngest detrital zircons in these metasedimentary rocks have concordant 206Pb/238U ages of ca. 230–180 Ma. Based on this finding and the Middle Jurassic metamorphic ages of the Heilongjiang Complex, we conclude that metasedimentary rocks of the Yilan Heilongjiang Complex were deposited during the Late Triassic-Early Jurassic. Approximately 55% of the detrital zircons yield ages of 297 to 180 Ma, with peaks at 270–245 Ma, 230–200 Ma and 200–180 Ma, while 27% of the detrital zircons yield ages of 544–412 Ma with a peak at 500–480 Ma. Proterozoic detrital zircons (~ 15%) were also identified, yielding ages of 2352 to 595 Ma, with most being of Neoproterozoic age. These results, combined with field relationships and previously published ages, suggest that detrital zircons in the Yilan Heilongjiang Complex were sourced mainly from igneous rocks in the Jiamusi and Songnen-Zhangguangcai Range massifs. Moreover, the protoliths of the metasedimentary rocks in the Yilan Heilongjiang Complex were most likely deposited in a forearc basin setting during convergence between the Jiamusi and Songnen-Zhangguangcai Range massifs.

This paper presents new geochronological and geochemical data for early Paleozoic intrusive rocks from the Khanka Massif in the Russian Far East, with the aim of elucidating the Paleozoic evolution and tectonic attributes of the Khanka Massif. New U–Pb zircon data indicate that early Paleozoic magmatism within the Khanka Massif can be subdivided into at least four stages: ~ 502, ~ 492, 462–445, and ~ 430 Ma. The ~ 502 Ma pyroxene diorites contain 58.28–59.64 wt% SiO2, 2.84–3.69 wt% MgO, and relatively high Cr and Ni contents. Negative eHf(t) values (− 1.8 to − 0.4), along with other geochemical data, indicate that the primary magma was derived from partial melting of mafic lower crust with the addition of mantle material. The ~ 492 Ma syenogranites have high SiO2 and K2O contents, and show positive Eu anomalies, indicating the primary magma was generated by partial melting of lower crust at relatively low pressure. The ~ 445 Ma Na-rich trondhjemites display high Sr/Y ratios and positive eHf(t) values (+ 1.8 to + 3.9), indicating the primary magma was generated by partial melting of thickened hydrous mafic crust. The ~ 430 Ma granitoids have high SiO2 and K2O contents, zircon eHf(t) values of − 5.4 to + 5.8, and two-stage model ages of 1757–1045 Ma, suggesting the primary magma was produced by partial melting of heterogeneous Proterozoic lower crustal material. The geochemistry of these early Paleozoic intrusive assemblages indicates their formation in an active continental margin setting associated with the subduction of a paleo-oceanic plate beneath the Khanka Massif. The eHf(t) values show an increasingly negative trend with increasing latitude, revealing a lateral heterogeneity of the lower crust beneath the Khanka Massif. Regional comparisons of the magmatic events indicate that the Khanka Massif in the Russian Far East has a tectonic affinity to the Songnen–Zhangguangcai Range Massif rather than the adjacent Jiamusi Massif.

The Jiamusi Block is located in the easternmost Central Asian Orogenic Belt (CAOB) and its tectonic affinity and evolution is highly controversial. Here we describe newly discovered Neoproterozoic orthogneisses and early Paleozoic granitoids of the Mashan Complex from the Jiamusi Block. SIMS U-Pb dating for zircons from three high-grade orthogneisses yields protolith and metamorphic ages ranging from 757 to 751 Ma and from 530 to 476 Ma, respectively. LA-ICP-MS U-Pb dates for zircons from four gneissic granitoids define two stages of early Paleozoic magmatism (i.e., 530–502 Ma, and 490–476 Ma). These new data, together with recent published ages, indicate that the basement rocks of the Jiamusi Block record an important Neoproterozoic-early Paleozoic magmatic (ca. 895–476 Ma) and metamorphic (ca. 563–476) event, and we accordingly infer that the granulite facies metamorphism might have occurred before 541–476 Ma, and around 567–561 Ma. Geochemical and zircon Hf isotopic data suggest that the ca. 752 Ma rift-related gneisses were derived from dominantly juvenile crustal rocks with both the heat and material involvement of a depleted asthenosphere mantle at relatively low pressures, which then underwent an ancient wall-rock assimilation, whereas the ca. 490–476 Ma post-collisional granitoids originated from reworking of an ancient crustal source and subsequently experienced intensive crystal fractionation. The good correlation on the ca. 755–115 Ma geological events between the Jiamusi and Khanka blocks suggests they formed a contiguous crustal unit. The existing data indicate that this combined block cannot be directly derived from the Siberia, North China, South China, and Tarim cratons. Instead, it might be either a rifted portion of the Sayang-Baikal orogen or derived from a peri-Gondwana position. We evaluate the model that the Jiamusi-Khanka Block may have originated as part of the Late Neoproterozoic-Cambrian Kuunga orogen trapped between South India and East Antarctica-Australia. Sometime after ca. 470 Ma, it rifted away from East Gondwana and drifted northward to collide with the Songliao Block of NE China in the Early Jurassic.

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 th...

A combined study of LA-ICP-MS zircon U-Pb dating and geochemical analyses (major and trace elements, and Hf isotopic compositions) for five Permian granitic plutons (Mingyi, Tuoyaozi, Mengjiagang, Hengtoushan, and Qingbei plutons) from the Jiamusi Massif was carried out to determine their ages, petrogenesis, and tectonic evolution. The studied granitic plutons are composed of syengranites, monzogranites, and granodiorites, and they were emplaced in the Early-Middle Permian (278–263 Ma). These granitic plutons are mostly high-K calc-alkaline and weakly peraluminous, and show consistent correlations of different oxides versus SiO 2 . They are all enriched in large ion lithophile elements (e.g., Rb, Th, K) and light rare earth elements, and depleted in high field strength elements (e.g., Nb, Ta, Ti) and heavy rare earth elements. And they have relatively homogeneous Hf isotopic compositions, with eHf(t) values varying from − 6.16 to + 2.95 and two-stage model ages ranging from 1681 to 1111 Ma. According to their emplacement ages, geochemical characteristics, and Hf isotopic compositions, we conclude that these granitoids might be originated from parental magmas with similar compositions but evolved different degrees of fractionation, and their magmas were derived from the partial melting of amphibolite-facies mafic lower crust. These data, combined with previous studies on contemporaneous magma-tectonic activities in the Jiamusi Massif and Songnen-Zhangguangcai Range Massif, indicate that two paralleled N-S trending Permian magmatic belts are distributed in these two massifs. The eastwards subduction of the Mudanjiang oceanic plate beneath the Jiamusi Massif induced crustal melting to produce the studied Permian N-S trending granitoids in the Jiamusi Massif. Furthermore, westwards subduction of the Mudanjiang oceanic plate beneath the Songnen-Zhangguangcai Range Massif gave rise to Permian magmatism along eastern margin of the Songnen-Zhangguangcai Range Massif. Taken together, we suggest that the Jiamusi Massif and Songnen-Zhangguangcai Range Massif were not collided before the Permian, and a double-side subduction model is favored for the tectonic evolution of the Mudanjiang Ocean during the Permian.

The Jiamusi Massif forms part of the eastern Central Asian Orogenic Belt (CAOB) and the Pacific oceanic tectonic domain, but its tectonic affinity is highly controversial. Here, we present U–Pb ages and Hf isotope compositions of detrital zircons from five metasedimentary rocks and one monzogranite within the Jiamusi Massif, and our aim was to constrain the depositional ages and provenance of the strata, as well as the tectonic affinity of the massif. Two specimens of two-mica schist from the Upper and Lower Kimkanskaya groups (Russian Far East) yielded zircon age populations at 572, 826, 891, 958, and 1776 Ma, and 682, 752, 835, and 925 Ma, respectively; a sericite schist and muscovite schist from the Majiajie Group (NE China) yielded zircon age populations at 951, 1232, 1419, 1643, and 2687 Ma, and 1151, 1276, 1444, 1623, 1805, and 2652 Ma, respectively; and a two-mica schist from the Ximashan Formation of the Mashan Group (NE China) yielded zircon age populations at 994, 1281, 1439, 1647, and 1805 Ma. Taking into account the general geological relationships in the area, zircon age populations, and Hf isotopic compositions, combined with an age of 492 Ma for a monzogranite that intrudes the Ximashan Formation, we conclude that the Lower Kimkanskaya Group formed in the Neoproterozoic and was sourced mainly from a Neoproterozoic terrane, whereas the Majiajie Group and Ximashan Formation formed in the Neoproterozoic but were sourced dominantly from a Mesoproterozoic terrane. Taking into account previous paleomagnetic data, our dating results and comparisons with zircon age populations in Precambrian rocks from northeastern Gondwana and the southern Siberia, North China, and Tarim cratons, suggest that the Jiamusi Massif has an affinity with the Tarim Craton.

New geochemical and Re–Os isotopic data of mantle xenoliths entrained in Cenozoic Sviyagino alkali basalts from the Russian Far East provide insights into the age and evolution of the sub-continental lithospheric mantle (SCLM) beneath the Khanka Massif, within the Central Asian Orogenic Belt (CAOB). These mantle xenoliths are predominantly spinel lherzolites with minor spinel harzburgite. The lherzolites contain high whole-rock concentrations of Al 2 O 3 and CaO, with low forsterite content in olivine (Fo = 89.5–90.3%) and low Cr# in spinel (0.09–0.11). By contrast, the harzburgite is more refractory, containing lower whole rock Al 2 O 3 and CaO contents, with higher Fo (91.3%) and spinel Cr# (0.28). Their whole rock and mineral compositions suggest that the lherzolites experienced low-degree (1–4%) batch melting and negligible metasomatism, whereas the harzburgite underwent a higher degree (10%) of fractional melting, and experienced minor post-melting silicate metasomatism. Two-pyroxene rare earth element (REE)-based thermometry (T REE ) yields predominant equilibrium temperatures of 884–1043 °C, similar to values obtained from two-pyroxene major element-based thermometry (T BKN = 942–1054 °C). Two lherzolite samples yield high T REE relative to T BKN (T REE − T BKN ≥ 71 °C), suggesting that they cooled rapidly as a result of the upwelling of hot asthenospheric mantle material that underplated a cold ancient lithosphere. The harzburgite with a low Re/Os value has an 187 Os/ 188 Os ratio of 0.11458, yielding an Os model age (T MA ) relative to the primitive upper mantle (PUM) of 2.09 Ga, and a Re depletion ages (T RD ) of 1.91 Ga; both of which record ancient melt depletion during the Paleoproterozoic (~ 2.0 Ga). The 187 Os/ 188 Os values of lherzolites (0.12411–0.12924) correlate well with bulk Al 2 O 3 concentrations and record the physical mixing of ancient mantle domains and PUM-like ambient mantle material within the asthenosphere. This indicates that the SCLM beneath the Khanka Massif had been formed since at least the Paleoproterozoic (~ 2.0 Ga), and was replaced by juvenile (Phanerozoic) mantle material accreted from the asthenosphere. The synthesis of available T RD ages for mantle-derived rocks and sulfides in xenoliths is consistent with the prior existence of a common Paleoproterozoic (~ 2.0 Ga) SCLM beneath the eastern CAOB. Finally, comparing of mantle T RD ages and the ages of crustal rocks suggests temporal and genetic links between crust and mantle formation during the evolution of the CAOB.

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 e 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.

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 e 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 e Nd (t) and variable zircon e 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 e 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.

The Raohe accretionary complex, located at the border between the Russian Far East and Northeastern China, is a significant part of the western Pacific Oceanic tectonic regime. Due to lack of precise age and geochemical constraints, the tectonic setting and petrogenesis of the magmatic rocks in this area remain undefined, resulting in debate about crustal growth mechanisms and subduction-related accretionary processes in Northeastern China. Here, we report whole-rock major and trace element and Sr-Nd isotope data, together with zircon U-Pb ages and in situ zircon Hf isotope data for calc-alkaline andesites, dacites, rhyolites, rhyolitic crystal tuffs, Nb-enriched andesites and basaltic andesites, and high-Mg andesites of the Raohe accretionary complex in NE China. Samples were collected from Late Triassic to Early Jurassic strata. However, geochronological results in this study indicated that the studied magmatism occurred in the Early Jurassic (187–174 Ma). The calc-alkaline volcanic rocks possess geochemical characteristics typical of arc magmas that form at active continental margins, such as moderate enrichments in large ion lithophile elements (LILEs) and light rare earth elements (LREEs), and depletions in high field strength elements (HFSEs). They have positive e Hf (t) values of +3.4 to +10.6 and relatively high ( 87 Sr/ 86 Sr) i values of 0.7047–0.7102. While the Nb-enriched andesites and basaltic andesites have higher TiO 2 , Hf, Nb, and Zr contents and higher Nb/Ta (24.0–87.6), Nb/U (11.9–75.9), (Nb/Th) PM (0.67–2.70), and (Nb/La) PM (1.95–5.00) ratios than typical arc basalts. They have negative e Nd (t) values (−5.5 to −6.0) and relatively variable ( 87 Sr/ 86 Sr) i values of 0.7047–0.7114, suggesting an origin via the partial melting of mantle wedge peridotite that had been metasomatized by slab-derived melt. The high-Mg volcanic rocks, characterized by high MgO and Mg # , TiO 2 , Al 2 O 3 , Cr, Ni, (La/Yb) N and (La/Sm) N , but low Ba/Th ratios, are geochemically similar to sanukitoids in southeastern Japan. The occurrence of calc-alkaline, Nb-enriched, and high-Mg volcanic rocks at modern arcs where oceanic slabs are subducting has been well documented. Therefore, we propose that a similar mechanism may explain the generation of the Early Jurassic volcanic rocks of the Raohe accretionary complex in Northeastern China.

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 206Pb/238U 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 eHf(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 eHf(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.

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 SiO2 = 71.29–78.08 wt%, A/CNK = 1.06–1.99, and Na2O/K2O = 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.

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 SiO2 (70.75–77.04 wt.%) and K2O (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 (Na2O + K2O = 8.22–8.90 wt.%), low MgO (0.04–0.09 wt.%) and P2O5 (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 eHf(t) (+ 7.89 to − 5.60) and two-stage Hf model ages (TDM2) 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.

We present zircon U–Pb ages, major and trace element analyses, and zircon Hf isotope data on the Late Cretaceous–Paleocene granitoids at the southern end of the Sikhote-Alin Orogenic Belt of the Russian Far East. These data are used to discuss the petrogenesis of the granitoids in the context of the paleo-Pacific subduction beneath the eastern Eurasia. Zircons from four granitoid samples give emplacement ages of ~ 56, ~ 83, ~ 91, and ~ 92 Ma. These granitoids with high SiO2 (73.43–76.76 wt%) are metaluminous to weakly peraluminous (A/CNK = 0.97–1.03) and belong to the high-K calc-alkaline series (K2O = 3.75–4.95 wt%). They are all enriched in light rare earth elements (LREEs) and large ion lithophile elements (LILEs), and relatively depleted in high field strength elements (HFSEs) with striking depletion also in Ba, Sr, P and Eu. They are petrographically and geochemically consistent with being of I-type granitoids. The zircons have εHf (t) values (− 0.8 to + 7.6) higher than whole-rock εHf (t) values predicted from whole-rock εNd (t) (− 4.1 to + 0.5) in the literature. All these observations suggest that primary magmas parental to these granitoids were likely to have derived from partial melting of a juvenile lower crust accompanied by assimilation with ancient mature crust during magma ascent and evolution. A recent study illustrates that the collision of an exotic terrane carried by the paleo-Pacific plate with the continental China at ~ 100 Ma accreted the basement of the Chinese continental shelf (beneath East and South China Seas), and resulted in a new plate boundary of transform nature between the NNW moving paleo-Pacific plate and the eastern margin of the shelf. Our new data and analysis of existing data support this hypothesis, but we hypothesize that this transform becomes transpressional in its northern segment with oblique subduction of the paleo-Pacific plate beneath northeastern Asia as manifested by the Late Cretaceous-Paleocene granitoids in the Russian Far East-NE China (97–56 Ma) and South Korea-SW Japan (96–71 Ma). These tectonic and magmatic events took place prior to the opening of the Huanghai, Bohai and Japan seas, which are of rift-origin from continental China much later. Our study emphasizes the necessity and significance of plate tectonics reconstruction in the greater northwestern Pacific region since the Cretaceous.

In this paper, we report zircon U–Pb ages, Hf isotopes and whole-rock geochemical data for the Permian to Early Triassic granitoids from the western margin of the Jiamusi Block (WJB), NE China. The intermediate to felsic (SiO2 = 59.67–74.04 wt%) granitoids belong to calc-alkaline series and are characterized by enrichments in light rare earth elements and large ion lithophile elements with pronounced negative Nb, Ta and Ti anomalies, revealing typical continental magmatic arc geochemical signatures. The zircon U–Pb determinations on the granodiorite, monzogranite, syenogranite and quartz diorite samples yielded ages between ca. 275–245 Ma, which, together with the published coeval intrusive rocks, indicates that Permian to Early Triassic continental arc magmatism occurred extensively in the WJB. The low and mainly negative zircon e Hf(t) values between −7.6 and +1.6 and the zircon Hf model ages of 1.2–1.8 Ga, which are significantly older than their crystallization ages, suggest that they were mainly derived from reworking of ancient crustal materials with a limited input of juvenile components. The geochemical systematics and petrogenetic considerations indicate that the studied granitoids were generated from a zone of melting, assimilation, storage, and homogenization, i.e., a MASHed zone at the base of Paleo- to Mesoproterozoic continental crust, where large portions of igneous rocks and minor clay-poor sediments involved in the source region. In combination with regional geological data, we argue that the Jiamusi Block was unlikely the rifted segment of the Songliao Block and two possible geodynamical models were proposed to interpret the formation of the ca. 275–245 Ma granitoids in the WJB. In the context of Permian global plate reconstruction, we suggest that Paleo-Pacific plate subduction was initiated in the Permian to Early Triassic beneath the Jiamusi Block, and even whole eastern NE China.

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.

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 SiO2 = 62.97–76.31 wt%, A/CNK = 1.03–1.51, and K2O/Na2O = 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.

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 SiO2 and total Na2O + K2O, 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 eHf(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 SiO2 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 eHf(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.

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 e 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 e 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.

Whole-rock major and trace element, and Sr, Nd, and Hf isotopic data, together with zircon U–Pb ages and in situ zircon Hf isotopes, are reported for Middle Jurassic igneous rocks of the Raohe accretionary complex, northeastern China, to investigate their petrogenesis and tectonic implications. The igneous rocks consist of pillow basalt, pyroxenite, gabbro, plagioclasite, and plagiogranite. The zircons from one plagioclasite and one plagiogranite are euhedral–subhedral and display fine-scale oscillatory growth zoning, indicating a magmatic origin. Zircon U–Pb dating gives an emplacement age of 169–167 Ma. The basalts are associated with late Paleozoic to middle Mesozoic sediments typical of ocean plate stratigraphy; i.e., limestone, bedded chert, and siliceous shale. The basalts, which show geochemical features similar to those of oceanic island basalts (OIBs), are enriched in TiO2, light rare earth elements (LREEs) (average: La/Smn = 2.12), and Nb (average: Zr/Nb = 12.24), and are characterized by positive Nb anomalies (averages: Nb/Thpm = 1.46, Nb/Lapm = 1.31). The rocks are depleted in heavy rare earth elements (HREEs) (average: Gd/Ybn = 2.03) and exhibit high eNd(t) (+8.2 to +8.3) and eHf(t) (+9.0 to +9.1) values. The geochemical features indicate the Jurassic OIB-like basalts were derived by a low degree of partial melting (

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 ea...