The Central Asian Orogenic Belt (CAOB) is the largest accretionary orogen in the world, which is responsible for considerable Phanerozoic juvenile crustal growth. The NE China and its adjacent areas ...compose the eastern segment of the CAOB, which is a key area for providing important evidence of the CAOB evolution and understanding the NE Asian tectonics. The eastern segment of the CAOB is composed tectonically of four micro-blocks and four sutures, i.e. Erguna block (EB), Xing'an block (XB), Songliao-Xilinhot block (SXB), Jiamusi block (JB), Xinlin-Xiguitu suture (XXS), Heihe-Hegenshan suture (HHS), Mudanjiang-Yilan suture (MYS) and Solonker-Xar Moron-Changchun-Yanji suture (SXCYS). The EB and XB were amalgamated by westward subduction, oceanic island accretions and final collision in ca. 500Ma. The XB and SXB were amalgamated by subduction-related Early Paleozoic marginal arc, Late Paleozoic marginal arc and final collision in the late Early Carboniferous to early Late Carboniferous. The JB probably had been attached to the SXB in the Early Paleozoic, but broken apart from the SXB in the Triassic and collided back in the Jurassic. The closure of Paleo-Asian Ocean had experienced a long continue/episodic subduction–accretion processes on margins of the NCC to the south and the SXB to the north from the Early to Late Paleozoic. The final closure happened along the SXCYS, from west Solonker, Sonid Youqi, Kedanshan (Keshenketengqi), Xar Moron River through Songliao Basin via Kailu, Tongliao, Horqin Zuoyizhongqi, Changchun, to the east Panshi, Huadian, Dunhua, Yanji, with a scissors style closure in time from the Late Permian-Early Triassic in the west to the Late Permian-Middle Triassic in the east. The amalgamated blocks should compose a united micro-continent, named as Jiamusi-Mongolia Block (JMB) after Early Carboniferous, which bounded by Mongo-Okhotsk suture to the northwest, Solonker-Xar Moron-Changchun suture to the south and the eastern margin of JB to the east.
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•Recent new data are reviewed, four blocks and four sutures have been recognized in the NE China, eastern CAOB.•A new tectonic model is suggested in the NE China.•Paleo-Asian Ocean is considered to be closed in the Late Permian-Middle Triassic.
The Central Asian Orogenic Belt (CAOB) is the largest accretionary orogen in the world with considerable Phanerozoic juvenile crustal growth. The eastern segment of the CAOB is occupied by NE China ...and its adjacent areas, which locates in a triangle area surrounded by Siberian Craton to the northwest, North China Craton (NCC) to the south and Pacific oceanic plate to the east. Therefore, the NE China is a key area to study the geological evolution of multiple tectonic systems and overprinting, which has become a hot research topic. In the past five decades, especially the last two decades, there have been many detailed geological investigations carried out and a lot of new data reported in NE China. A progress has been achieved in tectonic evolution, however, there are still many open questions and arguments dealing with the tectonic models, correlation of tectonic units, amalgamation of different blocks and their tectonic affinity. In this study, we did a detailed review of the tectonic evolution of NE China and regional comparison and correlation of the different tectonic units in the eastern segment of CAOB. We re-subdivided NE China into two old blocks of Erguna block (EB) and Jiamusi block (JB) with Precambrian basement and three accretionary terranes of Xing'an accretionary terrane (XAT), Songliao accretionary terrane (SAT) and Zhangguangcai accretionary terrane (ZGCAT), which are separated from each other by the Xinlin-Xiguitu suture (XXS), Hegenshan-Heihe suture (HHS), Longfengshan suture (LFS) and Mudanjiang-Yilan suture (MYS), respectively. The ZGCAT is dominantly composed of early Paleozoic magmatic arc materials and minor late Paleozoic igneous rocks with an old Yichun mini-block, while the SAT consists dominantly of the late Paleozoic magmatic rocks with two small old blocks of the Xilinhot and Longjiang mini-blocks. According to the tectonic correlation and comparation of different tectonic units, we established a new orocline tectonic model for the eastern CAOB: 1) the XAT and ZGCAT accreted to the southern (present position) margin of Ereendavaa-Erguna-Mamyn block (EEMB) and Bureya-Jiamusi-Khanka block (BJKB) with the closure of Xinlin-Xiguitu-Heilongjiang ocean during the early Paleozoic; 2) Subsequently, the SAT accreted to the southern (present position) margin of integrated XAT-ZGCAT terrane with the closure of Hegenshan-Nenjiang-Longfengshan ocean during the late Paleozoic. These initially W-E linear shaped accretionary orogenic belts were ultimately bent southward through Paleozoic time and constituted a huge Paleozoic orocline, NE China Orocline, which collided with NCC by a scissor-like style closure of Paleo-Asian Ocean (PAO) from west to east along the Solonker-Xar Moron-Changchun-Yanji suture (SXCYS) during the late Permian-middle Triassic. The NE China Orocline, together with Tuva-Mongol Orocline and Kazakhstan Orocline in the western CAOB, constituted a huge multiple orocline tectonic system in the CAOB during the Paleozoic era. Our study will contribute to the understanding on tectonic evolutions of CAOB and the NE Asian, and suggests that the orocline should be a common tectonic model for accretionary orogeny.
•NE China consists of two Precambrian blocks and three Paleozoic accreted terranes.•A new orocline tectonic model is established for first time in NE China.•Blocks in NE China had been integrated in later Early Carboniferous.
The E–W trending Yanshan belt, an intraplate fold-thrust belt located in the northern North China Craton, has experienced several episodes of Mesozoic deformation, which resulted in the widely ...distributed magmatism and mountain-basin tectonics that completely re-shaped the topography of the eastern North China Craton. The eastern part of the famous Chinese Great Wall was built on the high range of the southeastern Yanshan mountain belt juxta-posed to the plain, which directly relates to the Bohai Bay basin. Our study focuses on which tectonic processes created such mountain-basin couple in Mid-Late Mesozoic times. The U-Pb LA-ICP-MS dating of zircons yield ages of 114 to 201 Ma for various granites and 115 to 116 Ma for volcanic rocks from Yixian and Jiufotang Fms. The detrital zircons from the Lower Cretaceous sandstones yield four age groups of 2587 to 2460 Ma, 2222 to 1828 Ma, 297 to 190 Ma and 187 to 100 Ma, which are all sourced from the Qinglong and surrounding areas and indicating that the Qinglong area started to uplift after the Middle Jurassic. The Qinglong area underwent multiple deformation by NE–SW compression in the Middle-Late Jurassic times, WNW–ESE compression in the Late Jurassic to Early Cretaceous, ENE–WSW extension in the Early Cretaceous and NNW–SSE compression in the Late Cretaceous during the final stage of the Yanshanian orogeny. Meanwhile, widely distributed granite intrusions and emplacement of the Upper Jurassic-Lower Cretaceous volcanic rocks indicate a large amount of magma input into the area. The Qinglong area with the Great Wall along its southern margin close to adjacent plain to the south was uplifted to form the Qinglong highland and surrounding related basins by combination of the following three processes: the multiple tectonic Late Jurassic and Late Cretaceous shortening processes related to Yanshanian orogeny, Early Cretaceous regional extension triggered by slab-retreat of the Paleo-Pacific ocean and inflation of large amount magma at depth during Jurassic and Early Cretaceous.
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•Early Cretaceous basin provenance analysis has been carried out.•4 sets of paleostress regime are recognized.•Qinglong highland was uplifted during the Late Jurassic to Late Cretaceous.•Uplift resulted from tectonic compression and magma inflation.
•The Neoproterozoic Ali River ophiolitic mélange is first identified in the northern Great Xing’an Range, NE China and were tectonically emplaced prior to 557 Ma.•The ophiolitic mélange consists of ...Neoproterozoic mafic-ultramafic blocks dispersed in a sedimentary matrix.•The Ali River ophiolitic mélange is an origin of the SSZ-type ophiolite.•The ophiolitic mélange represents a Neoproterozoic suture zone formed by arc-microcontinent amalgamation between the Erguna and Xing’an blocks.
In this study, we report three Neoproterozoic ophiolitic mélanges in the Ali River (Jifeng-Gaxian-Huanerku) area from the northern Great Xing’an Range, NE China. Detailed field mapping reveal that all three mélanges disperse in a strongly sheared metasedimentary matrix composed mainly of mica-schist, quartz-schist and marble. These mélanges, which have undergone polyphase deformation with northwest-verging nappe structures, are composed of a suite of amphibolite-facies mafic to ultramafic blocks including serpentinite, olivine pyroxenite, pyroxenite, diabase, gabbro and basalt. Lithological and geochemical characteristics of these ultramafic-mafic rocks suggest that their protoliths were from an ophiolitic mélange formed in a Neoproterozoic supra-subduction zone. The protolith ages were constrained by LA-ICP-MS/SHRIMP U-Pb dating of zircons from the Jifeng gabbro, the Gaxian pyroxenite, and the Huanerku gabbro, which yielded ages of 647 ± 5, 628 ± 10 and 697 ± 3 Ma, respectively. The zircons from the gabbros have obvious positive εHf (t) values that range from +8.3 to +17.2 (average = +13.5) with corresponding TDM1 ages of ca. 680 Ma, indicating that these rocks are the remnants of juvenile crust derived from depleted mantle in the Neoproterozoic. All rock types in the mélange underwent amphibolite facies metamorphism. The tectonic emplacement of these ophiolitic mélanges was no later than 557 ± 2 Ma, which is the age of continental arc-type granodiorites (negative εHf (t) values from -7.4 to -17.8) that intruded these rocks. The mafic-ultramafic rocks in the Ali River mélanges are interpreted to be fragments of a ca. 690–620 Ma supra-subduction zone ophiolite that was incorporated into the Xinlin-Xiguitu suture zone during subduction-accretion. Together with the ca. 500 Ma Toudaoqiao blueschists, the Ali River ophiolitic mélange in the northern Great Xing’an Range provides important evidence for the Neoproterozoic subduction-accretion-collision processes associated with the amalgamation of the Erguna and Xing’an blocks.
Mashan Complex in the southeastern margin of the Jiamusi Massif has traditionally been interpreted to be the oldest stratigraphic sequence in eastern NE China. Here we investigated the Mashan Complex ...in the Ximashan area and present lots of new LA–ICP–MS zircon U–Pb, petrological and mineralogical chemical data, in addition with phase equilibria modeling, to constrain the timing of metamorphism, P–T conditions and the P–T path of the Mashan Complex, and furthermore to deduce the crustal evolution of the Jiamusi Massif. The protoliths of the metapelites from the Mashan Complex in the Ximashan area are clay rocks and sandstones, whose provenance is dominantly felsic rocks which formed from a continental island arc. Three metamorphic generation assemblages (M2–M4) are recognized in the studied samples: a peak granulite facies stage, a post-peak near-isothermal decompression stage, and a late near-isobaric cooling stage, which together define a clockwise P–T path. It reveals important information related to the collision orogeny, subsequent uplift, and post-collision process. Zircon U–Pb dating of two metapelitic samples yielded metamorphic ages of the older group varying from 535 ± 6 to 480 ± 5 Ma, which can be perfectly correlated with the age range (501 ± 6 to 498 ± 6 Ma) of magmatic activities recorded by the gneissic granite sample. The data presented here, together with those published, allow us to preliminarily infer that the peak of the granulite-facies metamorphism in the Ximashan area of the Jiamusi Massif might have occurred at 530–500 Ma. The younger of the metamorphic ages (476–453 Ma) should be regarded as the age of late stage. Therefore, a collision orogeny regime is favored to interpret the metamorphic evolution of metapelites of the Mashan Group in the Mashan area.
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•The metapelites of the Mashan Complex in the Ximashan area of the Jiamusi Massif were involved in multiple-stage metamorphism.•P–T conditions and the P–T path are reestablished by pseudosections and geothermobarometry.•Three metamorphic stages with a clockwise P–T path were recognized.•The peak of the granulite facies metamorphism might have occurred at some time before 530–500 Ma.
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•The depositional age of the Xiufeng Formation was estimated as 159 Ma.•The Mohe Formation has a bidirectional provenance from 150 Ma.•The tectonic setting transformed from ...compression to extension during 135–128 Ma.•A series of E-W and NE-SW-trending normal faults occurred since the Early Barremian.•The final closure of the Mongol-Okhotsk Ocean has been limited to 150–135 Ma.
The Mohe basin is located to the south of the eastern Mongol–Okhotsk suture belt and contains critical stratigraphic records and thrust-nappe structures for understanding the closure of the eastern Mongol–Okhotsk Ocean. This paper discusses the formation ages, provenance, and tectonic setting of the Xiufeng and Mohe formations, and further reveals the timing of the final closure of the Mongol–Okhotsk Ocean and the tectonic evolution of the Mohe basin. The weighted mean 206Pb/238U ages for the youngest zircon of these samples indicate that the maximum depositional ages of the Xiufeng, Mohe and Tamulangou Formations were conservatively estimated at 159 Ma, 150 Ma and 128 Ma, respectively. From Late Triassic to Late Jurassic (150 Ma), the Mongol-Okhotsk Ocean was consumed by bidirectional subduction expressed by subduction under the Siberian Craton and the Erguna Block, respectively. The intense subduction led to the compression of the continental arc and the basement uplift of the Erguna Block, which provided abundant clastic sediments to the Xiufeng-Ershierzhan Formations. During the Late Jurassic-Valanginian (150–135 Ma), the Mongol-Okhotsk Ocean closed rapidly, which finally caused the collision between the Erguna Block and the Siberian Craton. Meanwhile, the southern margin of the Siberian Craton was uplifted and started furnishing sediments into the Mohe-Kaikukang Formations, which may have a bidirectional provenance. The subsequent crustal shortening associated with collision between the Erguna Block and the Siberian Craton led to nappe structures, syn‐collisional folds, and nearly N-S-trending reverse and oblique-slip faults occurred along the northwestern margin of the Mohe basin. Between 135 and 128 Ma, the Mohe basin entered the stage of tectonic setting transformation, which is the crucial period for the Mohe basin to transform from compression to extension. Since the Early Barremian (ca. 128 Ma), the compressional environment was transformed into a post-orogenic extensional tectonic environment, and a series of nearly E-W and NE-SW-trending normal faults occurred, which might have been controlled by the slab rollback of the Paleo-Pacific Plate and detachment of the Mongol-Okhotsk oceanic plate after the closure of the Mongol-Okhotsk Ocean.
•Four metamorphic generation assemblages were recognized in high-grade granulite facies rocks of the Mashan Complex.•A clockwise P-T path with nearly isothermal decompression segments was ...established.•The peak of the granulite facies metamorphism might have occurred at ca. 530 Ma, and its final cooling stage could take place at ca. 490 Ma.
The nature and age of the Mashan Complex (or Mashan Group) in northeast China is key for determining the Precambrian geological evolution and origins of the Jiamusi Massif. Here we present a detailed investigation of high-grade granulite-facies rocks of the Mashan Complex from the Liumao area, Heilongjiang Province, China. This includes zircon U–Pb dating, petrological and geochemical analysis, geothermobarometry, phase equilibria modelling, and a P–T path. The metamorphic rocks consist mainly of two groups: pelitic and felsic granulites; amphibolite-facies Sil–Grt–Bi, Sil–Grt, and Grt–Bi gneisses. The protoliths of the metamorphic rocks were clay rocks and sandstones, which were derived dominantly from silicic rocks in a continental island arc setting. In the pelitic granulites, four metamorphic assemblages (M1–M4) were recognised. Three metamorphic assemblages (M2–M4) were identified in the felsic granulites. Geothermobarometric data and phase equilibria modelling indicate that the M2, M3, and M4 assemblages in the pelitic granulite were metamorphosed at 9.2 kbar/845–865 °C, 4.7–5.1 kbar/820–865 °C, and 4.0–4.8 kbar/660–720 °C, respectively. These features imply a collisional orogenic process with a clockwise P–T path with nearly isothermal decompression segments. Similar results were obtained for the felsic granulite, with the metamorphic P–T conditions of the peak assemblage (M2) evaluated as 9.0–9.2 kbar/845–870 °C. The similar P–T paths indicate that the rocks underwent an evolutionary process that started with crustal thickening (M2), followed by rapid crustal uplift (M3), and then final cooling (M4). Based on our new zircon U–Pb age data, the peak of granulite-facies metamorphism in the Liumao area of the Jiamusi Massif occurred at ca. 530 Ma and final cooling occurred at ca. 490 Ma.
As seismic data from the lower crust becomes more readily available, it is important to link seismic properties to the ongoing processes within lower crustal evolution. This includes high ...temperature, pre‐ and post‐migmatization solid state deformation as well as melt‐present deformation. We selected two tonalitic migmatites with variable former melt content (one metatexite and one diatexite) from the lower crustal Daqingshan area, northern North China Craton to assess the link between seismic properties and rock structure and rheology. Field observation along with microstructural features suggest that the characteristics of hornblende and plagioclase within the residuum of the metatexite can be used to derive information on the pre‐melt deformation. Residuum's plagioclase CPO (crystallographic preferred orientations) is consistent with high temperature dislocation creep as the main deformation mechanism; similarly, hornblende shows a strong CPO related to dislocation creep. During syn‐melt (melt present) conditions, phenocrysts of plagioclase in the metatexite's neosome and K‐feldspar and peritectic hornblende in the diatexite's neosome are present. The rheology of the rock was dominated by melt; hence is inferred to follow Newtonian flow. After melt crystallization deformation is minor but again dominated by dislocation creep. The seismic properties (seismic velocity, anisotropy, Vp/Vs ratio, etc.) for pre‐ and post‐melt have similar values expected values for solid mafic rocks, whilst the syn‐melt seismic velocities are generally lower and Vp/Vs ratios and seismic anisotropies are higher.
Key Points
Tonalitic migmatites show distinct deformation signatures and seismic properties during pre‐, syn‐, and post‐migmatization
Power‐law creep dominates solid phases' deformation, near‐Newtonian flow is typical for deformation in rocks with high melt content
Migmatites have low Vs and extreme high seismic anisotropies in the syn‐melt condition
•The Mashan Complex were involved in multiple-stage metamorphism.•Four generations of metamorphic mineral assemblages were recognized.•A clockwise P-T path with nearly isothermal decompression ...segments was established.•Peak of the granulite facies metamorphism might have occurred at ca. 530 Ma.
The Mashan Complex is the oldest metamorphic rock series in the Jiamusi Massif, which consists mainly of amphibolite to granulite facies metamorphic rocks accompanied by various granitic rocks. Herein, we investigate the pelitic granulites from this complex as well as associated granites and identify four distinct mineral assemblages corresponding to different metamorphic stages. The prograde metamorphism (M1) is recorded by the core of the garnet and inclusions within: Grtcore–Bi–Sil–Qz. The peak granulite facies metamorphism (M2) is distinguished by the garnet mantle and the related mineral assemblages in the matrix: Bi–Kfs–Grtmantle–Ilm–Sil–Qz. The post-peak decompression stage (M3) is characterized by the formation of cordierite corona and minerals in the cordierite of the matrix: Bi–Liq–Crd–Pl–Kfs–Grt–Ilm–Sil–Qz–Mt. The retrograde stage (M4) is featured by the garnet rim and the nearby assemblages: Bi–Crd–Pl–Kfs–Grtrim–Ilm–Sil–Qz–Mt. According to the phase equilibria modeling, the metamorphic P–T conditions from M2 to M4 were estimated as 6.5–8.5 kbar/815–825 °C, 5.3–5.7 kbar/780–795 °C, and 4.5–5.3 kbar/730–775 °C, respectively, which together define a clockwise P–T path. LA–ICP–MS U–Pb dating for zircons from four metamorphic rocks shows that most of the detrital material came from middle Paleoproterozoic, middle Mesoproterozoic and early Neoproterozoic source rocks. In addition, metamorphic zircon grains in the metamorphic rocks yield two groups of ages at ca. 530 Ma and ca. 500 Ma, which are regarded as the peak of granulite-facies metamorphic (M2) and the retrograde cooling metamorphic (M4) ages, respectively.
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•The Keluo Complex is dominated by at least four stages of deformed magmatic rocks.•Two major deformation events were recognized in this Complex.•D1 is related to the subduction and ...closure of the Mongol-Okhotsk Ocean.•D2 resulted from the superimposition of the two extensional settings.
The Da Hinggan Mountains (DHM) are located in the eastern segment of the Central Asian Orogenic Belt (CAOB) and represent a prominent geomorphic marker of NE China, although its evolution history and exhumation/uplift mechanisms remain equivocal. Here, we present results from a comprehensive study on the field and micro-structures, kinematics, rheology, quartz EBSD fabrics, geochemistry and geochronology of the Keluo Complex (KC) exposed in the northern DHM. The KC is dominated by deformed Early Carboniferous to earliest Permian rocks (337–297.1 Ma) and is invaded by Early Mesozoic multi-stage granitic intrusions (219.8–175.5 Ma). These were further overprinted by magmatism, metamorphism, and deformation during the Late Jurassic (152.0–157.7 Ma) and late Early Cretaceous (118.3 Ma). The latest Carboniferous/earliest Permian rocks formed in a post-collisional extensional environment that might be related to the collision of the Xing'an and Songnen massifs. The Early Mesozoic rocks were derived from magma generated by partial melting of the lower continental crust within an active continental margin setting related to the subduction of the Mongol-Okhotsk Ocean. Two prominent deformation events (D1 and D2) were recognized in the KC, which occurred in Late Jurassic and late Early Cretaceous. The D1 is dominated by SW-trending sinistral ductile shearing accompanied by moderate to high-temperature deformation (500–600 °C) resulting from NW–SE compression. The D2 is a bi-directional extensional and detachment deformation corresponding to a low temperature (300–400 °C) deformation developed at a shallow-level ductile regime resulting from NW–SE extension. The D1 deformation was influenced by subduction and closure of the Mongol-Okhotsk Ocean, whereas the D2 deformation is correlated to the superposition of the extension after the closure of the Mongol-Okhotsk Ocean and the rollback of the Paleo-Pacific Plate. Our results provide new insights into the tectonic history of the DHM domain of the CAOB.
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