A large amount of igneous rocks in NE China formed in an extensional setting during Late Mesozoic. However, there is still controversy about how the Mongol-Okhotsk Ocean and the Paleo-Pacific Ocean effected the lithos...A large amount of igneous rocks in NE China formed in an extensional setting during Late Mesozoic. However, there is still controversy about how the Mongol-Okhotsk Ocean and the Paleo-Pacific Ocean effected the lithosphere in NE China. In this paper, we carried out a comprehensive study for andesites from the Keyihe area using LA-ICP-MS zircon UPb dating and geochemical and Hf isotopic analysis to investigate the petrogenesis and tectonic setting of these andesites. The U-Pb dating yields an Early Cretaceous crystallization age of 128.3±0.4 Ma. Geochemically, the andesites contain high Sr(686-930 ppm) and HREE contents, low Y(11.9-19.8 ppm) and Yb(1.08-1.52 ppm) contents, and they therefore have high Sr/Y(42-63) and La/Yb(24-36) ratios, showing the characteristics of adakitic rocks. Moreover, they exhibit high K2O/Na2O ratios(0.57-0.81), low Mg O contents(0.77-3.06 wt%), low Mg# value(17-49) and negative εHf(t) values(-1.7 to-8.5) with no negative Eu anomalies, indicating that they are not related to the oceanic plate subduction. Based on the geochemical and isotopic data provided in this paper and regional geological data, it can be concluded that the Keyihe adakitic rocks were affected by the Mongol-Okhotsk tectonic regime, forming in a transition setting from crustal thickening to regional extension thinning. They were derived from the partial melting of the thickened lower crust. The closure of the Mongol-Okhotsk Ocean may finish in early Early Cretaceous, followed by the collisional orogenic process. The southern part region of its suture belt was in a post-orogenic extensional setting in the late Early Cretaceous.展开更多
The Mongol-Okhotsk Ocean,which has been closing gradually from the west to the east beginning since the Late Paleozoic,was an important part of the Central Asian Orogenic Belt.It influenced the tectonic framework of N...The Mongol-Okhotsk Ocean,which has been closing gradually from the west to the east beginning since the Late Paleozoic,was an important part of the Central Asian Orogenic Belt.It influenced the tectonic framework of Northeast Asia in the Mesozoic,especially the Late Mesozoic arc-basin system that is widely distributed in the Great Xing’an Range.However,the manner in which the Mongol-Okhotsk Ocean affected the sedimentary basin development remains poorly understood.To address this issue,we conducted U-Pb dating of detrital zircon deposited sedimentary basins of the central Great Xing’an Range.By examining the possible provenances of the detrital zircon and the structural controls of the basins,we found that a key sedimentary unit was deposited around Late Jurassic-Early Cretaceous.Its provenance was a felsic source in a back-arc setting of an active continental margin.The findings also suggest the existence of a unified geodynamic setting that affected the coeval development of basins in the northern Great Xing’an Range and the Yanshan fold-thrust belt along the northern margin of North China Craton.This research helps to better understand the complex tectonic processes which shaped the Northeast Asia during the Late Mesozoic.展开更多
The tectonic setting of Jurassic magmatism in the Northeast China(NE China)is unclear.Here,we present new petrological,whole-rock geochemical,zircon U-Pb geochronological,and zircon Lu-Hf isotope data for Jurassic gra...The tectonic setting of Jurassic magmatism in the Northeast China(NE China)is unclear.Here,we present new petrological,whole-rock geochemical,zircon U-Pb geochronological,and zircon Lu-Hf isotope data for Jurassic granitoids of the Wulong region,Liaodong Peninsula,NE China.Laser ablation-inductively coupled plasma-mass spectrometry(LA-ICP-MS)zircon U-Pb data indicate that these granitoids were emplaced at 165-156 Ma.The biotite monzogranite,two-mica monzogranite,monzogranite,granodiorite,biotite granodiorite,and syenogranite are strongly peraluminous(A/CNK=1.09-1.29),contain peraluminous minerals such as muscovite,have high normative corundum abundances(1.26 wt.%-3.28 wt.%),and have high K2_(O)/Na2O ratios(0.76-1.48),all of which indicate an S-type granite affinity.However,the biotite granodiorite and syenogranite have high Sr(391 ppm-570 ppm)and low Y(3.06 ppm-5.94 ppm)contents,with high Sr/Y(65.8-185.9)ratios,and the two-mica monzogranite,monzogranite,and granodiorite have relatively high Sr(138 ppm-379 ppm)and low Y(3.38 ppm-8.71 ppm)contents,with high Sr/Y ratios(19.1-77.9).All of the analyzed samples have negative zircon eHf(t)values(-41.4 to-20.6)with old two-stage Hf model ages(TDM2(Hf)=2.50-3.76 Ga).Therefore,we infer that the biotite monzogranite is the typical feature of S-type granite that was derived by partial melting of metagraywacke.The monzogranite,two-mica monzogranite,granodiorite,biotite granodiorite,and syenogranite exhibit geochemical characteristics of S-type granite with K-rich adakitic features,and were possibly derived by mixing of melts from clastic crustal materials and ada-kitic magmas.There are voluminous Jurassic igneous rocks in the NE China.By combining our study with the previous researches,this paper infers that the Jurassic magmatism within the Erguna-Xing'an Massif was related to the southward subduction and closure of the Mongol-Okhotsk Ocean;the Early Jurassic magmatism to the east of the Songliao Basin and in the northern North China Cra-ton(NCC)was related to the subduction展开更多
Mongol-Okhotsk Orogenic Belt is the last main orogen that constructs modern tectonic framework of northeastern Asia. It has recorded the long-term evolution of the Mongol-Okhotsk Ocean(MOO) from its Early Paleozoic in...Mongol-Okhotsk Orogenic Belt is the last main orogen that constructs modern tectonic framework of northeastern Asia. It has recorded the long-term evolution of the Mongol-Okhotsk Ocean(MOO) from its Early Paleozoic initial opening,through the Late Paleozoic-Early Mesozoic subduction, to its Mesozoic final closure, leading to the amalgamation of the Siberian Craton(SIB) and North China-Amuria Block(NCC-AMB). Opening of the MOO can be traced to the early stage of the Early Paleozoic. Northward subduction of the Mongol-Okhotsk oceanic slab beneath the southern margin of the SIB initiated in the Silurian, whereas the southward subduction beneath the northern margin of the NCC-AMB started in the Late Devonian. The bidirectional subduction of the Mongol-Okhotsk oceanic slab resulted in pulse arc magmatism, with three main peaks in the earliest Carboniferous, Late Permian, and Late Triassic-Early Jurassic. In the Late Triassic, the collision between the AMB and Western Mongolian Blocks led to the bending of the Western Mongolian Blocks, which caused the initial closure of the MOO in its western segment. Due to the clockwise rotation of the SIB and counterclockwise rotation of the NCC-AMB, the MOO showed a scissor-like closure from west to east. The final closure of the MOO occurred in the Middle-Late Jurassic, which also resulted in the formation of the Mongol Orocline. Since then, the amalgamation of blocks in northeastern Asia has finished, and the northeastern Asian continent went into the intraplate evolutional stage.展开更多
The southern Great Xing'an Range is the most critical Sn-polymetallic metallogenic belt in northeast China.However,the tectonic setting of the Early Cretaceous magmatic-metallogenic”flare-up“event remains uncert...The southern Great Xing'an Range is the most critical Sn-polymetallic metallogenic belt in northeast China.However,the tectonic setting of the Early Cretaceous magmatic-metallogenic”flare-up“event remains uncertain.This paper presents an integrated study on the occurrence,petrology,zircon U-Pb ages,whole-rock geochemistry,and in situ zircon Hf isotopes for Wenduerchagan granites of Xi Ujimqin Banner,central-eastern Inner Mongolia.These granites consist primarily of granite porphyry(with ages of 137±1 Ma and 138±1 Ma)and(porphyritic)alkali feldspar granite(with an age of 141±2 Ma),corresponding to the early Early Cretaceous.They are A-type granites characterized by high silicon,alkali,and TFeO/MgO contents while being depleted of Ba,Nb,Ta,Sr,P,and Ti.They show right-dipping trend rare-earth element distribution characteristics with negative Eu anomalies(Eu/Eu^(*)=0.01-0.20)and weak heavy rare-earth element fractionation((Gd/Yb)_(N)=0.77-2.30).They demonstrate homogeneous zircon Hf isotopic compositions(positiveε_(Hf)(t)values from+5.3 to+7.1 and young two-stage Hf model ages of 851-742 Ma)and high zircon saturation temperatures(av.810℃).These geochemical characteristics indicate that Wenduerchagan granites originated from the partial melting of juvenile crust under high-temperature and low-pressure conditions.Wenduerchagan granites most likely formed in a post-collisional compression-extension transition regime caused by the closure of the Mongol-Okhotsk Ocean,when combined with regional geology.Such a transition regime can probably be attributed to the upwelling of the asthenospheric mantle caused by the break-off of a subducted Mongol-Okhotsk oceanic slab.Upwelling asthenospheric mantle provided sufficient energy and favorable tectonic conditions for magmatism and mineralization of the Early Cretaceous.展开更多
Based on the analysis of known geodynamic models that explain the processes in various geodynamic settings of the Meso-Cenozoic stages of the development of continental margins and the tectonic-magmatic events accompa...Based on the analysis of known geodynamic models that explain the processes in various geodynamic settings of the Meso-Cenozoic stages of the development of continental margins and the tectonic-magmatic events accompanying these processes, as well as on the basis of our own data obtained as a result of many years of research on the axial structure of the Central Asian Fold Belt-Mongol-Okhotsk orogenic belt and the influence of interdependent structures on the post-Mesozoic evolution of the eastern flank of the Mongol-Okhotsk orogenic belt was substantiated by us. The closure of the Mongol-Okhotsk basin due to the approach of the Siberian and North China cratons was accompanied by a change in geodynamic conditions: subduction, collision, intraplate-rift and was reflected in the formation of synchronous igneous complexes in the frame of the Mongol-Okhotsk orogenic belt. In the northern frame of the belt, the distribution of magmatites is cut off by the structure of the Selenga-Stanovoy superterrane in the west. The northern boundary of the superterrane is the zone of the Dzheltulak fault. In the south, it borders on the Mongol-Okhotsk orogenic belt along the zone of tectonic melange. We believe that evolutionary processes within the orogenic belt and its framing continued into the post-Mesozoic time after the final formation of the belt as an orogen. The position of the Selenga-Stanovoy superterrane in the late Mesozoic did not correspond to the modern one. The structures of the Central Asian fold belt located between the Mongol-Okhotsk orogenic belt and the Siberian craton in the Cenozoic were influenced by collisional processes occurring between the Indian and Eurasian plates. And these processes were not only the “driving force” for the movement of the Selenga-Stanovoy superterrane in the post-Mesozoic time, but also changed the structure of the Mongol-Okhotsk orogen, dividing it into two flanks.展开更多
The Late Mesozoic tectono-thermal evolution and geodynamic setting of the Great Xing’an Range(GXR),particularly in the south margin,are still ambiguous.In this study,we present original low-temperature thermochronolo...The Late Mesozoic tectono-thermal evolution and geodynamic setting of the Great Xing’an Range(GXR),particularly in the south margin,are still ambiguous.In this study,we present original low-temperature thermochronological data of six granitoid samples collected from Maanzi pluton in the south margin of the GXR.The apatite and zircon(U-Th)/He ages vary of 70.8 ± 4.3-119.0 ±7.0 Ma and 120.0 ± 7.1-146.7 ± 8.7 Ma,respectively.Further numerical inverse modeling results reveal that the granitoid plutons experienced a rapid cooling and exhumation stage during Early Cretaceous with a rate of ~5.0-6.0 ℃/Ma and ~0.14-0.17 mm/yr,respectively,including the western minor pluton emplaced during Early Permian and the major pluton crystallized in latest Jurassic,corresponding to the extensional tectonics in NE China.The rapid exhumation processes in the south margin of the GXR during the Early Cretaceous could be related to both the rollback of Paleo-Pacific oceanic plate and the collapse of thickened crust in the Mongol-Okhotsk Orogen.展开更多
The Late Paleozoic–Early Mesozoic Mongol-Okhotsk Ocean extended between the Siberian and Amur–North China continents.The timing and modalities of the oceanic closure are widely discussed.It is largely accepted that ...The Late Paleozoic–Early Mesozoic Mongol-Okhotsk Ocean extended between the Siberian and Amur–North China continents.The timing and modalities of the oceanic closure are widely discussed.It is largely accepted that the ocean closed in a scissor-like manner from southwest to northeast(in modern coordinates),though the timing of this process remains uncertain.Recent studies have shown that both western(West Transbaikalia)and eastern(Dzhagda)parts of the ocean closed almost simultaneously at the Early–Middle Jurassic boundary.However,little information on the key central part of the oceanic suture zone is available.We performed U-Pb(LA-ICP-MS)dating of detrital zircon from wellcharacterized stratigraphic sections of the central part of the Mongol-Okhotsk suture zone.These include the initial marine and final continental sequences of the East Transbaikalia Basin,deposited on the northern Argun-Idemeg terrane basement.We provide new stratigraphic ages for the marine and continental deposits.This revised chronostratigraphy allows assigning an age of~165–155 Ma,to the collisionrelated flexure of the northern Argun-Idemeg terrane and the development of a peripheral foreland basin.This collisional process took place 5 to10 million years later than in the western and eastern parts of the ocean.We demonstrate that the northern Argun-Idemeg terrane was the last block to collide with the Siberian continent,challenging the widely supported scissor-like model of closure of the MongolOkhotsk Ocean.Different segments of the ocean closed independently,depending on the initial shape of the paleo continental margins.展开更多
Central Asian and Pacific mobile belts are the two geological superstructures of Eastern Asia. They keep many geological secrets. There is a region of the interaction of the structures in the frames of the margin ofEa...Central Asian and Pacific mobile belts are the two geological superstructures of Eastern Asia. They keep many geological secrets. There is a region of the interaction of the structures in the frames of the margin ofEast Asia. The region is ambiguous. It is denominated in tectonic superposition or covering (interference) of the segments of the structures. The main goal of the research work is to establish the boundary line of the jointing of two superstructures. Here we show the role of the Mesozoic tectonic restructuring and magmatism in the interaction of the structures. The region of their jointing is the boundary line between Bureja-Jziamusy and Badzhal terrains. The boundary line in the frames of Mongol-Okhotsk orogenic belt is disputable. Geochronological and paleomagnetic data and chemical composition of the volcano-plutonic rocks of the eastern margin of Mongol-Okhotsk belt and of the structures of Central-Asian mobile belt were recently obtained. The data allow us to review the region of the joint of the two structures of easternAsia. It was suggested to draw the boundary line of the joint (in this case-interference) of Central Asian mobile belt and Pacific mobile belt in the frames of the eastern margin of Mongol-Okhotsk orogenic belt along the margin of the disappearance of late Mesozoic oversubductional volcano-plutonic complexes in the western direction. The structure of Bureja-Jziamusy superterrain was related to the structures of the Pacific mobile belt. The proposed model of the region of jointing of two East Asian superstructures enables us to reconsider the tectonic and geodynamical and metallogeny schemes of evolution of the Eastern margin ofAsia.展开更多
Multi-stage igneous rocks developed in the recently discovered Huoluotai Cu-(Mo)deposit provide new insights into the controversial late Mesozoic geodynamic evolution of the northern segment of the Great Xing’an Rang...Multi-stage igneous rocks developed in the recently discovered Huoluotai Cu-(Mo)deposit provide new insights into the controversial late Mesozoic geodynamic evolution of the northern segment of the Great Xing’an Range(NSGXR).Zircon U-Pb dating suggests that the monzogranite,ore-bearing granodiorite porphyry,diorite porphyry,and granite porphyry in the deposit were emplaced at 179.5±1.6,148.9±0.9,146.1±1.3,and 142.2±1.5 Ma,respectively.The Re-Os dating of molybdenite yielded an isochron age of 146.9±2.3 Ma(MSWD=0.27).The Jurassic adakitic monzogranite and granodiorite porphyry are characterized by high SiO_(2)and Na_(2)O contents,low K_(2)O/Na_(2)O ratios,low Mg O,Cr,and Ni contents,low zirconεHf(t)values relative to depleted mantle,and relatively high Th contents.They were produced by partial melting of a subducted oceanic slab,with involvement of marine sediments in the magma source and limited interaction with mantle peridotites during magma ascent.The Late Jurassic diorite porphyry is characterized by moderate SiO_(2) contents,high Mg O,Cr,and Ni contents,and positive dominatedεHf(t)values,indicating it was produced by partial melting of a subduction-modified lithospheric mantle wedge and underwent limited crustal contamination during magma ascent.The early Early Cretaceous adakitic granite porphyry shows high SiO_(2) and K_(2)O contents and K_(2)O/Na_(2)O ratios,low Mg O,Cr,and Ni contents,enriched Sr-Nd isotopic compositions,and slightly positive zirconεHf(t)values,suggesting it was produced by partial melting of thickened mafic lower crust.The NSGXR experienced a tectonic history that involved flat-slab subduction(200-160 Ma),and tearing and collapse(150-145 Ma)of the Mongol-Okhotsk oceanic lithosphere.The period of magmatic quiescence from ca.160 to 150 Ma was a response to flat-slab subduction of the Mongol-Okhotsk oceanic lithosphere.Crustal thickening in the NSGXR(145-133 Ma)was due to the collision between the Amuria Block and the Siberian Craton.展开更多
Mongol-Okhotsk orogenic belt was formed during almost all the Phanerozoic period. The bimodal late Paleozoic-early Mesozoic formations were stated in the frames of the western section of Mongol-Okhotsk belt. Their for...Mongol-Okhotsk orogenic belt was formed during almost all the Phanerozoic period. The bimodal late Paleozoic-early Mesozoic formations were stated in the frames of the western section of Mongol-Okhotsk belt. Their formation is connected with the collision of north Asian and Sino-Korean continents. These collision processes were conjugated with the dimensioned intraplate processes in the region. The rocks of the bimodal volcano-plutonic complex were also stated in the frames of the eastern section of Mongol-Okhotsk orogenic belt. This should proof the identity of geological processes, which accompanied the collision of north Asian and Sino-Korean continents, during all the stage of the formation of the Mongol-Okhotsk belt.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 41872234 and 41340024)Self-determined Foundation of Key Laboratory of Mineral Resources Evaluation in Northeast Asia, Ministry of Land and Resources (Grant No. DBYZZ-18-08)Graduate Innovation Fund of Jilin University
文摘A large amount of igneous rocks in NE China formed in an extensional setting during Late Mesozoic. However, there is still controversy about how the Mongol-Okhotsk Ocean and the Paleo-Pacific Ocean effected the lithosphere in NE China. In this paper, we carried out a comprehensive study for andesites from the Keyihe area using LA-ICP-MS zircon UPb dating and geochemical and Hf isotopic analysis to investigate the petrogenesis and tectonic setting of these andesites. The U-Pb dating yields an Early Cretaceous crystallization age of 128.3±0.4 Ma. Geochemically, the andesites contain high Sr(686-930 ppm) and HREE contents, low Y(11.9-19.8 ppm) and Yb(1.08-1.52 ppm) contents, and they therefore have high Sr/Y(42-63) and La/Yb(24-36) ratios, showing the characteristics of adakitic rocks. Moreover, they exhibit high K2O/Na2O ratios(0.57-0.81), low Mg O contents(0.77-3.06 wt%), low Mg# value(17-49) and negative εHf(t) values(-1.7 to-8.5) with no negative Eu anomalies, indicating that they are not related to the oceanic plate subduction. Based on the geochemical and isotopic data provided in this paper and regional geological data, it can be concluded that the Keyihe adakitic rocks were affected by the Mongol-Okhotsk tectonic regime, forming in a transition setting from crustal thickening to regional extension thinning. They were derived from the partial melting of the thickened lower crust. The closure of the Mongol-Okhotsk Ocean may finish in early Early Cretaceous, followed by the collisional orogenic process. The southern part region of its suture belt was in a post-orogenic extensional setting in the late Early Cretaceous.
基金supported by the National Natural Science Foundation of China(Nos.42130305 and 41872234).
文摘The Mongol-Okhotsk Ocean,which has been closing gradually from the west to the east beginning since the Late Paleozoic,was an important part of the Central Asian Orogenic Belt.It influenced the tectonic framework of Northeast Asia in the Mesozoic,especially the Late Mesozoic arc-basin system that is widely distributed in the Great Xing’an Range.However,the manner in which the Mongol-Okhotsk Ocean affected the sedimentary basin development remains poorly understood.To address this issue,we conducted U-Pb dating of detrital zircon deposited sedimentary basins of the central Great Xing’an Range.By examining the possible provenances of the detrital zircon and the structural controls of the basins,we found that a key sedimentary unit was deposited around Late Jurassic-Early Cretaceous.Its provenance was a felsic source in a back-arc setting of an active continental margin.The findings also suggest the existence of a unified geodynamic setting that affected the coeval development of basins in the northern Great Xing’an Range and the Yanshan fold-thrust belt along the northern margin of North China Craton.This research helps to better understand the complex tectonic processes which shaped the Northeast Asia during the Late Mesozoic.
基金This research was funded by the NationalKey R&D Program of China(No.2018YFC0603804)the National Natural Science Foundation of China(No.41402060)+3 种基金Science and Technology Project of Department ofEducation,Jilin Province(No.JJKH20200946KJ)the NaturalScience Foundation of Jilin Province(No.20170101201JC)Self-Determined Foundation of Key Laboratory of MineralResources Evaluation in Northeast Asia,Ministry of NaturalResources(Nos.DBY-ZZ-19-13 and DBY-ZZ-19-15)Supported by Graduate Innovation Fund of Jilin University(No.101832020CX211).
文摘The tectonic setting of Jurassic magmatism in the Northeast China(NE China)is unclear.Here,we present new petrological,whole-rock geochemical,zircon U-Pb geochronological,and zircon Lu-Hf isotope data for Jurassic granitoids of the Wulong region,Liaodong Peninsula,NE China.Laser ablation-inductively coupled plasma-mass spectrometry(LA-ICP-MS)zircon U-Pb data indicate that these granitoids were emplaced at 165-156 Ma.The biotite monzogranite,two-mica monzogranite,monzogranite,granodiorite,biotite granodiorite,and syenogranite are strongly peraluminous(A/CNK=1.09-1.29),contain peraluminous minerals such as muscovite,have high normative corundum abundances(1.26 wt.%-3.28 wt.%),and have high K2_(O)/Na2O ratios(0.76-1.48),all of which indicate an S-type granite affinity.However,the biotite granodiorite and syenogranite have high Sr(391 ppm-570 ppm)and low Y(3.06 ppm-5.94 ppm)contents,with high Sr/Y(65.8-185.9)ratios,and the two-mica monzogranite,monzogranite,and granodiorite have relatively high Sr(138 ppm-379 ppm)and low Y(3.38 ppm-8.71 ppm)contents,with high Sr/Y ratios(19.1-77.9).All of the analyzed samples have negative zircon eHf(t)values(-41.4 to-20.6)with old two-stage Hf model ages(TDM2(Hf)=2.50-3.76 Ga).Therefore,we infer that the biotite monzogranite is the typical feature of S-type granite that was derived by partial melting of metagraywacke.The monzogranite,two-mica monzogranite,granodiorite,biotite granodiorite,and syenogranite exhibit geochemical characteristics of S-type granite with K-rich adakitic features,and were possibly derived by mixing of melts from clastic crustal materials and ada-kitic magmas.There are voluminous Jurassic igneous rocks in the NE China.By combining our study with the previous researches,this paper infers that the Jurassic magmatism within the Erguna-Xing'an Massif was related to the southward subduction and closure of the Mongol-Okhotsk Ocean;the Early Jurassic magmatism to the east of the Songliao Basin and in the northern North China Cra-ton(NCC)was related to the subduction
基金supported by the National Natural Science Foundation of China (Grant No. 92155203)。
文摘Mongol-Okhotsk Orogenic Belt is the last main orogen that constructs modern tectonic framework of northeastern Asia. It has recorded the long-term evolution of the Mongol-Okhotsk Ocean(MOO) from its Early Paleozoic initial opening,through the Late Paleozoic-Early Mesozoic subduction, to its Mesozoic final closure, leading to the amalgamation of the Siberian Craton(SIB) and North China-Amuria Block(NCC-AMB). Opening of the MOO can be traced to the early stage of the Early Paleozoic. Northward subduction of the Mongol-Okhotsk oceanic slab beneath the southern margin of the SIB initiated in the Silurian, whereas the southward subduction beneath the northern margin of the NCC-AMB started in the Late Devonian. The bidirectional subduction of the Mongol-Okhotsk oceanic slab resulted in pulse arc magmatism, with three main peaks in the earliest Carboniferous, Late Permian, and Late Triassic-Early Jurassic. In the Late Triassic, the collision between the AMB and Western Mongolian Blocks led to the bending of the Western Mongolian Blocks, which caused the initial closure of the MOO in its western segment. Due to the clockwise rotation of the SIB and counterclockwise rotation of the NCC-AMB, the MOO showed a scissor-like closure from west to east. The final closure of the MOO occurred in the Middle-Late Jurassic, which also resulted in the formation of the Mongol Orocline. Since then, the amalgamation of blocks in northeastern Asia has finished, and the northeastern Asian continent went into the intraplate evolutional stage.
基金financial support from the National Natural Science Foundation of China(Grant Nos.41802222 and 42002102)the China Geological Survey Program(Grant Nos.1212011220453,DD20190570,DD20221692,DD20230053 and DD20230355)+1 种基金the Key R&D and Promotion Projects in Henan Province(Grant No.212102310030)the Open Fund of Hubei Key Laboratory of Resources and Eco-Environment Geology(Grant No.KJ2022-35)。
文摘The southern Great Xing'an Range is the most critical Sn-polymetallic metallogenic belt in northeast China.However,the tectonic setting of the Early Cretaceous magmatic-metallogenic”flare-up“event remains uncertain.This paper presents an integrated study on the occurrence,petrology,zircon U-Pb ages,whole-rock geochemistry,and in situ zircon Hf isotopes for Wenduerchagan granites of Xi Ujimqin Banner,central-eastern Inner Mongolia.These granites consist primarily of granite porphyry(with ages of 137±1 Ma and 138±1 Ma)and(porphyritic)alkali feldspar granite(with an age of 141±2 Ma),corresponding to the early Early Cretaceous.They are A-type granites characterized by high silicon,alkali,and TFeO/MgO contents while being depleted of Ba,Nb,Ta,Sr,P,and Ti.They show right-dipping trend rare-earth element distribution characteristics with negative Eu anomalies(Eu/Eu^(*)=0.01-0.20)and weak heavy rare-earth element fractionation((Gd/Yb)_(N)=0.77-2.30).They demonstrate homogeneous zircon Hf isotopic compositions(positiveε_(Hf)(t)values from+5.3 to+7.1 and young two-stage Hf model ages of 851-742 Ma)and high zircon saturation temperatures(av.810℃).These geochemical characteristics indicate that Wenduerchagan granites originated from the partial melting of juvenile crust under high-temperature and low-pressure conditions.Wenduerchagan granites most likely formed in a post-collisional compression-extension transition regime caused by the closure of the Mongol-Okhotsk Ocean,when combined with regional geology.Such a transition regime can probably be attributed to the upwelling of the asthenospheric mantle caused by the break-off of a subducted Mongol-Okhotsk oceanic slab.Upwelling asthenospheric mantle provided sufficient energy and favorable tectonic conditions for magmatism and mineralization of the Early Cretaceous.
文摘Based on the analysis of known geodynamic models that explain the processes in various geodynamic settings of the Meso-Cenozoic stages of the development of continental margins and the tectonic-magmatic events accompanying these processes, as well as on the basis of our own data obtained as a result of many years of research on the axial structure of the Central Asian Fold Belt-Mongol-Okhotsk orogenic belt and the influence of interdependent structures on the post-Mesozoic evolution of the eastern flank of the Mongol-Okhotsk orogenic belt was substantiated by us. The closure of the Mongol-Okhotsk basin due to the approach of the Siberian and North China cratons was accompanied by a change in geodynamic conditions: subduction, collision, intraplate-rift and was reflected in the formation of synchronous igneous complexes in the frame of the Mongol-Okhotsk orogenic belt. In the northern frame of the belt, the distribution of magmatites is cut off by the structure of the Selenga-Stanovoy superterrane in the west. The northern boundary of the superterrane is the zone of the Dzheltulak fault. In the south, it borders on the Mongol-Okhotsk orogenic belt along the zone of tectonic melange. We believe that evolutionary processes within the orogenic belt and its framing continued into the post-Mesozoic time after the final formation of the belt as an orogen. The position of the Selenga-Stanovoy superterrane in the late Mesozoic did not correspond to the modern one. The structures of the Central Asian fold belt located between the Mongol-Okhotsk orogenic belt and the Siberian craton in the Cenozoic were influenced by collisional processes occurring between the Indian and Eurasian plates. And these processes were not only the “driving force” for the movement of the Selenga-Stanovoy superterrane in the post-Mesozoic time, but also changed the structure of the Mongol-Okhotsk orogen, dividing it into two flanks.
基金supported by the National Natural Science Foundation of China(Nos.42002168,42127801,41688103,41773046)the China Geology Survey(Nos.DD20190001,DD20190004)the China Postdoctoral Science Foundation(No.2020M670400)。
文摘The Late Mesozoic tectono-thermal evolution and geodynamic setting of the Great Xing’an Range(GXR),particularly in the south margin,are still ambiguous.In this study,we present original low-temperature thermochronological data of six granitoid samples collected from Maanzi pluton in the south margin of the GXR.The apatite and zircon(U-Th)/He ages vary of 70.8 ± 4.3-119.0 ±7.0 Ma and 120.0 ± 7.1-146.7 ± 8.7 Ma,respectively.Further numerical inverse modeling results reveal that the granitoid plutons experienced a rapid cooling and exhumation stage during Early Cretaceous with a rate of ~5.0-6.0 ℃/Ma and ~0.14-0.17 mm/yr,respectively,including the western minor pluton emplaced during Early Permian and the major pluton crystallized in latest Jurassic,corresponding to the extensional tectonics in NE China.The rapid exhumation processes in the south margin of the GXR during the Early Cretaceous could be related to both the rollback of Paleo-Pacific oceanic plate and the collapse of thickened crust in the Mongol-Okhotsk Orogen.
基金conducted in the frame of the grant of the Ministry of Science and High Education of the Russian Federation No.075-15-2019-1883。
文摘The Late Paleozoic–Early Mesozoic Mongol-Okhotsk Ocean extended between the Siberian and Amur–North China continents.The timing and modalities of the oceanic closure are widely discussed.It is largely accepted that the ocean closed in a scissor-like manner from southwest to northeast(in modern coordinates),though the timing of this process remains uncertain.Recent studies have shown that both western(West Transbaikalia)and eastern(Dzhagda)parts of the ocean closed almost simultaneously at the Early–Middle Jurassic boundary.However,little information on the key central part of the oceanic suture zone is available.We performed U-Pb(LA-ICP-MS)dating of detrital zircon from wellcharacterized stratigraphic sections of the central part of the Mongol-Okhotsk suture zone.These include the initial marine and final continental sequences of the East Transbaikalia Basin,deposited on the northern Argun-Idemeg terrane basement.We provide new stratigraphic ages for the marine and continental deposits.This revised chronostratigraphy allows assigning an age of~165–155 Ma,to the collisionrelated flexure of the northern Argun-Idemeg terrane and the development of a peripheral foreland basin.This collisional process took place 5 to10 million years later than in the western and eastern parts of the ocean.We demonstrate that the northern Argun-Idemeg terrane was the last block to collide with the Siberian continent,challenging the widely supported scissor-like model of closure of the MongolOkhotsk Ocean.Different segments of the ocean closed independently,depending on the initial shape of the paleo continental margins.
文摘Central Asian and Pacific mobile belts are the two geological superstructures of Eastern Asia. They keep many geological secrets. There is a region of the interaction of the structures in the frames of the margin ofEast Asia. The region is ambiguous. It is denominated in tectonic superposition or covering (interference) of the segments of the structures. The main goal of the research work is to establish the boundary line of the jointing of two superstructures. Here we show the role of the Mesozoic tectonic restructuring and magmatism in the interaction of the structures. The region of their jointing is the boundary line between Bureja-Jziamusy and Badzhal terrains. The boundary line in the frames of Mongol-Okhotsk orogenic belt is disputable. Geochronological and paleomagnetic data and chemical composition of the volcano-plutonic rocks of the eastern margin of Mongol-Okhotsk belt and of the structures of Central-Asian mobile belt were recently obtained. The data allow us to review the region of the joint of the two structures of easternAsia. It was suggested to draw the boundary line of the joint (in this case-interference) of Central Asian mobile belt and Pacific mobile belt in the frames of the eastern margin of Mongol-Okhotsk orogenic belt along the margin of the disappearance of late Mesozoic oversubductional volcano-plutonic complexes in the western direction. The structure of Bureja-Jziamusy superterrain was related to the structures of the Pacific mobile belt. The proposed model of the region of jointing of two East Asian superstructures enables us to reconsider the tectonic and geodynamical and metallogeny schemes of evolution of the Eastern margin ofAsia.
基金funded by the Natural Science Foundation of Jilin Province(No.20180101089JC)Key Projects of Science and Technology Development Plan of Jilin Province(No.20100445)+5 种基金National Key R&D Program of China(2017YFC0601304)the Natural Science Foundation of Liaoning Province(2020-BS-258)the Department of Education of Liaoning Province(LJ2020JCL010)a Discipline Innovation Team Project of Liaoning Technical University(LNTU20TD-14)Graduate Innovation Research Project of Jilin University(Grant NO.101832020CX201)Heilongjiang Research Project of Land and Resources(201605,201704)。
文摘Multi-stage igneous rocks developed in the recently discovered Huoluotai Cu-(Mo)deposit provide new insights into the controversial late Mesozoic geodynamic evolution of the northern segment of the Great Xing’an Range(NSGXR).Zircon U-Pb dating suggests that the monzogranite,ore-bearing granodiorite porphyry,diorite porphyry,and granite porphyry in the deposit were emplaced at 179.5±1.6,148.9±0.9,146.1±1.3,and 142.2±1.5 Ma,respectively.The Re-Os dating of molybdenite yielded an isochron age of 146.9±2.3 Ma(MSWD=0.27).The Jurassic adakitic monzogranite and granodiorite porphyry are characterized by high SiO_(2)and Na_(2)O contents,low K_(2)O/Na_(2)O ratios,low Mg O,Cr,and Ni contents,low zirconεHf(t)values relative to depleted mantle,and relatively high Th contents.They were produced by partial melting of a subducted oceanic slab,with involvement of marine sediments in the magma source and limited interaction with mantle peridotites during magma ascent.The Late Jurassic diorite porphyry is characterized by moderate SiO_(2) contents,high Mg O,Cr,and Ni contents,and positive dominatedεHf(t)values,indicating it was produced by partial melting of a subduction-modified lithospheric mantle wedge and underwent limited crustal contamination during magma ascent.The early Early Cretaceous adakitic granite porphyry shows high SiO_(2) and K_(2)O contents and K_(2)O/Na_(2)O ratios,low Mg O,Cr,and Ni contents,enriched Sr-Nd isotopic compositions,and slightly positive zirconεHf(t)values,suggesting it was produced by partial melting of thickened mafic lower crust.The NSGXR experienced a tectonic history that involved flat-slab subduction(200-160 Ma),and tearing and collapse(150-145 Ma)of the Mongol-Okhotsk oceanic lithosphere.The period of magmatic quiescence from ca.160 to 150 Ma was a response to flat-slab subduction of the Mongol-Okhotsk oceanic lithosphere.Crustal thickening in the NSGXR(145-133 Ma)was due to the collision between the Amuria Block and the Siberian Craton.
文摘Mongol-Okhotsk orogenic belt was formed during almost all the Phanerozoic period. The bimodal late Paleozoic-early Mesozoic formations were stated in the frames of the western section of Mongol-Okhotsk belt. Their formation is connected with the collision of north Asian and Sino-Korean continents. These collision processes were conjugated with the dimensioned intraplate processes in the region. The rocks of the bimodal volcano-plutonic complex were also stated in the frames of the eastern section of Mongol-Okhotsk orogenic belt. This should proof the identity of geological processes, which accompanied the collision of north Asian and Sino-Korean continents, during all the stage of the formation of the Mongol-Okhotsk belt.
