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Zeng-zhen Wang - One of the best experts on this subject based on the ideXlab platform.
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An example of Phanerozoic continental crustal growth: The West Junggar Orogenic Belt, Northwest China
Lithos, 2020Co-Authors: Bo Zheng, Bao-fu Han, Bo Liu, Zeng-zhen Wang, L.x. FengAbstract:Abstract It is generally accepted that continental crustal growth occurred principally during Precambrian, whereas the Phanerozoic growth seems insignificant. However, the West Junggar Orogenic Belt (WJOB), a key part of Central Asian Orogenic Belt in NW China, underwent significant crustal growth during Phanerozoic. A compilation of 683 whole-rock Sr–Nd isotopic data shows that WJOB has different crustal structures and/or compositions from adjacent areas. All igneous rocks in WJOB are characterized by depleted Sr–Nd isotopes, with initial 87Sr/86Sr ratios from 0.7022 to 0.7060, eNd (t) values from +3.0 to +9.2, and Nd model ages from 0.9 to 0.3 Ga. These features are obviously different from the large variations in Sr–Nd isotopes in adjacent Tianshan Orogenic Belt (Tianshan) to the south and Altay Orogenic Belt (Altay) to the north. The continental crustal growth in WJOB resulted from the transformation of pre-existing juvenile crust and mantle wedge during the successively southward subduction of oceanic lithosphere beneath the Ediacaran to Ordovician Tangbale-Mayile arc in southern WJOB, the Silurian to Devonian Boshchekul-Chingiz arc and Early Carboniferous Zharma-Saur arc in northern WJOB, followed by the addition of mantle-derived materials in a post-collisional setting throughout WJOB during Late Carboniferous to Permian, with little or no involvement of Precambrian crust. Such a pattern of continental crustal growth in WJOB is significantly different from those of the adjacent Tianshan and Altay as well as the Hercynian Orogenic Belt in French Massif Central, where Precambrian crustal materials are largely involved in. Thus, WJOB would probably be a good example of Phanerozoic continental crustal growth around the world.
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Ediacaran to Paleozoic magmatism in West Junggar Orogenic Belt, NW China, and implications for evolution of Central Asian Orogenic Belt
Lithos, 2019Co-Authors: Bo Zheng, Bao-fu Han, Bo Liu, Zeng-zhen WangAbstract:Abstract The formation of the Central Asian Orogenic Belt is thought to be related to the evolution of the Paleo-Asian Ocean surrounded by the Siberian, European, and Tarim-North China cratons. The West Junggar Orogenic Belt (WJOB) in the southern Central Asian Orogenic Belt is part of the Kazakhstan-Junggar terrane between the Altay Orogenic Belt to the north and the Tianshan Orogenic Belt to the south. It is characterized by the development of the latest Ediacaran to Paleozoic intra-oceanic island arcs and accretionary complexes, including the latest Ediacaran to Ordovician Tangbale-Mayile arc-accretionary system in the south and Ordovician to Early Carboniferous Boshchekul-Chingiz arc and Zharma-Saur arc in the north, and a remnant ocean between them. Our work reveals that the Shinaizha, Kekesayi, and Barleik dioritic plutons within the Tangbale-Mayile arc are typical of arc-related magmatism and were formed between 572 and 505 Ma, which indicate the Ediacaran to Middle Cambrian subduction of the southern Paleo-Asian Ocean. However, these arc plutons were strongly deformed and surrounded by younger rocks, implying that the magmatic arc might be dismembered and involved into the Ordovician to Devonian accretionary complexes. The Boshchekul-Chingiz arc was recorded from Late Ordovician and its arc magmatism peaked in Late Silurian to Early Devonian. The arc moved northward due to the retreat of the south-facing Irtysh-Zaysan subduction zone, which resulted in the formation of contemporaneous A-type or peralkaline magmatic rocks or bimodal volcanics in response to the within-arc extension. The northward migration of the subduction zone led to the formation of the Devonian to Early Carboniferous Zharma-Saur arc. The earliest Late Carboniferous I-type granitoids occurred sporadically in WJOB, followed by pervasive occurrences of Late Carboniferous to Early Permian A- and I-type granitoids in WJOB and adjacent areas. The Late Carboniferous granitoids, combined with the Late Carboniferous stitching plutons within the Irtysh-Zaysan suture zone to the north and the North Tianshan suture zone to the south of WJOB, suggest the Kazakhstan-Junggar terrane collided with Altay and Tianshan Orogenic Belts in the latest Early Carboniferous (ca. 320 Ma).
Bo Zheng - One of the best experts on this subject based on the ideXlab platform.
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An example of Phanerozoic continental crustal growth: The West Junggar Orogenic Belt, Northwest China
Lithos, 2020Co-Authors: Bo Zheng, Bao-fu Han, Bo Liu, Zeng-zhen Wang, L.x. FengAbstract:Abstract It is generally accepted that continental crustal growth occurred principally during Precambrian, whereas the Phanerozoic growth seems insignificant. However, the West Junggar Orogenic Belt (WJOB), a key part of Central Asian Orogenic Belt in NW China, underwent significant crustal growth during Phanerozoic. A compilation of 683 whole-rock Sr–Nd isotopic data shows that WJOB has different crustal structures and/or compositions from adjacent areas. All igneous rocks in WJOB are characterized by depleted Sr–Nd isotopes, with initial 87Sr/86Sr ratios from 0.7022 to 0.7060, eNd (t) values from +3.0 to +9.2, and Nd model ages from 0.9 to 0.3 Ga. These features are obviously different from the large variations in Sr–Nd isotopes in adjacent Tianshan Orogenic Belt (Tianshan) to the south and Altay Orogenic Belt (Altay) to the north. The continental crustal growth in WJOB resulted from the transformation of pre-existing juvenile crust and mantle wedge during the successively southward subduction of oceanic lithosphere beneath the Ediacaran to Ordovician Tangbale-Mayile arc in southern WJOB, the Silurian to Devonian Boshchekul-Chingiz arc and Early Carboniferous Zharma-Saur arc in northern WJOB, followed by the addition of mantle-derived materials in a post-collisional setting throughout WJOB during Late Carboniferous to Permian, with little or no involvement of Precambrian crust. Such a pattern of continental crustal growth in WJOB is significantly different from those of the adjacent Tianshan and Altay as well as the Hercynian Orogenic Belt in French Massif Central, where Precambrian crustal materials are largely involved in. Thus, WJOB would probably be a good example of Phanerozoic continental crustal growth around the world.
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Ediacaran to Paleozoic magmatism in West Junggar Orogenic Belt, NW China, and implications for evolution of Central Asian Orogenic Belt
Lithos, 2019Co-Authors: Bo Zheng, Bao-fu Han, Bo Liu, Zeng-zhen WangAbstract:Abstract The formation of the Central Asian Orogenic Belt is thought to be related to the evolution of the Paleo-Asian Ocean surrounded by the Siberian, European, and Tarim-North China cratons. The West Junggar Orogenic Belt (WJOB) in the southern Central Asian Orogenic Belt is part of the Kazakhstan-Junggar terrane between the Altay Orogenic Belt to the north and the Tianshan Orogenic Belt to the south. It is characterized by the development of the latest Ediacaran to Paleozoic intra-oceanic island arcs and accretionary complexes, including the latest Ediacaran to Ordovician Tangbale-Mayile arc-accretionary system in the south and Ordovician to Early Carboniferous Boshchekul-Chingiz arc and Zharma-Saur arc in the north, and a remnant ocean between them. Our work reveals that the Shinaizha, Kekesayi, and Barleik dioritic plutons within the Tangbale-Mayile arc are typical of arc-related magmatism and were formed between 572 and 505 Ma, which indicate the Ediacaran to Middle Cambrian subduction of the southern Paleo-Asian Ocean. However, these arc plutons were strongly deformed and surrounded by younger rocks, implying that the magmatic arc might be dismembered and involved into the Ordovician to Devonian accretionary complexes. The Boshchekul-Chingiz arc was recorded from Late Ordovician and its arc magmatism peaked in Late Silurian to Early Devonian. The arc moved northward due to the retreat of the south-facing Irtysh-Zaysan subduction zone, which resulted in the formation of contemporaneous A-type or peralkaline magmatic rocks or bimodal volcanics in response to the within-arc extension. The northward migration of the subduction zone led to the formation of the Devonian to Early Carboniferous Zharma-Saur arc. The earliest Late Carboniferous I-type granitoids occurred sporadically in WJOB, followed by pervasive occurrences of Late Carboniferous to Early Permian A- and I-type granitoids in WJOB and adjacent areas. The Late Carboniferous granitoids, combined with the Late Carboniferous stitching plutons within the Irtysh-Zaysan suture zone to the north and the North Tianshan suture zone to the south of WJOB, suggest the Kazakhstan-Junggar terrane collided with Altay and Tianshan Orogenic Belts in the latest Early Carboniferous (ca. 320 Ma).
Jianshe Lei - One of the best experts on this subject based on the ideXlab platform.
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Pn anisotropic tomography under the entire Tienshan Orogenic Belt
Journal of Asian Earth Sciences, 2015Co-Authors: Zhigang Zhou, Jianshe LeiAbstract:Abstract We present a new anisotropic tomography of the uppermost mantle under the Tienshan Orogenic Belt and surrounding regions using a number of Pn arrival-time data hand-picked from portable seismic stations and chosen from the Xinjiang provincial observation bulletins and the EHB datasets. Our results exhibit prominent lateral heterogeneities in the study region. Distinct low-velocity anomalies are visible under the tectonically active regions, such as the Tienshan Orogenic Belt and western Kunlun Mountains, whereas pronounced high-velocity anomalies are imaged beneath the stable blocks, such as the Kazakh shield, the Junggar, Tarim, Qaidam, and Turpan-Hami basins, and the Tajik depression. Most strong earthquakes (Ms > 7.0) are mainly distributed along the transition zone of high to low velocity anomalies, suggesting a possible correlation between the strong earthquakes and the upper mantle structure. The fast directions of Pn anisotropy beneath the Tienshan Orogenic Belt are generally parallel to its striking orientation, whereas those beneath Pamir show a northward arc-shaped distribution. The Pn fast-velocity directions on the boundaries of the Kazakh shield and the Tarim and Junngar basins are approximately perpendicular to the strike of the Tienshan Orogenic Belt. By integrating with previous findings, our results suggest that the Tarim and Kazakh lithospheric materials could have underthrusted beneath the Tienshan Orogenic Belt that leads to the hot mantle material upwelling under the Tienshan Orogenic Belt, which is attributable to the Indo-Asian collision. These dynamic processes could play important roles in the Tienshan mountain building.
M. Santosh - One of the best experts on this subject based on the ideXlab platform.
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Role of mantle dynamics in rebuilding the Tianshan Orogenic Belt in NW China: A seismic tomographic investigation
Journal of Geodynamics, 2018Co-Authors: M. SantoshAbstract:Abstract The Tianshan Orogenic Belt, Junggar terrane and Altai terrane are located at the southwestern part of the Central Asian Orogenic Belt (CAOB). Here, we investigate the velocity structure beneath the Xinjiang region in NW China, which includes the Tarim terrane, Tianshan Orogenic Belt, Junggar terrane and Altai terrane with a view to evaluate the mantle dynamics based on teleseismic data recorded by 103 seismic stations. Our tomographic results show both high and low velocity perturbations beneath the Tianshan Orogenic Belt. We suggest that the high velocity perturbations beneath this Orogenic Belt might represent the northward subducted lithosphere of the Tarim Basin and the southward subducted lithosphere of the Junggar Basin. The low velocity structure beneath the Tianshan Orogenic Belt might represent asthenosphere upwelling that triggered the extensive magmatism which contributed to rebuilding of the Tianshan Orogenic Belt.
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neoproterozoic arc trench system and breakup of the south china craton constraints from n morb type and arc related mafic rocks and anOrogenic granite in the jiangnan Orogenic Belt
Precambrian Research, 2014Co-Authors: Jinlong Yao, Liangshu Shu, M. SantoshAbstract:Abstract The early Neoproterozoic Jiangnan Orogenic Belt, located in the southeastern margin of the Yangtze Block, is considered to mark the suture zone between the Yangtze and Cathaysia Blocks. The eastern part of this Belt consists of the Huaiyu and Jiuling terranes, separated by the NE Jiangxi fault zone which represents the back-arc marginal sea. The western part of the Jiangnan Orogenic Belt is characterized by the Jiangnan arc and back-arc sea. Neoproterozoic mafic–ultramafic rock suites are exposed along both the Jiangshan-Shaoxing-Pingxiang-Shuangpai and the NE Jiangxi suture zones, whereas I-, S- and A-type granites occur widely in the Jiangnan region. Here, we present new LA–ICP–MS zircon U–Pb data, Hf isotopes and whole rock geochemistry for the mafic rocks and granite from the Jiangnan Orogenic Belt. The N-MORB (normal mid-ocean ridge basalts) type basalts from the Nanqiao of Liuyang area in the west Jiangnan Orogenic Belt show low K2O contents (0.74–0.16 wt.%), belonging to tholeiitic series, and display LREE (light rare earth element) depleted REE (rare earth element) patterns, with positive Pb, Sr anomaly and minor negative Ti anomalies. The other mafic suites in the Daolinshan, Yiyang and Liuyang areas exposed in the eastern and western segments of the Jiangnan Orogenic Belt show distinctive geochemical signatures of volcanic arc, with zircon U–Pb ages of 863 ± 6 Ma. Most of these rocks show negative Nb, Ta, Zr, Hf and Sr anomalies and have LREE enriched REE patterns, with minor negative Eu anomaly. These features coincide with those of the arc and fore-arc rock assemblages in the eastern Huaiyu Terrane and adjacent areas. AnOrogenic granites of 790 ± 5 Ma are also found in the Daolinshang area. Our Hf isotopic data further reveal that the zircons from both the dolerite and A-type granite in the Daolinshan area possess positive ɛHf(t) values, yielding latest Mesoproterozoic to early Neoproterozoic model ages. Combined with previous studies, our data confirm the existence of an arc-trench system in the Jiangnan Orogenic Belt at ca. 863 Ma. Therefore, we infer that the amalgamation of the Yangtze and Cathaysia Blocks in the eastern part occurred at some time after ca. 863 Ma. This was followed by breakup at ca. 790 Ma which was triggered by mantle upwelling, as evidenced by the Daolinshan A-type granite with positive ɛHf(t) values
Bao-fu Han - One of the best experts on this subject based on the ideXlab platform.
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An example of Phanerozoic continental crustal growth: The West Junggar Orogenic Belt, Northwest China
Lithos, 2020Co-Authors: Bo Zheng, Bao-fu Han, Bo Liu, Zeng-zhen Wang, L.x. FengAbstract:Abstract It is generally accepted that continental crustal growth occurred principally during Precambrian, whereas the Phanerozoic growth seems insignificant. However, the West Junggar Orogenic Belt (WJOB), a key part of Central Asian Orogenic Belt in NW China, underwent significant crustal growth during Phanerozoic. A compilation of 683 whole-rock Sr–Nd isotopic data shows that WJOB has different crustal structures and/or compositions from adjacent areas. All igneous rocks in WJOB are characterized by depleted Sr–Nd isotopes, with initial 87Sr/86Sr ratios from 0.7022 to 0.7060, eNd (t) values from +3.0 to +9.2, and Nd model ages from 0.9 to 0.3 Ga. These features are obviously different from the large variations in Sr–Nd isotopes in adjacent Tianshan Orogenic Belt (Tianshan) to the south and Altay Orogenic Belt (Altay) to the north. The continental crustal growth in WJOB resulted from the transformation of pre-existing juvenile crust and mantle wedge during the successively southward subduction of oceanic lithosphere beneath the Ediacaran to Ordovician Tangbale-Mayile arc in southern WJOB, the Silurian to Devonian Boshchekul-Chingiz arc and Early Carboniferous Zharma-Saur arc in northern WJOB, followed by the addition of mantle-derived materials in a post-collisional setting throughout WJOB during Late Carboniferous to Permian, with little or no involvement of Precambrian crust. Such a pattern of continental crustal growth in WJOB is significantly different from those of the adjacent Tianshan and Altay as well as the Hercynian Orogenic Belt in French Massif Central, where Precambrian crustal materials are largely involved in. Thus, WJOB would probably be a good example of Phanerozoic continental crustal growth around the world.
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Ediacaran to Paleozoic magmatism in West Junggar Orogenic Belt, NW China, and implications for evolution of Central Asian Orogenic Belt
Lithos, 2019Co-Authors: Bo Zheng, Bao-fu Han, Bo Liu, Zeng-zhen WangAbstract:Abstract The formation of the Central Asian Orogenic Belt is thought to be related to the evolution of the Paleo-Asian Ocean surrounded by the Siberian, European, and Tarim-North China cratons. The West Junggar Orogenic Belt (WJOB) in the southern Central Asian Orogenic Belt is part of the Kazakhstan-Junggar terrane between the Altay Orogenic Belt to the north and the Tianshan Orogenic Belt to the south. It is characterized by the development of the latest Ediacaran to Paleozoic intra-oceanic island arcs and accretionary complexes, including the latest Ediacaran to Ordovician Tangbale-Mayile arc-accretionary system in the south and Ordovician to Early Carboniferous Boshchekul-Chingiz arc and Zharma-Saur arc in the north, and a remnant ocean between them. Our work reveals that the Shinaizha, Kekesayi, and Barleik dioritic plutons within the Tangbale-Mayile arc are typical of arc-related magmatism and were formed between 572 and 505 Ma, which indicate the Ediacaran to Middle Cambrian subduction of the southern Paleo-Asian Ocean. However, these arc plutons were strongly deformed and surrounded by younger rocks, implying that the magmatic arc might be dismembered and involved into the Ordovician to Devonian accretionary complexes. The Boshchekul-Chingiz arc was recorded from Late Ordovician and its arc magmatism peaked in Late Silurian to Early Devonian. The arc moved northward due to the retreat of the south-facing Irtysh-Zaysan subduction zone, which resulted in the formation of contemporaneous A-type or peralkaline magmatic rocks or bimodal volcanics in response to the within-arc extension. The northward migration of the subduction zone led to the formation of the Devonian to Early Carboniferous Zharma-Saur arc. The earliest Late Carboniferous I-type granitoids occurred sporadically in WJOB, followed by pervasive occurrences of Late Carboniferous to Early Permian A- and I-type granitoids in WJOB and adjacent areas. The Late Carboniferous granitoids, combined with the Late Carboniferous stitching plutons within the Irtysh-Zaysan suture zone to the north and the North Tianshan suture zone to the south of WJOB, suggest the Kazakhstan-Junggar terrane collided with Altay and Tianshan Orogenic Belts in the latest Early Carboniferous (ca. 320 Ma).