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Feng Wang - One of the best experts on this subject based on the ideXlab platform.
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early middle paleozoic subduction collision history of the south eastern central asian orogenic belt evidence from igneous and metasedimentary rocks of central jilin province ne china
Lithos, 2016Co-Authors: Ying Zhang, Zhiwei Wang, Wenliang Xu, Zijin Wang, Feng Wang, Chuan YangAbstract:Abstract To constrain the Early–Middle Paleozoic tectonic evolution of the south-eastern segment of the Central Asian Orogenic Belt (CAOB), we undertook zircon U–Pb dating and analyzed major and trace elements and zircon Hf isotope compositions of Late Cambrian to Middle Devonian igneous and metasedimentary rocks in central Jilin Province, NE China. LA–ICP–MS zircon U–Pb dating indicates that the Early–Middle Paleozoic magmatism in central Jilin Province can be divided into four episodes: Late Cambrian (ca. 493 Ma), Middle Ordovician (ca. 467 Ma), Late Ordovician–Early Silurian (ca. 443 Ma), and Late Silurian–Middle Devonian (425–396 Ma). The progression from subduction initiation to maturity is recorded by Late Cambrian low-K tholeiitic meta-diabase, Middle Ordovician medium-K calc-alkaline pyroxene andesite, and Late Ordovician to Early Silurian low-K tonalite, which all have subduction-related characteristics and formed in an evolving supra-subduction zone setting. Late Silurian to Middle Devonian calc-alkaline igneous rocks, with the lithological association of granodiorite, monzogranite, rhyolite, dacite, and trachydacite, show progressively increasing K 2 O contents from medium K to shoshonite series. Furthermore, the Early–Middle Devonian monzogranites are characterized by high K 2 O, Sr/Y, and [La/Yb] N values, indicating they were generated by the melting of thickened lower crust. These results suggest a transition from subduction to post-orogenic setting during the Late Silurian–Middle Devonian. Our interpretation is supported by the maximum age of molasse deposition in the Zhangjiatun member of the Xibiehe Formation. Overall, we suggest that Late Cambrian tholeiitic meta-diabase, Middle Ordovician pyroxene andesite, and Late Ordovician–Early Silurian tonalite formed above the northward-subducting and simultaneously seaward-retreating of Paleo-Asian Ocean plate. Subsequently, the northern arc collided with the North China Craton and post-orogenic extension occurred during the Late Silurian–Middle Devonian.
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early paleozoic amalgamation of the songnen zhangguangcai range and jiamusi massifs in the eastern segment of the central asian orogenic belt geochronological and geochemical evidence from granitoids and rhyolites
Journal of Asian Earth Sciences, 2012Co-Authors: Feng Wang, En Meng, Huahua Cao, Fuhong GaoAbstract:Abstract To constrain the early Paleozoic tectonic evolution of the Songnen–Zhangguangcai Range and Jiamusi massifs, we undertook zircon U–Pb dating and geochemical analyses (major and trace elements, and Hf isotopic compositions) of early Paleozoic igneous rocks in the Lesser Xing’an–Zhangguangcai Range of eastern Heilongjiang province, NE China. The zircons from one diorite, two rhyolites, and four granitoids are euhedral–subhedral and display fine-scale oscillatory growth zoning, indicating a magmatic origin. LA–ICP–MS zircon U–Pb age data indicate the occurrence of magmatic events in the late Ordovician (443–451 Ma) and middle Silurian (424–430 Ma). The late Ordovician igneous rocks are composed mainly of diorite, tonalite, and rhyolite, whereas the middle Silurian igneous rocks consist mainly of monzogranites. The early Paleozoic igneous rocks have SiO2 = 59.65–76.11 wt.%, MgO = 0.13–1.23 wt.%, and Na2O + K2O = 4.68–7.77 wt.%, and are chemically a calc-alkaline series. They are characterized by enrichment in light rare earth elements and large ion lithophile elements, and depletion in heavy rare earth elements and high field strength elements such as Nb, Ta, and Ti, consistent with the chemistry of igneous rocks from an active continental margin setting. In situ Hf analyses of zircons show that eHf(t) values of zircons that formed in the early Ordovician (captured and inherited zircons in late Ordovician igneous rocks) range from −0.1 to +7.1; those of zircons that formed in the late Ordovician (including captured and inherited zircons in middle Silurian monzogranite) vary from −2.6 to +5.6; and those of zircons that formed in the middle Silurian vary from −3.0 to +3.2. The progressive decrease in zircon eHf(t) values from the early Ordovician to the middle Silurian suggests an increasing involvement of ancient crust in the magma sources, corresponding to the transition from subduction to collision. Take together, these data suggest that the formation of late Ordovician diorite, tonalite, and rhyolite in the Zhangguangcai Range, adjacent to the Mudanjiang Fault, may have been related to the westward subduction of an oceanic plate between the Songnen–Zhangguangcai Range and Jiamusi massifs. In contrast, coeval rhyolites from the Lesser Xing’an Range, located far from the Mudanjiang Fault, may have formed in the supra-subduction zone. The occurrence of a middle Silurian monzogranite association, combined with geochronological data for detrital zircons from Early Devonian sedimentary rocks in eastern Heilongjiang province, suggests that the amalgamation between the Songnen–Zhangguangcai Range and Jiamusi massifs occurred in the middle Silurian.
Chuan Yang - One of the best experts on this subject based on the ideXlab platform.
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early middle paleozoic subduction collision history of the south eastern central asian orogenic belt evidence from igneous and metasedimentary rocks of central jilin province ne china
Lithos, 2016Co-Authors: Ying Zhang, Zhiwei Wang, Wenliang Xu, Zijin Wang, Feng Wang, Chuan YangAbstract:Abstract To constrain the Early–Middle Paleozoic tectonic evolution of the south-eastern segment of the Central Asian Orogenic Belt (CAOB), we undertook zircon U–Pb dating and analyzed major and trace elements and zircon Hf isotope compositions of Late Cambrian to Middle Devonian igneous and metasedimentary rocks in central Jilin Province, NE China. LA–ICP–MS zircon U–Pb dating indicates that the Early–Middle Paleozoic magmatism in central Jilin Province can be divided into four episodes: Late Cambrian (ca. 493 Ma), Middle Ordovician (ca. 467 Ma), Late Ordovician–Early Silurian (ca. 443 Ma), and Late Silurian–Middle Devonian (425–396 Ma). The progression from subduction initiation to maturity is recorded by Late Cambrian low-K tholeiitic meta-diabase, Middle Ordovician medium-K calc-alkaline pyroxene andesite, and Late Ordovician to Early Silurian low-K tonalite, which all have subduction-related characteristics and formed in an evolving supra-subduction zone setting. Late Silurian to Middle Devonian calc-alkaline igneous rocks, with the lithological association of granodiorite, monzogranite, rhyolite, dacite, and trachydacite, show progressively increasing K 2 O contents from medium K to shoshonite series. Furthermore, the Early–Middle Devonian monzogranites are characterized by high K 2 O, Sr/Y, and [La/Yb] N values, indicating they were generated by the melting of thickened lower crust. These results suggest a transition from subduction to post-orogenic setting during the Late Silurian–Middle Devonian. Our interpretation is supported by the maximum age of molasse deposition in the Zhangjiatun member of the Xibiehe Formation. Overall, we suggest that Late Cambrian tholeiitic meta-diabase, Middle Ordovician pyroxene andesite, and Late Ordovician–Early Silurian tonalite formed above the northward-subducting and simultaneously seaward-retreating of Paleo-Asian Ocean plate. Subsequently, the northern arc collided with the North China Craton and post-orogenic extension occurred during the Late Silurian–Middle Devonian.
Wenliang Xu - One of the best experts on this subject based on the ideXlab platform.
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early middle paleozoic subduction collision history of the south eastern central asian orogenic belt evidence from igneous and metasedimentary rocks of central jilin province ne china
Lithos, 2016Co-Authors: Ying Zhang, Zhiwei Wang, Wenliang Xu, Zijin Wang, Feng Wang, Chuan YangAbstract:Abstract To constrain the Early–Middle Paleozoic tectonic evolution of the south-eastern segment of the Central Asian Orogenic Belt (CAOB), we undertook zircon U–Pb dating and analyzed major and trace elements and zircon Hf isotope compositions of Late Cambrian to Middle Devonian igneous and metasedimentary rocks in central Jilin Province, NE China. LA–ICP–MS zircon U–Pb dating indicates that the Early–Middle Paleozoic magmatism in central Jilin Province can be divided into four episodes: Late Cambrian (ca. 493 Ma), Middle Ordovician (ca. 467 Ma), Late Ordovician–Early Silurian (ca. 443 Ma), and Late Silurian–Middle Devonian (425–396 Ma). The progression from subduction initiation to maturity is recorded by Late Cambrian low-K tholeiitic meta-diabase, Middle Ordovician medium-K calc-alkaline pyroxene andesite, and Late Ordovician to Early Silurian low-K tonalite, which all have subduction-related characteristics and formed in an evolving supra-subduction zone setting. Late Silurian to Middle Devonian calc-alkaline igneous rocks, with the lithological association of granodiorite, monzogranite, rhyolite, dacite, and trachydacite, show progressively increasing K 2 O contents from medium K to shoshonite series. Furthermore, the Early–Middle Devonian monzogranites are characterized by high K 2 O, Sr/Y, and [La/Yb] N values, indicating they were generated by the melting of thickened lower crust. These results suggest a transition from subduction to post-orogenic setting during the Late Silurian–Middle Devonian. Our interpretation is supported by the maximum age of molasse deposition in the Zhangjiatun member of the Xibiehe Formation. Overall, we suggest that Late Cambrian tholeiitic meta-diabase, Middle Ordovician pyroxene andesite, and Late Ordovician–Early Silurian tonalite formed above the northward-subducting and simultaneously seaward-retreating of Paleo-Asian Ocean plate. Subsequently, the northern arc collided with the North China Craton and post-orogenic extension occurred during the Late Silurian–Middle Devonian.
Wenjiao Xiao - One of the best experts on this subject based on the ideXlab platform.
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late Silurian early devonian adakitic granodiorite a type and i type granites in nw junggar nw china partial melting of mafic lower crust and implications for slab roll back
Gondwana Research, 2017Co-Authors: Wenjiao Xiao, Brian F Windley, Chao Yuan, Shun YuAbstract:Abstract Late Silurian–early Devonian magmatism of the NW Junggar region in the Central Asian Orogenic Belt provides a critical geological record that is important for unraveling regional tectonic history and constraining geodynamic processes. In this study, we report results of Zircon U–Pb ages and systematic geochemical data for late Silurian–early Devonian largely granitic rocks in NW Junggar, aiming to constrain their emplacement ages, origin and geodynamic significance. The magmatism consists of a variety of mafic to felsic intrusions and volcanic rocks, e.g. adakitic granodiorite, K-feldspar granite, syenitic granite, gabbro and rhyrolite. U–Pb zircon ages suggest that the granitoids and gabbros were emplaced in the late Silurian–early Devonian (420–405 Ma). Adakitic granodiorites are calc-alkaline, characterized by high Sr (407–532 ppm), low Y (12.2–14.7 ppm), Yb (1.53–1.77 ppm), Cr (mostly
Shu Jiang - One of the best experts on this subject based on the ideXlab platform.
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difference analysis of organic matter enrichment mechanisms in upper ordovician lower Silurian shale from the yangtze region of southern china and its geological significance in shale gas exploration
Geofluids, 2019Co-Authors: Zhenxue Jiang, Shu Jiang, Kun Zhang, Yan Song, Yizhou Huang, Chuanxun ZhouAbstract:The upper Ordovician-lower Silurian shale has always been the main target of marine shale gas exploration in southern China. However, the shale gas content varies greatly across different regions. The organic matter content is one of the most important factors in determining gas content; therefore, determining the enrichment mechanisms of organic matter is an important problem that needs to be solved urgently. In this paper, upper Ordovician-lower Silurian shale samples from the X-1 and Y-1 wells that are located in the southern Sichuan area of the upper Yangtze region and the northwestern Jiangxi area of the lower Yangtze region, respectively, are selected for analysis. Based on the core sample description, well logging data analysis, mineral and elemental composition analysis, silicon isotope analysis, and TOC (total organic carbon) content analysis, the upper Ordovician-lower Silurian shale is studied to quantitatively calculate its content of excess silicon. Subsequently, the results of elemental analysis and silicon isotope analysis are used to determine the origin of excess silicon. Finally, we used U/Th to determine the characteristics of the redox environment and the relationship between excess barium and TOC content to judge paleoproductivity and further studied the mechanism underlying sedimentary organic matter enrichment in the study area. The results show that the excess silicon from the upper Ordovician-lower Silurian shale in the upper Yangtze area is derived from biogenesis. The sedimentary water body is divided into an oxygen-rich upper water layer that has higher paleoproductivity and a strongly reducing lower water that is conducive to the preservation of sedimentary organic matter. Thus, for the upper Ordovician-lower Silurian shale in the upper Yangtze region, exploration should be conducted in the center of the blocks with high TOC contents and strongly reducing water body. However, the excess silicon in the upper Ordovician-lower Silurian shale of the lower Yangtze area originates from hydrothermal activity that can enhance the reducibility of the bottom water and carry nutrients from the crust to improve paleoproductivity and enrich sedimentary organic matter. Therefore, for the upper Ordovician-lower Silurian shale in the lower Yangtze region, exploration should be conducted in the blocks near the junction of the two plates where hydrothermal activity was active.
