Paleozoic multiple accretionary and collisional tectonics of the Chinese Tianshan orogenic collage |
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| Institution: | 1. Laboratory of Isotope Thermochronology, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;2. National Key Laboratory of Continental Structure and Dynamics, Beijing 100037, China;3. John De Laeter Center for Isotope Research, Applied Geology/Applied Physics, Curtin University, Perth, WA 6945, Australia;1. State Key Laboratory of Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;2. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China;3. Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China;1. Department of Earth Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong;2. Department of Geology and Planetary Science, University of Pittsburgh, Pittsburgh, PA 15260-3332, USA;3. Department of Geology, Northwest University, Xi''an 710069, China;1. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;2. Xinjiang Research Center for Mineral Resources, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China;3. CAS Center for Excellence in Tibetan Plateau Earth Sciences, China;4. Department of Geology, University of Leicester, Leicester LE1 7RH, UK;5. Beijing Institute of Geology for Mineral Resources, Beijing 100012, China;6. Tianjin Institute of Geology and Mineral Resources, Tianjin 300170, China |
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| Abstract: | Subduction-related accretion in the Junggar–Balkash and South Tianshan Oceans (Paleo-Asian Ocean), mainly in the Paleozoic, gave rise to the present 2400 km-long Tianshan orogenic collage that extends from the Aral Sea eastwards through Uzbekistan, Tajikistan, Kyrgyzstan, to Xinjiang in China. This paper provides an up-to-date along-strike synthesis of this orogenic collage and a new tectonic model to explain its accretionary evolution.The northern part of the orogenic collage developed by consumption of the Junggar–Balkash Ocean together with Paleozoic island arcs (Northern Ili, Issyk Kul, and Chatkal) located in the west, which may have amalgamated into a composite arc in the Paleozoic in the west and by addition of another two, roughly parallel, arcs (Dananhu and Central Tianshan) in the east. The western composite arc and the eastern Dananhu and Central Tianshan arcs formed a late Paleozoic archipelago with multiple subduction zones. The southern part of the orogenic collage developed by the consumption of the South Tianshan Ocean which gave rise to a continuous accretionary complex (Kokshaal–Kumishi), which separated the Central Tianshan in the east and other Paleozoic arcs in the west from cratons (Tarim and Karakum) to the south. Cross-border correlations of this accretionary complex indicate a general southward and oceanward accretion by northward subduction in the early Paleozoic to Permian as recorded by successive southward juxtaposition of ophiolites, slices of ophiolitic mélanges, cherts, island arcs, olistostromes, blueschists, and turbidites, which are mainly Paleozoic in age, with the youngest main phase being Late Carboniferous–Permian. The initial docking of the southerly Tarim and Karakum cratons to this complicated late Paleozoic archipelago and accretionary complexes occurred in the Late Carboniferous–Early Permian in the eastern part of the Tianshan and in the Late Permian in the western part, which might have terminated collisional deformation on this suture zone. The final stages of closure of the Junggar–Balkash Ocean resembled the small ocean basin scenario of the Mediterranean Sea in the Cenozoic. In summary, the history of the Altaids is characterized by complicated multiple accretionary and collisional tectonics. |
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