Late Triassic initial closure of the Mongol-Okhotsk Ocean in the western segment: Constraints from sedimentological,detrital zircon ages and paleomagnetic evidence |
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| Institution: | 1. Servicio Geológico Colombiano, Colombia;2. Cardiff University, United Kingdom;3. Smithsonian Tropical Research Institute, Panama;4. Universidad Nacional de Colombia, Colombia;1. College of Earth Sciences, Jilin University, Changchun 130061, China;2. Key Laboratory of Mineral Resources Evaluation in Northeast Asia (Jilin University), Ministry of Natural Resources, Changchun 130061, China;1. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;2. College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China;3. Key Laboratory of Computational Geodynamics, University of Chinese Academy of Sciences, 19A Yuquanlu, Beijing 100049, China;4. State Key Laboratory of Nuclear Resources and Environment, East China University of Technology, Nanchang 330013, China;1. Key Laboratory of Marine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong 266071, China;2. Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266061, China;3. Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China;4. China Nonferrous Metals (Guilin) Geology and Mining Co. Ltd., Guilin 541004, China;5. University of Chinese Academy of Sciences, Beijing 100049, China;6. School of Resources and Environmental Science, Quanzhou Normal University, Quanzhou 362000, China;1. School of Earth Resources, China University of Geosciences, Wuhan, China;2. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China;3. School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China;4. Center for Advanced Research on the Mantle (CARMA), Chinese Academy of Geological Sciences, Beijing 100037, China;5. Department of Earth Sciences, The University of Hong Kong, Hong Kong, China |
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| Abstract: | The Mesozoic evolution of the Mongol-Okhotsk Ocean (MOO) has significantly affected the configuration of the modern Asian continent. Although a scissor-like closure of the MOO has long been proposed, when and how the MOO closed are still hotly debated, especially the timing of initial closure of the MOO in its western segment, hindering our understanding of both the evolution of the MOO and tectonics of the northern Asian continent. In order to uncover the timing of initial closure of the MOO, we performed a multidisciplinary study in sedimentology, detrital zircon U-Pb dating and paleomagnetic on the Late Triassic clastic strata from the Tarvagatay Block and the Amuria Block (AMB) on the both sides of the Mongol-Okhotsk Suture. The upper Triassic strata on both sides of the suture were dominated by plant fossil-bearing alluvial-fluvial facies sediments, which unconformably overlain pre-Triassic geological units, indicating a terrestrial setting after the closure of the MOO. Detrital zircon U-Pb dating results revealed consistent age distribution patterns for samples from both sides of the suture with a predominant peak at ～253–251 Ma and a secondary peak at ～359–357 Ma, representing two main arc magmatic events during the bidirectional subduction of the MOO in the Late Devonian-Early Carboniferous and Late Permian-Early Triassic. Coeval Late Triassic paleomagnetic poles were obtained from the northern AMB and Tarvagatay Block, revealing a comparable paleolatitude of the AMB (～31–33°) and Tarvagatay Block (～32–34°) in the Late Triassic, arguing for that the western segment of the MOO should have closed at the Late Triassic. The compilation of sedimentology, detrital zircon U-Pb dating, magmatic and paleomagnetic evidence provides integrated constraints on the Late Triassic initial closure of the MOO in its western segment. |
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| Keywords: | Mongol-Okhotsk Ocean Sedimentology Detrital zircon U-Pb ages Paleomagnetism Late Triassic initial closure |
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