Early Mesozoic magmatism and tectonic evolution of the Qinling Orogen: Implications for oblique continental collision |
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| Institution: | 1. Key Laboratory of Orogen and Crustal Evolution, Peking University, Beijing 100871, China;2. School of Earth Sciences and Resources, China University of Geosciences, Xueyuan Road, Haidian District, Beijing 100083, China;3. Centre for Exploration Targeting, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia;1. State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China;2. School of Earth Science and Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration, Guilin University of Technology, Guilin 541004, China;3. School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China;4. Shandong Institute of Geological Sciences, Key Laboratory of Gold Mineralization Processes and Resource Utilization subordinated to the Ministry of Land and Resources, Jinan 250013, China;1. Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, Peking University, Beijing 100871, PR China;2. Development Research Center, China Geological Survey, Beijing 100037, PR China;3. Department of Energy and Mineral Engineering, The Pennsylvania State University, University Park, PA 19602, USA;1. State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Northern Taibai Str. 229, Xi’an 710069, China;2. Collaborative Innovation Centre of Continental Tectonics, Northwest University, Northern Taibai Str.229, Xi’an 710069, China;3. School of Earth Science and Resources, China University of Geosciences, Xueyuan Road 29, Beijing 100083, China;4. Department of Earth Science, University of Adelaide, Adelaide, SA 5005, Australia |
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| Abstract: | The Qinling Orogenic Belt in Central China is formed by an oblique continental collision between the North China and South China Blocks. In this review, we summarize the knowledge of the early Mesozoic magmatism, in combination with the coeval metamorphic characteristics, regional structural features and depositional history in the foreland and hinterland basins along the Qinling-Dabie Orogen. The early Mesozoic tectonic evolution of the Qinling is divided into four stages. Stage I (~250–235 Ma) is characterized by medium-K calc-alkaline magmatism in the western Qinling induced by slab roll-back. Meanwhile, ultrahigh-pressure metamorphism was triggered by continental subduction in the Sulu-Dabie, indicating a diachronous closure of the ocean. Stage II (~235–225 Ma) is recognized as a magmatic gap. Depositional variations of sedimentary facies and compressional deformations with an increased crustal thickness reflect the initial collision in the Qinling. Stage III (~225–210 Ma) is distinguished by a magmatic flare-up event. Abundant mantle-derived melts coupled with extensive crustal-derived melts were coeval with rapid uplift, strike-slip movement and regional crustal thickening in the Qinling as well as retrograde metamorphism in the Sulu-Dabie. The main tectonic driver was the propagating detachment of the subducted oceanic slab at gradually shallower depth from the Sulu-Dabie to the Qinling. Stage IV (~210–190 Ma) magmatism is dominated by high silica granites derived from metasedimentary rocks. The rapid denudation rates and extensional structures indicate gravitational collapse and regional delamination of the thickened crust. In addition to the strike-slip faults and block extrusion, the Qinling is characterized by asymmetric distribution patterns of magmatism and metamorphism, different melting mechanisms over time; diachronous depositions, differential uplift and non-uniform crustal thickening, and regional delamination of the thickened orogenic root. All these features are the result of the oblique collision, which is a common process in nature, and therefore could be applied to other orogens. |
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