Tectonic entities connection between West Junggar (NW China) and East Kazakhstan |
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| Institution: | 1. The Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, School of Earth and Space Sciences, Peking University, Beijing 100871, China;2. The Institute for Geoscience Research (TIGeR), Department of Applied Geology, Curtin University, GPO Box U1987, Perth, WA 6845, Australia;3. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;4. Department of Geosciences, National Taiwan University, Taipei 10617, Taiwan;5. Beijing SHRIMP Center, Chinese Academy of Geological Sciences and Department of Geosciences, University of Mainz, Germany;1. Department of Earth Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China;2. Department of Geology and Planetary Sciences, University of Pittsburgh, Pittsburgh, PA, USA;3. Department of Geology, Northwest University, Xi''an 710069, China;1. State Key Laboratory of Biogeology and Environmental Geology, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China;2. No. 207 Geology Brigade of Sichuan Bureau of Exploration and Development of Geology and Minerals Resources, Leshan 614000, China;1. Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, CAS, Beijing 100029, PR China;2. Institutions of Earth Science, Chinese Academy of Sciences, Beijing 100029, PR China;3. University of Chinese Academy of Sciences, 100049 Beijing, China;4. United States Geological Survey, Reno, Nevada 89557, United States;5. Institute of Geology and Geophysics, CAS, Beijing 100029, PR China;6. College of Resource and Environment Sciences, Xinjiang University, 830046, PR China;7. School of Geosciences and Resources, China University of Geosciences, Beijing 100083, PR China;8. State Key Laboratory of Geological Processes and Mineral Resources, Science Research Institute, China University of Geosciences, Beijing 100083, PR China;9. Shanxi Center of Geological Survey, Xi''an, Shanxi 710068, PR China;10. Panjin Zhonglu Oil&Gas Technology Services Co. Ltd, Liaoning 124000, PR China;1. Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, School of Earth and Space Sciences, Peking University, Beijing 100871, China;2. Department of Geology, Saint Mary''s University, Halifax, Nova Scotia B3H 3C3, Canada;3. Geological Survey of Canada (Atlantic), Bedford Institute of Oceanography, P.O. Box 1006, Dartmouth, Nova Scotia B2Y 4A2, Canada |
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| Abstract: | West Junggar (NW China) and East Kazakhstan are situated in the southwest of the Central Asian orogenic belt (CAOB). Tectonic entities in the two areas share the same tectonic evolution history and make up the famous horseshoe-shaped orocline in Central Asia. This paper presents a newly compiled cross-border tectonic sketch map of West Junggar and East Kazakhstan and proposes the extension of the Chingiz–Tarbagatai belt and the North Balkhash-West Junggar belt.The Chingiz–Tarbagatai Belt in East Kazakhstan consists mainly of Middle-Late Ordovician differentiated volcanic rocks, pyroclastic sediments and flysch; while in the Tarbagatai Mountain in China, Tarbagatai (Kujibai) ophiolite is newly found with zircon (gabbro) age of 478 ± 3 Ma and the Ordovician flysch metamorphosed to a greenschist facies is distinguished from Devonian–Carboniferous rock associations. Therefore, the Early Paleozoic Chingiz–Tarbagatai belt of East Kazakhstan evidently extends to the northern part of West Junggar along the Tarbagatai orogenic belt.The North Balkhash-West Junggar belt lying south to the Chingiz–Tarbagatai belt is separated by the EW-trending Baiyanghe–Heshituoluogai depression in West Junggar. Early Ordovician–Early Silurian ophiolitic fragments and related pyroclastic sediments are widely exposed in Tekturmas, North Balkhash and Agadyr of East Kazashtan. Similarly, Early Paleozoic ophiolites have also been verified in Tangbale, Mayile, Baerluke, Darbut and Karamay of West Junggar in recent years. Therefore, nearly all ophiolites in West Junggar and East Kazakhstan are proved to have formed in Early Paleozoic, which suggests that the evolution of the paleo-ocean in the two areas reached its peak in the Early Paleozoic. Based on the ages of the Tangbale, Karamay and Hongguleleng ophiolites, an Early Paleozoic continental accretionary belt extending from Tangbale to Hongguleleng is determined at the NW margin of the Junggar basin for the first time. According to spatiotemporal comparison, ophiolites exposed in West Junggar and East Kazakhstan might originate from the same paleo-ocean tectonic region, and then the North Balkhash in East Kazakhstan and the West Junggar were offset for a long distance with respect to each other by the major Junggar dextral fault.Because of the large-scale accretion of continental crust before Silurian, the Late Paleozoic ocean in West Junggar and East Kazakhstan became smaller with residual nature, and extensive arc-basin-trench systems might be absent during the closure of this residual ocean. |
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