| Latest Triassic to Early Jurassic Thrusting and Exhumation in the Southern Ordos Basin, North China: Evidence from LA-ICP-MS-based Apatite Fission Track Thermochronology |
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| 作者姓名： | ZHANG Shaohu LIU Chiyang YANG Minghui BAI Jianke WANG Jianqiang |
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| 作者单位： | 1 State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi''an 710069, China,1 State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi''an 710069, China,2 State Key Laboratory of Petroleum Resource and Prospecting, College of Geosciences, China University of Petroleum, Beijing 102200, China,1 State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi''an 710069, China；3 Research Center of Orogenic Geology, Xi''an Center of Geological Survey, China Geological Survey, Xi''an 710054, China and 1 State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi''an 710069, China |
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| 摘 要： | The contractional structures in the southern Ordos Basin recorded critical evidence for the interaction between Ordos Basin and Qinling Orogenic Collage. In this study, we performed apatite fission track(AFT) thermochronology to unravel the timing of thrusting and exhumation for the Laolongshan-Shengrenqiao Fault(LSF) in the southern Ordos Basin. The AFT ages from opposite sides of the LSF reveal a significant latest Triassic to Early Jurassic time-temperature discontinuity across this structure. Thermal modeling reveals at the latest Triassic to Early Jurassic, a ~50°C difference in temperature between opposite sides of the LSF currently exposed at the surface. This discontinuity is best interpreted by an episode of thrusting and exhumation of the LSF with ~1.7 km of net vertical displacement during the latest Triassic to Early Jurassic. These results, when combined with earlier thermochronological studies, stratigraphic contact relationship and tectono-sedimentary evolution, suggest that the southern Ordos Basin experienced coeval intense tectonic contraction and developed a north-vergent fold-and-thrust belt. Moreover, the southern Ordos Basin experienced a multi-stage differential exhumation during Mesozoic, including the latest Triassic to Early Jurassic and Late Jurassic to earliest Cretaceous thrust-driven exhumation as well as the Late Cretaceous overall exhumation. Specifically, the two thrust-driven exhumation events were related to tectonic stress propagation derived from the latest Triassic to Early Jurassic continued compression from Qinling Orogenic Collage and the Late Jurassic to earliest Cretaceous intracontinental orogeny of Qinling Orogenic Collage, respectively. By contrast, the Late Cretaceous overall exhumation event was related to the collision of an exotic terrain with the eastern margin of continental China at ~100 Ma.
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| 收稿时间： | 2018/2/25 0:00:00 |
| 修稿时间： | 2018/5/10 0:00:00 |
Latest Triassic to Early Jurassic Thrusting and Exhumation in the Southern Ordos Basin,North China: Evidence from LA‐ICP‐MS‐based Apatite Fission Track Thermochronology |
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| Authors: | ZHANG Shaohu LIU Chiyang YANG Minghui BAI Jianke and WANG Jianqiang |
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| Institution: | 1. State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, China;2. State Key Laboratory of Petroleum Resource and Prospecting, College of Geosciences, China University of Petroleum, China;3. Research Center of Orogenic Geology, Xi'an Center of Geological Survey, China Geological Survey, China |
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| Abstract: | The contractional structures in the southern Ordos Basin recorded critical evidence for the interaction between Ordos Basin and Qinling Orogenic Collage. In this study, we performed apatite fission track (AFT) thermochronology to unravel the timing of thrusting and exhumation for the Laolongshan‐Shengrenqiao Fault (LSF) in the southern Ordos Basin. The AFT ages from opposite sides of the LSF reveal a significant latest Triassic to Early Jurassic time‐temperature discontinuity across this structure. Thermal modeling reveals at the latest Triassic to Early Jurassic, a ～50°C difference in temperature between opposite sides of the LSF currently exposed at the surface. This discontinuity is best interpreted by an episode of thrusting and exhumation of the LSF with ～1.7 km of net vertical displacement during the latest Triassic to Early Jurassic. These results, when combined with earlier thermochronological studies, stratigraphic contact relationship and tectono‐sedimentary evolution, suggest that the southern Ordos Basin experienced coeval intense tectonic contraction and developed a north‐vergent fold‐and‐thrust belt. Moreover, the southern Ordos Basin experienced a multi‐stage differential exhumation during Mesozoic, including the latest Triassic to Early Jurassic and Late Jurassic to earliest Cretaceous thrust‐driven exhumation as well as the Late Cretaceous overall exhumation. Specifically, the two thrust‐driven exhumation events were related to tectonic stress propagation derived from the latest Triassic to Early Jurassic continued compression from Qinling Orogenic Collage and the Late Jurassic to earliest Cretaceous intracontinental orogeny of Qinling Orogenic Collage, respectively. By contrast, the Late Cretaceous overall exhumation event was related to the collision of an exotic terrain with the eastern margin of continental China at ～100 Ma. |
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| Keywords: | fission track thermochronology thermal history modeling thrusting and exhumation Ordos Basin Qinling Orogenic Collage |
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