| Typical Soft–Sediment Deformation Structures Induced by Freeze/Thaw Cycles: A Case Study of Quaternary Alluvial Deposits in the Northern Qiangtang Basin, Tibetan Plateau |
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| 作者姓名： | ZHONG Ning LI Haibing JIANG Hanchao LU Haijian ZHENG Yong HAN Shuai YE Jiachan |
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| 作者单位： | 1 Key Laboratory of Deep–Earth Dynamics, Ministry of Natural Resources, Beijing 100037, China
2 Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China；3 Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing, 100081, China,1 Key Laboratory of Deep–Earth Dynamics, Ministry of Natural Resources, Beijing 100037, China
2 Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China,4 State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China,1 Key Laboratory of Deep–Earth Dynamics, Ministry of Natural Resources, Beijing 100037, China
2 Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China,1 Key Laboratory of Deep–Earth Dynamics, Ministry of Natural Resources, Beijing 100037, China
2 Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China,1 Key Laboratory of Deep–Earth Dynamics, Ministry of Natural Resources, Beijing 100037, China
2 Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China and 1 Key Laboratory of Deep–Earth Dynamics, Ministry of Natural Resources, Beijing 100037, China
2 Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China |
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| 基金项目： | During this study, the authors carefully read the book “Soft sedimentary deformation structures-earthquake and ancient earthquake records” by Qiao Xiufu et al., 2017, which has greatly helped us to understand, assess and interpret the soft sedimentary deformation structures in the area. We thank Drs. Qiao Xiufu, Su Dechen, Pan Jiawei, He Xiangli and Chen Andong for their fruitful discussion. We are also grateful A.J. (Tom) Van Loon for valuable suggestions and the English improvement. This work is supported by projects from the National Natural Science Foundation of China (41807298, 41702372, 41672211), the China Postdoctoral Science Foundation (2019M650788), National Key Research and Development Project of China (2016YFC0600310), the China Geological Survey (DD20160022, DD20190059), and the Basic Research Funds (JYYWF201810) of the Institute of Geology, CAGS. |
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| 摘 要： | With the objective of establishing a distinction between deformation structures caused by freeze/thaw cycles and those resulting from seismic activity, we studied three well–exposed alluvial deposits in a section at Dogai Coring, northern Qiangtang Basin, Tibetan Plateau. Deformation is present in the form of plastic structures(diapirs, folds and clastic dykes), brittle structures(micro–faults) and cryogenic wedges. These soft–sediment deformation features(except the micro–faults) are mainly characterized by meter–scale, non–interlayered, low–speed and low–pressure displacements within soft sediments, most commonly in the form of plastic deformation. Taking into account the geographic setting, lithology and deformation features, we interpret these soft–sediment deformation features as the products of freeze/thaw cycles, rather than of earthquake–induced shock waves, thus reflecting regional temperature changes and fluctuations of hydrothermal conditions in the uppermost sediments. The micro–faults(close to linear hot springs) are ascribed to regional fault activity; however, we were unable to identify the nature of the micro–faults, perhaps due to disturbance by subsequent freeze/thaw cycles. This study may serve as a guide to recognizing the differences between deformation structures attributed to freeze/thaw cycles and seismic processes.
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| 关 键 词： | soft–sediment deformation structures freeze/thaw cycles Dogai Coring Qiangtang Basin |
| 收稿时间： | 2019/2/11 0:00:00 |
| 修稿时间： | 2019/12/20 0:00:00 |
Typical Soft–Sediment Deformation Structures Induced by Freeze/Thaw Cycles: A Case Study of Quaternary Alluvial Deposits in the Northern Qiangtang Basin,Tibetan Plateau |
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| Authors: | ZHONG Ning LI Haibing JIANG Hanchao LU Haijian ZHENG Yong HAN Shuai and YE Jiachan |
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| Abstract: | With the objective of establishing a distinction between deformation structures caused by freeze/thaw cycles and those resulting from seismic activity, we studied three well–exposed alluvial deposits in a section at Dogai Coring, northern Qiangtang Basin, Tibetan Plateau. Deformation is present in the form of plastic structures (diapirs, folds and clastic dykes), brittle structures (micro–faults) and cryogenic wedges. These soft–sediment deformation features (except the micro–faults) are mainly characterized by meter–scale, non–interlayered, low–speed and low–pressure displacements within soft sediments, most commonly in the form of plastic deformation. Taking into account the geographic setting, lithology and deformation features, we interpret these soft–sediment deformation features as the products of freeze/thaw cycles, rather than of earthquake–induced shock waves, thus reflecting regional temperature changes and fluctuations of hydrothermal conditions in the uppermost sediments. The micro–faults (close to linear hot springs) are ascribed to regional fault activity; however, we were unable to identify the nature of the micro–faults, perhaps due to disturbance by subsequent freeze/thaw cycles. This study may serve as a guide to recognizing the differences between deformation structures attributed to freeze/thaw cycles and seismic processes. |
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| Keywords: | soft–sediment deformation structures freeze/thaw cycles Dogai Coring Qiangtang Basin |
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