Architectures and evolution of arid alluvial fans: Insights from a flume experiment |
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| Authors: | Zhu Yi-Jie Xia Rui Zheng Yun-Ke Liu Chen-Hu Yu Bin Lü Jun-Ling Feng Wen-Jie |
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| Institution: | 1. School of Geoscience,Yangtze University,Wuhan 430100,China;2. State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing),Beijing 102249,China;3. CNOOC International Limited,Beijing 100028,China; |
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| Abstract: | Using time-lapse cameras and a 3D laser scanner,74 groups of geomorphic data of alluvial fans were obtained through flume experiments. Then a detailed sedimentary analysis based on these data was performed by using a quantitative software to reveal the sedimentary evolution process of the arid alluvial fan and its depositional architecture. Results suggest that there are obvious differences in hydrodynamics,water flow patterns and growth pattern during the evolution of arid alluvial fans. Based on these differences,the experiment is divided into three stages,including an early,middle,and late stage. In the early stage,the fan surface hydrodynamics was relatively strong,and the sheet flow dominated the deposition. According to the distribution of sheet flow deposits,it can be divided into wide-spread sheet flow deposition and local sheet flow deposition. In the middle period of the experiment,the hydrodynamic strength and expansion rate at the middle-distal part of the fan body reduced. The non-confined channel which is close to the source dominated the deposition,and terminal lobe was mainly deposited on the edge of the river channel. In the late stage of the experiment,the hydrodynamic further reduced causing by the large fan surface and confined channels were the main deposits. Through the flume experiment,an arid alluvial fan depositional architecture model with a three-layer structure has been established. The bottom layer is of a sheet flow lobe complex,the middle layer is characterized by unconfined channels and terminal lobes,and the top layer is constituted by stacked confined channels and small terminal lobes. |
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| Keywords: | alluvial fan sedimentary characteristics flume experiment quantitively sedimentary analysis sedimentary architecture model |
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