| 尼日利亚西部大陆边缘海底峡谷下部结构研究 |
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| 作者姓名： | JIMOH Rasheed Olayink TANG Yong LI Jiabiao AWOSIKA Larry Folajimi LI He AKINNIGBAGE Edward Akintoye ADELEYE Adedayo Oluwaseun |
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| 作者单位： | 浙江大学海洋学院, 舟山, 316021;国家海洋局第二海洋研究所, 杭州, 310012;国家海洋局 海底科学重点实验室, 杭州, 310012;尼日利亚海洋与深海研究所, 尼日利亚, 12729,国家海洋局第二海洋研究所, 杭州, 310012;国家海洋局 海底科学重点实验室, 杭州, 310012,国家海洋局第二海洋研究所, 杭州, 310012,大陆架界限委员会, 联合国海洋事务与法律部, 纽约,国家海洋局第二海洋研究所, 杭州, 310012;国家海洋局 海底科学重点实验室, 杭州, 310012,浙江大学海洋学院, 舟山, 316021;国家海洋局第二海洋研究所, 杭州, 310012;尼日利亚海洋与深海研究所, 尼日利亚, 12729,浙江大学海洋学院, 舟山, 316021;国家海洋局第二海洋研究所, 杭州, 310012;尼日利亚海洋与深海研究所, 尼日利亚, 12729 |
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| 基金项目： | The National Natural Science Foundation of China under contract No. 41470648; the Public Science and Technology Research Funds Projects of Ocean under contract No. 201205003; the National Program on Global Change and Air-Sea Interaction, SOA under contract No. 631 GASI-GEOGE-01. |
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| 摘 要： | Multi-beam,sub-bottom and multichannel seismic data acquired from the western Nigerian continental margin are analysed and interpreted to examine the architectural characteristics of the lower parts of the submarine canyons on the margin.The presence of four canyons: Avon,Mahin,Benin,and Escravos,are confirmed from the multi-beam data map and identified as cutting across the shelf and slope areas,with morphological features ranging from axial channels,moderate to high sinuosity indices,scarps,terraces and nickpoints which are interpreted as resulting from erosional and depositional activities within and around the canyons.The Avon Canyon,in particular,is characterised by various branches and sub-branches with complex morphologies.The canyons are mostly U-shaped in these lower parts with occasional V-shapes down their courses.Their typical orientation is NE–SW.Sedimentary processes are proposed as being a major controlling factor in these canyons.Sediments appear to have been discharged directly into the canyons by rivers during the late Quaternary low sea level which allows river mouths to extend as far as the shelf edge.The current sediment supply is still primarily sourced from these rivers in the case of the Benin and Escravos Canyons,but indirectly in the case of the Avon and Mahin Canyons where the rivers discharge sediments into the lagoons and the lagoons bring the sediments on to the continental shelf before they are dispersed into the canyon heads.Ancient canyons that have long been buried underneath the Avon Canyon are identified in the multichannel seismic profile across the head of the Avon Canyon,while a number of normal faults around the walls of the Avon and Mahin Canyons are observed in the selected sub-bottom profiles.The occurrence of these faults,especially in the irregular portions of the canyon walls,suggests that they also have some effect on the canyon architecture.The formation of the canyons is attributed to the exposure of the upper marginal area to incisions from erosion during the sea level lowstand of the glacial period.The incisions are widened and lengthened by contouric currents,turbidity currents and slope failures resulting in the canyons.
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| 关 键 词： | 尼日利亚西部大陆边缘 海底峡谷 控制因素 沉积过程 断层作用 |
| 收稿时间： | 2017/7/17 0:00:00 |
The architecture of the lower parts of submarine canyons on the western Nigerian continental margin |
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| JIMOH Rasheed Olayink,TANG Yong,LI Jiabiao,AWOSIKA Larry Folajimi,LI He,AKINNIGBAGE Edward Akintoye,ADELEYE Adedayo Oluwaseun.The architecture of the lower parts of submarine canyons on the western Nigerian continental margin[J].Acta Oceanologica Sinica,2018,37(7):28-40. |
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| Authors: | JIMOH Rasheed Olayink TANG Yong LI Jiabiao AWOSIKA Larry Folajimi LI He AKINNIGBAGE Edward Akintoye and ADELEYE Adedayo Oluwaseun |
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| Institution: | 1.Ocean College,Zhejiang University,Zhoushan,China;2.Second Institute of Oceanography,State Oceanic Administration,Hangzhou,China;3.Key Laboratory Submarine Geosciences,State Oceanic Administration,Hangzhou,China;4.Nigerian Institute for Oceanography and Marine Research,Lagos PMB,Nigeria;5.Commission on the Limits of the Continental Shelf,C/O Division of Ocean Affairs and Law of the Sea,New York,USA |
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| Abstract: | Multi-beam, sub-bottom and multichannel seismic data acquired from the western Nigerian continental margin are analysed and interpreted to examine the architectural characteristics of the lower parts of the submarine canyons on the margin. The presence of four canyons: Avon, Mahin, Benin, and Escravos, are confirmed from the multi-beam data map and identified as cutting across the shelf and slope areas, with morphological features ranging from axial channels, moderate to high sinuosity indices, scarps, terraces and nickpoints which are interpreted as resulting from erosional and depositional activities within and around the canyons. The Avon Canyon, in particular, is characterised by various branches and sub-branches with complex morphologies. The canyons are mostly U-shaped in these lower parts with occasional V-shapes down their courses. Their typical orientation is NE–SW. Sedimentary processes are proposed as being a major controlling factor in these canyons. Sediments appear to have been discharged directly into the canyons by rivers during the late Quaternary low sea level which allows river mouths to extend as far as the shelf edge. The current sediment supply is still primarily sourced from these rivers in the case of the Benin and Escravos Canyons, but indirectly in the case of the Avon and Mahin Canyons where the rivers discharge sediments into the lagoons and the lagoons bring the sediments on to the continental shelf before they are dispersed into the canyon heads. Ancient canyons that have long been buried underneath the Avon Canyon are identified in the multichannel seismic profile across the head of the Avon Canyon, while a number of normal faults around the walls of the Avon and Mahin Canyons are observed in the selected sub-bottom profiles. The occurrence of these faults, especially in the irregular portions of the canyon walls, suggests that they also have some effect on the canyon architecture. The formation of the canyons is attributed to the exposure of the upper marginal area to incisions from erosion during the sea level lowstand of the glacial period. The incisions are widened and lengthened by contouric currents, turbidity currents and slope failures resulting in the canyons. |
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| Keywords: | western Nigerian continental margin submarine canyons architecture controlling factors sedimentary processes tectonic evolution |
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