The architecture of the lower parts of submarine canyons on the western Nigerian continental margin
The architecture of the lower parts of submarine canyons on the western Nigerian continental margin
复制标题
地形对地震动影响研究综述
DOI：
10.1007/s13131-018-0000-00
复制
发表时间：
2018-07
期刊：
影响因子：
--
通讯作者：
TANG Yong
中科院分区：
文献类型：
--
作者：
JIMOH Rasheed Olayinka1;TANG Yong
本文分析和解释了尼日利亚西部大陆边缘的多波束、浅海底和多道地震资料，以研究该边缘海底峡谷下部的结构特征。四个峡谷的存在：Avon、Mahin、Benin和Escravos从多波束数据图中得到确认，并被确定为横穿大陆架和斜坡区，其形态特征包括轴向河道、中等至高弯曲指数、陡崖、阶地和缺口点，这些被解释为峡谷内部和周围的侵蚀和沉积活动造成的。特别是埃文峡谷，其特点是各种分支和子分支具有复杂的形态。峡谷的下部大部分是U形的，偶尔也有V形的。它们的典型方位是NE-SW。沉积过程被认为是这些峡谷的主要控制因素。沉积物似乎是在第四纪晚期的低海平面期间由河流直接排入峡谷的，这使得河口可以延伸到陆架边缘。在贝宁河和埃斯克拉沃斯河的情况下，目前的沉积物供应仍然主要来自这些河流，但在埃文河和马欣河的情况下，沉积物的供应是间接的，河流将沉积物排入泻湖，泻湖将沉积物带到大陆架，然后分散到峡谷顶部。在横跨埃文峡谷顶部的多道地震剖面中，确定了长期埋藏在埃文峡谷下面的古老峡谷，而在选定的海底剖面中，观察到埃文和马欣峡谷壁周围的一些正断层。这些断层的出现，特别是在峡谷壁的不规则部分，表明它们对峡谷结构也有一些影响。峡谷的形成是由于冰川期海平面低水位时，上边缘地区暴露于侵蚀的切口。等深流、浊流和边坡失稳使切痕加宽、加长，形成峡谷。
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.during the glacial period. The incisions are widened and lengthened by contouric currents, turbidity currents and.slope failures resulting in the canyons.
登录
查看更多内容
DOI：
10.1016/j.dsr.2012.01.014
发表时间：
2012-06
期刊：
--
影响因子：
--
作者：
F. D. Leo;J. Drazen;Eric W. Vetter;A. Rowden;C. Smith
通讯作者：
F. D. Leo;J. Drazen;Eric W. Vetter;A. Rowden;C. Smith
影响因子：
3.5
作者：
S. W. Petters
通讯作者：
S. W. Petters
影响因子：
4.2
作者：
E. Wiles;A. Green;M. Watkeys;W. Jokat;R. Krocker
通讯作者：
E. Wiles;A. Green;M. Watkeys;W. Jokat;R. Krocker
影响因子：
4.2
作者：
M. Deptuck;Z. Sylvester;C. Pirmez;C. O’Byrne
通讯作者：
M. Deptuck;Z. Sylvester;C. Pirmez;C. O’Byrne
影响因子：
3.5
作者：
J. R. Allen
通讯作者：
J. R. Allen