Late Quaternary evolution of the Madeira Abyssal Plain, Canary Basin, NE Atlantic
Late Quaternary evolution of the Madeira Abyssal Plain, Canary Basin, NE Atlantic
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大西洋东北部加那利盆地马德拉深海平原的晚第四纪演化
DOI：
10.1111/j.1365-2117.1992.tb00147.x
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发表时间：
1992
期刊：
影响因子：
3.2
通讯作者：
P. Weaver
中科院分区：
文献类型：
--
作者：
R. G. Rothwell;T. Pearce;P. Weaver
加那利盆地的最深处，马德拉深海平原，接受来自一个大流域的外来沉积物，如果包括其陆上延续，面积为3.36乘以106平方公里。在过去10年中，一项国际研究工作从该平原上采集了160多个沉积物岩心，高分辨率地层学的发展使人们能够逐层对比各个浊积岩。晚第四纪期间马德拉深海平原上的沉积作用主要是由薄的远洋间隔分隔的厚浊积岩泥。岩芯密度使得能够绘制整个深海平原的每个沉积单元的地图，从而建立沉积物堆积的逐层图像。在过去的300 kyr，600 km3的浊积岩相比，60 km3的远洋沉积物已沉积在平原上。在较大浊积岩的粗基底相中发育的沉积结构比简单模型预测的要复杂得多，这是由于涌动的水流、波动的流速和来自邻近高地的反射。在过去的30万年里，浊流进入深海平原的入口点发生了转换。从300 ka到200 ka，富含有机质的浊积岩主要从南部侵位，但在200 ka左右，这个源关闭，随后富含有机质和火山的浊积岩，其中包括由巨大的，可能是超浓缩流沉积的单位，从北方或东部源侵位。虽然仅限于晚第四纪，所提供的数据提供了一个详细的案例研究的海洋盆地填充物的演变。
The deepest part of the Canary Basin, the Madeira Abyssal Plain, receives allochthonous sediments derived from a large drainage basin which, if its subaerial continuation is included, covers an area of 3.36 times 106 km2. An international research effort over the last 10 years has recovered over 160 sediment cores from the plain, and the development of a high-resolution stratigraphy has enabled individual turbidites to be correlated layer by layer. Sedimentation on the Madeira Abyssal Plain during the late Quaternary is dominated by thick turbidite muds separated by thin pelagic intervals. The core density has allowed the mapping of each sedimentary unit throughout the abyssal plain, thus building up a layer by layer picture of sediment accumulation. Over the last 300 kyr, 600 km3 of turbidites compared to 60 km3 of pelagic sediments have been deposited on the plain. Sedimentary structures developed in the coarse basal facies of the larger turbidites are more complex than simple models predict due to surging flows, fluctuating flow velocities and reflection from adjacent high ground. Over the last 300 kyr, there has been a switching of entry points for turbidity currents entering the abyssal plain. From 300 ka to 200 ka, organic-rich turbidites were emplaced predominantly from the south but around 200 ka this source switched off and subsequent organic- and volcanic-rich turbidites, which included units deposited by giant, possibly hyperconcentrated flows, were emplaced from northern or eastern sources. Although restricted to the late Quaternary, the data presented provides a detailed case study of the evolution of an oceanic basin fill.