Time-integrated 3D approach of late Quaternary sediment-depocenter migration in the Tagus depositional system: From river valley to abyssal plain
Time-integrated 3D approach of late Quaternary sediment-depocenter migration in the Tagus depositional system: From river valley to abyssal plain
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DOI：
10.1016/j.earscirev.2015.11.002
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发表时间：
2016-02
影响因子：
12.1
通讯作者：
G. Vis;C. Kasse;D. Kroon;J. Vandenberghe;Simon J. A. Jung;S. Lebreiro;T. Rodrigues
中科院分区：
文献类型：
--
作者：
G. Vis;C. Kasse;D. Kroon;J. Vandenberghe;Simon J. A. Jung;S. Lebreiro;T. Rodrigues
大陆至深海盆地沉积物体积的量化是了解源-汇沉积体系中沉积物分布过程的关键。使用我们自己的和已发表的数据，我们提出了第一个量化的沉积物体积变化的盆地沿着欧洲西南部的一条主要河流的过程中，冰川消退。在塔霍河和北大西洋同等盆地中，这一定量记录的突出点显示了海平面、气候和土地利用在沉积物分布中的关键作用。在末次盛冰期的海平面低水位期间，沉积物的绕过使塔霍河盆地挨饿，随后沉积主要发生在塔霍河深海平原上。在冰消期海平面上升期间，主要沉积物沉积中心通过大陆架迅速转移到下塔霍河谷。最后，主要沉积中心进一步向陆地转移到下塔霍河谷海平面高的立场在全新世。在高标准阶段（最后7千公里），沉积物通量增加了2.5倍，由于气候和土地利用的变化。在过去的12千年（0.04-0.1毫米/年）的平均流域剥蚀率与欧洲其他集水区。我们的研究清楚地表明了详细了解三维沉积中心分布、大小和年代的附加价值。这使我们能够确定增加的沉积物通量在过去的7千公里，这是没有确定单独使用本地观测钻孔。塔霍河沉积体系的独特之处在于，它结合了由岩石圈限制的下塔霍河谷中的巨大可容纳空间、陡峭的低位面坡度和狭窄的大陆架，以及在大陆架坡折处缩进的峡谷。
Quantification of sediment volumes in continental to deep ocean basins is key to understanding processes of sediment distribution in source-to-sink depositional systems. Using our own and published data we present the first quantification of sediment-volume changes in basins along the course of a major southwest European river during the deglaciation. The salient points of this quantitative record in the Tagus and equivalent North Atlantic basins show crucial roles for sea level, climate and land-use in the distribution of sediments. The bypass of sediments starved the Tagus basins, and subsequently sedimentation mainly occurred on the Tagus Abyssal Plain during the sea-level lowstand of the Last Glacial Maximum. The main sediment depocenter rapidly shifted via the continental shelf to the Lower Tagus Valley during sea-level rise in the deglaciation period. Finally, the main sediment depocenter shifted further landward into the Lower Tagus Valley during sea-level high stand in the Holocene. During the high-stand phase (last 7 ky), sediment flux increased up to 2.5 times, due to climate and land-use changes. The average catchment denudation rate during the last 12 ky (0.04–0.1 mm/y) is in agreement with those of other European catchments. Our study clearly demonstrates the added value of detailed knowledge of 3D depocenter distribution, size and chronology. This allowed us to identify an increased sediment flux during the last 7 ky, which was not identified using local observations from boreholes alone. The uniqueness of the Tagus depositional system lies in the combination of a large accommodation space in the bedrock-confined Lower Tagus Valley, the steep lowstand-surface gradient and the narrow continental shelf with canyons indenting the shelf break.