南海北部莺琼陆坡浊流沉积数值模拟分析
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本文为国家重点研究开发计划项目(编号2017YFC0306703)和国家自然科学基金项目(编号U1806230)联合资助的成果。


Numerical simulation and analysis of the turbidity current deposit in Yingqiong continental slope in the northern South China Sea
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    摘要:

    南海具有优越的地理位置和特殊的构造环境,其丰富充足的沉积物源、复杂多样的地形地貌以及广泛分布的陆坡都为浊流的发育提供了良好条件和理想场所。南海北部更是有华南大陆以及台湾岛的大量陆源沉积物搬运至陆坡,加上陆坡区合适的坡度,浊流沉积十分发育。南海北部陆坡发育有大量不同规模的海底滑坡,浊流沉积分布广泛。在南海北部莺琼陆坡的钻孔记录和地震数据中,发现多次的地层倒转,多是浊流沉积造成。本文在地质、地形和地层数据基础上,利用Sedsim软件对莺琼陆坡浊流沉积进行数值模拟分析。研究表明,浊流的流动和沉积特征随着浊流发育而不同。浊流形成初期,整体流速较慢,部分较粗的沉积物在陆坡中上部产生少量沉积;浊流形成中期,流体在陆坡上不断加速,在陆坡上的沉积不明显;浊流沉积后期,浊流在陆坡坡折处受到减速的作用,沉积物的主体发生沉积,剩余沉积物搬运到平坦地形沉积;沉积地形为逆流迁移状;浊流沉积基本分布在10 km范围内,沉积厚度会随流动距离的增加而减小,且会出现层状沉积。

    Abstract:

    The South China Sea has a superior geographic location and a special tectonic environment. Its abundant and sufficient sediment sources, complex and diverse landforms and widely distributed continental slopes provide good conditions and ideal places for the development of turbidity currents. In the northern South China Sea, a large number of terrigenous sediments from the South China mainland and Taiwan Island are transported to the continental slope. Coupled with the suitable slope of the continental slope area, the turbidity current deposits are very developed.There are many submarine landslides of different scales and turbidity current deposits in the northern continental slope of the South China Sea. In the borehole records and seismic data of Yingqiong continental slope in the northern South China Sea, many stratigraphic reversals were found, most of which were caused by turbidity current deposition. Based on the geological, topographic and stratigraphic data, we used Sedsim software to simulate and analyze the turbidity current deposition in Yingqiong continental slope. The results show that the flow and sedimentary characteristics of turbidity current are different with the development of turbidity current. At the early stage of turbidity current, the overall velocity is slow, and some coarser sediments deposit a little in the middle and upper part of the continental slope. In the middle stage of turbidity current formation, the fluid accelerates continuously on the continental slope, and the deposition is not obvious. At the later stage of turbidity current deposition, the turbidity current is slowed down at the slope break, and the main body of sediments is deposited, and the remaining sediments are transported to the flat topography. The sedimentary topography is in the form of counter- current migration, and turbidity current deposition is basically distributed within the range of 10km. The thickness of turbidity current deposition will decrease with the increase of flow distance, and layered deposition will occur.

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杨茜,冯秀丽,李梦帅.2022.南海北部莺琼陆坡浊流沉积数值模拟分析[J].地质学报,96(4):1412-1420.
Yang Xi, Feng Xiuli, Li Mengshuai.2022. Numerical simulation and analysis of the turbidity current deposit in Yingqiong continental slope in the northern South China Sea[J]. Acta Geologica Sinica,96(4):1412-1420.

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  • 收稿日期:2020-10-10
  • 最后修改日期:2020-12-15
  • 录用日期:2021-03-08
  • 在线发布日期: 2021-09-13
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