南海东沙群岛以北海底沙波稳定性分析

A stability analysis of seabed sand waves in waters north of Dongsha Islands of South China Sea

利用在南海东沙群岛北部至西北海域为工程目的所采集的海底地形测量、底质取样、海底底流测量资料,以及以往的区域地质、地球物理资料,采用沉积学、构造学和海洋水动力学综合研究方法,对该区海底沙波形成及稳定性进行了综合分析。认为该区海底沙波是在目前水动力环境下所形成,为今生,海底表层沉积物为晚更新世地层受到冲刷改造的再沉积。沙波形成主要受潮流底流的水动力作用控制,并与构造抬升有关。沙波具有一定的活动性,主要由SE向NW方向移动,且活动性逐渐减弱。北区段海底沙波稳定,中区段海底沙波较稳定,它们对海底工程建设不会造成影响;而南区段海底沙波较为活动,当沙波发生较大规模移动时,对海底工程建设会造成一定影响。

The genesis and stability of seabed sand waves in the waters north and northwest of the Dongsha Islands have been analyzed by synthetical study of sedimentology, tectonics and marine hydrodynamics using surveying data of submarine topography, shallow sediments, sea bottom currents as well as former regional geological and geophysical data. It is supposed that the sand waves have been formed under present hydrodynamic environment, and the seabed surface layer sediments have been formed by the redeposition of the Upper Pleistocene reconstruction through erosion action. The formation of sand waves is controlled mainly by underset of tidal current, and also related to tectonic uplift. The sand waves move to some extent, with the main direction from SE to NW, yet this trend is gradually becoming weak. The sand waves show high stability in the northern section and relative stability in the mid section, which have little influence on seafloor engineering; whereas they move about frequently in the southern section, which will have some influence on seafloor engineering in case of relatively large scaled movement.