陈业伟^1,,
宋海斌^1,,,
关永贤²,
耿明会¹,
刘胜旋²
1. 海洋地质国家重点实验室, 同济大学海洋与地球科学学院, 上海 200092
2. 国土资源部海底矿产资源重点实验室, 广州海洋地质调查局, 广州 510760

基金项目: 国家自然科学基金（41576047，41506054），国家自然科学基金重大计划重点项目（91128205）资助


详细信息

作者简介: 陈业伟, 男, 1993年生, 主要从事海洋地球物理研究.E-mail:ywchen@tongji.edu.cn

通讯作者: 宋海斌, 教授, 主要从事海洋地球物理与地震海洋学研究.E-mail:hbsong@tongji.edu.cn

中图分类号: P738;P631

收稿日期:2017-04-05
修回日期:2018-01-10
上线日期:2018-03-05

Discovery of the reticular sand dunes in the Dongsha region of South China Sea and their genesis

CHEN YeWei^1,,
SONG HaiBin^1,,,
GUAN YongXian²,
GENG MingHui¹,
LIU ShengXuan²
1. State Key Laboratory of Marine Geology, School of Ocean and Earth Science, Tongji University, Shanghai 200092, China
2. Key Laboratory of Marine Mineral Resources, Ministry of Land and Resources, Guangzhou Marine Geological Survey, Guangzhou 510760, China


More Information

Corresponding author: SONG HaiBin,E-mail:hbsong@tongji.edu.cn

MSC: P738;P631

--> Received Date: 05 April 2017
Revised Date: 10 January 2018
Available Online: 05 March 2018


摘要
摘要:基于多波束测深和高分辨率多道反射地震数据，以及遥感资料研究南海北部东沙海域深水沙丘，总结底形形态分布特征，分析其水动力成因.按照空间分布形态将沙丘分为平行沙丘、波状沙丘和网状沙丘，本文首次发现水下网状沙丘，重点讨论网状沙丘的特征分布和形成机制.网状沙丘发育在东沙环礁东北部水深约352~420 m之间，研究发现其延伸方向共有三个走向：NS、NE-SW和EW，前两个方向为西向传播的内波所致，而最后一个则很有可能是由洋盆西向传播的内波遇到东沙环礁后形成衍射，向北传播的内波引起了向南的近海底底流，冲刷海底底层，剥蚀出足够的沉积物颗粒，从而形成EW走向的水下沙丘.值得一提的是，在多边形网状沙丘的上方，反射地震剖面揭示水层中发育与下方沙丘相当波长的高频震荡内波，并且在遥感资料上也发现相关的衍射和内波干涉区域，而内波干涉很有可能导致高频震荡，从而形成网状沙丘.本研究丰富了水下沙丘形态类型，探讨了新型水下沙丘的形成机制，在陆坡底沙运动及工程应用中具有重要的价值.
关键词: 水下沙丘/
网状沙丘/
高频震荡/
多波束测深/
东沙海域

Abstract:Based on multi-beam bathymetry and multi-channel seismic reflection data, as well as remote sensing data, we study the subaqueous sand dunes in the Dongsha region of the northern South China Sea, summarize the distribution features of the badforms, and analyze their hydrodynamic genesis. According to the spatial distribution characteristics, the subaqueous sand dunes are divided into parallel, wavy and reticular features. We focus on the distribution and formation mechanism of the reticular dunes which are distributed on the upper continental slope at depths of 352~420 m in the northeastern area to the Dongsha Atoll. The study shows that there are three directions of sand dune crest/trough extension:NS, NE-SW and EW. The former two are induced by the internal waves of westward propagation. While the last is likely to be formed by northward diffracted internal waves when they encounter the Dongsha Atoll. The northward propagating internal waves induce the southward bottom current. The bottom flow caused from internal waves can flush the seafloor and suspend the sediments, thus can form the subaqueous sand dunes of EW direction. It is worth mentioning that, above the polygonal reticular dunes, the seismic reflection sections reveal that the trough-to-trough wavelength is consistent between the high-frequency oscillating internal waves and subaqueous sand dunes. The relevant diffraction and internal wave interference regions can be recognized in the remote sensing data, and the internal wave interference is likely to cause high-frequency oscillation, thus forming a reticular dune field.
Key words:Subaqueous sand dunes/
Reticular dunes/
High-Frequency oscillating/
Multi-Beam bathymetry/
Dongsha region



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