| Morphology and maintenance of steep dunes near dune asymmetry transitional areas on the shallow shelf (Beibu Gulf, northwest South China Sea) | |
| Ma, Xiaochuan1,2,3; Yan, Jun1,2,3; Song, Yongdong1; Liu, Xiansan1; Zhang, Jianxing1; Traykovski, Peter A.4 | |
| 2019-06-01 | |
| 发表期刊 | MARINE GEOLOGY
 |
| ISSN | 0025-3227 |
| 卷号 | 412页码:37-52 |
| 通讯作者 | Ma, Xiaochuan([email protected]) |
| 摘要 | Symmetrical dunes can be found in areas where dune asymmetry changes sense, but in areas where dunes are not expected to be moving the development and maintenance of symmetrical dunes are poorly understood. In the southeastern Beibu Gulf, we have identified five typical dune asymmetry transitions at the depths of shallower than 50 m basing on the latest bathymetric data. Those regions are separated into two classes according to their different shapes and locations. Sand transport directions are deduced by dune migrations between surveys, simulated regional currents, and sand size trends. The two classes of the regions are found to experience opposing net sand transports from the north and south. Around the asymmetry transitions, the dunes have impressive steep sections, relatively symmetrical shapes, and almost straight crests. They have a general Height-Length (H-L) relation: H = 0.0575 L-1.0836 (R-2 = 0.834), which is steeper than dunes in other seas. Some of the dunes have extraordinary large heights exceeding a quarter of water depth, which is attributed to the preserved sand body, bidirectional sand accretion, erosion in troughs, and absence of significant erosion on crests. The steepness and straight crests of dunes adapt to the nearly symmetrical or weak asymmetrical reversing currents, which induce flow separations and reversals on both flanks of the dunes. It also suggests that dunes develop differently under sufficient and limited sand supply. Dunes will gradually grow in size when being continually supplied with sand. However, if sand supply is restricted, dunes may separate or turn into more isolated individuals to sustain the H-L relation. The H-L relation of dunes can be maintained during either growth or separation. Overall, the nearly symmetrical or weak asymmetrical reversing currents maintain the steep shapes of dunes while variations in sand supply affect their sizes. To work out the detailed transports of sediment, future observations of flow structures and related models of such two-sided steep dunes are still required. |
| 关键词 | Steep dunes Morphology Maintenance Flow separation Beibu Gulf |
| DOI | 10.1016/j.margeo.2019.03.006 |
| 收录类别 | SCI |
| 语种 | 英语 |
| 资助项目 | National Natural Science Foundation of China[41876035]###2438; National Natural Science Foundation of China[41406061]###1058; National Natural Science Foundation of China[41876035]; National Natural Science Foundation of China[41406061] |
| WOS研究方向 | Geology ; Oceanography |
| WOS类目 | Geosciences, Multidisciplinary ; Oceanography |
| WOS记录号 | WOS:000472687400004 |
| 出版者 | ELSEVIER SCIENCE BV |
| 引用统计 | |
| 文献类型 | 期刊论文 |
| 条目标识符 | http://ir.qdio.ac.cn/handle/337002/161771 |
| 专题 | 海洋地质与环境重点实验室 |
| 通讯作者 | Ma, Xiaochuan |
| 作者单位 | 1.Chinese Acad Sci, CAS Key Lab Marine Geol & Environm, Inst Oceanol, Qingdao, Shandong, Peoples R China 2.Qingdao Natl Lab Marine Sci & Technol, Lab Marine Geol, Qingdao, Shandong, Peoples R China 3.Chinese Acad Sci, Ctr Ocean Mega Sci, Qingdao 266071, Shandong, Peoples R China 4.Woods Hole Oceanog Inst, Dept Appl Ocean Phys & Engn, Woods Hole, MA 02543 USA |
| 第一作者单位 | 中国科学院海洋研究所 |
| 通讯作者单位 | 中国科学院海洋研究所 |
| 推荐引用方式 GB/T 7714 | Ma, Xiaochuan,Yan, Jun,Song, Yongdong,et al. Morphology and maintenance of steep dunes near dune asymmetry transitional areas on the shallow shelf (Beibu Gulf, northwest South China Sea)[J]. MARINE GEOLOGY,2019,412:37-52. |
| APA | Ma, Xiaochuan,Yan, Jun,Song, Yongdong,Liu, Xiansan,Zhang, Jianxing,&Traykovski, Peter A..(2019).Morphology and maintenance of steep dunes near dune asymmetry transitional areas on the shallow shelf (Beibu Gulf, northwest South China Sea).MARINE GEOLOGY,412,37-52. |
| MLA | Ma, Xiaochuan,et al."Morphology and maintenance of steep dunes near dune asymmetry transitional areas on the shallow shelf (Beibu Gulf, northwest South China Sea)".MARINE GEOLOGY 412(2019):37-52. |
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| Morphology and maint（9659KB） | 期刊论文 | 出版稿 | 限制开放 | CC BY-NC-SA | 浏览 | |
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