...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Global and planetary change >Modern sedimentation and morphology of the subaqueous Mekong Delta, Southern Vietnam
【24h】

Modern sedimentation and morphology of the subaqueous Mekong Delta, Southern Vietnam

机译：越南南部湄公河三角洲现代沉积和形态

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The Mekong River Delta is among the Asian mega-deltas and is influenced by various factors including tides (meso-tidal system), waves, coastal currents, monsoon-driven river discharge and human impact (agriculture, fishing, sand dredging, tourism). The present study aims to document the seafloor relief, sediment distribution and sediment accumulation rates to interpret modern sediment transport directions and main sedimentation processes in the subaqueous Mekong Delta. The major results of this investigation include the detection of two delta fronts 200 km apart, one at the mouth of the Bassac River (the biggest branch of the Mekong Delta) and the other around Cape Ca Mau (most south-western end of the Mekong Delta). Additionally, a large channel system runs in the subaqueous delta platform parallel to the shore and between the two fronts. The sediment accumulation rates vary greatly according to the location in the subaqueous delta and have reached up to 10 cm/yr for the last century. A cluster analysis of surface sediment samples revealed two different sediment types within the delta including a well-sorted sandy sediment and a poorly sorted, silty sediment. In addition, a third end member with medium to coarse sand characterised the distant parts of the delta at the transition to the open shelf. The increase of organic matter and carbonate content to the bottom set area and other sedimentary features such as shell fragments, foraminiferas and concretions of palaeo-soils that do not occur in delta sediments, supported grain size-based classification. Beginning in front of the Bassac River mouth, sedimentary pattern indicates clockwise sediment transport alongshore in the western direction to a broad topset area and the delta front around Cape Ca Mau. Our results clearly show the large lateral variability of the subaqueous Mekong Delta that is further complicated by strong monsoon-driven seasonality. River, tidal and wave forcing vary at local and seasonal scales with sedimentary response to localised short-term depositional patterns that are often not preserved in long-term geological records.
机译：湄公河三角洲属于亚洲大三角洲，受潮汐（中潮系统），海浪，沿海水流，季风驱动的河流排放和人类影响（农业，渔业，挖沙，疏tourism，旅游业）等多种因素的影响。本研究旨在记录海底浮雕，沉积物分布和沉积物积累速率，以解释湄公河三角洲水下现代沉积物的输送方向和主要沉积过程。这项调查的主要结果包括探测到两个相距200 km的三角洲前沿，一个位于Bassac河口（湄公河三角洲的最大分支），另一个位于Cap Mau角附近（湄公河最西南端）。三角洲）。另外，大型水道系统在水下三角洲平台中与海岸平行且在两个前沿之间运行。沉积物的沉积速率根据水下三角洲的位置而有很大不同，在上个世纪达到了每年10厘米。对地表沉积物样本进行的聚类分析显示了三角洲内两种不同的沉积物类型，包括分类良好的沙质沉积物和分类较差的粉质沉积物。另外，具有中度至中度粗砂的第三端部件在过渡到开放式架子的过程中描绘了三角洲的遥远部分。三角洲沉积物中未出现的底物区域有机质和碳酸盐含量的增加以及其他沉积特征，例如贝壳碎片，有孔虫和古土壤的固结物，并未出现在三角洲沉积物中。从巴萨克河河口的前方开始，沉积模式表明顺时针的泥沙沿西方向沿海岸向宽阔的顶部地区以及卡茂角附近的三角洲前缘输送。我们的结果清楚地表明，湄公河三角洲水底的较大的横向变化性，再加上强烈的季风驱动的季节性因素进一步加剧了。河流，潮汐和波浪的强迫在局部和季节性尺度上会有所不同，对局部短期沉积模式的沉积响应通常不会保存在长期地质记录中。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号