苏北-南黄海西部第四纪长江埋藏古河道分布研究进展

Research progress on distribution of Quaternary buried paleo-Yangtze River channels in the North Jiangsu-western South Yellow Sea

  • 摘要: 长江作为连接青藏高原与西太平洋边缘海的最重要水系之一,其形成演化研究备受学者关注。详细梳理了近几十年来苏北-南黄海西部埋藏古河道的相关研究成果,对本区第四纪以来长江古河道的埋藏分布状况进行了综述。研究显示,本区长江埋藏古河道特别发育,并在第四纪期间经历了多次迁移、往返摆动。由于本区面积广大且古地貌条件复杂、研究分析所采用的钻孔空间分辨率偏低、高质量的岩芯缺乏和采样密度不够以及测年方法局限等因素限制,目前对长江古河道迁移路线的认识仍存在较多争议:一种观点认为受新构造运动的影响,第四纪以来长江古河道大致在扬州-泰州-姜堰-海安-弶港一线以南摆动,但对于其具体入海位置仍存在较多争议;另一种观点认为受长江三角洲地区差异性构造沉降与地形障碍影响,长江古河道自苏北平原、经北翼地区而逐渐南迁。此外,在毗邻的南黄海西部陆架区也发现了一系列形成于晚更新世末期近东西向的长江古河道。作为长江古河道变迁的一个关键研究区,今后需在提高钻孔研究分辨率、建立第四纪高精度可靠年代标尺、加强长时间尺度物源及海陆记录对比研究等方面进一步开展深入研究。查明长江古河道的埋藏分布规律,将有助于深入认识第四纪长江沉积物源-汇系统的形成演化过程和机制,丰富该区古地貌与沉积环境演化信息,对于资源环境的合理开发利用和工程建设选址亦可提供重要的基础科学依据。

     

    Abstract: Based on published literatures, a thorough review is made on the distribution of Quaternary buried paleo-Yangtze River channels in the region of North Jiangsu and western South Yellow Sea (NJ-WSYS). The review suggests that Quaternary paleo-river channels are particularly developed in the region left behind by the paleo-Yangtze River. Owing to its wide distribution and complex paleogeomorphology, in addition to lack of high-quality sediment cores, low sampling density and limited dating data, there still remains many disputes on the migration pattern of the Yangtze River paleochannels. One view believes that subject to the neotectonic movement, the Quaternary Yangtze River channel flowed into the sea following the variable paths to the south of a line that through Yangzhou, Taizhou, Jiangyan, Haian and Jianggang, however, there are many controversies on the exact location of the estuary for a specific river course. Another view, however, suggests that due to the effect of differential tectonic subsidence and topographic barrier, the paleo-Yangtze River, shifting from the North Jiangsu Plain, flowed towards south and through the northern flank of Yangtze River delta. In addition, a series of nearly EW-trending Yangtze River paleochannels have also been found on the adjacent continental shelf of the western South Yellow Sea, which were formed at the end of Late Pleistocene. As a key research area for the paleo-Yangtze River channel migration, therefore, it is still needed to increase the research resolution of sediment cores, to improve the dating accuracy and resolution of the ages to establish reliable chronostratigraphic frameworks, and to reinforce the analysis of sediment provenance in long time scale and correlation of land-sea sedimentary record in the NJ-WSYS. To ascertain the distribution of buried Yangtze River paleochannels in this area will contribute to the further understanding of the evolution processes and mechanisms of the Quaternary Yangtze River sediment source-to-sink system, enrich the knowledge on the evolution of paleogeomorphology and sedimentary environments, and provide the scientific basis for rational exploitation and utilization of resources and engineering constructions.

     

/

返回文章
返回