地理学报 ›› 1983, Vol. 50 ›› Issue (2): 128-140.doi: 10.11821/xb198302003

• 论文 • 上一篇    下一篇

海洋因素对镇江以下长江河段沉积的影响

李从先, 李萍, 成鑫荣   

  1. 同济大学海洋地质研究所
  • 出版日期:1983-04-15 发布日期:1983-04-15

THE INFLUENCE OF MARINE FACTORS ON SEDIMENTARYCHARACTERISTICS OF YANGTZE RIVERCHANNEL BELOW ZHENJIANG

Li Cong-xian, Li Ping, Cheng Xin-rong   

  1. Institute of Marine Geology, Tongji University
  • Online:1983-04-15 Published:1983-04-15

摘要: 在进行三角洲沉积相分析中,常常遇到各种相指标互相矛盾和海进界线及地层界线互不吻合的现象。为了正确认识三角洲层序和三角洲地区冰后期沉积层的结构,我们选择长江镇江以下河段作为对象,进行水文和现代沉积的观测。

关键词: 潮汐河段, 镇江, 江心, 涨潮流, 长江, 盐度, 有孔虫, 沉积物, 微体化石, 海相介形虫

Abstract: The authors, after analysing the field investigation data, conclude that the influence of marine factors on sedimentary characteristics of Yangtze River channel below Zhenjiang as follows:1. The velocity of the ebb flow upstream from Taipingzhou and downstream from Jiangxinsha in Yangtze River below Zhenjiang is higher than that of the reaches between them. The velocity of the flood flow shows progressive decreasing upstream from the river mouth up to Taipingzhou. The river reaches in which flood flow developed is about 130 km long.2. The sediments in Yangtze channel below Zhenjiang become gcadually finer do-wnstream. There are gravelly sands upstream from Taipingzhou, medium and fine sands between Taipingzhou and Jiangzinsha, from then the silty sands and sandy silts distributed in spotty pattern downstreams. The distribution of sediment size disagrees with the velocity change of the flow in the river mouth area where sand becomes finer when the flow velo-city becomes faster.3. The marine microfossils go upstream as far as the flood current does up to Tai-pingzhou. The living foraminifera in south distributaries of Yangtze River mouth may reach Hengsha where the 0.2% of low water isohaline is located. The living foraminifers in north distributaries may reach 20 km up stream from the river mouth where isohaline 1-1.5% is. The living ostrocodes may appear near Jiangxinsha.The extent of flood current upstream, the boundary of the fresh and brackishwater, and the reach of the marine microfossils agree with each other or discord from one another are innate in sedimentary environment. The concept is useful in the interpretation of the contradication of the various environmental factors and the disagreement between trangre-ssive and stratigraphic boundaries in the deltaic sequence.