【摘要】 本文主要讨论了长江口外现代水下地形地貌与沉积结构、构造特征。 地貌形态为一向东南扩展的现代水下三角洲舌状体。其北部在苏北沿岸流及波潮流的作用下正受改造而破坏。 在长江口外60m深处,发现低海面长江入海古河口。从而推论冰后期海侵在该处有过停顿。 调查区由西向东,沉积物可分成四个带。Ⅰ,粉砂—细砂带;Ⅱ,粉砂质泥带;Ⅲ,砂—粉砂—泥带;Ⅳ,残留砂带。更多还原

【Abstract】 This paper deals mainly with the characteristics of subaqueous topography and sediments off modern Changjiang estuary.It is shown, from the recent investigations during 1980-1984, that delta lobe proper is progradating progressively in southeast direction. The area within 10m bathy-metric contour is distinguished itself by its diversity in subaqueous topography, such as distributaries, distributary mouth bars, tidal creeks, etc. The northern part of the delta, however, is undergoing erosion and retreating owing to the reworking of the southeast moving longshore current and in-and-out tidal currents.In addition, a past river mouth of Changjiang River around 60m contour, which was formed at a lower sea level and represents a peroid of stjllstand during post-glacia,tion transgression, has been identified.The studied area can be divided, from west to east, into four sedimentary facies-zones, i. e., (1) silt sand zane,. (2) silty clay zone, (3) sand-silt-mud zone and (4) relic-sand zone.更多还原