【摘要】 通过对长江口北支兴隆沙XL2孔25个沉积物样品的有孔虫定量分析,发现该孔自下而上有4个有孔虫组合带(含10个有孔虫组合亚带),有孔虫分异度偏低,丰度变化大,壳径偏小,含有壳径细小的浮游有孔虫,部分壳体有机械破坏现象,这些特点反映出埋葬群在形成过程中受潮流的搬运、机械分选和破坏作用。结合沉积物粒度分析和环境磁学分析,揭示了该孔沉积环境自下而上按潮流脊—潮汐水道—潮流脊—潮坪演变的模式,进而探讨了长江口北支沉积水动力和物源。更多还原

【Abstract】 The quantitative analysis of foraminifers was carried out from Core XL2 in Xinglong sand of the north branch,the Yangtze River Estuary.It is found that there are 4 foraminiferal assemblage zones(including 10 foraminiferal assemblage sub-zones).The variety of the foraminiferal bundance is big,the diversity is low,and the shell dia-meter is smaller.There are also some pelagic foraminifers with smaller shell diameter.There are certain amount of broken foraminiferal shells showing the mechanical transportation.All the above characteristics imply the function of tidal current during the burial of foraminiferal assemblages.Based on the foraminiferal assemblges,magnetic properties and lithofacies,we suggest four modes of sedimentary environment for the evolution Xinglong sand bar:tidal current ridge→tidal channel→tidal current ridge(intertidal zone)→supratidal zone(supertidal zone),forming the sedimentary sequence of the filled estuary.更多还原