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本研究获取了位于长江三角洲北翼吕四外古残留台地之上的SR11孔,通过对该孔上部22.2m地层粒度、磁化率、有孔虫属种和14 C年代的研究,重建了该河间台地全新世海岸环境变迁历史。结合辐射沙洲核部其他钻孔资料,本研究认为:末次盛冰期北坎和三余之间古长江支谷与干流河谷之间存在残留的谷间台地,向东向南延伸至吕四外的潮滩及近滨地带。9—5cal ka BP期间,吕四外的残留河间台地主要处于浅海环境,但部分时段频繁受到风暴活动影响。该阶段后期,海平面上升速率减缓,台地演化至潮下带下部环境。5cal ka BP以后,海平面上升到-3m以上,台地逐渐演化到潮间带下部-潮下带上部的粉(细)砂滩环境。吕四外残留台地之上的全新统地层中未发现潮流沙脊相沉积。
In this study, an SR11 hole located above the Lvsi epicontinental station in the northern wing of the Yangtze River Delta was obtained. This river was reconstructed by studying the grain size, magnetic susceptibility, foraminifera species and 14C age of the 22.2m formation in the upper part of the hole The epoch of Holocene coastal environment change history. Based on the data of other boreholes in the core of Shahu Island, this study suggests that there are residual valley stations between the northern and middle reaches of the last glaciation, and the troughs extending to the east and south to the outside of the L4 Beach and the coastal area. During the period of 9-5 ka ka BP, the residual inter-river platform outside Lu 4 is mainly in the shallow sea environment, but it is frequently affected by storms during some periods. In the latter part of this period, the rate of sea level rise slowed down and the platform evolved to the lower tide environment. After 5 ka ka BP, the sea level rose to above -3 m, and the platform gradually evolved to the fine sand beach environment in the lower part of the intertidal zone - the upper part of the subtidal zone. No sediments of tidal current are found in the Holocene strata above the Lv Si residue platform.