【摘要】 庵东浅滩位于潮差和流速急剧变化的杭州湾南岸,不同断面潮坪沉积物粒度特征明显不同,但粒度参数的垂向变化却是有规律的,并可相互对比.依据粒度参数可进行潮坪沉积亚相的划分,其中砂和粘土的体积分数是主要依据,分选系数是重要依据,偏态和峰态变化比较复杂,只具参考价值.由沉积物粒度特征确定的高、中、低潮坪界线与仅依潮位划分的界线相似,仅位置有所区别,但前者能更好地反映沉积与动力之间的关系,而且更便于古代潮坪沉积的对比研究.采用粒径趋势分析方法推断钻孔岩芯中沉积物的净搬运方向,其结果与已知潮流向基本一致,说明趋势分析方法在钻孔沉积物输运方向的研究中也有一定的适用性,可用于古流向研究.更多还原

【Abstract】 Andong tidal flats fringe the southern bank of the Hangzhou Bay with sharp longshore changes in tidal ranges and currents.Grain-size characteristics change from one section to the other alongshore,but with a similar vertical trend that is used to discriminate subfacies boundaries of tidal-flat deposits.Variations in sand and clay fractions are key evidence to discriminate intertidal facies boundaries,and another important proof comes from sorting coefficient.Changes in skewness and kurtosis are complex and have their limited value in subfacies division.The boundaries among upper,middle,and lower tidal-flat successions defined by grain-size parameters,are similar to those defined by tidal levels with a small vertical shift.However,the newly developed method is useful for ancient intertidal subfacies analyses when tidal data are inaccessible.The method of “grain-size trend” was employed to extract information in net sediment-transportation directions from drilling cores.The inferred sediment-transportation directions correspond to current fields dominated either by floods or ebbs,indicating that grain-size trend is a useful method in the paleocurrent study of buried or lithified sediments.更多还原