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通过分析时间序列的卫片资料、4m高的露头剖面的沉积学和元素地球化学特征,研究钱塘江涌潮河段的滩槽冲淤变化规律、涌潮沉积特征和沉积层序.涌潮河段河道宽浅,受径流与潮流相互作用强烈,冲淤频繁且剧烈,滩槽演替存在约20a的周期,与流域年代际洪、枯期转变有关.在滩槽叠置的垂向层序中,底部为河槽、低潮滩相的厚层块状砂质沉积,发育各种变形沉积构造,为典型的涌潮沉积;顶部为高潮滩相的潮汐韵律沉积,发育典型的潮汐成因的双黏土层、大小潮周期;二者之间的中潮滩相呈渐变过渡.C-M图和概率累计曲线可较好地区分涌潮沉积与潮成砂、泥质沉积.涌潮沉积层Si/Al、Zr/Al、Ti/Al等元素比值较高,而潮汐韵律层Fe/Al、Mn/Al等元素比值较高,这与它们的赋存方式和水动力分异有关.Si、Zr和Ti主要见于石英和重矿物中,因此在强水动力沉积层中富集;而Fe、Mn易被黏土矿物吸附,在水动力较弱的中高潮滩富集.
By analyzing the time series of patch data, sedimentology and elemental geochemical characteristics of 4m outcrop profile, the ebb and flow variation of tidal channel, tidal sedimentary characteristics and sedimentary sequence in the tidal reach of Qiantang River are studied. Shallow and shallow, and strongly influenced by runoff and tidal current, with frequent and drastic erosion and erosion, there are about 20 years of beach trough succession, which is related to the interdecadal flood and dry period transition of the basin.In the vertical sequence of trough overlap, At the bottom, massive thick sandy sediments in the fluvial and low tidal flat facies develop various deformation sedimentary structures, which are typical tidal sediments. At the top are tidal prosodic deposits of high tidal flat facies, Tidal cycle between the tidal flat and the transitional tidal flat between the two.The CM curve and the probability cumulative curve can be used to distinguish the tidal sediments and the tidal sand and muddy sediment.The tidal sedimentary layers Si / Al, Zr / Al , Ti / Al and so on, while the ratios of Fe / Al, Mn / Al and so on are higher in the tidal rhythm layer, which is related to their mode of occurrence and hydrodynamic differentiation.Si, Zr and Ti are mainly found in quartz and In heavy minerals, it is enriched in strong hydrodynamic sediments; Fe and Mn are susceptible Mineral soil adsorption, water power weak in the high intertidal enrichment.