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五、河口有孔虫群的搬运与潮汐作用其实,在强烈水动力条件下,底栖有孔虫可以呈悬移状态搬运的事实,早已见诸文献.英国在英吉利海峡一带(Murray 1965;Murray et al.,1982),美国在加里福尼亚岸外(Lidz,1968;Loose,1970)等处,都报道了浮游样品中有底栖有孔虫出现.长江口与易北河口类似的发现,进一步说明了这种搬运作用在河口有孔虫埋葬群形成中所起的重要作用.潮汐河口的潮流可以使一定大小的有孔虫空壳泛起,甚至使固着不牢的小个体活有孔虫脱离基底、卷入潮流,然后搬运到水动力弱的地区与较细粒沉积物同时沉降堆积.相反,在河流或潮流强盛的粗粒沉积区,细小的壳体与细粒沉积物一起被冲刷而去,留下比较粗大的壳体.当然,下一次强烈的潮汛或者风暴,还可以将细粒沉积物中的壳体连同矿物颗粒一起重新掀起,发生再悬移作用,直到最终埋葬为止.上述长江口内洪水期与枯水期底质中有孔虫丰度与壳径的重大差异,肯定与这种再悬移作用造成的粒度再分配有关.但是无论如何,总是壳体与矿物颗粒一起发生分选,有孔虫壳径与沉积物粒径相应的发生变化.
In fact, under strong hydrodynamic conditions, the fact that benthic foraminifera can be transported in a suspended state has long been documented. In the English Channel (Murray 1965; Murray et al., 1982). The United States reported the presence of benthic foraminifera in planktonic samples at the shore of California (Lidz, 1968; Loose, 1970), etc. The findings of the Yangtze Estuary and the Elbe Estuary are similar , Which further illustrates the important role played by this handling in the formation of the burrowing foraminifera in estuaries.The trend of the tidal estuary can make a certain size of the foraminifera empty shell panic, The foraminifera detaches from the substrate, becomes involved in the tide, and is then transported to areas of weak hydrodynamics for sedimentation at the same time as the finer sediments. In contrast, fine housings, together with fine-grained sediments, Washed away, leaving a relatively thick shell, of course, the next strong tide or storm, you can also fine-grained sediment shell together with the mineral particles set off again, the occurrence of resuspension until the final burial So far in the Yangtze River Estuary flood Significant differences in abundance and shell diameter of foraminifera in the sediments between dry and dry periods are certainly associated with particle size redistribution resulting from this resuspension, but in any event, shell and mineral particles are always sorted together, with The pore diameter of borer and sediment changed accordingly.