江苏中部海岸全新世中期温暖期风暴潮频率的研究

通过对采集于江苏省盐城市上冈镇的三个柱状沉积剖面(W,M,E)的岩性特征及其对比关系的分析、沉积物14C年代的测定以及沉积物样品的粒度、磁化率特征的分析,结合有孔虫和颗石藻的分析结果,判定研究沉积层段为全新世中期的潮滩沉积.孢粉分析结果显示当时的气候较现在温暖.以潮汐层理的周期性特征为依据,对以泥为主的潮滩沉积剖面中每隔10~20cm有规律出现的一层砂作了分析,结果表明这一沉积特征为季节性的潮滩沉积旋回.在此基础上,观察沉积剖面中的风暴潮事件的记录状况,估算出剖面中记录的与9711号台风风暴潮强度相当的风暴潮的发生频率为二至四年一遇,而依据盐城市东台梁垛河闸多年的现代最高潮位资料,应用耿贝尔(Gum-bel)曲线拟合法计算出的9711号台风所引起的风暴潮频率为十二年一遇,即全新世中期温暖期的台风风暴潮的频率比现在大.据此推测全球变暖后台风风暴潮的频率将会增加.

Researches on coastal storm surge frequency during the warm period of Middle Holocene in central Jiangsu Province in China

Three column sections have been collected from Shanggang, Yancheng City,Jiangsu Province to analyse the storm surge frequency during the warm stage in Middle Holocene. The results of lithology, dating age by ^14C, foraminifera assemblages, calcareous nannofossils and palynological features indicate that the deposits were tidal flat deposits formed in the warm period of Middle Holocene and it was warmer at that time than today. According to the periodicity of tide deposits, the sand layers being characterized by every 15 cm or so in the silt sections are analyzed, and the result shows it is seasonal tide deposits periodicity. On the basis of these researches, the characteristics of storms recorded in the sections are observed and it shows that the relatively stronger storm surge frequency is once every 2-4 a, yet the estimated result on the data of the highest water level value of every year in the Liangduo gate of Yancheng by the way of Gumbel curve fit indicates that the modern storm surge with equivalent intensity occurs once every 12 a. So the storm surge frequency in the warm period in Middle Holocene is higher than that of today and it can been speculated on that the frequencv will increase with global warming.