基于磁组构特征的江汉平原全新世古洪水事件

Magnetic Fabric of Holocene Palaeo-Floods Events in Jianghan Plain

在对江汉平原江陵剖面全新世沉积物的沉积环境和年代学分析的基础上,利用由现代洪水沉积所建立的洪泛沉积物磁组构参数标志,对江汉平原全新世以来的古洪水事件进行了初步研究.结果表明:(1)江汉平原全新世以来(有史料记载前),共有55个特大洪水沉积层(事件).(2)全新世以来特大洪水(期)演化可分为两个大的阶段:第一阶段(9875～3000aBP)低频期,该阶段洪水发生频率不高,且洪水周期比较稳定,主要以近千年和500～625a周期为主;第二阶段(3000aBP～现在)为洪水频发期.洪水发生的周期以300～200a为主,反映出洪水发生的频率具有加快的趋势.

Based on the study of sedimentary environment and chronology for Holocene sediments from Jiangling profile, Jianghan plain, this paper studies these events on palaeo-flood which took place in Jianghan plain since Holocene, using some marks of magnetic fabric parameters of flood sediment. The main results are as follows： （1） There are 55 large events of flood sediment since Holocene in Jianghan plain （excluding record data in history）. （2） According to evolution, these events are divided into the stage of low frequency （9 875--3 000 a BP）, which is more stable and has an approximate period of mainly one thousand year and 500--625 a, and the stage of high frequency （3 000 aBP-now）, which is more frequent than the former, showing an increasing tendency and has a period of frequent occurrence of mainly 300--200 a.