【摘要】 江汉平原肖寺地区在3098aB.P.至1326aB.P.间形成了约200cm的河流及漫滩沼泽相沉积,在对该地区一个典型剖面沉积特征初步研究的基础上,以2.5cm为间距,对剖面的12.5～197.5cm段系统采集了79个样品,并进行了粒度和质量磁化率的测定与分析。结果表明:沉积物磁化率值的大小与沉积相,尤其是与沉积物的粒度存在相关性。一般规律是河流相粉砂的磁化率值大,而湖沼相粉砂质粘土及泥炭的磁化率值偏低。粒度和磁化率值的变化在一定程度上指示了古水文事件,粗砂组分含量及磁化率的高峰可能指示了特大越岸洪水事件。粒度和磁化率值变化同时也揭示了江汉平原肖寺地区冷期洪水事件频率明显高于暖期,可能与西风带的范围与强度有关。更多还原

【Abstract】 Fluvial and swamp sediments with the thickness of 200 cm have been deposited in Xiaosi area in the Jianghan Plain since 3098 a B.P.to 1326 a B.P..On the basis of the characteristics of the classical profiles described by the field work,a number of 79 samples were collected systematically from the profiles with the interval of 2.5cm from 12.5cm to 197.5cm measured by the grain sizes and the magnetic susceptibility.The data also support that the value of magnetic susceptibility from the fine-grained in the fluvial facies higher than the clay from the lacustrine facies and peat,respectively.The alteration of grain sizes and magnetic susceptibility rates can be used to indicate the paleo-flood events in some cases.The contents of the coarse sands and the high peak related to the magnetic susceptibility rates might be directed the huge flood events.From the analysis of results,it is obvious that the frequencies of flood events happened during cold period higher than warm period,it might be related to the strength and scope of the Westernlines.更多还原