【作者】 刘飞；

【导师】 郑祥民；

【作者基本信息】 华东师范大学 ， 第四纪地质， 2006， 博士

【摘要】 黄土沉积是陆地上良好的古环境信息载体。长期以来，我国黄土研究者对黄河中游地区的黄土，长江中下游地区的下蜀黄土进行了较为系统和全面的深入研究。目前，下蜀黄土与黄河中游地区的黄土同为风尘沉积已经成为众多研究者的共识。在西部黄土研究中，能够反映黄土沉积时期气候变化的各项指标在下蜀黄土研究中也得到了广泛的应用。晚更新世时期，粉尘堆积几乎遍布了东海近海陆架地区，东海岛屿上存在的黄土地层与下蜀黄土一样，同为我国风尘沉积的一个体系。岛屿黄土地层分布在我国的海陆交界地带，敏感地记录了冬夏季风的变迁，将西部黄土研究中的粒度、磁化率以及地球化学指标应用于东海岛屿黄土研究并反映冬夏季风的波动具有重要意义。本文通过对下蜀黄土泰山新村剖面、东海嵊山岛、浪岗山岛屿黄土系统的粒度分析、磁性分析、地球化学分析、以及成壤作用分析，并进行对比，揭示东海岛屿黄土沉积时期的环境变迁以及沉积模式。 本项研究的主要成果和认识包括以下几方面： 1．通过粒度测试分析，下蜀黄土，东海嵊山岛黄土砂粒，粉砂，粘粒组成符合中国黄土的地带性规律。嵊山岛黄土的粘粒平均含量达到34.8％，物质组成中高空西风气流携带的细小风尘物质占有较大的比重，并且经历了比西部黄土更强的成壤作用。浪岗山黄土砂粒平均含量为13.87％，接收了较多的近源风尘物质。 2．嵊山岛黄土磁性矿物含量较少，剖面上部约60cm以不完整反铁磁性矿物为主，经历了较强的成壤作用，剖面中部(-60～-200cm)以稳定单畴磁性颗粒对磁化率贡献最大，下部(-200～-260cm)则是多畴和超顺磁颗粒共存。浪岗山黄土对磁化率贡献较大的是多畴磁性颗粒。下蜀黄土含有较多的磁性矿物，决定磁化率变化趋势的是磁性矿物的晶粒大小，稳定单畴磁性颗粒含量决定了古土壤层磁化率的波动趋势，在黄土层中，则是多畴颗粒对磁化率的贡献较大。 3．经过CBD的处理，嵊山岛黄土的磁化率值平均降低80％，浪岗山黄土平均降低了67％，下蜀黄土泰山新村剖面黄土降低范围在84％～89％之间。嵊山岛黄土中磁性矿物因淋滤作用发生转化，且黄土中近源物质含量占有一定比例，因此CBD溶解的矿物所占比例与西北黄土相差不大。对比CBD处理前后其他磁性参数可以发现，CBD处理溶解的磁性晶粒不仅仅是超顺磁晶粒，可能还溶解了相当一部分稳定单畴甚至假单畴范围内的磁性晶粒。经过CBD处理以后的磁性颗粒以多畴为主。处理以后的黄土磁化率值由我国西北地区向东南逐渐递减，符合风力模拟试验中粉尘的变异规律。本文推断CBD处理后的磁化率值代表了原始粉尘中磁性矿物的含量多少和矿物组合特征。 4．对粉尘物质风力分异简单模拟试验发现，随着距离的大幅度增加，重力分异作用逐渐明显，短距离能出现较大分异的粒级是粗粉砂。随着搬运距离的增加，更多还原

【Abstract】 Systemic and overall researches are made on the loess,which is one kind of good carrier of paleo-environmental information of land,distributed on Loess Plateau Northwest China and on the hills in west of Yangtze Delta which named Xiashu Loess. It has been an agreement that loess on Plateau is the sediment of aeolian dust and so with Xiashu Loess. All of the proxies which are used in the research of loess distributed in Northwest China to reflect the variation of paleoclimate have been widely used in the research of Xiashu Loess. Hard Clay distributed under the plain in east part of Yangtze Delta and the loess covered on the Shengshan Islands which locates in East China Sea were found that they were the same kind of aeolian sediments deposited in late Pleistocene by Prof.Zheng XM. For the reason of thin stratum and the great effects made by contemporary environment, it is an valuable research whether the proxies which are widely used in northwest to reflect paleoclimatal fluctuations could be used in the loess research successfully in this area. Paleo-environmental changes and the sedimentary mode of loess on islands are discussed in this paper and compared with the profile of Taishan New village on the proxies of grain size, magnetism,geo-chemistry and pedogenesis.Results and acknowledgements of this paper include five aspects as follows: 1.Through the analysis of experimental outcome of grain size , it’s confirmed that the three profiles have the same components carried by wind which consistent with the rule of belt distribution about Loess in China except loess on Langgangshan Islands. The clay content of Xiashu Loess and Loess on islands is higher than that in Northwest China, which indicates that primary components of Xiashu loess and loess on islands are the fine particles carried by westerlies and fine partiles formed by pedogenesis. Being the concentration of sand in Langgangshan loess is 13.81%,which is even higher than that in loess distributed in Northwest China, the loess on Langgangshan Islands including much dust nearby are confirmed.2.The content of magnetic minerals of loess on Shengshan Island is less comparatively. The top part about 60cm thickness of the profile contains more anti-ferromagnetic minerals which indicates the violent pedogenesis and weathering. Concentration of stable singe domain (SSD) magnetic minerals更多还原