摘要
上海地区全新世沉积物之下,埋藏着一层暗绿色、黄褐色硬质粘土层,它一直被认为是全新统的基底而被作为划分全新统与更新统的重要标志层。本文认为该硬土层为晚玉木冰期晚期沉积的风尘物质经次生变化而形成;是长江三角洲西部下蜀黄土在东部平原的延续。
Many studies have shown that the Holocene basement stratum in Shanghai region consists of hard clay with upper dark-green and lower yellowish-brown layer. Extensive field investigation and integrated laboratory analysis on dark-green and yellowish-brown hard day have been carried out in our work. It is suggested that the aeolian loess, deposited under the dry-cold climatic condition during the late Wurm Glacial Period, is likely the origin of the hard clay Stratum as Holocene basement. This paper proposes that Shanghai region and even the continental shelf of the East China Sea probably widely received loess deposit and, therefore, the eastern limit of loess deposit in China during the late period of late Pleistocene is not only in Nanjing-Zhenjian but goes further to the east. Aeolian loess was transformed into yellowish-brown hard clay through a long period of weathering,leaching and diagenesis. The upper layer was changed into dark-green under the reducing environment as a results of Holocene transgression
关键词
暗绿色硬土层
风积
黄土
上海
dark-green hard clay, yellowish-brown hard clay, aeolian loess.
