长江三角洲地区晚更新世硬粘土层成因研究

长不工三角洲地区全新统下伏的硬粘土层具有粘粒胶膜，裂隙，植物根茎等暴露成标志，系古土壤。古土壤层厚 度多在２．０ｍ以上；剖面具有多个粘聚层，但缺乏钙积层；半数以上研究钻孔的古土壤层中出现有孔虫；剖面的磁化率值低而平稳，磁组构参数变化范围广。

STUDIES ON ORIGIN OF THE LATE PLEISTOCENE STIFF CLAYS AT THE YANGTZE DELTA

The stiff clays beneath the Holocene strata at the Yangtze Delta are considered to be paleosols by their subaerial pedogenesis characteristics, such as cutans, cracks and microcracks, plant roots and debris, etc. The paleosol sections, which are more than 2.0 meter thick, contain several clay accumulation layers, however, the sections are lack of caliche. Foraminifera occurs in paleosols of more than half of the study cores. Magnetic susceptibilities of the paleosol sections are low and lack of distinct fluctuations, and the magnetic fabric parameters alternate within a wide scope. The above characteristics of the paleosol sections suggest that the parent materials of the paleosols are of flood plain deposits, and the paleosols are the results of successive deposition and continuing pedogenesis on flood plain.