长江三角洲南翼晚更新世古土壤及其成土环境

Late Pleistocene Paleosols and Soil-forming Environment at the Southern Flank of the Yangtze Delta

长江三角洲南翼全新统下伏的硬粘土层具有粘粘胶膜、土壤结构体、裂隙和微裂隙、植物根系和植物碎石等古土壤特征，系古土壤．软锰矿的分布指示地下水位在地面以下３ｍ左右，这由于冰期低海面本区相对海拔较大所致．裂隙的广泛发育及充填与地下水位的技大波动表明当时干区季节分明，古季风的影响较现在强．古土壤层厚度较大，而且西厚东薄，这与海侵海退造成的成土时间不同有关．

The first stiff clays at the southern flank of the Yangtze Delta are considered to be paleosols by their cutsns, pods, clay-filled cracks, nodules, motifes, roots, plant debris, and their absence of sedimentary structures, etc. It is inferred from the concentration of MnO2.nH2O that the depth of groundwater was abode three met6rs, which is due to the higher elevation of this area during the period of glacial low stand of sea level. The well-developed and clay-filled cracks,along with the fluctuations of groundwater, indicate that the dry and wet seasons were distinctive and the effects of monsoon were stronger than nowadays.Paleosols are thicker than modern BOils, and are thinner in the east than in the west of this area, which relates to the different time spans of pedogenesis caused by transgression and regression.