石油与天然气地质 ›› 1995, Vol. 16 ›› Issue (4): 313-318.doi: 10.11743/ogg19950403

• 论文 • 上一篇    下一篇

长江三角洲晚更新世暗绿色硬粘土的早期成岩作用

李萍, 陈刚   

  1. 同济大学海洋地质与地球物理系, 上海, 200092
  • 收稿日期:1994-03-22 修回日期:1994-09-12 出版日期:1995-12-25 发布日期:2012-01-16
  • 基金项目:

    国家教委基金

EARLY DIAGENESIS OF LATE PLEISTOCENE DARK-GREEN STIFF CLAY IN THE YANGZI RIVER DELTA

Li Ping, Chen Gang   

  1. Department of Marine Geology and Geophysics, Tongji University, Shanghai
  • Received:1994-03-22 Revised:1994-09-12 Online:1995-12-25 Published:2012-01-16

PDF (PC)

545

被引次数

3

摘要：

长江三角洲晚更新世暗绿色硬粘土层是一个埋藏的古土壤层。它具有土壤的基本性质:(1)具植物根孔、植物碎屑及网状黑色腐殖质;(2)具粘土化作用;(3)存在淋溶、淀积作用;(4)缺乏层理。但与一般土壤却又有明显的区别;(1)上部致密、坚硬,超固结比2.1～2.2,下部则固结程度较差,与一般土壤剖面正好相反;(2)呈绿色和黄绿色;(3)普遍合形态各异的结核,其成分由上至下为黄铁矿→菱铁矿、菱锰矿→褐铁矿、软锰矿,反映由还原-氧化环境的过渡。原因在于早期成岩作用的改造使其特征发生了变化。富氧的海水在细菌的作用下,使古土壤中的有机质被分解,从而使其具备了早期成岩作用的条件。伴随着游离氧的消耗以及氧化离子的还原作用,形成硫化氢、低价铁、低价锰等,使古土壤的颜色、硬度、结核和粘土矿物发生了明显的变化,从而改变了古土壤的整体面貌。

关键词: 长江三角洲, 晚更新世, 绿色硬粘土, 古土壤, 成岩作用

Abstract:

Dark-green stiff clay of Late Pleistocene in the Yangzi River Delta is a buried Paleosol Bed.It possesses the basic property of soil:1.contains root holes,fragments and dark network humus of plants;2.underwent clayization;3.eluviaton and illuviation could be found;4.lacking of lamination.The distinct defferences between the paleosol and ordinary soil are:1.The upper part of the paleosol is light,stiff,and the ratio of hyperconsolidation is 2.1～2.2,but the lower part is less consolidated.This is contrary to ordinary soil; 2.The paleosol is green and yellow-green;3.The paleosol contains various types of nodules.They are mainly pyrite→siderite→dialogite→limonite and pyrolusite from top to bottom,reflecting a transition process of reducing-oxidizing environment.Oxygen-rich sea-water resolved the organic matter in the paleosol through the action of bacteria.With the consumption ot free oxygen and the reduction of oxidized ions,HS-,Fe+2,Mn+2 thus formed.This resultes in distinct changes of the colour,the hardness,the nodules and the clay minerals of the paleosol,thus changing the whole of the soil's property.