Research on the Quaternary Laterite and Paleoclimate in the Dongting Basin
LAI Hong-zhou MO Duo-wen LI Xin-po (College of Environmental Sciences, Peking University, Beijing 100871)
There are many Quaternary laterites around the Dongting Basin. The survey on some typical laterite profiles on the field was carried, and sampling in the Yueshan laterite profile, Yueyang City. Some experiments on the soil samples, such as magnetic susceptibilities, clay minerals and size analysises had been done, and the characteristics of the Quaternary laterite profiles in the Dongting Basin were studied, then the Quaternary paleoclimate evolution in the Dongting Basin was discnssed. The Yueshan laterite profile has the distinct stratigraphical facies and the evident profile characteristics, and it has a good stratigraphical correlation with other laterites in the South China. The analyses of magnetic susceptibilities and clay minerals of the Yueshan laterite profile indicate the rules of the Quaternary climate change in the Dongting Basin as follows: the climate of the Dongting Basin in the early stage of the Middle Pleistocene is dry and cold, and the climate of the Dongting Basin in the late stage of the Middle Pleistocene is humid and hot. The climate in the early stage of the late Pleistocene still keep humid and hot, but the climate begin to turn dry and cold in the late stage of the late Pleistocene. The climate of the Dongting Basin turn humid and hot in the Holocene once more. The size analysis indicates that the sedimentary environment of the Yueshan laterite is flood plain in the basin.