Ages and Grain-size Characteristics of Reticulate Red Clay on First Terrace in Dongjiang Rivers, Southern Nanling Mountains

• 1、School of Geography,South China Normal University
• 2、School of Geography,South China Normal University
• 3、Guangzhou Institute of Geochemistry Chinese Academy of Sciences

Abstract：A series of weak reticulate red clay and strong reticulate red clay with total thichness of 4.35 m were observed at Linjiang profile of first terrace, Dongjiang Rivers, southern Nanling Mountains.The top age of weak reticulate red clay is 71.40±6.60 TL ka B.P, and the age near the bottom of the reticulate red clay is 99.10±5.90 OSL ka B.P..The results of grain-size analyses show that both reticulate red clay are mainly composed of silty clay, but weak reticulate red clay is more coarser than strong reticulate red clay, the former contains more sand(>50um) contents and displays markedly bimode grain-size distribution; the latter consists of more silt and clay and displays approximately single peak in grain-size distribution.The weathering degree reflected by clay or colloid clay of strong and weak reticulate red clay corresponds to the peak values of SPECMAP and Sulu sea oxygen isotope curves, which is indicative of the fairly warm and humid periods from the last interglaciation to the early of last glacial. All these evidences make clear that the reticulate red clay in Linjiang is likely to be formed during the early late Pleistocene, i.e.,from the last interglacial to the early last glacial.

Keywords： Dongjiang Rivers Linjiang Profile First Terrace Reticulate Red Clay Grain-size Characterstics