中文摘要：

为研究百色盆地红土剖面中粘土矿物的特征并恢复盆地中更新世以来的古气候演化序列，利用X射线衍射分析对百色盆地大旺红土剖面中粘土矿物进行了深入、系统的研究。结果表明，沉积物的粘土矿物组成主要为伊利石、高岭石及蛭石（或羟基铝蛭石），但在约0．26Ma处其相对含量出现明显变化，表明百色盆地中更新世中期至晚更新世早期表生风化作用逐渐加强，其气候条件经历了从“相对干凉→暖湿”的演化。这一结果与河湖相沉积物磁化率所记录的MIS7．5（0．26Ma）“冰期→间冰期”转折时期相一致。沉积物中伊利石结晶度结果显示，其（001）衍射峰半高宽值从早期的相对平稳转变为晚期的波动性变化，说明百色地区气候经历了相对冷干到相对暖湿的转型，与粘土矿物相对含量变化、河湖相沉积物磁化率变化、邻区钙华沉积及南海各古气候指标所揭示的记录相一致。

英文摘要：

Baise basin is a strike-slip basin formed in Early Paleogene, Southern China. Due to the uplift during the Quaternary time, multi-stage terraces developed along the Youjiang River, and accretionary red earth sediments occurred commonly in the basin, especially along the river terraces. As the typical sediments in Southern China, the red earth sediments are comparable to the loess-paleosol sequences in Northern China. Clay minerals are the most important components of red earth sediments, which are widely used as indicator of climate changes. With attention on global change research over the world, in recent years clay mineralogy of Quaternary sediments has become more and more attractive in reconstructing paleoclimate and paleoenvironmental evolution in terrestrial environment, and their effectiveness has been recognized by large numbers of researchers. To reconstruct the paleoclimate changes of the Baise basin, Southern China, clay mineralogy of the Dawang red earth sediments was investigated using ESR dating and X-ray diffraction （XRD） methods. The Dawang red earth section （23°51＇47°36＂N, 106°39＇25°91＂E） is located in Dawang Village of Youjiang District, Baise city, Guangxi Zhuang Autonomous Region. The profile can be divided into five layers from top to bottom, according to color, grain size, and the degree of tuberculosis of the sediments. Samples for analysis of clay mineralogy were collected at 10cm interval along the section, with a total number of 97 samples. The samples for ESR dating were collected at 1.5m, 5.5m, and 9.7m depth of the profile, and were determined to have the age of 108±13ka, 396±39ka, and 459±45ka, respectively, in agreement with the occurrence of the third river terraces of the Youjiang River. XRD analysis shows that clay mineral compositions of the sediments are dominated by illite, kaolinite, and vermiculite （or hydroxy-interlayered-vermiculite） , while a sharp change in relative contents of clay minerals occurs at ca. 0.26Ma, suggesting increasing weatheri