【摘要】 九江第四纪红土中植物硅酸体、孢粉记录表明 :该地红土是湿热环境下的产物 ;红土形成时期发育了亚热带常绿落叶阔叶类植被 ;九江第四纪红土中植物硅酸体保存不如中国北方黄土。古土壤 A层被侵蚀及铁、铝氧化物的高含量可能是造成红土中植物硅酸体保存不佳的主要原因 ;亚热带植被中乔木类植物硅酸体抗溶解力弱 ;红土中禾本科植物硅酸体保存与风化指标、全有机碳成正相关 ;禾本科植物硅酸体总量自剖面底部 (网纹红土 )—顶部 (褐黄土层 )逐渐增多 ,可能暗示中更新世晚期以来存在较为普遍的气候恶化趋势 ,气候总体向变冷、变干方向发展 ;红土剖面 5 m及 3.0 m左右古土壤 A层的出现及剖面风化指标与元素地球化学特征表明 :该地红土经历了堆积与风化同时进行的加积型风化过程。更多还原

【Abstract】 Red earth in South China is commonly referred to as one of the most important geological records for reconstructing paleoclimatic change in the lower latitude. Here this paper presents the preliminary results of phytolith and pollen analyses of red earth profile of Jiujiang City, Jiangxi Province. This red earth section is about 18m thick (29°40′N, 116°01′E), and consists of two pedogenic units. The upper part is a layer of yellowish silty clay, while the lower part a layer of red clay with yellow and white worm shaped veins. 33 soil samples were collected from the red earth section for phytolith and pollen investigations. Phytolith and pollen analyses indicate the vegetation during the period of formation of red earth was characterized by subtropical evergreen broad leaved forest. The main reasons that the phytolith was poorly preserved may be related to high values of aluminum and iron oxides, and “A” horizons of paleosoil eroded. The investigation also shows that the preservation of phytolith in the red earth was correlated with the variations of geochemical parameters, i. e. Grain size, CIA, TOC. Phytoliths in the red earth were mainly from the grass. The subtropical tree phytoliths were less resistant to dissolution. The grass phytolith amount increased down section. The results of phytolith analysis, associated with the geochemical parameters, reveal a deterioration of climate over central China since late Pleistocene, and this is probably related to the drying process reflected by the dust flux records of the loess deposits. The occurrence of “A” horizons of paleosoil, at the depth of 5m, 3.5m in the red earth section respectively, implies that the red earth was not only the production of eluvial weathering, but was accompanied with an accelerated accumulation in dust materials as well.更多还原