中文摘要：

浙江金衢盆地第四纪红土分布广泛，是开展红土与全球变化研究的理想场所之一。汤溪红土沉积剖面的粒度组成研究表明：砂（〉63μm）含量极少，平均1.58％，粉砂（4～63μm）和黏粒（〈4μm）为众数粒组，其含量的平均值分别为48．51％和49．91％，频率曲线呈双峰式，推测红土母质具风成特性，沉积后经历了较强的风化成壤作用；均质红土与网纹红土具有相似的粒度分布特征，但网纹红土的分选更为复杂，底部有近源物质的混入；汤溪红土粒度的纵向变化旋回和纵向变化趋势，可能指示了中更新世以来南方气候的不稳定性和气候逐渐变干冷的趋势。

英文摘要：

Jinhua-Quzhou basin is one of the red earth regions in Zhejiang Province, which is an ideal area to study red earth sediments and global change. Grain size distribution in Tangxi section was measured, and the results are as follows： ①It contains no gravel （〉2 mm）; low content of sand （〉63 μm）; and high content of both clay （〈4 μm） and silt fraction （4-63 μm）, which probably indicates aeolian characteristics from their parent materials and the pedogenic processes. The average contents of silt fraction, clay and sand are respectively 48. 51%, 49.91% and less than 1.58%. The grain-size frequency curves of the red earth show the double-peak mode in the section-the 10-63 μm particle group and the one less than 4 μm are its ＂two dominating modes＂. ②The sedimentary environment for typical red clay unit and that for vermiculated red clay unit are similar. However, the probability accumulation curves of red earth suggest that sorting of the vermiculated red clay unit would be more complicated. ③The vertical changes of grain size in Tangxi section probably reflect the trend of dry-cold paleoclimate and the climatic variability since mid-Pleistocene in South China.