福建东南部第四纪红土沉积粒度特征及成因分析

Granularity characteristics and genetic analysis of Quaternary red earth in the southeast of Fujian

在野外考察采样和实验分析基础上,对福建东南部若干红土剖面粒度特征及其沉积环境进行了初步研究.结果表明:1)福建东南部红土粒度组成以粉砂为主,含量65.09%～70.07%,砂含量11.90%～28.40%,粘粒6.51%～18.03%.2)粒度频率曲线以多峰为主并有明显变化,各剖面第一众数在4～71μm之间,第二众数在118～746μm之间,第三众数<1μm;概率累积曲线以四段式为主.3)粒度参数总体平均粒径较粗、分选差、峰度平缓,由晚更新世早期到晚期各个粒度参数的变化趋于复杂.这些特征表明研究区红土近源水动力搬运和快速混杂堆积的特点,其后经历较强化学风化作用,晚更新世全球气候恶化对研究区红土搬运沉积过程和风化过程产生明显影响.

Based on the field investigation and experimental analysis, this paper focuses on the research of several red earth profiles in southeast part of Fujian. The results show that：l）Granularity composition of red earth is dominated by silt（2-63 μm）and its content is 65.09%-70. 07%, while sand（〉63 μm）accounts for 11.90 %-28.40% and clay（〈2 μm）is 6.51% -18.03%. 2）Frequency curves of red earth granularity are mainly multi-peak and have significant changes. The first mode of each profile is from 4 to 71 μm; The second mode of samples of profiles lies between 118 and 746 μm; The third mode is less than 1μm; The probability accumulate curves of the red earth are mainly four-segment pattern. 3）Granularity parameters reflect relatively coarse in grain size, poor in sorting and gently in peakedness; Change in each granularity parameters complicate from the earlyer late pleistocene to the later period. It shows that red earth sediment are produced by near provenance, hydrodynamic deposit and rapid accumulation, and then came through strong chemical weathering process;Deterioration of global climate produce a significant impact on deposition of red earth handling and weathering process during late pleistocene in the study area.