中文摘要：

第四纪红土是中国南方古环境演化与气候变迁的最佳载体之一，记录了南方的古地理、古气候环境变迁信息。典型红土剖面由现代红壤层、均质层、网纹层、砾石层或基岩层组成，均质红土磁化率值多在80×10^-8～250×10^-8m^3／kg，网纹红土磁化率约低一个数量级。红土的磁化率-温度（χ—T）曲线、等温剩磁获得曲线、XRD和TEM分析认为，成土过程产生的细粒磁性矿物（包括磁铁矿、磁赤铁矿和赤铁矿）是红土磁性的主要载体。对红土的岩石磁学和矿物学综合分析认为，红土磁性矿物的含量、粒度、类型等可能指示其形成时期的某种环境变化，红土磁性是南方第四纪环境变迁研究的重要手段，但由于红土的物源以及受后期化学风化改造的复杂性，红土的环境磁学研究需要新的思路和方法。

英文摘要：

Quaternary red earth, covering an extensive area in subtropical-tropical regions of Southern China, is considered to be one of the best archives of Quaternary paleoenvironment and paleoclimate. The typical red earth profile usually consists of homogenous red earth in the upper part and reticular red earth horizons in the lower part. Magnetic susceptibility of the homogenous red earth ranges from 80×10^-8to250×10^-8m^3/kg , while that of the reticular red earth is usually less than 10×10^-8Sm^3/kg. The χfd%value（ defined as（ χlf - χhf）/χlf ×100, where χlf and χhf are susceptibility measured at 0.47kHz and 4.7kHz frequencies, respectively）of the homogenous red earth is about 10%, while that of the reticular red earth is less than 5%. It is found out that magnetic susceptibility of Quaternary red earth is positively correlated with gfd% value. Rock magnetism, X-ray diffraction （ XRD）, and transmission electron microscopy（ TEM ）were used to characterize the magnetic mineralogy of the red earth. Results show that superparamagnetic （SP）and stable single domain （SSD）maghemite/magnetite grains of pedogenic origin make dominant contributions to the enhanced magnetic susceptibility of the red earth. It is suggested that mineralogy assemblage, concentration, and grain size of the ferrimagnetic minerals in red earth are potential indicators of paleoenvironment and paleoclimate. Thus, environmental magnetism of the red earth can serve as a Useful tool to retrieve the paleoenvironmental processes and paleoclimatic changes of the Quaternary in Southern China. The magnetic properties of Quaternary red earth have been used as proxy indicators of paleoenvironmental and paleoclimatic changes. For example, variations in magnetic susceptbility values of Quaternary red earth provide a good correlation with Chinese loess/paleosol and deep-sea sequences. However, because of the absence or loss of magnetic minerals in Quaternary red earth profile, other researchers hold the opposite conclusion that magn