华南红土主元素表生地球化学特征

华南红土从其母岩到表土,普遍表现为主元素SiO2、K2O、Na2O淋失,Fe2O3、Al2O3、N、S富集。红土饱和水含量最高的是D2型红土,最低的是老红沙型红土。在岩石与上层红土风化特征中,风化强度以γ型红土最强,而灰岩型红土最弱;淋溶系数最大的是灰岩型红土,最小的为γ型红土;变异系数最大的为灰岩型红土,最小的为Q2型红土。从空间上看,红土的表生地球化学特征、红土成分的变异系数、红土的淋溶系数、红土的风化率和风化强度、红土湿度和温度等均受母岩、气候纬度效应制约。相关分析表明,华南红土中的水含量和土温与Fe2O3含量呈正相关关系。初步研究表明,华南红土的表生地球化学特征是长期和多种环境变化的真实记录。

Supergenic geochemical characteristics of major elements in red soils in South China

The compositions of the red soils and their parent rocks in South China were sampled and analyzed,and the water contents and temperatures of the soils were also measured.The results show that the soils and the rocks are poor in SiO2,K2O and Na2O and rich in Fe2O3,Al2O3,N and S.The red soil of D2 has the highest water content,but the red soil of Laohongsha the lowest.The red soil of granite has the strongest strength of weathering,but the red soil of limestone the weakest.But the leaching and precipitation coefficients are in reverse order.Variation coefficient of the red soil of limestone is the biggest,but in the red soil of Q2 the smallest.From space,supergenic geochemical characteristics,variation coefficient of chemical compositions,leaching and precipitation coefficient,weathering rate and intensity,moisture and temperature of the red soils are influenced by parent rock and climate latitudinal effect.Correlation analyses suggest a positive correlation between water content,soil temperature and content of Fe2O3 in red soils.Supergenic geochemical characteristics of red soils in South China are the real record of long-time and manifold environment changes.