A Preliminary Study On Characteristics Of The Quaternary Vermicular Red Clay And Its Paleoclimate Significance From WJ Section In Lushan Area

The Quaternary Red Clay in southern China is the product developed in the geological history, which be viewed as an important carrier of past environment for studying paleoclimatic changes in southern China. The typical accumulation Quaternary profile of continental deposit in t he southern China, especially in the Yangtze river basin,generally includes four layers: loess, homogeneous red clay, vermicular red clay and gritty red clay.The previous studies of paleoclimatic of the Quaternary Red Clay mainly regard the vermicular red clay as a whole in macro view. However, white mottles clay, red matrix clay and iron-manganese oxides are now understand to be so interconnected and embedded in each other that they have special structure base on the field observation. The article focus on the research of WJ profile in JiuJiang city, JiangXi Province. Now we has isolated the white mottles clay and red matrix clay of the same horizon, base on the research of grain size, element geochemistry, susceptibility, micro-morphological characters, chromaticity, try to detect the past regional climate and environmental signs from the micro angle. The main conclusion in this paper are as follows:WJ profile in JiuJiang city had undergone more strong chemical weathering than LuoChuan profile in northern china and YanziJi profile in Nanjing city, which indication that the climate of southern china maybe more dry and cold than northern china. The climate and environment index of white mottles clay and red matrix clay show the research area’s change and reflect the process of warm and humid to dry and cold, and also show the paleoclimate cycle.There are marked distinctions between the chromaticity characteristics of white mottles clay and red matrix clay. The L*,a*,h* have correlation with climate and environment index,it mean that the chromaticity can be an new climate and environment index in the research of The Quaternary Red Clay.Base on the research of micro-morphological characters about the white mottles clay and red matrix clay, we can found that the white mottles clay and red matrix clay to to be so interconnected and embedded in each other, there are some special cracks and iron-manganese oxides in both of them. The special cracks have an important role in the formation of white mottles clay and red matrix clay, just like the passage of element migration, they maybe exist before the white mottles clay.The migration and enrichment of iron play an important role in the formation of vermicular red clay.The mass percentages of iron in the transition region of white mottles clay and red matrix clay increased in the order: red matrix clay, transition region, white mottles clay. The migration degree of iron in white mottles clay and the enrichment degree in red matrix clay have nearly equal degree. The mass percentage of iron in the iron-manganese concretions decreased from outside to inside. The iron element not only has an important on soil color and susceptibility, but also plays the decisive role in the formation and distribution of iron-manganese concretions.But further research is needed to the relationship between the iron and the paleoclimate environment.