The Study Of Cause And Sedimentary Environment Of Quaternary Red Earth In Fujian

Selecting three different types of the late quaternary red earth profiles in Fujian inland, this paper used granularity, magnetic susceptibility and geochemical element etc. as sedimentary environment indexes for analysis. And then the selected red earth would be compared with the aggradation red earth and the sedimentary red earth. The paper tried to explore the causes and sedimentary environment evolution of red earth. The results were as follows:(1) Grain-size characteristics showed that the consistency was poor. Affected by lithology and sedimentary dynamics, the main components of grain-size composition were different. Most of the frequency curves were multimodal. The size fraction was relatively coarse grained and the sorting features were generally poor. The grain size parameters were dispersed in projection.(2) Characteristics of magnetic parameters showed that similarities and differences coexisted. Generality showed that χIf increaseed and χfd decreasesed in red earth surface. Correlation between SIRM and Soft IRM was strong in red earth profile. The differences indicated that magnetic parameters were quite different in the same or different sedimentary types of red earth, which might be related to multiple mass sources and the near-souce transportation.(3) Geochemical characteristics showed that major elements were dominated by SiO2, Al2O3and Fe2O3. Readily leaching components lost seriously. Contents of trace elements demonstrated greater differences between each profile. Rare earth elements composition and distribution mode were different in different profiles, which had many similarities with red soils in Southern China.(4) Studies on the sedimentary environment of CL-profile in chronology framework showed that distribution and change of granularity, major element recorded in regional sedimentary environmental had changed. It reflected that climate evolved from damp-heat to dry-cool in the late Pleistocene during red earth development period in eastern Fujian.