福建长乐第四纪红土微量元素揭示的气候环境变化

在野外考察采样基础上,结合OSL和ESR测年确定红土沉积年代,对福建长乐(CL)红土剖面微量元素地球化学特征及指示的古环境意义进行了初步研究。结果表明:CL剖面中微量元素的含量和分布特征呈有规律的波动变化,反映出区域风化成壤过程中不同元素的地球化学行为存在差异。较高的Mn、Nb、Rb、Cr含量或较低的Ni、As、Sr、Zn、V含量大体指示红土沉积风化作用增强,气候暖湿;反之,则可能指示生物化学风化作用减弱,气候温干或凉干。早更新世晚期以来,研究区古气候经历了温干-暖湿,暖湿,暖湿-干冷,温干-暖湿,暖湿的变化过程。研究揭示出CL剖面微量元素记录的区域气候变化过程既是对全球气候变化的响应,同时也表现出亚热带季风区红土沉积风化的特殊性。

Climate Change Indicated by Quaternary Red Earth Trace Elements at Changle in Fujian Province

Based on the field investigation and combined with the OSL and ESR dating,this paper focuses on the research of red earth profile of Changle(CL) in Fujian province.The results show that: the content of trace element at CL profile has a regular fluctuation change in their concentration and distribution.It is suggested that there are different geochemical behaviors between these element during weathering and pedogenesis.Higher content of Mn,Nb,Rb,Cr,Pb or lower Ni,As,Sr,Zn,V in CL profile means a warm and wet climate,and luxuriant vegetation.Lower content of Mn,Nb,Rb,Cr,Pb or Higher content of Ni,As,Sr,Zn,V in CL profile means a cold and dry climate.Since the early Pleistocene the climate of Changle has experienced 4~5 times climates changes in dry-wet and cold-warm fluctuations.It shows that since the late early-Pleistocene,the climate changes recorded by the content and their ratio of trace element at CL profile is the specific response to the global climatic changes,and meanwhile it displays special zonality at the subtropical monsoon region.