武汉黄棕壤中铁锰结核的环带构造、元素富集特点与环境变化意义

土壤铁锰结核的环带记录了土壤成土过程和环境条件。文章利用扫描电镜及能谱探针分析测定了铁锰结核剖面上某些元素的含量与分布,研究表明:结核内部为不规则环带,Mn、Fe、Ca呈环带分布,大部分Ca赋存于铁锰结核的外层环带,Si、Al在剖面上呈匀态分布;结核剖面上Mn、Fe、Ca的含量呈波形曲线,根据它们的变幅,推测出该结核经历了10次以上的干湿交替过程,其中在结核生长初期经历了较弱的干湿交替环境,而在其生长后期处于相对较强的干湿交替环境;通过相关分析与因子分析,结核剖面上Ba、Ca、Co、Pb的富集与氧化锰矿物有关,而Ni、P的富集与氧化铁矿物有关

CHARACTERISTICS OF BAND STRUCTURE IN IRON-MANGANESE NODULES FROM YELLOW-BROWN SOIL IN WUHAN

Band structure in iron manganese nodule reveals cyclic changes of the environment under which the nodule was formed. Some element contents were measured using scanning electron microscopy equipped with energy dispersive X ray analyzer. Scanning from the edge to the center of the nodule showed the irregular band structure. The fluctuation of the contents of main chemical components, SiO 2, Fe 2O 3 MnO 2 and CaO was found along the section of nodule. CaO is usually located at the outmost part of each band. At least 10 cycles of fluctuation can be seen indicating seasonal water logging during the time of nodule formation. It was suggested that at the beginning of nodule growth it is in weak seasonal water logging but later on it was in strong seasonal water logging. Accumulation of Ba, Ca, Co and Pb in the nodule is associated with Mn. And that of Ni and P is associated with Fe based on the factor analysis.