武汉黄棕壤铁锰氧化物胶膜的矿物学特征研究

Mineralogical characteristics of iron-manganese cutans in yellow brown earth of Wuhan

铁锰氧化物矿物胶膜是我国黄棕壤中重要的铁锰元素富集载体,选取我国华中地区典型的铁锰氧化物矿物胶膜样品,采用电感耦合等离子体原子发射光谱(ICP-AES)、偏光显微镜(POM)、环境扫描电子显微镜(ESEM)、能谱仪(EDX)、高分辨透射电子显微镜(HRTEM)、高能量X射线粉末衍射(XRD)等研究方法,对原位和分离处理后的黄棕壤铁锰胶膜进行了详细的矿物学表征.结果表明,黄棕壤铁锰氧化物矿物胶膜由表及里,由外到内依次呈现富锰条带、富铁锰条带、富铁条带、富锰铁条带、富铁条带,并且锰铁元素含量之比不规则降低,其所含铁锰氧化物矿物主要为锰钡矿、针铁矿、水钠锰矿、六方水锰矿、水羟锰矿,粒度为纳米级,形貌多样.

Iron-manganese cutans are important carriers for Fe and Mn in yellow brown earth. They have been playing important roles in recording history of the environment and affecting the environment. This paper focuses on the mineral characteristics of typical iron-manganese cutans in yellow brown earth. Various mineralogical methods, such as ICPAES, POM, ESEM, EDX, HRTEM, XRD, were applied to investigate iron-manganese oxides in cutan samples collected in Wuhan. The results show that iron-manganese cutans in yellow brown earth contain layering patterns, characterized successively by a high Mn layer, a high Mn Fe layer, a high Fe layer, a high Fe Mn layer and a high Fe layer, and Mn / Fe mass ratio decreases irregularly from the surface to the bottom. Iron-manganese cutans are mainly composed of nanoscaled Mn-（ hydr） oxides and Fe-（ oxy） hydroxide minerals composed of hollandite, birnessite, goethite, feitknechtite and vernadite, exhibiting diverse morphological features.