在中国南方第四纪红土剖面中普遍发育一种黑褐色, 形状规则或者不规则的新生体, 由于其含有较高的Fe和Mn元素而被称为铁锰结核。 铁锰结核被认为是土壤中温度、 水分、 氧化还原条件变化而形成的土壤新生体, 因此它被认为是环境信息的良好载体。 尤其是结核内部发育的环带状构造, 被认识是结核形成过程气候干湿变化的结果。 因此对结核内部微小区域的研究, 有助与理解红土母质的风化过程以及结核的形成原因。 X射线荧光光谱分析在20世纪80年代初已是一种成熟的分析方法, 是实验室、 现场分析主、 次量和痕量元素的首选方法之一。 运用帕纳科Zetium X射线荧光光谱仪的微小区域分析工具对铜陵第四纪红土中结核内部由核心至边缘的主量元素分布状况进行分析, 结果表明, XRF微小区域分析功能可以快速有效的分析样品内元素的分布状况。 结核内部元素分布情况来看, 铜陵剖面内铁锰结核内部颜色深浅变化主要是由于Mn元素含量的变化而引起的。 结核的核心Mn元素含量最高, 由核心向边缘呈现高低交替变化特征。 指示结核形成初期, 由于气候相对干旱, Mn元素由低价离子态氧化成高价化合物后发生淀积。 结核内部浅色环带Si和Al元素含量明显较深色环带高, 可能代表了相对湿润的气候时期。

There are lots of new growths in red clay presenting dark brown color and regular or irregular shapes in southern China. Because of high Fe and Mn concentrations, these nodules are called iron-manganese nodules. As a product of soil temperature, moisture and redox conditions, these iron-manganese nodules, especially the circular bands in the inner nodules, were considered as a kind of environmental information carrier, and aroused widespread interest of researchers. Therefore, the study of the tiny area inside the nodules helps to understand the weathering process of the parent material and the formation process of the nodule. In this paper, using a microbeam X-Ray fluorescence spectrometer, tiny areas of inner iron-manganese nodules collected from Quaternary red earth were analyzed. The results show that the microbeam X-Ray fluorescence spectrometer can be used to analyze tiny areas of inner nodules with higher accuracy. Microscopic images of the nodule show three dark bands and two light bands alternating from the core to the edge. The X-ray fluorescence spectrum analysis indicates that the dark bands contained more Mn and less Si and Al than light bands. Combined with previous research, the dark bands represent periods of drought, and light bands represent humid periods.