铁锰结核的元素组成及微形态特征

本文研究了钙质变性土中铁锰结核的矿质全量组成、微量元素丰度，微形态特征以及土壤和铁锰结核中各形态铁锰氧化物的组成特点，结果表明，铁锰结核中仍以ＳｉＯ２含量最高，但Ｆｅ２Ｏ３含量增加超过了Ａｌ２Ｏ３、ＭｎＯ含量大大超过了Ｋ２Ｏ、Ｎａ２Ｏ、ＴｉＯ２和ＭｇＯ的含量，所测定的９种微量元素中以Ｂａ含量最高，其次是Ｖ、Ｎｉ、Ｃｏ３种铁族元素，Ｃｕ和Ｐｂ含量也较高，但Ｚｎ和Ｃｒ含量较低，一般黑土层中的结核较小，

ELEMENTAL COMPOSITION AND MICROMORPHOLOGICAL CHARACTERISTICS OF IRON-MANGANESE CONCRETIONS

The chemical composition,microelement abundance,micromorphological characteristics of iron-manganese concretions and the forms of Fe oxides and Mn oxides in iron-manganese concretions and in soils were studied.The results show that the content of SiO 2 is the highest of the ten oxides .The content of Fe 2 O 3 exceeds that of Al 2 O 3, and the content of MnO exceeds that of K 2O ,Na 2 O,TiO 2 and MgO.Of the nine microelements Ba is the highest, and the average content order is as follows:Ba>V>Ni>Co>Pb>Sr>Cu>Zn>Cr.The concretions in the black horizons are relatively small and dark.Soil thin section observation indicates that there are some optically oriented linings on the surface of coarse grains and very few calcite in these concretions.However,the Fe-Mn concretions in the calcareous concretion horizons are mainly ferri-calcite and ferran-calcite nodules,and contain large amount of carbonate and calcite.The forms of Fe oxides in the iron-manganese concretions are mainly free iron oxides.The ratio of Fe d /Fe t is 78%,and the ratio of (Fe d -Fe 0 )/Fe d is 82.2%,which are higher than the ratio of free and crystal Fe oxides in the soils.The ratio of free and amorphorous Mn oxides are more than 90% and 30% respectively,which are higher than the ratio of free and amorphorous Fe oxides.Furthermore,the ratio of Mn oxides in the concretions have no evident difference in different horizons.All results indicate that manganese is more active than iron in the soils.