干润变性土及其结核的发生学特征与形成环境探讨

干润变性土是发育于半干旱环境下的特殊土壤类型。本文以金沙江典型干旱河谷———元谋盆地发育的干润变性土及铁质结核和碳酸盐结核为例,探讨其发生学特征及其反映的土壤形成环境。土表的铁质结核和碳酸盐结核在矿物组成、微形态等特性与下伏的干润变性土有成因上联系,但两类结核与干润变性土、干润富铁土等在元素含量组成差异明显,并具有不同的形成过程和环境;微地貌陡峭、排水迅速的干润变性土地表环境残留铁质结核,而在地表平坦或低洼的干润变性土地表环境下,径流速度慢,多形成碳酸盐结核。

Pedogenic Features and Forming Environment of Ustic Vertosols and Nodules in Yuanmou Basin

Ustic vertosols,formed in semi-arid environment,are peculiar soils.The studies on pedogenetic properties and forming conditions of ustic vertosols and iron nodules as well as carbonate were conducted in Yuanmou Basin,a typical Jinshajiang Dry Valley.Iron and carbonate nodules derived from underlying vertosols were deduced by mineral composition and micromorphology.However,the disparity was distinct in contents and properties of elements between the two kinds of nodules,ustic vertosols and ustic ferrisols.The two kinds of nodules were formed through different processes.Iron nodules were often developed and remained on the surface of ustic vertosols under conditions of steep slope and swift drainage while carbonates nodules were formed under conditions of level slope and slow drainage.