辽宁棕黄土母质的特征及其成因初探

辽东和辽北的黄土状沉积物称为棕黄土,以区别于典型黄土,分布于高出现代河床20～30米的岗台地上。根据产状、颗粒组成和矿物成分。它们可能是风成的。昌图县的棕黄土可能来自内蒙沙地,大连附近的黄土可能来自北面的海域,其中含有有孔虫,宽甸盆地中的棕黄土则以大气尘降落的形式形成的。各地棕黄土中的矿物组成也不同,缓效钾的含量与粘粒含量成正相关,表明伊利石是其中的主要组成成分。

Characteristics and Origin of Brown Loess in Liaoning Province

Brown Loess, the loess-like sediment in east and north Liaoning is so called as to differentiate it from the typical Loess. This kind of soil can be tound on the terraced land 20 to 30 meters above river bottom. Judging by its occurranee, it is believed that the soil is composed of wind transibor- ted substance. The Brown Loess in Changtu county probably came from Karaqing Desert of Inner Mongolia, because its particle size in the west is bigger than that in the east. In the west suburb of Dalian, the Brown Loess is derived from the beach sediment nearby, in which the fine particles were blown away by the wind, at a time when the sea level was much lower than it is now. The soil is sandy, and contains some foraminifers which live in the sea. The particle size of the Brown Loess in Kuandian basin is very small, between 0. 02 to 0. 002mm. It is formed by eolian dust. The heavy minerals in Brown Loess are not identical in different places. The amount of slow-releasing potassium in Brown Loess is in proportion to its clay content. This indicates that Illite is the major clay component in the soil.