摘要
洛川黄土剖面位于陕西省中部,洛川县城南5km 的坡头村附近。该剖面厚度大、地层发育较完整,系第四纪(Q_3—Q_1)风成堆积黄土中的典型剖面。前人从多方面进行过广泛深入研究。黄土的主要矿物成分为石英、长石和/或云母、方解石。在物质成分研究中提到过50多种矿物,但未涉及蛋白石。在黄土的风化成土作用研究中提到“植物蛋白岩偶见”(刘东生等,1985),但未作蛋白石矿物学工作。笔者这次发现的蛋白石,作了较多的矿物学研究。
The discovery of a small amount of micrograin opal minerals in the Luochuan loess profile by using electron microscope analysis is reported. The micromorphology under electron microscope, the crystal state (electron defraction), the chemical composition and some other characteristics of opal are described in the paper. Three different hinds of micromorphology, such as disk, needle and thin-film-shaped, are distinguished among the opals discovered here, but all of them are amorphous A-opals. The chemical compositions of most opal grains are rather pure, while Fe, Al, K and other impurity elements can be determined in a small number of the micrograins. The opal was formed in a epigenetic process in early diagenesis stage. Finally, the geological significance of the discovered opal is discussed in the naner.
出处
《地质科学》
CAS
CSCD
北大核心
1991年第4期399-402,共4页
Chinese Journal of Geology(Scientia Geologica Sinica)
关键词
黄土
蛋白石
洛川
Loess, Opal, Luochuan
