摘要
大同地开石呈团块状、网脉状、充填在侏罗纪煤系地层“陷落柱”的岩堆孔隙和洞穴中,是一种成岩后生作用的产物,大多数地开石是在后生氧化作用下,由高岭石逐渐转化形成,而大同地开石却是在地下深处与大气隔绝的封闭的还原环境里形成。经扫描电镜观察,该地开石晶体大都呈假六方板状,轮廓明显,晶面体平整光滑,(010)和(001)晶面普遍生长良好,晶体堆垛疏松,无光滑平整柱面的塔品和六角柱聚合体。
Dickite from Datong, which occurs as masses and network veins, fills in the interstices and pores of fragments of sandstone, conglomerate and coal slack in the Jurassic coal-measure strata, and intergrows with uninterrupted authigenic pyrite crystals. Normally, durlng diagenesis-epigenesis-oxidation, kaolinite is changed gradually into dickite with increasing temperature and pressure. Although it is the product of diagenesis-epigenesis, Datong dickite is in the reducing environment where it is buried deep underground and cut off from the air. Due to dissolution of alumino-silicates such as feldspars and micas by acidic water medium, K, Na, Ca etc. are carried away steadily, leading to Al and Si re-arrangement and direct precipitation and crystallization under the condition of aqueous solution, and finally the formation of dickite. As observed under the electron microscope, the dickite is, for the most part, uninterrupted pseudo-hexagonal slaty crystal with distinct outlines and neat and smooth crystal faces. Except that (010) and (001) crystal faces are well developed, the others are not so uniformally developed.
出处
《矿物学报》
CAS
CSCD
北大核心
1989年第2期183-186,200,共4页
Acta Mineralogica Sinica
关键词
地开石
高岭石
粘土矿物
扫描电镜
dickite
clay mineral
scanning electron microscope
Shanxi
