云贵地区二叠系瘤石灰岩的成因

The Origin of the Permian Nodular Limestones in Yunnan-Guizhou Region

云南东北部及贵州北部的二叠系中广泛发育了瘤石灰岩（亦称眼球石灰岩）。瘤石灰岩由颜色较浅、较纯净的石灰岩瘤和颜色较深、泥质含量较高、微缝合线发育密集的包层组成。组成瘤和包层的石灰岩类型一致，为生屑石灰岩、生屑质灰泥石灰岩、含生屑灰泥石灰岩或灰泥石灰岩。本次研究认为，瘤石灰岩是压溶成岩作用的产物。

Nodular limestones are widespread in Permian of Yunnan-Guizhou regionand consist of light-colored(light grey,grey or dark grey)pure limestone no-dules and dark-colored(greyish black )mud-containing limestone “wrappings”showing laminations which are actually swarms of microstylotites(also calledpressuresolution seams).Nodules and wrappings are commonly ccomposed of thesame type of limestones which might be biograin limestones,biograiny lime-mudlilmestones,biograin-bearing lime-mud limestones or lime-mud limestones Theabove studies have led the autors to believe that nodular limesfones,instead ofbeing products in a certain kind of sedimentary environmnt,were formed asa result of pressure-solution diagenesis