云贵地区二叠系瘤石灰岩的成因

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,不是某种沉积环境的标志

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

Nodular limestones are widespread in Permian of Yunnan-Guizhou region and consist of light-colored (light grey, grey or dark grey) pure limestone nodules and dark-colored (greyish black) mud-containing limestone "wrappings" showing laminations which are actually swarms of microstylotites (also called pressuresolution seams).Nodules and wrappings are commonly ccomposed of the same type of limestones which might be biograin limestones, biograiny lime-mud limestones, biograin-bearing lime-mud limestones or lime-mud limestones.The above studies have led the authors to believe that nodular limestones, instead of being products in a certain kind of sedimentary environment, were formed as a result of pressure-solution diagenesis.