湖北松滋下奥陶统大湾组碳酸盐岩压实作用

COMPACTION OF CARBONATE ROCKS IN LOWER ORDOVICIAN DAWAN FORMATION IN SONGZI, HUBEI

李建明 刘秉理 朱忠德 胡明毅 周涛

Li Jianming Liu Bingli Zhu Zhongde Hu Mingyi Zhou Tao

湖北松滋一带下奥陶统大湾组主要为一套盆地边缘—浅海陆棚相的含泥碳酸盐岩沉积,以发育瘤状构造为特征。其中普遍发育机械压实与压溶现象,包括化石颗粒变形、嵌入接触、缝合线及微缝合线、压溶粘土膜及束状粘土纹等标志.通过对角石类化石形变的定量研究,计算出各类岩石的压缩量,结果表明含泥碳酸盐岩的压缩量随着其中粘土矿物含量的增加而增加,灰岩、含泥灰岩、泥质灰岩、灰质泥岩及泥(页)岩的压缩量分别为4.19%、10.02%、23.00%、51.49%、62.51%。认为瘤状灰岩为差异压实-压溶作用形成。

The sequence of Dawan Formation(O)in Songzi,Hubci Province is dominantly argilliferous carbonate rocks of basin margin-neritic shelf facies characterized by nodular structures.It was found that mechanical compaction and pressure solution,mainly includ-ing:1.fossil plastic deformation and crushing;2.grains inlaying contact;3.stylolites and microstylolite;4.pressure solution argillaceous laminae etc.are well developed.It was calculated through quantitative study of cephalopod(Nautiloidea)fossil deformation that the compaction amount of argilliferous carbonate rocks increases with the amount of clay minerals.The compaction amount of limestone,argilliferous limestone,argillaceous limestone,lime mudstone and mudstone(shale)are respectively 4.19%,10.02%,23.00%,51.49%,62.51%.The origin of nodular limestone in Dawan Formation is related to dif-ferential compaction-pressure solution.

10.11743/ogg19930403