巴州坳陷下白垩统—中侏罗统的粘土矿物特征

Clay minerals from the Lower Cretaceous to Middle Jurassic strata in the Bazhou depression,eastern Qilian folded belt

关键词:  粘土矿物  成岩变化  巴州坳陷  民和盆地

Key words:  clay mineral  diagenetic change  Bazhou depression  Minhe basin

摘要:

根据岩石薄片、X衍射和扫描电镜分析资料,本文研究了巴州坳陷下白垩统一中侏罗统粘土矿物特征,发现粘土矿物分为伊利石、伊/蒙混层和绿泥石三种类型。粘土矿物的类型和含量随深度而变化,形成了伊/蒙混层带、混层迅速转化带和伊利石带。粘土矿物的转化和自生粘土矿物的形成是沉积地层非常重要的成岩变化。

Abstract:

The properties of clay minerals from the Lower Cretaceous to Middle Jurassic strata in the Bazhou depression have been explored by means of thin section analysis,X-ray diffraction analysis and scanning electron microscopy.The results of the study have con-tributed to the classification of the clay minerals into three types:illite,mixed-layer illite/montmorillonite and chlorite.The types and contents of the clay minerals also vary with in-creasing buried depth.Three clay mineral zones may be delimited for the Lower Cretaceous to Middle Jurassic strata in the study area on the basis of the evolution of the clay miner-als.They are mixed-layer illite/montmorillonite zone,rapid conversion zone of mixed layers and illite zone.The evolution of clay minerals and formation of authigenic clay have record-ed most important diagenetic changes of sedimentary strata in the study area.