In this research,the petrological characteristics of the siderite of the strata in Late Permian in western Guizhou are studied based on the observation of drilling cores and analysis of sample test results.Altogether,six vertical sedimentary sequences containing siderite and pyrite are categorized,five developmental patterns of siderite and pyrite are summarized,and it was found that the formation of theunattached multiple superimposed coalbed-methane systemwas largely controlled by the development of sider...