淮南新集二矿11-2煤含黄铁矿砂岩顶板特征及其沉积环境分析

Coal No.11-2 Pyritic Sandstone Roof Features and Sedimentary Environment Analysis in Xinji Coalmine No.2,Huainan

为了厘清淮南新集二矿采空区引起瓦斯燃烧事故的含黄铁矿砂岩顶板的沉积特征,对回采煤层11-2煤顶板含黄铁矿砂岩展开了岩石学和元素地球化学分析工作,研究表明:11-2煤层顶板砂岩中的黄铁矿呈现脉状、粉晶状充填于砂岩裂隙和节理之中,未见结核状、梅粒状结构特征,属于成岩后生黄铁矿;微量元素特征显示,砂岩承载较弱的古氧化环境信息,黄铁矿的富集表明后期以弱还原-还原环境为主,推测该套含黄铁矿砂岩的沉积区具有由早期氧化环境逐渐向后期还原环境演化的特征;结合前人研究成果,含该套黄铁矿砂岩形成于水动力条件较强的三角洲平原分流河道沉积环境。

To clarify causing gas burning accident pyritic sandstone roof sedimentary features in Huainan Xinji coalmine No.2 worked-out area carried out lithologic and elemental geochemical analysis for winning coal No.11-2 roof pyritic sandstone.The study has shown that the pyrite in sandstone presents vein and crystal powder filled in fissures and joints,without nodular,plum granular structural features can be seen,belongs to post-diagenetic pyrite.The trace elemental features have shown that the sandstone has presented weaker paleo-oxidation environmental information,the pyrite enrichment shows that the later stage mainly weak reduction-reduction environment.It is referred that pyritic sandstone deposition area has features of evolution from early oxidation environment gradually transited to later reduction environment.Combined with previous studies,pyritic sandstone should be formed in a stronger hydrodynamic delta plain distributary channel sedimentary environment.