【摘要】 四川盆地晚三叠世含煤地层为一套陆相含煤地层,根据区域性构造不整合面、下切谷充填砂岩底部冲刷面、地层颜色突变面可划分为4个层序,其中层序Ⅰ对应小塘子组,层序Ⅱ对应须家河组一段和二段,层序Ⅲ对应须家河组三段和四段,层序Ⅳ对应须家河组五段和六段。每个层序可划分出相应的低位体系域(LST)、湖侵体系域(TST)和高位体系域(HST)。层序Ⅲ和层序Ⅱ含煤性最好,层序Ⅰ含煤性最差。层序格架对含煤性、煤层分布和发育具有明显的控制作用,湖侵体系域晚期及高位体系域早期主要为滨岸沼泽和分流间湾环境,相对较快的湖平面上升速率为泥炭堆积提供持续增加的可容空间,有利于厚煤层的形成。更多还原

【Abstract】 The Upper Triassic Series is a set of coal-bearing strata,based on regional structural unconformity interface,incised valley filling sandstone bottom scouring face,stratum color abrupt change face can be divided into 4 sequences.In which,the sequence I corresponds to Xiaotangzi Formation,sequence II to first and second members of Xujiahe Formation,sequence III to third and fourth members of Xujiahe Formation,and sequence IV to fifth and sixth members of Xujiahe Formation.Every sequence can be subdivided into corresponding lowstand systems tract(LST),lacustrine transgressive systems tract(LTST) and highstand systems tract(HST).Sequences III and II have best coal-bearing property,while sequence I worst.Sequence framework has obvious controls on coal-bearing property,coal seam distribution and development.Late stage of LTST and early stage of HST were mainly in onshore bog and interdistributary embayment environments,relatively quick lake level rising rate provided peat accumulation with sustainable increasing accommodation space,thus in favor of thick coal seam formation.更多还原