东北地区早白垩世含煤岩系层序地层研究

利用煤田钻孔资料，对东北地区早白垩世主要盆地群的含煤岩系层序地层格架及聚煤规律进行研究。根据区域不整合面、下切谷砂砾岩体底面以及沉积相转换面等4类型层序界面，在研究区识别出6个层序界面，将区内含煤岩系划分为5个三级层序。层序Ⅰ属于盆地的初始断陷阶段，层序Ⅱ、层序Ⅲ是盆地持续沉降阶段，层序Ⅳ、层序Ⅴ时期是湖泊缓慢回升，萎缩的过程。聚煤作用从层序Ⅰ到层序Ⅴ的趋势依次为：弱，强，弱，强，弱。层序Ⅱ处于盆地的缓慢裂陷期，层序Ⅳ处于盆地缓慢回升期，这两个时期都有适度的湖平面上升速率，能保证可容空间增加速率与泥炭堆积速率之间的相对平衡关系，从而形成了区域性的厚煤层，这两个层序分别对应形成了区域上的下含煤段和上含煤段。

Study of sequence stratigraphy of the Early Cretaceous coal measures in Northeastern China

Sequence stratigraphy and coal accumulation of the Early Cretaceous coal measures in the northeastern China have been studied using outcrop and borehole data in this paper.Based on the regional unconformity surface，the erosional base of incise valley fill sandstone/conglomerates，the vertical facies reversal surface and paleontological evidence，a total of six sequence boundaries have been identified，which subdivide the Early Creataceous coal measures into five third-order sequences.SequenceⅠ was developed at the initial subsiding stage.SequenceⅡ and Sequence Ⅲ were developed during the further subsiding stage.While Sequence Ⅳ and SequenceⅤ were developed during the basin Shrinkage Stage.Sequence Ⅱ represented the early period of the basin subsiding stage and Sequence Ⅳ represented the beginning period of the basin shrinkage stage.Strength of coal accumulation tendency from SequenceⅠto Sequence Ⅴ was：weak，strong，weak，strong and weak.During these periods the relative balance between the increase rate of accommodation space and the peat accumulating rate favored the accumulation of the regional thick coal seams.These two sequences correspond to the lower coal seams and the upper coal seams.