华北地台东南部二叠纪岩相古地理

二叠纪早期，华北地台的陆表海不断向南退缩，从而在华北地台东南部开始了陆相三角洲的聚煤作用。伴随着三角洲体系的进积增生，含煤系数和煤层厚度由西北向东南同步增大，聚煤盆地和富煤带依次向东南迁移，含煤层位依次抬高，在淮河流域形成了二叠纪的富煤区。在秦岭纬向古构造的影响下，本区二叠纪岩相古地理的分区、分带及煤盆地的迁移展布，具有南北向变异、东西向延展的特点。晚二叠世由于南部的秦岭－北淮阳海槽脉动式抬升，导致海水沿确山海峡和肥东海峡向三角洲回流，三角洲的朵叶受到破坏，海湾泻湖和泥炭沼泽发育，沉积厂晚二叠世特有的淮南含煤组及用应的富煤带。

LITHOFACIES AND PALEOGEOGRAPHY OF PERMIAN PERIOD IN THE SOUTHEAST OF NORTH CHINA PLATFORM

In early Permian period,the epicontinental sea of North China Platform receded conti-nously to the south,thus the-coal accumulations of continental delta facies are generated inthe southeast of North China Platform.With the increase of the progradation of the delta,the coal-bearing coefficient and coal seam thickness increased synchronously from the North-west to the southeast,the accumulative basin and coal-rich belts migrated to the southeast successively and the coal-bearing horizons elevated simultaneously,and thus coal-rich areas of Permian period are formed in Huaihe river valley.Under the influence of Qinling latitudinal paleostructure,the rEgionalization and zona-tion of lithofacies-paleogeography and the wandering distribution of coal basin of Permian pe-riod in this area reveal the features of variation in S-N direction and extension in E-W direc- tion.Owing to the Qinling-Beihuaiyang ocean trough elevated pulsatively in late Permian Pe-riod,the seawater reflux along Queshan strait and Feidong strait to Huang-Huai(YellowRiver-Huaihe river)delta.With the lobes of the delta destroied,the gulf-lagoon and peat bogare developed,and the Huainan coal-bearing formation and coal-rich belt are deposited.