湖北省二叠纪梁山组沉积期岩相古地理特征与成煤规律

Permian Liangshan Formation Depositional Stage Lithofacies and Paleogeographic Characteristics and Coal-forming Pattern in Hubei Province

湖北省二叠纪梁山组沉积期是一次重要的成煤时期,由于煤层的不稳定性,其煤层层数、厚度、煤质等存在明显差异。通过岩性、煤层及古生物的研究对比,查明梁山组自下而上共含煤4层,煤层的形成与沉积特征受岩相古地理环境制约。就整个华南沉积盆地而言,从湖北到湖南,岩相古地理沉积模式为北高南低的古陆-潟湖-障壁岛-广海的沉积格局,湖北境内主要为古陆和海湾潟湖,位于湘鄂交界的江南古陆实为障壁岛,跨过障壁岛,便进入华南广海。湖北沉积区相单元主要为潟湖和潮坪,其中潮坪沼泽亚相为煤层形成的最佳环境,巴东麻沙煤田、松宜煤田和蒲圻煤田皆为该环境的沉积产物,其煤层的沉积特征与海侵机制和滞留时间密切相关。

The Permian Liangshan Formation depositional stage in Hubei province is an important coal-forming period.Since the instability of coal seams,their number,thickness and coal quality have existed obvious differences.Through lithologic,coal seam and paleontologic studies and correlations,have identified the Liangshan Formation contains 4 coal seams from bottom to top,coal seam formation and sedimentary characteristics were restricted by lithofacies and paleogeographic environment.In the point of whole South China sedimentary basin,from Hubei to Hunan,the lithofacies and paleogeographic sedimentation models were high in north,low in south old land-lagoon-barrier island-open sea sedimentary patterns,in Hubei Province was mainly old land and embayment lagoon,the Jiangnan old land at Hunan-Hubei boundary was really a barrier island,and across the barrier island,just the South China open sea.Facies units in the Hubei depositional region were mainly lagoon and tidal flat,in which,the tidal flat bog subfacies is the best coal-forming environment,the Badong Masha,Songyi and Puqi coalfields are all sedimentary results in such environment,the sedimentary features were closely related to transgression mechanism and lag of time.