Based on the study area field geological investigation and observation of core from 50 more boreholes,using laboratory test and analysis,theoretical theories of stratigraphy,sedimentology,geochemistry and coal geology carried out systematic study on the Longtan Formation coal measures sedimentary facies features.The paper has overall analyzed sequence stratigraphic,sedimentary facies,lithofacies and paleogeographic features;summed up coal accumulation model of Longtan Formation coal measures in the area.The result has identified delta,barrier coast 2 types of sedimentary facies,3 subfacies and 11 microfacies in the Longtan Formation.As a whole,lower part is tidal fiat subfacies,upper middle part delta plain subfacies and upper part delta front subfacies.In the formation has developed regional inconformity interface,maximum flooding surface and initial flooding surface 3 sequence interface types,accordingly partitioned the Longtan Formation in the area into 2 tertiary sequences and 4 systems tracts.The comprehensive study has considered that the delta plain environment is the most important environment of coal-forming during the Late Permian Epoch Longtan Stage in the area;tidal flat environment is the second.On this basis,combined with study area late Permian sedimentary facies features,the delta plain and tidal fiat coal-forming model put forward.%根据研究区野外地质调查及50余口钻孔岩心观察,结合相应的测井资料,运用室内测试分析方法及地层学、沉积学、地球化学、煤炭地质学等理论方法,对该区龙潭组沉积相特征进行了系统研究,全面分析了层序地层、沉积相及岩相古地理特征,总结了区内龙潭组的聚煤模式.结果显示:龙潭组共识别出三角洲、有障壁海岸2种沉积相类型、3种沉积亚相和11种沉积微相,总体呈现出其下部为潮坪亚相,中上为三角洲平原亚相,上部为三角洲前缘亚相.龙潭组主要发育区域不整合面、最大海泛面及初始海泛面三种层序界面类型,据此将研究区龙潭组划分为2个三级层序,4个体系域.综合研究认为三角洲平原沉积环境是研究区晚二叠世龙潭期最重要的成煤环境,其次为潮坪沉积环境.在此基础上结合研究区晚二叠世沉积相特征,提出了三角洲平原及潮坪成煤模式.
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