Characteristics and research progress of coal geology in South China Sea

Based on the systematic analysis of coalbearing strata information revealed by cores,drillings and seismic surveys in the northern basin of the South China Sea,using the research ideas and methods of the tectonic combined with basin evolution,drilling combined with seismic section identification and deposit combined with the peat accumulation main control factors,the tectonic characteristics and evolution law of the South China Sea basin group,the sedimentary and coalforming characteristics of each coal basin in South China Sea during late EoceneMiocene were analyzed,and the basic understanding of coalforming mechanism and coalbearing strata distribution in the South China Sea basin group were obtained.The results show that the Oligocene coalbearing strata were mainly developed in the northern basins of the South China Sea,while the southern basins of the South China Sea were more complex,with coalbearing strata developed in Eocene,Oligocene and Miocene.The coalbearing strata were mainly developed in the shallow water areas in the north,west and south basins of the South China Sea,including the delta plain,fan delta plain,river flood plain,lakeside plain,lagoontidal flat and other environments.In the late Eoceneearly Oligocene,river,lakeside,delta and fan delta deposits were generally developed in the northern and western margins basins of the South China Sea,and delta and coastal deposits were developed in the southern margins basins of the South China Sea,which were all good coalforming sittings.Among them,the coalforming intensity of the Oligocene was the largest.In the late Oligocene,the area affected by seawater in the South China Sea basin group was continuously expanded,and the continental basin scope was correspondingly reduced,and gradually evolved into the marineterrestrial transition facies basin and marine facies basin,and the coalforming intensity gradually weakened.In the Miocene,most part of the South China Sea basin group were marine sedimentary environment,and only the small deltas and fan deltas were developed at the edge of each coal basin,and the coalforming intensity was weak