抚顺煤田始新统沉积演化及其对煤和油页岩发育的控制

Eocene sedimentary evolution and its control over coal & oil shale development in Fushun Coalfield

通过野外露头测量、沉积特征分析、沉积相恢复、孢粉组合和地球化学数据对比,对抚顺煤田始新统沉积演化过程及其对煤和油页岩发育的控制作用进行研究。结果表明:抚顺煤田始新统从古城子组扇三角洲和沼泽环境开始,经历了计军屯组浅湖和半深-深湖环境,最终演化为西露天组旋回性沉积;古城子组煤层主要在气候温暖潮湿、河流输入持续增加的淡水沼泽环境中沉积;计军屯组油页岩主要在气候向寒冷干燥条件转化、河流输入减少、水体变咸的半深-深湖环境中沉积;贫矿油页岩作为煤到富矿油页岩的过渡层位显示了高等植物和水生有机质双重输入的特征;煤和油页岩沉积条件的不同造成有机质母质来源的差异和水介质条件的改变,引起与油页岩共生煤系的'富氢化'和生油潜力的增大。

Eocene sedimentary evolution and its control over development of coal and oil shale in Fushun Coalfield were investigated through out-crop measurement,deposit character analysis,facies reconstruction,as well as pollen assemble and geochemistry data comparison.The results indicate that the sedimentary evolution started from fan delta and swamp facies associations of the Guchengzi formation,then underwent shallow lake and semi-profundal to profundal facies associations of Jijuntun formation,eventually evoluted into cycle deposit of the Xilutian formation.Coal seam of Guchengzi formation was deposited in fresh-water swamp with increasing river inflow under warm and humid climate.However,oil shale of Jijuntun formation was deposited in saline semi-profundal to profundal lake with decreasing river inflow under relatively cold and arid climate.Lean oil shale as transitional layer from coal to rich oil shale implies organic input of aquatic organism together with high plant.Sedimentary environment changes of coal and oil shale cause variation of organic origin and water condition,resulting in ＂hydrogen-enrichment＂ and increasing hydrocarbon potential of coal deposit associated with oil shale in Fushun Coalfield.