准噶尔盆地南缘下—中侏罗统层序地层格架与聚煤规律

Sequence strata and coal accumulation of lower and middle Jurassic formation from southern margin of Junggar Basin,Sinkiang,China

应用层序地层学方法,基于对勘探资料以及古生物、地表露头剖面等的分析,将准噶尔盆地南缘下—中侏罗统划分为5个3级层序,并以地层叠置样式、岩性、岩相的变化,细分出低位、湖侵和高位体系域,在连井剖面层序对比的基础上建立了下—中侏罗统层序地层格架。识别出下—中侏罗统主要发育扇三角洲、三角洲、湖泊、沼泽等主要相类型,系统分析了沉积相的构成、演化与分布规律,明确了经典层序格架下的聚煤作用特征。认为层序构型控制了煤层的垂向分布,煤层主要发育在低位末期和高位初期,沉积环境控制了煤层的横向展布。

The middle and lower Jurassic in southern margin area of Junggar basin was divided into 5 sequences based on analyses of exploration lines,well,logging curve,paleontology,field outcrop profiles and seismic reflective.Lowstand,lacustrine transgressive and highstand systems tracts were subdivided by the stacking patterns of stratigraphy,changes of lithology and lithofacies.The sequence stratigraphic correlation in well-tie sections made it possible to construct the regional stratigraphic framework.Fan delta,delta,lacustrine and peat swamp sedimentary system facies were identified by fully applying the drilling,logging,palaeontology and field outcrop profiles data.The architecture,evolution,distribution of sedimentary faces of the middle and lower Jurassic in southern margin area of Junggar Basin was analyzed.The coal-accumulation features in sequence stratigraphic framework was clarified.Coal bed vertical distribution was controlled by the sequence architecture pattern.Coal bed is developed in the early lowstand systems tract and in the late highstand systems tract,and coal bed transverse distribution is controlled by the sedimentary environment.