和什托洛盖盆地下—中侏罗统层序地层学及聚煤规律研究

Sequence Stratigraphic Analysis and Coal Accumulation of the Lower and Middle Jurassic in Heshituoluogai Basin

运用层序地层学有关理论和方法,在钻井资料的基础上,对和什托洛盖盆地下—中侏罗统煤系地层进行了层序地层学与聚煤规律研究。将其下—中侏罗统分为7个三级层序,其中八道湾组、三工河组、西山窑组分别划分出3、2、2个三级层序。通过连井剖面的对比建立了层序地层格架。低位体系域主要发育辫状河、辫状河三角洲、三角洲沉积,湖扩体系域主要发育滨浅湖沉积,高位体系域主要发育三角洲和滨浅湖沉积。煤层主要发育于湖扩期和高位期,相对快的基底沉降和适宜的物源补给对煤的聚集是有利的。

Based on the principles and methods of the sequence stratigraphy,this study discuss the characteristics of the sequence stratigraphy and coal accumulation of the Jurassic in the Heshituoluogai Basin.3 third-order sequences in Bad-aowan formation,2 third-order sequences in Sangonghe formation,and 2 third-order sequences in Xishanyao formation are distinguished, respectively;Sequence stratigraphical frame was established by contrasting Well profile.The lowstand system tracts are mainly composed of braided river,braided river dalt,dalt sedments;the lake expansion tracts mainly com-posed of shore-shallow lake sedments,the highstand system tracts mainly composed of dalt and shore-shallow lake sed-ments.The coal seams are mainly developed in the lake-expansion and the high-stand system tracts.The relatively quik basin base subside and suitable source of supply is favorable to coal accumulation.