准噶尔盆地南缘西山窑组沉积特征及聚煤规律分析

Sedimentary Characteristics and Coal-accumulation Pattern of the Xishanyao Formation in Southern Margin Area of Junggar Basin

在对大量钻孔资料、测井资料、野外露头及古生物化石资料进行分析的基础上,应用经典层序地层学基本理论和方法,对准噶尔盆地南缘西山窑组进行了层序地层划分,共识别出SQ1和SQ2两个三级层序,并根据地层叠置样式、沉积旋回特征细分为6个体系域。通过沉积基础图件、沉积环境的分析明确了研究区西山窑组沉积演化特征:SQ1层序中,河控三角洲发育,在湖缘及泛滥平原区形成稳定的泥炭沼泽,且聚煤作用时间长,强度大,分布广,形成了稳定的厚煤层;SQ2层序中,由于构造变动频繁,后期剥蚀严重,导致聚煤作用逐渐减弱。对准噶尔盆地南缘西山窑组的沉积环境特征和煤层聚集规律的分析为下一步的煤炭勘探提供了依据。

Based on the analyses of data about drills,loggings,outcrops and palaeophytes,this paper studied the sequence stratigraphy of the Xishanyao Formation in southern margin area of Junggar basin.Two sequences of SQ1 and SQ2 were identified with the classic sequence stratigraphy method,and six system tracts were subdivided according to the superposition style of strata and sedimentation cycle.The characteristics of sedimentary evolution of the Xishanyao Formation were also defined by analyzing the sedimentary environment.In sequence SQ1,a river-dominated delta was developed;a stable peat swamp was formed in the lake edge and flood plain area,and stable and thick coal seams were also formed after a long-time and wide-range intense coal accumulation.In sequence SQ2,owing to the tectonic transformation and the strong denudation,the coal accumulation was gradually weakened.The result provides the basis for further exploration of coal resources in the Xishanyao Formation in southern margin area of Junggar basin.