辽西北票(金-羊)盆地北票组层序地层及沉积体系特征

Stratigraphic sequence and characteristics of depositional system of the Beipiao Formation in the Beipiao(Jin-Yang) basin,western Liaoning

为揭示北票(金-羊)盆地内北票组层序地层特征及沉积体系分布规律,应用层序地层学及沉积学理论和方法,综合利用野外露头、剖面等资料,建立了北票(金-羊)盆地北票组的层序地层格架,确定研究区的沉积相类型及分布规律。研究结果表明,北票(金-羊)盆地北票组可划分为2个三级层序,其内部可进一步划分为7个准层序组。在层序内识别出冲积扇、辫状河三角洲、湖泊3个沉积相。明确了沉积相的分布规律,向上形成由冲积扇到辫状河三角洲,再到湖相,最后是辫状河三角洲的沉积体系;平面上呈近北西—南东向展布的沉积体系,整体构成2个水进、水退的沉积体系。古地貌影响了底部冲积扇相沉积物的沉积特征。气候不仅影响了沉积物类型,且和湖平面变化共同控制了沉积物的演化规律。

Sequence-stratigraphic and sedimentologic theories and methods were employed in the study of sequence stratigraphic features and sedimentary system distribution in the Beipiao Formation of the Beipiao （Jin-yang） basin. Based on comprehensive utilization of field outcrop and profile data, the authors established sequence stratigraphic framework and determined the types and distribution of sedimenatry facies. The result shows that the formation can be described as two three-order sequences,which can be divided into 7 quasi-sequence sets. Sedimentary facies comprising alluvial fans,braided river deltas and lake deposits were identified in the sequence. Depositional facies vary vertically from alluvial fans to braided river delta and then to lake facies and finally to delta. Horizontally,the facies present themselves as a nearly NW-SE-trending sedimenatry system, i.e., a sedimentary sequence comprising water transgression and regression. Paleogeomorphology controlled the sedimentary characteristics of the sediments of alluvial fans and climate affected the types of sediments and controlled the evolution pattern of the sediments in the formation.