辽宁北票四合屯盆地下白垩统义县组沉积相

本文系统地论述了北票四合屯盆地下白垩统义县组沉积时期的演化，将盆地演化划分为继承性初始坳陷、火山洼地、湖盆沉降与扩展三个阶段，其后由于火山作用而使盆地封闭。与盆地演化相对应，建立了盆内义县组的沉积相序，自下而上依次为冲积扇与河流相、火山沉积相、河流相、湖相(滨湖亚相,浅湖亚相，半深湖亚相，浅湖亚相，滨湖亚相,浅湖亚相)、火山溢流相，并指出火山喷发间歇期湖盆的湖水进退规律、水体性质以及沉积环境特征。

Sedimentary facies of the Yixian Formation of Lower Cretaceous in Sihetun Basin of Beipiao,Liaoning Province

This paper systematically discusses the formation and evolution of the Sihetun Basin during the sedimentary period of the Yixian Formation of Lower Cretaceous.The evolution of the basin may be divided into three stages,namely,inherited initial depression,volcanic swale,and the subsidence and expansion of the lacustrine basin.The subsequent volcanism closed the basin.According to the evolution of the basin,a sedimentary facies sequence of the Yixian Formation is established as follows in an ascending order: the alluvial fan and fluvial facies,volcanic sediment facies,fluvial facies,lacustrine facies and volcanic effusive facies.The paper emphasizes on the dividing indicators of sedimentary facies and their origins and analyzes the transgression and regression of lake water,as well as the characters of water body and the sedimentary environment during the volcanic dormant period.