Based on first-hand material from the geological exploration of petroleum,we made a detailed study of the tectonic development in the Early Cretaceous and the distribution of basement rifts in the Songliao Basin.The sedimentary characteristics of this epoch and the tectono-paleogeography of the basin were expounded.The results show that in its early stages,the Songliao Basin was characterized by a detached faulted basin in which mainly lake facies developed among mountains.It became gradually one lake during the late stages of the Early Cretaceous.During this period,the fault activity in the Songliao Basin changed from a turbulent to a quiet development,the water area from small separated lakes to one large lake,in which the sedimentary facies were divided into asymmetric eastern and western parts.In the basin a volcanic clastic rock-alluvial fan system developed and a fan delta-lake-small delta-river system was mainly deposired.Our research also shows that the basement rifts not only controlled the distribution of fault depressions and the tectonic development in the Early Cretaceous,but had also an effect on the orientation of sedimentation,source area and river system,which determine the tectonopaleogeography of the Early Cretaceous. Based on first-hand material from the geological exploration of petroleum, we made a detailed study of the tectonic development in the Early Cretaceous and the distribution of basement rifts in the Songliao Basin. The sedimentary characteristics of this epoch and the tectono-paleogeography of the basin were expounded.The results show that in its early stages, the Songliao Basin was characterized by a detached faulted basin in which mainly lake facies developed among mountains.It has gradually one lake during the late stages of the Early Cretaceous. During this period, the fault activity in the Songliao Basin changed from a turbulent to a quiet development, the water area from small separated lakes to one large lake, in which the sedimentary facies were divided into asymmetric eastern and western parts. the basin a volcanic clastic rock- alluvial fan system developed and a fan delta-lake-small delta-river system was primarily deposed. Our research also shows that the basement rifts not only controlled the distribution of fault depressions and the tectonic development in the Early Cretaceous, but also an effect on the orientation of sedimentation, source area and river system, which determine the tectonopaleogeography of the Early Cretaceous.