Abstract: By an analysis of drilling seismic and coredata,sedimentary processes of the 3rd and 4thmember of Cretaceous Quantou formation in the north-eastern part of Songliao basin can bedescribed with a deIta-plain facies model and 12 microfacies have been divided.An approachfor paleo-channel trend analysis was proposed,which leads to delineating the multiple-orderpaleochannel belts and discovered the paleo Songhua River during Quantuo period.System-atic diagrams of sedimentary environment and river trend have revealed that the base level(lake level) directly affected the paleochannel size while the deep faults and fault-block activities controlled the position and shift of paleo rivers respectively.Disposition of the sedimen-tary systems indicated that during 3rd and 4th stage of Quantou period the northern Songliaobasin might be an alluvial-lacustrine plain formed by the deposition of paleo-Nen,paleo-Songhua Rivers and their tributaries and distributaries.The paleo-Songhua River stretchedparallel with the present Songhua River.It might wind its way through Sanjiang basin andjoin into paleo-Heilong River.This discovery could be of significant importance for the oil-gas exploration and development in Songliao basin and its adjacent areas.

Key words: sedimentary microfacies, paleochannel, tectonic movement, paleoclimate, control

摘要： 通过岩心、钻井和地质资料研究,发现松辽盆地东北部泉三、四段的沉积作用符合于三角洲平原相模式,并划分了12种微相.进而提出古河流趋向分析法,勾绘出多级古河道带,发现了泉头期的古松花江,系统的沉积环境与河流趋向图表明,侵蚀基面(湖水面)的高低,直接影响河流规模,而深断裂和断块活动则控制河流位置与迁移.沉积系统的配置表明,泉三、四期,松辽盆地北部为古嫩江、古松花江及其支流形成的冲积一湖积平原.古松花江平行并靠近今日松花江延伸,经王江盆地而汇入古黑龙江.这一系统的发现,对石油勘探布置和油气田开发有重要意义.

关键词: 沉积微相, 古河流, 构造运动, 古气候, 控制