Abstract:

Taking Fuyu oil-bearing layer of the Lower Cretaceous Quantou Formation in the Songliao Basin as an example,this article discusses the analysis methods of sequence stratigraphy of fluvial sedimentary system.It starts with the identification of the genetic types of fluvial system and facies tracts(micro-facies),including meander channels,crevasse channels,crevasse fans,alluvial plains,and shallow lakes,and recognition of the autocyclicity caused by fluvial overflow and the allocyclicity(base-level cycle) caused by base level changes.Then it analyzes the relation between the formation of different facies tracts and base-level change and identifies the sedimentologic and stratigraphic responses of turning points of base-level changes(i.e.,the base level turning from ascending to descending or vise versa) by applying the fluvial sedimentology theory.Finally,it establishes a framework for isochronous stratigraphic correlation of fluvial sequences.

Key words: autocyclicity, allocyclicity, base-level cycle, identification of cycle interfaces, sequence stratigraphic framework, fluvial facies, Fuyu oil-bearing layer, Songliao Basin