Sequence Stratigraphic Research Of Rapid Rifting Period In Lishu Faulted Depression

The Lishu rift in the southcast uplift zone of Songliao Basin is a graben basin which has developed since the Early Cretaceous controlled by Sangshutai fault. Based on the high-resolution sequence stratigraphy framework of Lishu rift, the paper studies on the 3rd sequence configuration and distribution characteristics, determines the stratum contact relationship above and below T4,T41 sum the seismic facies type of the fast rift period and clear the development law, distribution characteristics of the provenance system.Guided by the seismic stratigraphy theory, based on the 3-D high resolution seismic data of Lishu rift and combined with other geological data such as core and logging, the paper establish the sequence startigraphy correlation framework of Lishu rift, recognize 9 3rd sequence boundaries and 8 3rd sequences. The stratum in the middle is thicker than that in the north and south, and the western stratum is thicker than the eastern. The Sangshutai secondary depression zone is the depression and subsidence centre of Lishu rift, the stratum in the northern slope belt and the southeastern slope belt has suffered serious erosion.Based on the fine interpretation of the 3-D seismic data of Lishu rift, the paper determines the property and the planar distribution characteristics of the T42, T41. The contact relationships between stratum above T42,T41 and T42,T41 include conformity interface, hiatus interface and truncation. The contact relationships between stratum below T42,T41 and T42,T41 include conformity interface, gentle overlap and onlap.Based on the classification standard of seismic facies, the paper recognizes several seismic facies in the fast rift period of Lishu rift including high-amplitude, continuous, parallel-sub parallel, middle-amplitude, middle-continuous, foreset, middle, weak-amplitude, middle-continuous, weak-amplitude, discontinuous and wedge shaped foreset seismic facies. The middle, weak-amplitude, middle-continuous is the main seismic facies type in Lishu rift.Based on the analysis of heavy mineral and the statistics of the color of mudstone and the thickness of sandstone and gravel, the paper studies the development law and distribution characteristics of the provenance system of Lishu rift in the fast rift period. The northern slope belt and southeastern slope belt are the main provenance.