Abstract: Drilling/logging,3D seismic data and other information were combined with fault activity rate statistics to analyze quantitatively the characteristics of the Paleogene boundary fault activities and their control over sedimentation in southeastern margin of Qinnan Sag,Bohai sea.The result shows the boundary faults in the study area were significantly segmented into four sections:west Shibei1,east Shibei1,west Shibei2 and east Shibei2.Vertically,the faulting initiated during the deposition of Ek to Es⁴,and then went through two cycles of enhanced and subdued stages during the deposition of Es³,Es¹⁺²,Ed³, and Ed²,and finally inactivated during the deposition of Ed¹.Laterally,the boundary faulting was characterized by being intensive in the central part but weak at both ends during the same geological period.From a space angle,faulting activities were successively carrying on at the same location.The differences of boundary faulting controlled the differential rise and fall of basins,resulting in differential erosion in provenances and the formation of various deposition patterns and tectonic transfer zones,which further affected erosion rate of the provenances,subsidence rate,types and distribution of sedimentary facies,delta extension distance,as well as lithologies in depositional basins.

Key words: fault activity, deposition, provenance, erosion, Paleogene, Qinnan Sag, Bohai Sea