Based on analysis on regional geology

strata thickness

sedimentary characteristics and faulting intensity of Huimin sag

this paper studied the characteristics of structural activities and the depocenter migration patterns in different evolutionary periods of Huimin sag and explained their geodynamic mechanisms.New methods were proposed for delineation of depocenters.There were two dynamic depocenters or subsidence centers in Huimin sag in the Cenozoic era.The depocenters and subsidence centers basically coincided with each other except for Es

4

period.The depocenters had migrated to the southwest of Linyi

while the subsidence centers were still in the west of Zizhen during the Es

4

period.The Es

4

-Es

3

periodwas an important transition period for the migration of subsidence centers which migrated mainly along the N-S direction.In contrast

the migration was mainly along the E-W direction during Ek-Es

4

period and Es

3

-Ed period.In the western part of the sag

the depocenters migrated in "S"-shaped trajectory

while in the eastern part

they migrated anticlockwise.Sag-controlling faults were mainly active during Ek and Es

4

period

while subsag-controlling faults were predominant in Es

3

-Ed period.Both the sag-controlling and subsag-controlling faults were controlled by the NNW-trending extension structure and the right lateral strike-slip of Lanliao fault and Tanlu fault.And it was related to mantle convection caused by the velocity and angle changes of the Pacific plate subducting to the Eurasian plate and the collision of India-Eurasia plate.