An unique structural framework of Early Tertiary exists in Bohai Bay Basin

its radiate fault system and circular fault system are distributed around Bozhong Depression.The framework resulted from mantle diapirism.The Bohai Bay Basin has undergone two faulting thermal contraction stages ever since Early Tertiary.When the mantle swelled initially

the earth crust thinned

the basin began its faulting-controlled subsidence.Then the mantle’s temperature decreased

the basin entered its thermal contraction subsidence.