Sequence Filling Dynamics of Youjiang Basin,Southern China
CHEN Hong de QIN Jian xiong TIAN Jing chun PENG Jun HOU Zhong jian (State Key Laboratory of Oil/Gas Reservoir Geology and Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology,Chengdu 610059)
In the light of sequence basin earth theory in conjunction with previous stratigraphy,sedimentology,basin analysis and sequence stratigraphy,the sequence filling dynamics of Youjiang Basin has been studied in detail.Five hierachies of sequence boundaries and corresponding five hierachies of depositional sequences,1 super-order sequence,4 1st-order sequences,6 2nd-order sequences,11 sequence sets,47 3rd-order sequences and a certain amount of 4th-and 5th-order sequences have been recognized for the first time.Relationship between sequence boundary and geological events,and that of sequence hierachy and basin type have been discussed,and then sequence stratigraphic framework of Youjiang Basin has also been established.By the cognition that sequence development of rifting basin is mainly controlled by synsedimentary fault and fundamental subsidence,relationship between sequence genesis and basin structure has been set up. The sequence framework and filling proccess are obviously distinct within different genetic basins. Finally,the author delibrated the sequence filling dynamic process and related basin evolution of the Youjiang Basin.On the basis of the research result mentioned above,this paper suggests that the sequence filling process of the Youjiang Basin can be subdivided into four stages:intracontinental rifting,marginal rifting,retroarc rifting and foreland basin,constituting a complete tectonic cycles during Hercynian Indosinian stage.