Current construction of sequence stratigraphic framework is mainly based on the analysis of stratigraphic superposition patterns near the estuary

with their lateral variation in the sedimentary body neglected.So the division standards of system tracts are restricted by the range of sedimentary bodies

and the sequence stratigraphic division scheme is not unique.As a result

it's difficult to carry out stratigraphic correlation in a larger scope in a sag. The study took a case of Pearl River Mouth Basin clinoform in 13.8 Ma(belongs to the Middle Miocene)

and elaborated the characteristics of sequence boundary(SB)

and the lateral variations of stratigraphic superposition patterns in Falling Stage System Tract(FSST)and Low stand System Tract (LST)

through combination analysis of well and seismic data.The results show that a series of onlapping strata

which can be laterally tracked and correlated with LST progradation systems on seismic sections

should be named as LST rather than TST.Based on the principle of regional isochronous correlation

the definition of LST should be revised as a set of strata that are developed in the early of base-level rising cycle

marked by accommodation increasing rate being lower than the sediment supply rate

and contain lateral equivalent beds.While the definition of HST is revised as a set of strata that are formed in the late of base-level rising cycle

marked by the accommodation increasing rate being less than the sediment supply rate

and include a set of lateral equivalent beds. Meanwhile

the TST is defined as a set of strata with facies marker of the accommodation increasing rate being greater than the sediment supply rate and the lateral equivalents of LST and HST being excluded.Thus we proposed that the reconstruction of sequence stratigraphy framework should take estuary

shelf and deep water as an integrated whole

looking for the unique facies marker of each system tract

and carrying out systematic comparison and checking in three-dimensional space

rather than factitiously splitting a sedimentary system and then establish sequence stratigraphic frameworks separately.