Based on a detailed analysis of the dynamics characteristics of meandering stream and braided river deposits

3 parasequence models of fluvial deposit are preliminarily recognized in the Xujiahe Formation in central Sichuan basin.Two parasequences

i.e.the graded fining-upward parasequence and the graded coarsening-upward parasequence

occur in meandering river deposits.The graded fining-upward parasequence represents a water shallowing-upward facies sequence combination of subaqueous fluvial channel(lag deposits)

marginal bank

natural levee and flood plain deposits.Whereas the graded coarsening-upward parasequences represents a facies sequence combination of alternative flood plain-crevasse-splay deposits.The braided river parasequence mostly appear as a graded fining-upward and water shallowing-upward parasequence of facies sequence combination of subaqueous fluvial channel(lag deposits)

channel bar and overbank deposits

while the graded coarsening-upward braided river parasequences are not developed.The fluvial parasequence boundary is the erosional surface at the bottom of channel sandbodies and also is the onshore equivalent interface of the lake water or sea water flooding surface on the parasequence boundaries in lake/marine basins.However

it is more similar with the parasequence boundary of transgressive lag deposits rather than dark mudstone.In the graded coarsening-upward flood plain

crevasse splay or channel deposits

the parasequence boundary is the interface between exposed mudstone and upper dark flood mudstone.Based on the proposed fluvial parasequence models

the vertical supe-rimposition pattern of fluvial parasequence and its time-space evolution are analyzed

and the heterogeneity of fluvial parasequence are studied for the Upper Triassic Xujiahe Formation in central Sichuan basin.