LATERAL ACCRETION CROSS-BEDDING：THE MAIN TYPE OF SEDIMENTARYSTRUCTURES IN THE BRAIDED CHANNEL

Lateral accretion cross-bedding results from lateral accretion of sand bodies induced bythe lateral migration of channels and is very abundant in the braided channels. Its characteristics are: ① the overall shape of its sets is tabular, but its laminae are sigmoid, clearlyconverging both upward and downward. ② there is secondary cross-bedding or crosslaminations as well as slump structures in the inner part of some‘laminae'. ③ the setthickness has nothing to do with the grain size of the sediments. ④ the thickness, grainsize and composition of each lamination within the same set are significantly different eachother. ⑤the laminae dip is at approximate vertical angles to palaeocurrent direction. Thelateral accretion cross-beddings are very abundant in the braided channel as there are moretransverse circulation flows in it and more sand and less mud in the sediments.