Elevation and subsidence of base level

accompanying change of accommodation space

leading to denudation

transportation

passing by

sedimentation or undercompensation of sediments in various facies tracts

would result in cyclic sequences.The phenomena of synchronic formations having different thicknesses seen in isochronal correlation of terrestrial formations are the stratigraphic responses to facies differentiation and sedimentation volume partition.In the direction parallel with sources

lithofacies types might change from braided channel facies sequence to meandering stream and delta facies sequences;while in the direction perpendicular to the sources

the fluvial facies might change from channel fill to interchannel washover and flood plain deposits

or the delta facies might change from distributary channel deposit to inter-distributary bay deposit.Facies differentiation accompanied by sedimentation volume partition would result in different volume partitions of synchronous deposit in different facies traets.Palaeogeomorphology might have controlled the distribution of fluvial facies reservoirs.Transportation of palaeocurrent might lead to the deposition of channel sandbodies on the sequence boundary where valleys have been developed in the palaeogeomorphologic low-land with relatively large accommodation space.