Implications of tide-dominated lagoonal processes on the preservation of buried channels on a sediment-starved continental shelf

The Holocene sediment cover on outer parts of the USA continental shelf is thin and discontinuous. Much of the Holocene sediment in nearshore areas is reworked or removed by deep shoreface scour during the Holocene transgression. Shallow paralic sand-bodies that form between the basal and ravinement unconformities are partially erased by the retreating Holocene shoreface. In tide-dominated regions of the coast, lagoonal channels are deepened by swift, tidal currents. Deepening further enhances the topographic relief of the antecedent surface. During transgression the topographically higher parts of the surface are most susceptible to removal by shoreface wave-action while the deeper areas are filled and preserved. Tidal enhancement of channels also takes place at ebb tidal-deltas where ‘spillover’ and distributary channels cut and fill into shallow shoreface deposits.