RATES OF DELTA PROGRADATION DURING HIGHSTANDS - CONSEQUENCES FOR TIMING OF DEPOSITION IN DEEP-MARINE SYSTEMS

Estimated times required for 24 modern river systems to form a shelf-e dge delta range from 8.5 ka to 116.5 ka, depending on fluvial sediment supply, delta width, shelf volume and shelf transport rates. These va lues indicate that transport of sand into deep-marine systems is likel y to be significant during third-order highstands of relative sea-leve l. Factors such as shelf transport dynamics may slow delta progradatio n while submarine canyons cutting the shelf may reduce the rime before deep-marine deposition occurs. Interpreting ancient sand-rich deep-ma rine strata as lowstand deposits without sufficient palaeogeographic i nformation may not therefore always be appropriate.