WORLDWIDE INITIATION OF HOLOCENE MARINE DELTAS BY DECELERATION OF SEA-LEVEL RISE

Radiocarbon-dated deltaic sequences of Holocene age from different par ts of the world began to accumulate within a restricted time range, fr om about 8500 to 6500 years ago. Evaluation of major delta processes i ndicates that deceleration in sea-level rise was the key factor in Hol ocene delta formation. Within many deltas, there is as much as a 2000- year age range between basal deposits in seaward and landward cores. T his age difference records the progressive landward migration of near mean sea-level depositional environments during the lower to mid-Holoc ene. Establishment of a chronostratigraphic framework for Holocene del ta development provides a fundamental global baseline for distinguishi ng sea-level change from vertical land motion by tectonism and isostas y, and for evaluating rates of future marine incursion into low-lying deltas.