Worldwide Initiation of Holocene Marine Deltas by Deceleration of Sea-Level Rise

Radiocarbon-dated deltaic sequences of Holocene age from different parts of the world began to accumulate within a restricted time range, from about 8500 to 6500 years ago. Evaluation of major delta processes indicates that deceleration in sea-level rise was the key factor in Holocene delta formation. Within many deltas, there is as much as a 2000-year age range between basal deposits in seaward and landward cores. This age difference records the progressive landward migration of near mean sea-level depositional environments during the lower to mid-Holocene. Establishment of a chronostratigraphic framework for Holocene delta development provides a fundamental global baseline for distinguishing sea-level change from vertical land motion by tectonism and isostasy, and for evaluating rates of future marine incursion into low-lying deltas.