Modern River Deltas: Variability of Processes and Sand Bodies

Abstract Depositional facies in deltaic sediments result from interacting dynamic processes (climate, hydrologic characteristics, wave energy, tidal action, etc.) which modify and disperse transported riverine sediment. These processes, which vary in both intensity and frequency, control the eventual sedimentary framework of a delta. Approximately 400 similar process and form parameters were compared in 50 significant deltas to investigate the differences among the deltas and to generate distinctive deltaic frameworks. In addition, field studies were conducted in 16 of the deltas to field check the data and to gather additional subsurface and spatial data. The results of this study indicated that no one delta model could be formulated to use as a basis for predicting vertical sequences in all of the deltas. The study also indicated that sand-body distribution, geometry, and characteristics are primarily a function of wave-energy distributions, river-mouth dynamics, subsidence, and alongshore currents. The following deltas are used as examples in illustrating the common deltaic vertical sequences: Mississippi, Klang, Ord, Burdekin, Sao Francisco, and Senegal.