High-resolution sequence stratigraphy of fluvio–deltaic systems: Prospects of system-wide chronostratigraphic correlation

A basin-scale numerical model with a sub-grid parameterization of fluvio–deltaic processes and stratigraphy was used to study the relation between alluvial sedimentation and marine deltaic deposition under conditions of time-invariant forcing. The experiments show that delta evolution is governed by a robust morphodynamic feedback loop, which provides a link between major avulsions, delta-lobe switches, and sequestration of sediments on the delta plain. Major avulsions, driven by local superelevation, result in abandonment of delta lobes and initiation of new lobes. Progradation of the delta front lengthens the fluvial profile and reduces its gradient, which induces aggradation upstream. The aggradation, in turn, causes local superelevation of the channel belt. Each major avulsion causes a wave of incision to migrate upstream, whereas downstream of the avulsion point, the rate of aggradation temporarily increases until a new equilibrium situation has been established. The feedback loop explains storage and release of fluvial sediments without the need to invoke changes in upstream or downstream controls and provides a plausible mechanism for the generation of high-frequency incision–aggradation cycles as the sole result of compensational stacking.