Submarine channel stacking patterns controlled by the autogenic 3D kinematics of meander bends

Abstract

Abstract Channel kinematics play a pivotal but underappreciated role in determining submarine meandering channel stacking patterns. A stratigraphic forward model is here applied to turbidite systems to generate synthetic stratigraphic architectures and to compare channel trajectories recorded on cross-sections with the kinematics of meander bends. Various channel stacking patterns, which may be classified into four types, are obtained from a single set of constant parameters. This variety of stacking patterns observed from one 2D section to another is thus autogenic. It is the consequence of the 3D migration of meander bends. It reflects the number of consecutive bends that have intercepted the cross-section, which depends on the channel downstream migration rate. These 3D effects alone are sufficient to explain variations in the apparent migration rate and the reversal of migration direction. As a result, sigmoidal geometries can be preserved in aggrading systems without a significant change in channel geometry or varying aggradation and migration rates. Finally, despite these 3D effects, stratigraphic mobility numbers still provide good constraints on bend kinematics. These results should apply to meandering rivers and other meandering systems.