Preservation of meander channel and scour features under aggradational and non-aggradational conditions

Abstract

The internal architecture of channel belts commonlyconsists of channel-form bounding surfaces due to channelmigration and scouring (e.g. Miall, 1985). These boundingsurfaces are essential to our reconstructions of palaeochannel dimensions. It is therefore crucial tounderstand the suite of processes that form and transferthese surfaces into the fluvial rock record. Quantitativetheoretical relations have been derived between fluvialsurface processes and the formation of channel boundingsurfaces in the subsurface (e.g. Paola & Borgman, 1991). These indicate that the balance between lateral channelmigration and aggradation rate determines boundingsurface formation. How large the aggradation rate needs tobe to have a notable impact on bounding surfaceformation and how this affects preservation is currently notwell understood. While these subsurface bounding surfacesare straightforward to measure from the sedimentaryrecord and thus to characterize as a probability distribution,the conditions that formed these surfaces are unknown. The objective of this study is to quantify the relationbetween meander surface morphodynamics and theresulting meander belt internal architecture duringaggradation in contrast to non-aggradational conditions.