Exploring the Effects of Base-level Change and Differential Subsidence on Fluviodeltaic Channels with a Reduced-Complexity Model

Abstract:

Understanding the interplay between fluviodeltaic channel dynamics and external forcings is fundamental to our interpretation of stratigraphic records. While there have been great advances in subjects such as the effects of tectonic steering and base-level variation through field campaigns and physical experiments, numerical modeling has been relatively under-developed. This is partly due to the lack of models that are able to produce emergent channel dynamics, respond physically to various boundary conditions, and run efficiently over geological timescales.

In this work we apply a reduced-complexity model which satisfies the above criteria, DeltaRCM, to study how channel dynamics in a depositional system are affected by two factors: differential subsidence and base-level variation. In particular we investigate: (1) the changes in channel mobility with base-level rise; (2) how the fluvial surface is reworked with a set of tectonic styles and base-level cycles; (3) the preservation potential of the surface channel network in the sedimentary record. We present comparisons between our model results and physical experiments, with a discussion on the applicability of our reduced-complexity approach. An application on the Ganges-Brahmaputra-Jamuna Delta shows how the model can be used as a tool for hypothesis formulation.