Temporal Evolution of Submarine Channel Trajectory and Mobility: Quantitative Analysis and Comparison to Rivers

Abstract:

Submarine channels are the primary conduits for the transport of clastic detritus from the continents into the deep sea. During their evolution, these channels migrate, forming channel belts that record a complex history of vertical degradation, lateral migration, and vertical aggradation. Previous work drawing on seismic, outcrop, and modeled examples of submarine channel systems have qualitatively observed a significant component of vertical aggradation and a temporal trend transitioning from a phase dominated by lateral migration to one dominated by vertical aggradation. The processes that drive these changes in channel trajectory and their stratigraphic consequences remain poorly constrained. Furthermore, comparisons/contrasts between submarine channels and rivers often do not take into account the variability in channel trajectory/mobility, which clearly affects the resultant architecture.

This study compiles a global dataset of >320 channel trajectory and geometry measurements derived from a global suite 2-D cross sections including 21 submarine channel systems and 13 fluvial systems. These data enable the quantitative treatment of the temporal evolution of channel trajectory/mobility as well as highlighting key differences between submarine channels and rivers.

Submarine channels show a strong trend of decreasing channel mobility during their evolution, resulting in early stage lateral migration and late stage aggradation. Fluvial channels show a similar evolution, but with ~5x less aggradation and ~2x larger mobility values. Fluvial channel belts contain a large proportion of lateral accretion and have similar trajectories as early phase or degradational submarine channels, while late stage or aggradation submarine channel belts contain significantly more vertically stacked channel fill deposits. These submarine trajectory/mobility measurements provide a valuable quantitative basis for explaining the evolution of stratigraphic architecture of submarine channel systems and how it differs from channelized fluvial architecture. These data also help to constrain submarine channel evolution in a broader and more system-wide context.