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

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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 ocean. The complex history of degradation, aggradation, and lateral migration of submarine channels are recorded in channel belt deposits that include channel and overbank deposits. Previous work drawing on seismic, outcrop, and modeled examples of submarine channel belts 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 (i.e., a ‘J’ shape). The processes that drive these changes in channel trajectory and their stratigraphic consequences remain poorly constrained. Furthermore, comparisons/contrasts between submarine channels and rivers are often focused on planform data and do not take into account the variability in channel trajectory/mobility, which clearly affects the resultant stratigraphic architecture. This study compiles >320 channel trajectory and geometry measurements from a global sampling of 21 submarine systems and 13 fluvial systems. Derived from seismic and outcrop cross sections, these data enable the quantitative treatment of the temporal evolution of channel trajectory and mobility as well as highlighting key similarities and 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 similar temporal evolution, but with ∼2x larger mobility values and ∼5x less aggradation (normalized to channel depth). Fluvial channel belts contain a large proportion of lateral migration deposits and have similar trajectories as early phase or degradational submarine channels, while late stage or aggradational submarine channel belts contain significantly more vertically stacked channel fill deposits. These submarine trajectory and 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 systems. These data constrain submarine channel evolution in a broader and more system-wide context, and also serve as valuable inputs for reservoir modelling.