Eddy-Driven Sediment Transport in the Argentine Basin: Is the height of the Zapiola Rise hydrodynamically controlled?

TitleEddy-Driven Sediment Transport in the Argentine Basin: Is the height of the Zapiola Rise hydrodynamically controlled?
Publication TypeJournal Article
Year of Publication2015
JournalJournal of Geophysical Research
Volume120
Date Published02/2015
Abstract / Summary

In this study we address the question whether eddy-driven transports in the Argentine Basin can be held responsible for enhanced sediment accumulation over the Zapiola Rise, hence accounting for the existence and growth of this sediment drift. To address this question, we perform a 6-year simulation with a strongly eddying ocean model. We release two passive tracers, with settling velocities that are consistent with silt and clay size particles. Our experiments show contrasting behavior between the silt fraction and the lighter clay. Due to its larger settling velocity, the silt fraction reaches a quasi-steady state within a few years, with abyssal sedimentation rates that match net input. In contrast, clay settles only slowly, and its distribution is heavily stratified, being transported mainly along isopycnals. Yet, both size classes display a significant and persistent concentration minimum over the Zapiola Rise.We show that the Zapiola Anticyclone, a strong eddy-driven vortex that circulates around the Zapiola Rise, is a barrier to sediment transport, and hence prevents significant accumulation of sediments on the Rise. We conclude that sediment transport by the turbulent circulation in the Argentine Basin alone cannot account for the preferred sediment accumulation over the Rise. We speculate that resuspension is a critical process in the formation and maintenance of the Zapiola Rise.

URLhttp://onlinelibrary.wiley.com/doi/10.1002/2014JC010573/full
DOI10.1002/2014JC010573
Journal: Journal of Geophysical Research
Year of Publication: 2015
Volume: 120
Date Published: 02/2015

In this study we address the question whether eddy-driven transports in the Argentine Basin can be held responsible for enhanced sediment accumulation over the Zapiola Rise, hence accounting for the existence and growth of this sediment drift. To address this question, we perform a 6-year simulation with a strongly eddying ocean model. We release two passive tracers, with settling velocities that are consistent with silt and clay size particles. Our experiments show contrasting behavior between the silt fraction and the lighter clay. Due to its larger settling velocity, the silt fraction reaches a quasi-steady state within a few years, with abyssal sedimentation rates that match net input. In contrast, clay settles only slowly, and its distribution is heavily stratified, being transported mainly along isopycnals. Yet, both size classes display a significant and persistent concentration minimum over the Zapiola Rise.We show that the Zapiola Anticyclone, a strong eddy-driven vortex that circulates around the Zapiola Rise, is a barrier to sediment transport, and hence prevents significant accumulation of sediments on the Rise. We conclude that sediment transport by the turbulent circulation in the Argentine Basin alone cannot account for the preferred sediment accumulation over the Rise. We speculate that resuspension is a critical process in the formation and maintenance of the Zapiola Rise.

DOI: 10.1002/2014JC010573
Citation:
Weijer, W, ME Maltrud, WB Homoky, KL Polzin, and LR Maas.  2015.  "Eddy-Driven Sediment Transport in the Argentine Basin: Is the height of the Zapiola Rise hydrodynamically controlled?"  Journal of Geophysical Research 120.  https://doi.org/10.1002/2014JC010573.