Volumetric budget calculation of sediment and carbon storage and export for a late Holocene mid-shelf mudbelt system (NW Iberia)

Oberle, Ferdinand K. J.; Hanebuth, Till J J; Baasch, Benjamin; Schwenk, Tilmann

doi:10.1016/j.csr.2013.12.012

Cited by 22 publications

(10 citation statements)

References 68 publications

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“…This proved that waves and currents had enough energy to resuspend surface sediments into the water column under highly hydrodynamic conditions. This explains the near absence of fine sediment on the NW Iberian inner shelf, as previously observed by other studies in which the study area was described principally by the presence of rocky outcrops and, to a lesser extent, sandy mud patches with developed bedforms such as large‐wave ripples (see Figure b; López‐Jamar et al, ; Dias, González, et al, ,Dias, Jouanneau, et al, ; Oberle, Storlazzi, et al, ,Oberle, Hanebuth, et al, ). Based upon these observations, the NW Iberian inner shelf should be defined as a high resuspension inner shelf area (HRISA).…”

Section: Discussionsupporting

confidence: 83%

“…These rivers have been significantly modified by the construction of numerous dams that drastically diminish the particulate matter supply (Jouanneau et al, ). Sediment distribution is dominated by the Galician and Muros mud belts, mud patches, or depocenters situated between 100 and 120 m in the central part of the Rias Baixas area (Dias, González, et al, , Dias, Jouanneau, et al, ; Lantzsch et al, ; Oberle, Storlazzi, et al, , Oberle, Hanebuth, et al, ). A more detailed geomorphological description can be found in Van Weering et al ().…”

Section: Methodsmentioning

confidence: 99%

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Bottom Boundary Layer and Particle Dynamics in an Upwelling Affected Continental Margin (NW Iberia)

et al. 2019

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The dynamics of the bottom boundary layer and their effects on the development of nepheloid layers (NLs) on a high-energy and upwelling-affected margin, the NW Iberian continental shelf, were studied by means of ADP currents, wave time series, and across-shelf hydrographic surveys covering an entire annual cycle. The bottom boundary layer hydrodynamics showed that high levels of bottom shear stress over the inner shelf occurred mainly during downwelling seasons, when there was a coupling between storm waves and intense currents. This wave-current coupling promotes strong resuspension events that favored the generation of bottom NLs (BNLs). BNLs were well developed on the inner continental shelf inshore of a thermohaline front generated by the interaction of the Iberian Poleward Current and the West Iberian Buoyant Plume. The existence of this front limited the extent of offshore export of resuspended particles during the downwelling season. In contrast, during the upwelling season, only thin BNLs were developed, and surface NLs, principally composed by biogenic particulate material, were advected offshore in the Ekman layer, often as part of the development of upwelling filaments. Our study confirmed that wave orbital velocity under stormy conditions, in combination with the hydrography, could explain the shoreward boundary of the Galician mud depocenter.Plain Language Summary This manuscript mainly focuses on hydrodynamics of the bottom boundary layer and the effect of wave-current bottom shear stress on the development and modulation of nepheloid layers on the NW Iberia continental shelf during more than 1 year. During this period, we analyze the role of hydrographic seasonality of this coastal upwelling system in the behavior of nepheloid layers and the possible offshore export pathways of particulate matter to the adjacent ocean. In addition, wave climate over the continental shelf was analyzed together with this hydrographic context in order to explain the surface sediment distribution.

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Section: Discussionsupporting

confidence: 83%

Section: Methodsmentioning

confidence: 99%

Bottom Boundary Layer and Particle Dynamics in an Upwelling Affected Continental Margin (NW Iberia)

et al. 2019

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“…The suspended particle flux across the shelf edge off Galicia results mainly from an episodic winddriven downwelling which occurs predominantly during winter season (McCave and Hall, 2002;Oliveira et al, 2002;Varela et al, 2005). Remobilization of sand is, in contrast, related to wave-base action and is restricted to the inner-middle shelf zone Lantzsch et al, 2009Lantzsch et al, , 2010Oberle et al, 2014).…”

Section: The Sedimentary Systemmentioning

confidence: 96%

“…About 65% of the 2.25 Mt of sediments annually discharged by the regional NW Iberian rivers are supplied to the deep ocean Oberle et al, 2014). The suspended particle flux across the shelf edge off Galicia results mainly from an episodic winddriven downwelling which occurs predominantly during winter season (McCave and Hall, 2002;Oliveira et al, 2002;Varela et al, 2005).…”

Section: The Sedimentary Systemmentioning

confidence: 99%

Oceanic density fronts steering bottom-current induced sedimentation deduced from a 50 ka contourite-drift record and numerical modeling (off NW Spain)

Hanebuth

Zhang

Hofmann

et al. 2015

Quaternary Science Reviews

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“…MDCs often appear in the form of elongated belts and are highly vulnerable to environmental changes [ Gao and Collins , ]. Thus the sedimentary history preserved in MDCs contains valuable information for material budgeting of the global source‐to‐sink system and environmental variability [e.g., Naughton et al ., ; Sommerfield and Wheatcroft , ; Hanebuth and Lantzsch , ; Oberle et al ., ]. Despite their remarkable potential as environmental archives and their critical role for the global source‐to‐sink system, the driving forces that control formation and evolution of MDCs are still poorly understood [ Walsh and Nittrouer , ; Gao and Collins , ].…”

Section: Introductionmentioning

confidence: 99%

Storm‐driven bottom sediment transport on a high‐energy narrow shelf (NW Iberia) and development of mud depocenters

et al. 2016

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Bottom sediment transport on the NW Iberian shelf was monitored during a downwelling storm in September 2014. Collected data were analyzed and fed into a 3-D coastal ocean model to understand storm-driven sediment transport on the shelf and its impact on midshelf mud depocenters (MDCs). A significantly enhanced level of bottom sediment resuspension, nearly two orders of magnitude higher than that in the prestorm period, was recorded at the mooring site. Field data analysis reveals that it was induced by a short-lasting strong bottom current in combination with enhanced wave-current interaction. Simulation results indicate that this strong current was part of a coastal jet resulted from downwelling. An across-shelf horizontal density gradient as high as 0.32 g/m 4 occurred at the interface between the downwelling and the bottom waters, forming a remarkable front. Due to buoyancy effect, the downwelling water was mostly confined to the coast with a depth limit of 80 m in the south and 120 m in the north of the region, resulting in a northward-directed coastal jet. Simulation results suggest that during the storm, local near-bottom sediment suspensions with concentrations on the order of 10 kg/m 3 would be triggered by wave-current interaction and flow convergence associated with the front. Direct impact on the development of MDCs by transport and deposition of concentrated sediment suspensions is indicated by model results. The seaward limit of the front coincided with the shoreward edge of the MDC nucleus, suggesting the front as a primary control on the deposition of fine-grained sediment.

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Volumetric budget calculation of sediment and carbon storage and export for a late Holocene mid-shelf mudbelt system (NW Iberia)

Cited by 22 publications

References 68 publications

Bottom Boundary Layer and Particle Dynamics in an Upwelling Affected Continental Margin (NW Iberia)

Bottom Boundary Layer and Particle Dynamics in an Upwelling Affected Continental Margin (NW Iberia)

Oceanic density fronts steering bottom-current induced sedimentation deduced from a 50 ka contourite-drift record and numerical modeling (off NW Spain)

Storm‐driven bottom sediment transport on a high‐energy narrow shelf (NW Iberia) and development of mud depocenters

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