Zambezi continental margin: compartmentalized sediment transfer routes to the abyssal Mozambique Channel

Wiles, Errol; Green, Andrew N.; Watkeys, M. K.; Jokat, Wilfried

doi:10.1007/s11001-016-9301-4

Cited by 28 publications

(45 citation statements)

References 40 publications

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“…10c). This supports the recent hypothetical models that propose a northward transport of a significant fraction of sediment load over the shelf based on short sediment core data (Schulz et al 2011) and a compartmentalized tripartite regime supplying sediments into the Angoche Basin, the Bourcart-Hall Depression and the Zambezi Valley-Channel (Wiles et al 2017). This study along with other recent studies supports the hypothesis of Droz and Mougenot (1987) that a large fraction of the sediments bypass the shelf and flow south directly into the Mozambique Channel.…”

Section: Present-day Source To Sink Pathwaysupporting

confidence: 88%

“…However, the continuations of these valleys are beyond the resolution of the bathymetry. The last 20,000 years of have been strongly affected by sea level rise and flooding of the shelf transporting sediment further northwards on the shelf (Schulz et al 2011;Van der Lubbe et al 2014;Wiles et al 2017). If similar conditions also existed during the Pliocene then canyons would have been starved of sediments during sea level lowstand causing the inactivity in the Zambezi Valley.…”

Section: Late Miocene-pliocene/pleistocene Development Of the Zambezimentioning

confidence: 99%

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Response of Cenozoic turbidite system to tectonic activity and sea-level change off the Zambezi Delta

2017

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Section: Present-day Source To Sink Pathwaysupporting

confidence: 88%

Section: Late Miocene-pliocene/pleistocene Development Of the Zambezimentioning

confidence: 99%

Response of Cenozoic turbidite system to tectonic activity and sea-level change off the Zambezi Delta

2017

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“…At present the Zambezi submarine system is not directly connected to the river system (Schulz et al, 2011). The sediment is mainly dispersed by alongshore currents on the continental shelf during sea level high-stands (Schulz et al, 2011;Wiles et al, 2017a).…”

Section: Geological Settingmentioning

confidence: 99%

The influence of bottom currents on the Zambezi Valley morphology (Mozambique Channel, SW Indian Ocean): In situ current observations and hydrodynamic modelling

et al. 2019

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Mixed turbidite-contourite systems can be found in oceans where bottom currents and turbidity currents interact. The Zambezi turbidite system, located in the Mozambique Channel (SW Indian Ocean), is one of the largest sedimentary systems in the world in length and area of the related catchments. The oceanic circulation in the Mozambique Channel is intense and complex, dominated by eddies flowing southwards and deep currents flowing northwards along the Mozambican margin. Current measurements obtained from moorings at 3400-4050 m water depth in the Zambezi and Tsiribihina valleys show periods of intense currents at the seafloor with peaks of 40-50 cm s−1 that last up to one month and are not related to turbidity currents. These strong bottom-current events are correlated with a change in current direction and an increase in temperature. The periods of current intensification may be related to eddies, since they present similar frequencies (around 7 per year). Moreover, modelling results show that during periods of intense deep circulation an anticyclonic eddy is present between the Mozambican slope and the centre of the Mozambique Channel, which may block the northward transport of the deep water mass and thus enhance the southward transport along the western slope of Madagascar. According to our hydrodynamic modelling of the circulation near the seafloor, intense currents are often present along the Zambezi Valley, especially along the valley flanks. Multi-channel seismic reflection data show that the Zambezi turbidite system does not show the typical characteristics of turbidite systems, being dominated by erosional processes, which mainly affect the valley flanks. Levees associated with the valley are absent in the main axis of the system. The effect of bottom currents on sedimentation in the basin is evidenced by the low sedimentation rates that witness winnowing in the basin, the presence of contouritic sand in the Zambezi Valley flanks and the abundance of current-related bedforms observed in multibeam bathymetry and seismic data. The intense oceanic processes observed in the Mozambique Channel may transport a large part of the fine sediment out of the basin and erode the seafloor even at great depths. Therefore, the Zambezi turbidite Highlights ► In situ measurements and modelling show strong currents along the Zambezi Valley. ► Measured bottom currents in the Zambezi and Tsiribihina Valleys reach 53 cm s −1. ► Eddies block the Mozambique Undercurrent, enhancing southward flow along the valley. ► Bottom currents erode the Zambezi Valley flanks and control its morphology.

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“…More recently, scientific interest has increased considerably for the Zambezi turbidite system and new results based on higher resolution data sets were presented. Specific attention was paid to the transport of sediments on the upper margin (Schulz et al, 2011) and their delivery to the abyssal plain (Wiles et al, 2017a), the morphological character of the Zambezi Valley (Wiles et al, 2017b) and the influence of bottom currents on the seafloor morphology (Breitzke et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Late Quaternary geomorphology and sedimentary processes in the Zambezi turbidite system (Mozambique Channel)

et al. 2019

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The morphology and present-day sediment distribution of the Zambezi turbidite system was investigated using new bathymetric and sub-bottom profiler data as part of the PAMELA research project. The Zambezi turbidite system is composed of two depositional systems: a channelized fan (the Zambezi Fan) and a semi-confined fan (in the lntermediate Basin). The Zambezi Fan includes the Zambezi Valley, which is deeply incised in the Mozambique Channel and is more than three times as large and deep as the great Tanzanian and North Atlantic Mid-Ocean channels. The erosion in the Zambezi Valley is evidenced by its V-shaped morphology and the existence of a U-shaped thalweg affected by several generations of incisions. Based on echo facies and cores from literature, sediments of the Zambezi Fan are dominantly coarse-grained and fine-grained overbank deposits are infrequent. The distal portion of the Zambezi Fan is a main depositional area where typical transparent wedged-shape seismic bodies are interpreted as terminal lobes. Seismic facies in the Intermediate Basin are thought to represent mostly fine-grained turbidites intercalated with infrequent coarse-grained sheet-like turbidites. Hydrodynamic circulation (from surface eddies to the deep circulation of NADW) appears to have a great impact on the Mozambique Channel sedimentation and is suggested (1) to be involved in the delivery of the Zambezi River sediments along the Mozambique margin, (2) to entrain the upper suspended load of turbidity currents, contributing to the absence of fine-grained sedimentation and (3) to contribute to the erosion of the valley flanks leading to the exceptionally great dimensions of the valley. Highlights ► The Zambezi turbidite system comprises a channelized fan and a semi-confined fan. ► The Zambezi Valley has an atypical morphology compared to other turbidite systems. ► Erosional processes dominate in the valley. ► From echo facies, deposition appears mainly fine-grained in the semiconfined fan. ► Oceanic and turbidity currents control sediment distribution and erosion.

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Zambezi continental margin: compartmentalized sediment transfer routes to the abyssal Mozambique Channel

Cited by 28 publications

References 40 publications

Response of Cenozoic turbidite system to tectonic activity and sea-level change off the Zambezi Delta

Response of Cenozoic turbidite system to tectonic activity and sea-level change off the Zambezi Delta

The influence of bottom currents on the Zambezi Valley morphology (Mozambique Channel, SW Indian Ocean): In situ current observations and hydrodynamic modelling

Late Quaternary geomorphology and sedimentary processes in the Zambezi turbidite system (Mozambique Channel)

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