Active fault system across the oceanic lithosphere of the Mozambique Channel: Implications for the Nubia–Somalia southern plate boundary

Deville, É.; Marsset, Tania; Courgeon, Simon; Jatiault, Romain; Ponte, Jean-Pierre; Thereau, Estelle; Jouet, Gwénaël; Jorry, Stéphan; Droz, Laurence

doi:10.1016/j.epsl.2018.08.052

Cited by 39 publications

(51 citation statements)

References 48 publications

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“…This is probably due to the fact that faults offsets have been erased by incisions, indicating that the observed thalweg incisions post-date the activity of these faults. As it is being supposed that the faults remained active (or were reactivated) very recently (Deville et al, 2018), we can infer that the thalweg incisions are currently active.…”

Section: Accepted Manuscriptmentioning

confidence: 90%

“…The valley deflects towards the south when it approaches the Davie Ridge and passes through a Miocene fault zone, still active today (hatched in Fig. 1B) identified by Courgeon et al (2017) and Deville et al (2018) as a prolongation of the eastern branch of the East African Rift System. The valley flows thereon east of the Eparses carbonate platforms (Courgeon et al, 2016).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…to Pliocene sediments and resulted in the confinement of turbidites upstream the structural dome (Ponte, 2018).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

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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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Section: Accepted Manuscriptmentioning

confidence: 90%

Section: Accepted Manuscriptmentioning

confidence: 99%

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

et al. 2019

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“…Carbonate rocks affected by faulting and rock fall may be weaker, and thus more susceptible to submarine erosion. The recent activity of the normal faults and their associated seismicity (Deville et al ., ), may have fractured these carbonates and thus favoured sand production. Continuous erosion of the carbonates after the drowning of the platform may therefore have important implications for carbonate preservation in areas of intense oceanic circulation.…”

Section: Discussionmentioning

confidence: 99%

“…The major drowning events occurred during the Upper Miocene–Lower Pliocene, and probably were triggered by extensional tectonic deformation and/or renewed volcanism (Courgeon et al ., ). The tectonic and volcanic activities that affected the seamounts and the associated isolated carbonate platforms were probably related to the development of the East African Rift System (Courgeon et al ., , ; Deville et al ., ).…”

Section: Regional Settingmentioning

confidence: 97%

Deep‐water dunes on drowned isolated carbonate terraces (Mozambique Channel, south‐west Indian Ocean)

et al. 2019

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Subaqueous sand dunes are common bedforms on continental shelves dominated by tidal and geostrophic currents. However, much less is known about sand dunes in deep-marine settings that are affected by strong bottom currents. In this study, dune fields were identified on drowned isolated carbonate platforms in the Mozambique Channel (south-west Indian Ocean). The acquired data include multibeam bathymetry, multi-channel high-resolution seismic reflection data, sea floor imagery, a sediment sample and current measurements from a moored current meter and hullmounted acoustic Doppler current profiler. The dunes are located at water depths ranging from 200 to 600 m on the slope terraces of a modern atoll (Bassas da India Atoll) and within small depressions formed during tectonic deformation of drowned carbonate platforms (Sakalaves Seamount and Jaguar Bank). Dunes are composed of bioclastic medium size sand, and are large to very large, with wavelengths of 40 to 350 m and heights of 0Á9 to 9Á0 m. Dune migration seems to be unidirectional in each dune field, suggesting a continuous import and export of bioclastic sand, with little sand being recycled. Oceanic currents are very intense in the Mozambique Channel and may be able to erode submerged carbonates, generating carbonate sand at great depths. A mooring located at 463 m water depth on the Hall Bank (30 km west of the Jaguar Bank) showed vigorous bottom currents, with mean speeds of 14 cm sec À1 and maximum speeds of 57 cm sec À1 , compatible with sand dune formation. The intensity of currents is highly variable and is related to tidal processes (high-frequency variability) and to anticyclonic eddies near the seamounts (low-frequency variability). This study contributes to a better understanding of the formation of dunes in deep-marine settings and provides valuable information about carbonate preservation after drowning, and the impact of bottom currents on sediment distribution and sea floor morphology.

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Volcanoes at Divergent Plate Boundaries

Acocella

2021

Volcano-Tectonic Processes

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Active fault system across the oceanic lithosphere of the Mozambique Channel: Implications for the Nubia–Somalia southern plate boundary

Cited by 39 publications

References 48 publications

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

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

Deep‐water dunes on drowned isolated carbonate terraces (Mozambique Channel, south‐west Indian Ocean)

Volcanoes at Divergent Plate Boundaries

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