Impact of tectonic and volcanism on the Neogene evolution of isolated carbonate platforms (SW Indian Ocean)

Courgeon, Simon; Jorry, Stéphan; Jouet, Gwénaël; Camoin, Gilbert; BouDagher‐Fadel, Marcelle K.; Bachèlery, Patrick; Caline, Bruno; Boichard, R.; Révillon, Sidonie; Thomas, Y.; Thereau, Estelle; Guérin, Charline

doi:10.1016/j.sedgeo.2017.04.008

Cited by 44 publications

(66 citation statements)

References 93 publications

(103 reference statements)

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“…In contrast to Bassas da India, the Sakalaves Seamount, Hall Bank and Jaguar Bank drowned during the Upper Miocene–Lower Pliocene (Courgeon et al ., ). Therefore, it is very unlikely that the observed sediment bodies are the remains of sand produced when the platforms were active and close to the sea surface.…”

Section: Discussionmentioning

confidence: 97%

“…The initiation of shallow‐water carbonate sedimentation is thought to have taken place at the Sakalaves Seamount and in the Southern Mozambique Channel during Oligocene and Early Miocene times, respectively (Courgeon et al ., ). 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%

“…Hall Bank has a relatively homogeneous flat top, only interrupted by a 2 km wide flat‐bottomed depression at the north‐western part, which is interpreted as a volcanic crater (Courgeon et al ., ). Sediment has only accumulated in the northern part of the depression (characterized by low backscatter; Fig.…”

Section: Sediment Distributionmentioning

confidence: 97%

“…The blue arrows show the migration of the dunes interpreted from the dune asymmetry. Faults are represented with white dashed lines (based on Courgeon et al ., , ). T1: shallow terrace (200 to 240 m).…”

Section: Sediment Distributionmentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 97%

Section: Regional Settingmentioning

confidence: 97%

Section: Sediment Distributionmentioning

confidence: 97%

Section: Sediment Distributionmentioning

confidence: 99%

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

et al. 2019

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“…Tracing the stratigraphic distribution of the larger benthic foraminifera allows the understanding of the impact of climate, tectonic activity and volcanism on long-term (i.e. millions years) evolution of these shallow-water carbonate platforms (Courgeon et al, 2016(Courgeon et al, , 2017Gold et al, 2017aGold et al, , 2017b. Larger foraminifera and planktonic foraminifera overlap in occurrence in many localities allowing direct comparison of larger foraminifera "letter stages" biozones with oceanic planktonic scales (BouDagher-Fadel, 2002;BouDagher-Fadel, 2013, 2015Sharaf et al, 2013).…”

Section: Biostratigraphy and Phylogenetic Evolutionmentioning

confidence: 99%

Evolution and Geological Significance of Larger Benthic Foraminifera

2018

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Mantle xenolith-bearing phonolites and basanites feed the active volcanic ridge of Mayotte (Comoros archipelago, SW Indian Ocean)

Berthod

Médard

Muro

et al. 2021

Contrib Mineral Petrol

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Since 2018, the submarine east flank of Mayotte Island (Comoros archipelago) is the 24 site of a major and still ongoing eruption, located at 3.5 km depth bsl on a WNW-ESE 25 volcanic ridge. Oceanographic cruises carried out to monitor this seismo-volcanic crisis 26 allowed us to determine that this volcanic ridge is built by a bimodal sodic alkaline magmatic 27 series that includes basanites and phonolites. A petrological study of dredged samples allowed 28 us to image the magmatic system feeding the volcanic ridge and to determine the link 29 between basanitic and phonolitic magmas. The magmatic system feeding the volcanic ridge 30 comprises multiple levels of magma storage. Basanitic magmas generated at 80-100 km 31 mantle depth are stored in one or more deep reservoir(s) (≥ 37 km) and then in shallower 32 ManuscriptClick here to access/download;Manuscript;Manuscript.pdf Click here to view linked References -2 -basanitic and phonolitic lenses located close to the Moho interface before rising the surface. 33This study identifies three possible scenarios: (1) the deep basanitic magma rises directly and 34 quickly to the surface from the deep mantle reservoir (as is currently happening 60 km 35 offshore), (2) the basanitic magma stalls in a shallower reservoir near the Moho before 36 resuming its ascent toward the surface and erupting as porphyritic basanite, (3) the basanitic 37 magma stops and evolves to phonolite in these sub-crustal reservoirs. The phonolitic lavas are 38 produced by approximately 80% fractional crystallization (34% clinopyroxene, 30% 39 anorthoclase feldspar, 15.5% magnetite, 12.5% olivine, 5% apatite and 4% ilmenite) of a 40 hydrous basanitic magma at mantle depths (P > 0.6 GPa) under reduced oxygen fugacity 41 (~FMQ-1). In this third scenario, the phonolitic magma might be reactivated by the arrival of 42 a new batch of deeper basanitic magma. 43 44The deepest part (3.5 km bsl) of the eastern submarine flank of Mayotte is the site of a 47 long lasting and still ongoing (as of January 2021) effusive volcanic activity that followed an 48

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Impact of tectonic and volcanism on the Neogene evolution of isolated carbonate platforms (SW Indian Ocean)

Abstract: Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.

Cited by 44 publications

References 93 publications

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

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

Evolution and Geological Significance of Larger Benthic Foraminifera

Mantle xenolith-bearing phonolites and basanites feed the active volcanic ridge of Mayotte (Comoros archipelago, SW Indian Ocean)

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