Vertical movements and material transport during hotspot activity: Seismic reflection profiling offshore La Réunion

Voogd, B. de; Palomé, Salvador Pou; Hirn, A.; Charvis, Philippe; Muset, Josep Gallart; Rousset, D.; Dañobeitia, Juanjo; Perroud, H.

doi:10.1029/98jb02842

Cited by 53 publications

(80 citation statements)

References 38 publications

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“…Although the vertical movement of La Réunion Island is not quantifiable at this timescale, a limited subsidence is consistent with the subsidence rate related to thermal subsidence rate for an oceanic hotspot island, as estimated in Mauritius at 0.03 mm.yr -1 (Montaggioni and Faure, 1997). On a longer time scale (a few million years), the lack of significant subsidence of La Réunion volcanics is also emphasised by the fact that the lithosphere beneath La Réunion is not significantly flexed, instead of most oceanic volcanic islands, suggesting that another process compensates for the load of the volcanic construction (De Voogd et al, 1999).…”

Section: Shelf Break and Other Slope Changessupporting

confidence: 57%

Direct sediment transfer from land to deep-sea: Insights into shallow multibeam bathymetry at La Réunion Island

et al. 2013

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Submarine canyon heads are key areas for understanding the triggering factors of gravity currents responsible for the transfer of detrital sediment to the deep basins. This contribution offers a detailed picture of canyon heads off La Réunion Island, with high-resolution multibeam bathymetry in the water depth range of 4-220 m. The present feeding of the Cilaos turbidite system, one of the largest modern volcaniclastic systems in the world, is deduced from morphological and sedimentological interpretations of newly acquired data. The study highlights small-scale sedimentary features indicating hydrodynamic and sedimentary processes.A direct connexion between the Saint-Etienne river mouth and submarine canyons is evidenced by the complete incision of the shelf and the presence of canyon heads connected to the modern deltaic bar. This direct connection, supplied by river torrential floods (cyclonic floods every two or three years), suggests the continuity of high-density fluvial flows to submarine gravity flows, forming hyperpycnal flows in the canyon.The initiation of secondary submarine gravity flows by storm waves (large austral waves and cyclonic waves) is also proposed for submarine canyons with large canyon heads developed in the surf zone from a sandy coastal bar. Bedforms in active canyon axis are considered as an indicator of the frequent activity of high-density turbidity currents.Moreover, a morphological record of last glacial and deglacial sea level variations is preserved, and particularly the Last Glacial Maximum sea level with the presence of small vertical cliffs, observed in this bathymetric data, which likely corresponds to a paleo-shoreline or paleo-reefs.2

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Section: Shelf Break and Other Slope Changessupporting

confidence: 57%

Direct sediment transfer from land to deep-sea: Insights into shallow multibeam bathymetry at La Réunion Island

et al. 2013

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“…Large-scale flank collapse can transport 100-mto kilometer-scale megablocks into the moats (e.g., Moore et al, 1994). The moat has a maximum of 3 km thickness by up to 160 km width at Hawaii (e.g., ten Brink and Watts, 1985;Moore et al, 1994), a maximum of 455 m thickness by up to 250 km width at the Canary Islands (Collier and Watts, 2001;Gee et al, 2001), and a maximum of 520 m thickness by up to 130 km width at La Réunion island (southwestern Indian Ocean; de Voogd et al, 1999;Oehler et al, 2008) (widths as measured from Figure 1 and from Oehler et al [2008]). Relatively little sediment is deposited on the flanks of the actual seamounts; these are dominated by sediment erosion and bypass into the moat (Leslie et al, 2002).…”

Section: Discussion Of Formation Models and Comparison To Volcaniclasmentioning

confidence: 99%

“…Moat basins can accommodate the deposition of a thickness of up to 3 km of sediment from the adjacent seamounts through mass wasting of the igneous rocks and sedimentary cover (ten Brink and Watts, 1985). Even when a flexural moat is not obvious, major islands are typically surrounded by sedimentary debris aprons with up to 520-m-thick deposits extending >100 km away from the island (e.g., de Voogd et al, 1999). The subduction of a seamount chain's debris apron and/or moat sediments (hereafter referred to as "moat") offers a hitherto unconsidered opportunity for accretion of oceanic sediments at an otherwise "erosive" subduction margin.…”

Section: Introductionmentioning

confidence: 99%

Seamount chain–subduction zone interactions: Implications for accretionary and erosive subduction zone behavior

Clarke

Vannucchi

Morgan

2018

Geology

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Sediment volume at the trench and topographic highs on the incoming plate are two of the main factors controlling whether a forearc will undergo subduction erosion or accretion. On oceanic plates, topographic highs such as large seamount complexes are commonly associated with significant volumes of flanking volcaniclastic sediments in the form of >100-kmwide debris aprons, with the largest deposits found in flexural moat basins. We propose that subduction of these sediment accumulations promotes localized frontal accretion, even in otherwise non-accretionary margins. The Osa mélange in southwestern Costa Rica is a field example that provides new insights into the nature and occurrence of this interaction. The southwestern margin of Central America is punctuated by accreted Late Cretaceous-middle Eocene seamounts that formed at the Galápagos hotspot and accreted throughout the late Miocene. In contrast to most accreted seamounts along this margin, which retained their overall structure, the Osa mélange is a chaotic mixture of seamount lithologies. It consists of basalt, chert, and carbonate blocks in a fine-grained pelitic matrix composed predominantly of feldspar and pyroxene grains with rare quartz. This lithology is consistent with sediment from a seamount chain's debris apron, such as the Hawaiian moat sampled during Ocean Drilling Program (ODP) Leg 136 and the Canary Islands moat sampled by ODP Leg 157. Subduction of seamounts and their debris aprons promotes concurrent accretion and erosion over short distances along the trench. This introduces heterogeneity into the subduction channel, with implications for deformation within the subduction zone plate interface.

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“…In particular, recent geophysical studies have provided valuable data on the interior of the island through seismic de Voogd et al 1999;Gallart et al 1999), gravity (Malengreau et al 1999), and magnetic investigations (LØnat et al 2001). However, the geological structure and the evolution of this volcanic system remain insufficiently understood, partly due to a lack of studies on its submarine part.…”

Section: Introductionmentioning

confidence: 99%

Recurrence of major flank landslides during the last 2-Ma-history of Reunion Island

Oehler

Labazuy

Lénat³

2004

Bull Volcanol

100

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New detailed swath bathymetry and backscatter data corroborate the existence of four large bulges on the submarine flanks of Reunion Island. These fan-shaped promontories are 20-25 km wide at the coastline and 70-150 km across the seafloor 40-50 km offshore. Their surfaces are characterized by a speckle sonar pattern, indicating the presence of large blocks up to several hundred meters across. Each bulge results from the superposition of multiple landslide deposits whose older ones are dissected and delimited by erosive channels as much as 200 m deep and 20 km long. The submarine flanks of Reunion Island are thus mostly built by accumulation of debris avalanche fans. Morphologic and geologic evidence define large subaerial source areas for these mass-wasting events. In particular, inferred headwalls of most landslides having affected the Piton des Neiges massif generally coincide with the boundaries of its "cirques" (Mafate, Salazie, and Cilaos), whereas recurrent landslides have resulted in the formation of large concentric amphitheatre structures through the Piton de la Fournaise massif. Thus, about 15 slide events accompanied growth of the Reunion Island shield since 2 Ma.

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Vertical movements and material transport during hotspot activity: Seismic reflection profiling offshore La Réunion

Cited by 53 publications

References 38 publications

Direct sediment transfer from land to deep-sea: Insights into shallow multibeam bathymetry at La Réunion Island

Direct sediment transfer from land to deep-sea: Insights into shallow multibeam bathymetry at La Réunion Island

Seamount chain–subduction zone interactions: Implications for accretionary and erosive subduction zone behavior

Recurrence of major flank landslides during the last 2-Ma-history of Reunion Island

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