Structure of Réunion Island (Indian Ocean) inferred from the interpretation of gravity anomalies

Malengreau, Barbara; Lénat, Jean‐François; Froger, Jean‐Luc

doi:10.1016/s0377-0273(98)00114-0

Cited by 65 publications

(72 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The most recent published work on the gravity structure of the island of La Réunion is Malengreau et al (1999), but new data has since been collected (Lambert, unpublished data, 2003;Lénat et al, unpublished data, 2003;Levieux unpublished data, 2004), allowing us to strengthen the interpretation. The Bouguer anomaly map of La Réunion is dominated by two large positive anomalies: one centered on Piton des Neiges volcano and the other on the eastern coast.…”

Section: Gravitymentioning

confidence: 86%

See 1 more Smart Citation

Growth and collapse of the Reunion Island volcanoes

2007

Self Cite

View full text Add to dashboard Cite

International audienceThis work presents the first exhaustive study of the entire surface of the Reunion Island volcanic system. The focus is on the submarine part, for which a compilation of all multibeam data collected during the last 20 years has been made. Different types of submarine features have been identified: a coastal shelf, debris avalanches and sedimentary deposits, erosion canyons, volcanic constructions near the coast, and seamounts offshore. Criteria have been defined to differentiate the types of surfaces and to establish their relative chronology where possible. Debris avalanche deposits are by far the most extensive and voluminous formations in the submarine domain. They have built four huge Submarine Bulges to the east, north, west, and south of the island. They form fans 20–30 km wide at the coastline and 100–150 km wide at their ends, 70–80 km offshore. They were built gradually by the superimposition and/or juxtaposition of products moved during landslide episodes, involving up to several hundred cubic kilometers of material. About 50 individual events deposits can be recognized at the surface. The landslides have recurrently dismantled Piton des Neiges, Les Alizés, and Piton de La Fournaise volcanoes since 2 Ma. About one third are interpreted as secondary landslides, affecting previously emplaced debris avalanche deposits. On land, landslide deposits are observed in the extensively eroded central area of Piton des Neiges and in its coastal areas. Analysis of the present-day topography and of geology allows us to identify presumed faults and scars of previous large landslides. The Submarine Bulges are dissected and bound by canyons up to 200 m deep and 40 km long, filled with coarse-grained sediments, and generally connected to streams onshore. A large zone of sedimentary accumulation exists to the north–east of the island. It covers a zone 20 km in width, extending up to 15 km offshore. Volcanic constructions are observed near the coast on both Piton des Neiges and Piton de la Fournaise volcanoes and are continuations of subaerial structures. Individual seamounts are present on the submarine flanks and the surrounding ocean floor. A few seem to be young volcanoes, but the majority are probably old, eroded seamounts. This study suggests a larger scale and frequency of mass-wasting events on Reunion Island compared to similar islands. The virtual absence of downward flexure of the lithosphere beneath the island probably contributes to this feature. The increased number of known flank–failure events has to be taken into consideration when assessing hazards from future landslides, in particular, the probability of landslide-generated tsunamis

show abstract

Section: Gravitymentioning

confidence: 86%

“…fr/index.php?halsid=7468eeeb21a717fe9f1334ac4d670bae& view_this_doc=tel-00010498&version=1). High-resolution Malengreau et al (1999), Charvis et al (1999, Gallart et al (1999), and Lénat et al (2001). Les Alizés volcano has been destroyed and cannot be observed on land; its inferred previous shape is shown.…”

Section: Introductionmentioning

confidence: 97%

Growth and collapse of the Reunion Island volcanoes

2007

Self Cite

View full text Add to dashboard Cite

show abstract

“…2.1 Ma to 12 ka (McDougall 1971;Deniel et al 1992). An ancient volcano underlying the Piton de la Fournaise was proposed by Malengreau et al (1999) based on gravimetric anomalies and by a gabbroic and cumulate complex identified between 1 and 3 km below sea level (bsl) with deep geothermal exploration drill hole in the Grand Brûlé area (Fig. 2c), in the eastern part of the island (Rançon et al 1989).…”

Section: Lithospheric Structure Beneath La Réunion Hotspot Track 109mentioning

confidence: 99%

Crustal and uppermost mantle structure variation beneath La Réunion hotspot track

Fontaine¹,

Barruol²,

Tkalčić

et al. 2015

Geophys. J. Int.

View full text Add to dashboard Cite

“…On the other hand, relative positive anomalies such as the signal in the middle of the caldera and spatially related with volcanic edifices (Fig. 3) are interpreted as being produced by dense intrusive bodies (e.g., Rymer and Brown, 1986;Malengreau et al, 1999;Gudmundsson and Högnadóttir, 2007), due to the crystallization of the densest mineralogical phases during magma ascent and emplacement. Finally, positive anomalies outside of the caldera are interpreted as the response to the uplift of dense Paleozoic basement.…”

Section: Bouguer Residual Anomalymentioning

confidence: 99%

Nuevos antecedentes sobre la estructura interna de la caldera La Pacana mediante un estudio gravimétrico (Andes centrales, Chile).

Delgado

Pavez

2015

Andgeo

View full text Add to dashboard Cite

ABSTRACT. La Pacana (central Andes, Northern Chile) is one of the largest resurgent calderas in the world, formed 4 Ma ago during an eruption with a VEI of 8.7. We undertake a gravimetric study to contribute new insights into the inner structure and evolution of this caldera. The La Pacana Bouguer residual anomaly is asymmetric and has an average amplitude of -12 to -14 mGal, which we interpret as being produced by the low-density intracaldera ignimbrite infill. A reinterpretation of the caldera stratigraphy plus the available geochronology suggests that the current shape of La Pacana was produced by the collapse of two nested calderas, roughly limited by the axis where the resurgent dome changes its orientation, with the oldest eruption in the southern part of La Pacana. The gravity data suggests that these southern and northern nested structures would have collapsed with downsag and trap-door geometries respectively, evidence of asymmetric subsidence. Intra caldera ignimbrite thicknesses were calculated with 2.5D forward models and show that the ignimbrite infill in its southern and northern parts reach ∼0.6-1.1 km and ∼2.5-3 km respectively. Using Gauss's theorem, we calculate the volume of the intra caldera ignimbrite infill is ∼3,400-3,500 km 3 , in agreement with previous estimates and with models that show that the larger the caldera diameter, the larger the erupted volume.Keywords: La Pacana caldera, Volcanology, Gravimetry, Caldera collapse.RESUMEN. Nuevos antecedentes sobre la estructura interna de la caldera La Pacana mediante un estudio gravimétrico (Andes centrales, Chile). La Pacana (Andes centrales, norte de Chile) es una de las calderas resurgentes más grandes del mundo, formada 4 Ma atrás en una erupción con un VEI de 8,7. Hemos realizado un estudio gravimétrico de la caldera para contribuir con nuevos antecedentes sobre su estructura interna y evolución. La anomalía residual de Bouguer de La Pacana es asimétrica y tiene una amplitud promedio de entre -12 a -14 mGal, la que se interpreta que es producida por el relleno de baja densidad de ignimbritas intracaldera. Una reinterpretación de la estratigrafía de la caldera junto con la geocronología disponible sugiere que la forma actual de La Pacana fue producida por el colapso de dos calderas anidadas, cuyo límite aproximado sería el eje donde el domo resurgente cambia su orientación, y con la erupción más antigua en la parte sur de La Pacana. Los datos gravimétricos sugieren que estas estructuras anidadas sur y norte habrían colapsado con geometrías de tipo downsag y trap-door respectivamente, evidencias de subsidencia asimétrica. Los espesores de las ignimbritas intracaldera fueron calculados con modelos directos en 2.5D los cuales muestran que el relleno en sus partes sur y norte alcanza a los ∼0,6-1,1 km y ∼2,5-3 km respectivamente. Mediante el teorema de Gauss, calculamos que el volumen de las ignimbritas intracaldera llega a los ∼3.400-3.500 km 3 , de acuerdo con estimaciones previas y con modelos que muestran que mientras más grande es el di...

show abstract

Structure of Réunion Island (Indian Ocean) inferred from the interpretation of gravity anomalies

Cited by 65 publications

References 15 publications

Growth and collapse of the Reunion Island volcanoes

Growth and collapse of the Reunion Island volcanoes

Crustal and uppermost mantle structure variation beneath La Réunion hotspot track

Nuevos antecedentes sobre la estructura interna de la caldera La Pacana mediante un estudio gravimétrico (Andes centrales, Chile).

Contact Info

Product

Resources

About