Isabelle Thinon

French Geological Survey | BRGM

Unlike subaerial volcanic activity, deep submarine eruptions are difficult to detect, observe and monitor. The objective of this paper is to describe a large and complex volcanic region, named the Horseshoe area, recently discovered at ~1500 m below sea level on the eastern upper submarine slope of Mayotte Island. The area is crucial because, since...

Heat flow in the Northern Mozambique Channel is poorly constrained, with only a few old measurements indicating relatively low values of 55–$62~\text{mW/m}^2$. During the SISMAORE cruise to the Northern Mozambique Channel, we obtained new heat flow measurements at four sites, using sediment corers equipped with thermal probes. Three of the sites yi...

Geophysical and geological data from the North Mozambique Channel acquired during the 2020–2021 SISMAORE oceanographic cruise reveal a corridor of recent volcanic and tectonic features 200 km wide and 600 km long within and north of Comoros Archipelago. Here we identify and describe two major submarine tectono-volcanic fields: the N’Droundé provinc...

In 2019, a new underwater volcano was discovered at 3500 m below sea level (b.s.l.), 50 km east of Mayotte Island in the northern part of the Mozambique Channel. In January 2021, the submarine eruption was still going on and the volcanic activity, along with the intense seismicity that accompanies this crisis, was monitored by the recently created...

The Pyrenees is a collisional orogen built by inversion of an immature rift system during convergence of the Iberian and European plates from Late Cretaceous to late Cenozoic. The full mountain belt consists of the pro-foreland southern Pyrenees and the retro-foreland northern Pyrenees, where the inverted lower Cretaceous rift system is mainly pres...

The “Fani Maoré” eruption off the coasts of Mayotte has been intensively monitored by applying methods similar to those used for subaerial eruptions. Repeated high-resolution bathymetric surveys and dredging, coupled with petrological analyses of time-constrained samples, allowed tracking the evolution of magma over the whole submarine eruptive seq...

A multichannel seismic reflection profile acquired during the SISMAORE cruise (2021) provides the first in-depth image of the submarine volcanic edifice, named Fani Maore, that formed 50 km east of Mayotte Island (Comoros Archipelago) in 2018–2019. This new edifice sits on a 140 m thick sedimentary layer, which is above a major, volcanic layer up t...

In 2019, a new underwater volcano was discovered at 3500m below sea level (b.s.l.), 50 km east of Mayotte Island in the northern part of the Mozambique Channel. In January 2021, the submarine eruption was still ongoing and the volcanic activity, along with the intense seismicity that accompanies this crisis, is monitored by the recently-created REV...

A new submarine volcano has been discovered offshore Mayotte, a part of the Comoros volcanic archipelago located between Africa and Madagascar. The edifice arose from the sea-floor following a seismo-volcanic crisis that started in May 2018. This seismo-volcanic activity highlights very deep magma reservoirs and dykes in the East Mayotte volcanic s...

A new submarine volcano has been discovered offshore Mayotte, a part of the Comoros volcanic archipelago located between Africa and Madagascar. Regarding this seismo-volcanic activity, a 3-D passive tomography was conducted, in order to determine the structure of the volcanic plumbing system (Foix et al., 2021). Using > 3,000 earthquakes from an on...

The present-day tectonic setting of the Western Mediterranean region, from the Pyrénées to the Betics and from the Alps to the Atlas, results from a complex 3-D geodynamic evolution involving the interactions between the Africa, Eurasia and Iberia plates and asthenospheric mantle dynamics underneath. In this paper, we review the main tectonic event...

Volcanic eruptions shape Earth’s surface and provide a window into deep Earth processes. How the primary asthenospheric melts form, pond and ascend through the lithosphere is, however, still poorly understood. Since 10 May 2018, magmatic activity has occurred offshore eastern Mayotte (North Mozambique channel), associated with large surface displac...

Since 2018, the submarine east flank of Mayotte Island (Comoros archipelago) is the site of a major eruption located at 3.5 km depth bsl on a WNW-ESE volcanic ridge. Samples brought by oceanographic cruises carried out to monitor this seismo-volcanic crisis indicate that this volcanic ridge is built by a bimodal sodic alkaline magmatic series that...

The aim of this paper is to provide a conceptual framework that integrates the role of inheritance in the study of rifts, rifted margins and collisional orogens based on the work done in the OROGEN project, which focuses on the Biscay-Pyrenean system. The Biscay-Pyrenean rift system resulted from a complex multistage rift evolution that developed o...

The architecture and nature of the continental lithosphere result from billions of years of tectonic and magmatic evolution. Continental deformation over broad regions form collisional orogens which evolution is controlled by the interactions between properties inherited from hits long-lasting evolution and plate kinematics. The analysis of present...

The brutal onset of seismicity offshore Mayotte island North of the Mozambique Channel, Indian Ocean, that occurred in May 2018 caught the population, authorities, and scientific community off guard. Around 20 potentially felt earthquakes were recorded in the first 5 days, up to magnitude Mw 5.9. The scientific community had little pre-existing kno...

The architecture and tectono-magmatic evolution of the lithosphere of Europe are the result of a succession of subduction, rifting and inputs from plumes that have modified the lithospheric mantle since the Neoproterozoic (750-500 Ma). These events gave birth to contrasting crust-mantle and lithosphere-asthenosphere mechanical coupling between stro...

Producing accurate structural maps is a pre-requisite to unravel the tectonic evolution of a region. For this purpose, magnetic anomaly maps are helpful data sets for the identification and mapping of geological features. We compiled 154 marine surveys and 7 aeromagnetic campaigns covering the Bay of Biscay, its surrounding continental shelves and...

Slab tearing induces localized deformations in the overriding plates of subduction zones and transfer zones accommodating differential retreat. Because the space available for retreating slabs is limited in the Mediterranean realm, slab tearing during retreat has been a major ingredient of the evolution of this region since the end of the Eocene. T...

Following an intense seismic crisis in May 2018, a large submarine effusive eruption offshore the island of Mayotte (SW Indian Ocean) has extruded at least 6.4 km 3 of magma, making it the largest witnessed submarine eruption as well as the largest effusive eruption since Iceland's 1783 Laki eruption. We present a detailed petrological and geochemi...

The Comoros volcanic archipelago is related to a complex E-W zone of immature right-lateral wrenching of the lithosphere in the context of the Lwandle and Somalian plate boundaries. A major volcano-tectonic crisis began in May 2018 offshore Mayotte, the easternmost island of the archipelago, resulting in the construction of a large submarine volcan...

On May 10th, 2018, an unprecedented long and intense seismic crisis started offshore, east of Mayotte, the easternmost of the Comoros volcanic islands. The population felt hundreds of events. Over the course of one year, 32 earthquakes with magnitude greater than 5 occurred, including the largest event ever recorded in the Comoros (Mw = 5.9 on May...

The role of NW-SE transfer zones during the opening of the Northwestern Mediterranean Basin has long been evidenced, mostly from seismic-reflection and magnetic data. Each of these features corresponds to transverse basement steps and/or fractures controlling the progressive deepening from the Valencia Basin toward the center of the Liguro-Provença...

The Sotta – Bonifacio – Santa Teresa di Gallura sheet is located in the far south of the island of Corsica, also covering the northernmost tip of La Gallura in Sardinia via the Strait of Bonifacio. Volcanic and sedimentary formations of Miocene age, unconformably overlying a structurally deformed basement of Hercynian age, form the Bonifacio Causse...

The western part of the Gulf of Lion (GoL) passive margin, at the foot of the Pyrenees mountain chain hosts the Catalan magnetic anomaly (CMA), a significant NW-SE-trending linear magnetic anomaly 50 km long with no associated gravimetric signal. The CMA is located on the continental slope near the NW-SE-trending Catalan transfer zone (CTZ), and it...

The Pyrenean Belt ends against the Gulf of Lion passive margin. The mechanism responsible for dismantling the mountain belt during Oligocene rifting has not yet found a proper explanation. The Late Eocene and Oligocene period is characterized by a first order change in subduction dynamics in the Mediterranean and the subduction zones started to ret...

The aim of this study is to unravel the tectono-sedimentary evolution of a hyper-thinned rift, based on the example of the Mauléon Basin, a basin filled by thick synrift deposits. The integrated study combines field data, detailed geological mapping and seismic interpretation. The field study focuses on the Iberian margin of the Mauléon Basin. Seis...

The aim of the last geothermal exploration campaign at the Lamentin lowland (Martinique) was to specify the characteristics and the extent of the local geothermal system. In this purpose, previous data were re-processed and new field data were acquired through geological, gravimetric, electromagnetic (CSEM and TEM) and fluids geochemical surveys. A...

A new high-resolution bathymetric map combined with a regional Digital Elevation Model (DEM) analysis reveal the modalities of occurrence and emplacement of post-spreading magmatism along the NNE-SSW oriented, 1000 km long Tore-Madeira Rise (TMR) as well as its relationship with the activity of major fault systems including the Estremadura Fault Sy...

The Mayotte Island (Indian Ocean, Comoros archipelago) is facing an exceptional, offshore, volcano-tectonic crisis. It started on May 2018, with a seismic activity eastward of Mayotte and peaked in May - June 2018 with 29 5<M<5.9+ shocks. The shocks migrated both ESE and WNW, along a N115°E trending volcanic ridge (Lemoine et al., 2019). At the ESE...

The Mayotte island (Indian Ocean, Comoros archipelago) is undergoing an exceptional offshore volcano-tectonic seismic crisis which started May 10th, 2018, peaked with a magnitude Mw5.9 on the 15th of the same month, and has produced more than two thousand M4+ events to date (Bertil 2019). To monitor this crisis, since February 2019, several French...

Volcanic eruptions are foundational events shaping the Earth's surface and providing a window into deep Earth processes and composition. Most eruptions occur on established volcanoes, exploiting longstanding magma reservoirs and pathways. Those creating new volcanoes are rare and usually too small or too remote to be well monitored, particularly in...

The Messinian Salinity Crisis (MSC) is a huge outstanding succession of events that has deeply modified the Mediterranean area within a short time span at the geological scale and led to the emplacement of one of the youngest and most debated salt giant on Earth. In 2011, the Seismic atlas of the Messinian salinity crisis markers in the Mediterran...

The Messinian Salinity Crisis (MSC) is a huge outstanding succession of events that has deeply modified the Mediterranean area within a short time span at the geological scale and led to the emplacement of one of the youngest and most debated salt giant on Earth. In 2011, the Seismic atlas of the Messinian salinity crisis markers in the Mediterra...

The Albian Mauléon basin is a privileged field laboratory to unravel the tectono-sedimentary evolution of a highly subsiding asymmetric hyper-thinned rift. The evolution of this basin is synchronous to the one of the Bay of Biscay continental margins that are characterized by a hyper-thinned continental crust and a probable exhumed mantle at the oc...

La Manche orientale a été affectée et façonnée depuis le Mésozoïque par des évènements tectoniques localisés le long de limites de plaques (ouverture de l’Océan Atlantique Nord, orogenèses pyrénéenne et alpine). Actuellement, le Bassin de Dieppe-Hampshire correspond à un synclinal NW-SE traversant la Manche dans sa partie orientale. Les états de co...

The Lower Cretaceous is a key period of Western Europe since it spanned the opening of the Bay of Biscay together along the North Pyrenean Basins. Recent studies highlight the role of crustal detachment on the genesis of the adjacent asymmetric Mauléon and Parentis basins (southward and westward continuation of the Aquitan Basin). Similar studies h...

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The Eastern English Channel has been shaped since Mesozoic times by distant tectonic events along European plate boundaries (opening of the North Atlantic Ocean, Pyrenean and Alpine orogeneses). Currently, the Dieppe-Hampshire Basin corresponds regionally to a NW-SE oriented syncline crossing the English Channel with the terminations of the basin o...

The Dieppe-Hampshire Basin, located in the Eastern English Channel and part of the Anglo-Paris Basin, developed during the Paleogene coeval with an overall tectonic inversion of Western European basins, in response to the opening of the North Atlantic Ocean and Pyrenean-Alpine deformation episodes. Former studies provided a first outlook of the str...

In the last fifty years, the Messinian Salinity Crisis (MSC) has been widely investigated in the Mediterranean Sea, but a major basin remains fewly explored in terms of MSC thematic: the Western Tyrrhenian Basin. The rifting of this back-arc basin is considered to occur between the Middle-Miocene and the Early-Pliocene, thus including the MSC, givi...

Carte Géologique Terre-Mer La réalisation de la carte géologique du plateau continental de Basse-Provence repose sur l’interprétation de profils de sismique réflexion 2D et sur l’intégration d’échantillons de roches prélevés sur le fond marin par dragage et carottage et présente un essai de corrélation entre la cartographie géologique à terre et ce...

The Dieppe-Hampshire Basin, located in the eastern English Channel, between SE of England and the French Coast, developed within the Anglo-Paris Basin during the Cenozoic, a period of overall tectonic inversion, in response to the opening of the North Atlantic Ocean and Pyrenean-Alpine deformation episodes. Former studies have given a first idea of...

The Dieppe-Hampshire Basin is a Cenozoic basin crossing the eastern English Channel. This basin and its borders developed during the Cenozoic, a period of overall tectonic inversion, in response to the opening of the North Atlantic Ocean and Pyrenean-alpine deformation episodes. Both extensional and subsequent compressional deformations within this...

The Dieppe-Hampshire Basin is a Cenozoic basin crossing the eastern English Channel, between SE of England and the French coast. This basin and its borders developed during the Cenozoic, a period of overall tectonic inversion, in response to the opening of the North Atlantic Ocean and Pyrenean-alpine deformation episodes. Both extensional and subse...

Imaging deep active volcanic areas remains a challenge in our understanding of their activity and evolution, especially in subduction zones. Study of magnetic anomalies is appropriate to access such dynamics in depth. The magnetic anomaly pattern of the Lesser Antilles Arc (LAA) subduction is studied through Curie Point Depth (CPD), interpreted as...

Le Bassin de Dieppe-Hampshire est un bassin tertiaire situé en Manche orientale qui s’étend du Sud-Est de l’Angleterre jusqu’au littoral fran¸cais des régions Nord-Pas-de-Calais, Picardie et Haute-Normandie. Ce domaine se met en place dans un contexte d’inversion des bassins mésozoïques bordiers, en réponse à l’ouverture de l’Atlantique Nord et aux...

Another storage option (the so-called “deep offshore” option) is the trapping of CO2 in deep-sea sediments at lower temperature and higher pressure than the standard options, the onshore and offshore storage options. In those conditions, CO2 may be liquid and denser than seawater. In that case, the injected liquid CO2 may be gravitationally trapped...

The seaward extension of onshore formations and structures were previously almost unknown in Provence. The interpretation of 2D high-resolution marine seismic profiles together with the integration of sea-bottom rock samples provides new insights into the stratigraphic, structural and paleogeographic framework of pre-Messinian Salinity Crisis (MSC)...

The Eastern Sardinian passive continental margin formed during the opening of the Tyrrhenian Sea, which is a back-arc basin created by continental rifting and oceanic spreading related to the eastward migrating Apennine subduction system (middle Miocene to Pliocene). Up to now, rifting in this key area was considered to be pro parte coeval with the...

The Messinian Salinity Crisis (MSC), which widely affected the whole Mediterranean basin, induced rapid and spectacular palaeoenvironmental changes. It led to a major erosion of the onshore areas and the upper parts of the continental shelves and slopes, as well as important evaporitic deposits in the offshore deep basins. The Corsica Basin belongs...

Colloque Flotte Océanographique Côtière - Bordeaux- 11 - 12 juin 2015.

Deep saline aquifers are the most important potential storage reservoirs for CO2 under supercritical conditions. Another option is the trapping of CO2 in deep-sea sediments at low temperature, either in liquid state or as gas hydrates. The Negative Buoyancy Zone (NBZ) and the Gas Hydrate Stability Zone (GHSZ) are used to calculate the theoretical s...

In the continuation of the innovative study carried out at the scale of La Réunion Island to generalize Curie Point Depth (CPD) determinations at the scale of oceanic volcanic islands, we present here a similar work at the scale of the Lesser Antilles Arc. Assuming that magnetic anomalies are concentrated within the oceanic crust and using the grow...

In order to better constrain the relationship between tectonics and sedimentation of the Eastern Sardinian Margin, from the Messinian to the present day (METYSS project), a lithostratigraphic study was carried out on the Late Neogene deposits along the Cedrino Valley (eastern Sardinia). The late Neogene evolution is documented from sedimentological...

The interpretation of high-resolution 2D marine seismic profiles together with the analysis of sea-bottom cores allowed a stratigraphic and structural framework of the Provence continental shelf to be proposed. The integration of onshore and offshore stratigraphy, structure and geomorphology provided new insights into Messinian paleotopography and...

Le projet METYSS-METYSAR est un chantier terre-mer bénéficiant du soutien programmatique « Actions Marges » qui a notamment pour objectif de contraindre les relations entre tectonique, sédimentation, et évolution géodynamique de la Marge Est- Sarde (Gaullier et al., 2014). L’ouverture arrière-arc de la Mer Tyrrhénienne, entre la Sardaigne et le dom...

Cartographie géologique du plateau continental et sismique marine très haute résolution en Manche : amélioration de la connaissance géologique du bassin de Paris Fabien Paquet1, Isabelle Thinon1, Eric Lasseur1, Renaud Couëffé1, Justine Briais1;2, Olivier Dugue3, Christian Dupuis4, François Guillocheau2, Florence Quesnel1;5, Cécile Robin2, Bernadett...