The capacity of the visual system to process information about multiple objects at any given moment in time is limited. This is because not all information can be processed equally or in parallel and subsequently reach consciousness. Previous research has utilized behavioural experiments to explore visual attention. More recently research, however, has used electroencephalography (EEG) to measuring the electrical brain activity in the posterior scalp. By time locking visual stimulus events to fluctuations in scalp activity researchers have been able to estimate the time course of attentional changes by measuring changes in these event-related potentials (ERP). One component in particular (N2pc) has been a reliable tool in measuring either the suppression of, or the shift of attentional to, both ignored and attended items in the visual scene. The N2pc is measured by comparing the ERP activity contralateral and ipsilateral to the visual field of interest. More recently, evidence has been presented that the mechanisms of attention thought to be represented by the N2pc (suppression and attentional selection) could be separated into different ERP components (Pd: indexing attentional suppression of an ignored item; and Nt: indexing attentional selection of the target) and measured independently. In six experiments, using ERPs, this thesis employs these components to explore the mechanisms and strategies of the human attentional system. Additionally, this thesis focuses on the impact of different types of simultaneous processing load on the attentional system and how the mechanisms of this system are influenced. Experiment 1 explores the idea that the type or valence of information to be ignored may influence the ability to suppress it. Results of this experiment 4 show that neither the type nor valence of the irrelevant information modulated the amplitude of the distractor positivity (Pd), indicating suppression of the irrelevant distractor was not altered. Noted in experiment 1 was also the presence of an early negativity (Ne) that appeared to represent attentional capture of the ignored lateral stimulus. Experiment 2 demonstrated that the valence of the lateral target did not alter the target negativity (Nt), indicating a different pattern of results between the Nt and the N2pc reported in previous studies (e.g. Eimer & Kiss, 2007; Feldmann-Wüstefeld et al., 2010). Experiment 2 also showed a similarity of the target negativity (Nt) to the early negativity (Ne; the N2pc like component observed in exp 1) toward face and non-face stimuli. This comparison supported the idea that the early negativity (Ne) reflected attentional capture of the ignored lateral distractor and as a result was relabelled the distractor negativity (Nd) in subsequent experiments. Experiment 3 showed that the salience of the lateral image did not modulate the Pd as should be the case if the Pd reflected sensory-level processing. An early contralateral negativity (similar to the Nd observed in exp 1) was altered by the salience of the distractor which added support to the hypothesis that this reflects attentional capture of the lateral ignored image. Experiment 4 attempted to manipulate working memory (WM) to assess the effect of WM load on attentional capture and suppression. While the results did indicate modulation of suppression under WM load, the limitations of the design of experiment 4 made any definitive interpretation of the results unreliable. The results of experiment 5 showed that suppression, as indexed by the Pd, was not altered by cognitive load. However, reductions in attentional capture under high cognitive load, as indexed by the distractor negativity (Nd), were observed and contradict the results of previous experiments (c.f. Lavie & De Fockert, 2005) 5 where cognitive load resulted in an increase in attentional capture. Although, there appears to be some issue in the authors interpretation of the results of these experiments (see chapter 6 for discussion). The results of Experiment 6 show the opposite effect with a significant increase in the laterality of the Pd under high perceptual load. A similar increase in the laterality of the Pd was not reflected in terms of valence though, where suppression of threat related distractors was not altered under high perceptual load. The hypothesis that an increase in perceptual load will result in a decrease in attentional capture was generally supported by the results of experiment 6. Under high perceptual load angry face distractors captured attention, as indexed by the laterality of the Nd, with neutral face distractors showing a reduction in attentional capture. While under low perceptual load, both angry and neutral face distractors resulted in a significant (and similar) laterality of the Nd. The thesis concludes by discussing issues concerning Lavie’s Load Theory of attention and outlines some potential misinterpretations of previous data that have led to the proposal that cognitive load results in a decrease in attentional resources and therefore a decrease in attentional capture of ignored stimuli. It is argued in this thesis that the results of Lavie and de Fockert (2005), which concluded that the increase in cognitive load resulted in a decrease in attentional capture, are more likely to be due to changes in attentional capture (i.e. a reduction) and changes in RT (i.e. an increase), under cognitive load being separate responses to the availability of resources, one that focusses attention on the goal directed task and the other that results in extended processing time to carry out the more difficult task. In this case both ‘changes’ appear to work to prioritise resources in favour of the goal directed task.

From flamenco guitarists to parlour pianists, Matisse’s images of music-making often appear within decorative scenes of gleaming carpets, multi-coloured costumes and lavishly embroidered wall hangings. All of these textiles and more comprised what he called ‘ma bibliothèque de travail’, a working library of inspiration that he maintained throughout his career. ‘I am made up of everything I have seen,’ he remarked, to which he might have added, ‘and heard.’ Practising, performing, listening and concert-going: music, like textiles, was a lifelong pursuit. But his passion for them is not simply of anecdotal significance, nor does it explain their mere co-existence as the subject-matter of his art. Rather, just as music and textiles are interwoven at every stage of his life, so too is their structural and conceptual significance in his work. In a series of case studies, a single textile from his working library is paired with the art it inspired: the kasāya robe and 'The Song of the Nightingale'; the Moghan rug and the Symphonic Interiors; and the Bakuba velours and 'Jazz'. In each case, visual form is found to have musical counterpart, both in the textiles themselves and as represented by Matisse. This opens up new, more imaginative possibilities of interpreting his visual musicality, which is found to be metaphysical, modal and motivic in concept. Finally, these separate strands are drawn together in a single synoptic analysis of the Chapel of the Rosary, the artist’s self-proclaimed masterpiece and ‘total’ work of art. This thesis explores the expansive musical space created by the reduced visual form of textiles. Considered together for the first time, these enduring and inseparable continuities of Matisse’s art – music and textiles – suggest not only a means of unravelling his own visual musicality, but point towards a much-needed methodology for interpreting this notion more broadly.

This thesis investigates Dalí’s adoption of religious iconography to help represent themes that he had conceptualised through Surrealism, psychoanalysis and other thought systems. His selective use of sources was closely bound to his life circumstances, and I integrate biographical details in my analysis of his paintings. I identify unexpected sources of Dalí's images, and demonstrate how alert he was to the psychological motivations of traditional art. I find he made especial use of the iconography of martyrdom – and the perceptual and cognitive mechanics of the contemplation of death – that foreground the problem of the sexual and mortal self. Part I examines the period 1925-7, when Dalí developed an aesthetic outlook in dialogue with Lorca, formulated in his text, 'Sant Sebastià'. Representations of Sebastian and other martyr saints provided patterns for Dalí's exposition of the generative and degenerating self. In three chapters, based on three paintings, I plot the shift in Dalí's focus from the surface of the physical body – wilfully resistant to emotional engagement, and with classical statuary as a model – to its problematic interior, vulnerable to forces of desire and corruption. This section shows how Dalí's engagement with religious art paradoxically brought him into alignment with Surrealism. In Part II, I contend that many of the familiar images of Dalí’s Surrealist period – in which he considered the self as a fundamentally psychic rather than physical entity – can be traced to the iconography of contemplative saints, particularly Jerome. Through the prism of this re-interpretation, I consider Jerome's task of transcribing Biblical meaning in the context of psychoanalytical theories of cultural production. In Part III, I show how Dalí's later, overt use of religious imagery evolved from within his Surrealism. I trace a condensed, personalised life-narrative through Dalí’s paintings of 1948-52, based on Biblical mythology, but compatible with psychoanalytical theory: from birth to death to an ideal return to the mother's body.

The assemblage of ca. 6–4 Ma volcanic rocks exposed at the Sagehen Research station in the Truckee-Tahoe region of the northern Sierra Nevada, United States, is interpreted to be, within the Ancestral Cascades volcanic arc, a Lassen-type stratovolcano complex. Sagehen is of particular importance because it is one of the few Tertiary arc volcanic centres in California which has not been heavily glaciated during the Pleistocene. The volcanic rocks are variably porphyritic or aphanitic, including abundant plagioclase with clinopyroxene and amphibole. The rocks range from basalt to basaltic-andesite to andesite in composition. Basalts are olivineand clinopyroxene-bearing with minor phenocrysts of plagioclase. The basaltic-andesites are primarily pyroxene bearing while the andesites contain pyroxene-, plagioclase- and hornblende porphyritic phases. Sagehen arc lavas are calc-alkaline and enriched in the large ion lithophile elements and depleted in High Field Strength Elements. The basalts are depleted in Zr and Hf while the andesites are enriched with Zr and Hf relative to the middle rare earth elements. Compared to previously studied Ancestral Cascade arc samples, Sagehen region basalts have lower 143Nd/144Nd isotopic values that do not correspond to proposed mantle-lithosphere mixing lines, while the andesite samples appear to represent the interplay of these two components on a 87Sr/86Sr vs. 143Nd/144Nd. The trace element data and isotopic plots suggest that the melts that produced the basalts are from subduction modified mantle wedge peridotites that ponded near the base of the lithosphere similar to the generation of other subduction related calc-alkaline lavas along convergent continental margins. The andesitic samples appear to be the result of further modification through crustal assimilation as seen in the higher isotopic Sr contents in the andesites and Ce/Smpmn vs. Tb/Ybpmn plots. Finally, the proposed map units from Sylvester & Raines (2007) were found to contain various geochemical facies based on the samples collected indicating that some map units may have to be redefined or sub-divided.

L’objectif de cette thèse est d’apporter de nouvelles contraintes sur l’hydrologie de l’Atlantique Nord-Est et de la Méditerranée occidentale depuis la dernière période glaciaire à partir de l’analyse de la composition isotopique du Nd (εNd) dans des échantillons d’eau de mer ainsi que des coraux profonds et des foraminifères, prélevés dans des carottes sédimentaires marines. Les changements de l’hydrologie des masses d’eau intermédiaire (LIW, MSW, AAIW et masses d’eau intermédiaire des gyres subtropical et subpolaire) ont été plus particulièrement étudiés car leur rôle sur les transferts de sels en Atlantique Nord et in fine sur l’AMOC est actuellement mal contraint. Ce travail a été mené au cours des périodes de changements hydrologiques majeurs et abrupts de l’océan qui se sont produits lors des variations climatiques rapides de la dernière période glaciaire (événements d’Heinrich et cycles de Dansgaard-Oeschger) et lors du dépôt du Sapropel S1 en Méditerranée orientale. Dans un premier volet, nous avons amélioré la couverture spatiale des valeurs d’εNd des masses d’eau de l’Atlantique Nord-Est et de la mer d’Alboran, préalable indispensable pour restituer l’hydrologie passée de ces régions avec le traceur εNd. Nous avons ensuite mis en évidence un changement majeur du schéma de circulation de la Méditerranée occidentale durant la période de dépôt du sapropel S1, marquée par une forte réduction des masses d’eau de la Méditerranée orientale (LIW) au sud de la Sardaigne au profit de celles provenant du Golfe du Lion (WIW). Ce changement hydrologique ainsi que ceux qui s’opèrent en Méditerranée depuis la dernière période glaciaire ne sont pas associés à de fortes modifications des valeurs d’εNd de la LIW de la mer d’Alboran et de la mer des Baléares, suggérant une stabilité de la signature isotopique en Nd de la MOW au cours du temps. Ceci a permis, à partir d’un enregistrement d’εNd obtenus sur des coraux profonds du Golfe de Cadix, de mettre en évidence une contribution plus importante de l’AAIW plus radiogénique et donc une pénétration plus marquée en Atlantique Nord de cette masse d’eau lors des périodes de fortes réductions de l’AMOC, liées à la déstabilisation des calottes de glace de l’Hémisphère Nord. / : The purpose of this thesis is to constrain the hydrology of the North-East Atlantic and western Mediterranean Sea since the last glacial period from neodymium isotopic composition (εNd) measured on seawater, cold water corals and foraminifera. In particular, hydrological changes of intermediate water masses (LIW, AAIW, MSW, mid-subtropical and subpolar gyre water) have been studied as their role on salt budget in North Atlantic and ultimately on AMOC are currently poorly constrained. This work has been conducted at times of major and abrupt hydrological changes that occurred during rapid climatic variations of the last glacial period (Heinrich and Dansgaard-Oeschger events) and during the last sapropel deposit (S1) in eastern Mediterranean Sea. In a first step, we have improved the spatial distribution of water masses εNd values in North-east Atlantic and Alboran Sea, what is an absolute prerequisite in order to track past hydrological changes in these areas with εNd proxy. Next, we have highlighted a major change of the western Mediterranean circulation pattern during the sapropel S1 deposit, which is marked south of Sardinia by a strong reduction of eastern-sourced water masses (LIW) in favor of western-sourced water masses (WIW). This hydrological change as well as those occurring in Mediterranean Sea since the last glacial period was not associated with strong modifications of εNd values in Alboran and Balearic Sea, suggesting a stability of Nd isotopic signature of MOW over the time. This has highlighted, from an εNd record obtained on cold water corals in the Gulf of Cadiz, an enhanced contribution of more radiogenic AAIW and therefore a stronger northward penetration in North Atlantic at times of reduced AMOC linked to iceberg discharges from Northern Hemisphere ice sheets.

No description available.

La lithosphère continentale est physiquement et chimiquement segmentée. La cartographie des isotopes radiogéniques de roches plutoniques acides, représentatives de la croûte continentale, et de laves basiques, représentatives du manteau, possède des similarités avec la cartographie sismique de la lithosphère sous-jacente. Ces similitudes permettent d'interpréter les observations sismiques en étudiant leurs caractéristiques chimiques et leur âge. Les isotopes du plomb permettent de dater et d'identifier l'empilement de segments crustaux qui forment la croûte. L'écart des âges modèles du plomb avec d'autres systèmes identifie le recyclage crustal et le réchauffement de la croûte au dessus de la température du système plomb-plomb. Le système plomb-plomb donne également accès au sous-étudié rapport Th/U qui contraint la profondeur de la source des roches continentales. Certains échantillons de l'ouest U.S.A. proviennent de la croute inférieure, et se sont formés par l'extension crustale ou par un flux de matériel au sein de la croûte. Les isotopes du néodyme et de l'hafnium marquent la fusion du manteau lithosphérique enrichis sous le Colorado Plateau, une région où est observée le détachement du manteau lithosphérique sub-continental. Ce manteau fond par décompression adiabatique, par extension localisée ou remontée asthénosphérique engendrée par la convection locale. Au final, l'association des systèmes isotopiques du plomb, du néodyme, et de l'hafnium avec la sismologie est une approche puissante pour étudier la formation et la déformation de la lithosphère continentale.

Les études sur les procédés de soudage et sur la fiabilité des structures assemblées apparaissent actuellement comme un domaine de recherche actif, ouvert et complexe, car elles nécessitent de combiner de nombreuses connaissances dans différents domaines de la physique, de la mécanique et des procédés. La distribution des contraintes résiduelles joue un rôle important dans la vie des structures en favorisant la rupture par fatigue ou par fissuration. Ainsi, une meilleure compréhension des contraintes résiduelles évite l'utilisation de facteurs de sécurité plus élevés et, par conséquent permet de mieux optimiser le cycle de vie des structures soudées. A travers ce travail de thèse, nous nous sommes intéressés au soudage par laser d’un acier dual phase DP600, soudé en configuration par recouvrement, dont l’application est l’utilisation dans le domaine automobile. Cette thèse présente deux volets : un volet expérimental et un volet numérique.L’étude expérimentale nous a permis d’une part d’appréhender les conséquences métallurgiques et mécaniques du procédé laser sur l’acier DP600 et d’autre part d’utiliser et de valider les résultats numériques des modèles développés. L’étude numérique a eu pour objectif de prédire l’histoire thermique, métallurgique et l’évolution des caractéristiques mécaniques des tôles soudées par faisceau laser. Nous avons développé, sur un code de calcul par élémentsfinis Abaqus, trois modèles numériques. Le modèle thermomécanique, nous a permis de simuler la distribution spatio-temporelle de la température. Dans ce cas, le chargement appliqué est dépendant des paramètres du procédé etdes caractéristiques du faisceau laser et est associé à des conditions aux limites. Pour le modèle mécanique, nous avonsconsidéré un comportement élasto-plastique avec un chargement thermique transitoire, résultat du modèle thermique.Le deuxième modèle thermo-métallurgique nous a permis de simuler les phénomènes d’austénisation pendant la phase de chauffage (modèle de Waeckel) et de prendre en compte les fractions volumiques des phases martensitiques générées par les transformations de phases austénite–martensite lors du refroidissement (modèle de Koistinen-Marburger). Enfin, dans la dernière partie de simulation, nous avons réalisé le couplage thermo-metallo-mécanique. Les résultats obtenus dans la partie précédente, ont été implémentés dans deux modèles mécaniques : le modèle mécanique classique et le modèle mécanique avec prise en compte de la déformation liée aux effets de dilatation métallurgique. Cet effet a été intégré à travers le coefficient de dilatation thermique des phases ferritiques et martensitiques et des fractions volumiques obtenues à partir du modèle thermo-métallurgique. Les résultats ont montré que la répartition des contraintes résiduelles dans la zone de fusion et dans la zone affectée thermiquement sous l’effet de la déformation thermo-métallurgique donne des valeurs supérieures à celles estimées par le modèle élasto-plastique classique. / Studies on welding processes and the reliability of assembled structures currently appear as an area of active research, open and complex as they need to combine knowledge in many different fields of physics, mechanics and processes. The distribution of residual stress plays an important role in the life of welded structures by promoting fatigue failure or cracking. Thus, a better understanding of residual stress avoids the use of higher safety factors and therefore helps to optimize the life cycle of welded structures. Through this work, we are interested in laser welding of steel DP600 dual phase welded overlap configuration, the application is the use in the automotive field. This thesis has two components: an experimental and a numerical part. The experimental study allowed us, firstly to understand the metallurgical and mechanical effects of laser welding on steel DP600 and secondly to use and validate the numerical results of the developed models. The numerical study aimed to predict the thermal history, and metallurgical changes in mechanical properties of laser beam welded sheets. We have developed three numerical models by using a finite element code inside Abaqus. The thermomechanical model allowed us to simulate the temporal and spatial distribution of temperature. In this case, the applied load is dependent on the processing parameters and characteristics of the laser beam and is associated with boundary conditions. For the mechanical model, we considered an elastoplastic behavior with a transient thermal loading result of the thermal model. The second thermo-metallurgical m odel allowed us to simulate the phenomena austenitizing during the heating phase (Waeckel model) and take into account the volume fraction of martensitic phase transformations generated by the austenite-martensite transformation during cooling (Koistinen-Marburger model). Finally, in the last part of simulation, we have achieved the metallothermo- mechanical coupling. The results obtained in the previous section have been implemented in two mechanical models: the classical mechanics model and the mechanical model taking intoaccount the deformation due to the effects of metallurgical expansion. This effect has been built through the coefficient ofthermal expansion of ferritic and martensitic phases and volume fractions obtained from the thermo-metallurgical model. The results showed that the distribution of residual stresses in the fusion zone and the heat affected as a result of the eformation thermometallurgical field gives values higher than those estimated by the classical elastic-plastic model.

In 1989 the American Surrealist associated painter, sculptor, and writer Dorothea Tanning (1910-2012) suggested an intermedial dimension to her multifaceted œuvre in her essay ‘Some Parallels in Word and Pictures.’ Taking this essay as a critical point of departure, this thesis offers an intertextual theorisation of Tanning’s practice. It concerns the role of narrative in her work, and the way in which she borrows from the histories of art and literature as source materials. The thesis presented here is that Tanning’s work from the context of Surrealism and beyond makes reference to the fairy tales and other, more extensive works of literature which she read in her youth whilst at work in her public library in Galesburg, Illinois, whether implicitly in visual references or explicitly in her works’ titles. Throughout, the library is read as a key source of inspiration. This is true too of the impact which Tanning’s belated visit to the Louvre had on her post-Surrealist stylistic development. Broadly, this thesis aims to rethink the methodologies used to interpret Surrealism, and reunite the literary and visual aspects upon which the Surrealist movement was initially founded. This interdisciplinary approach contributes fresh perspectives by marrying the history of Surrealism with that of the fairy tale, including that of Lewis Carroll, Hans Christian Andersen, and the fairy tale illustrations of Gustave Doré, Maxfield Parrish, Arthur Rackham, and John Tenniel. The anti-fairy tale emerges as useful critical tool in defining the intertext which appears when Surrealism and the fairy tale are paired. The ‘demythologising’ project of Angela Carter is useful to call upon in the articulation of the anti-fairy tale, and her work is easily placed in dialogue with that of Tanning, especially in terms of its feminist leanings. The dialogic, intertextual theories of Mikhail Bakhtin, further developed by Julia Kristeva and Roland Barthes, support this reading of Tanning’s visual narratives. More recently such theories of intertextuality have manifested themselves in the work of Dutch narratologist Mieke Bal who proposes a model of ‘preposterous history’ in order to creatively re-read the relationship between source (or pre-text) and intertext. This research is primarily text-based and devotes long-awaited attention to Tanning’s literary works which are read visually, including her short story ‘Blind Date’ (1943), and her novel 'Abyss' (1977), later reworked and republished as 'Chasm: A Weekend' (2004). I argue that her novel provides textual continuity with her Surrealist visual narratives of the 1940s creating a more cyclical, ‘preposterous’ shape to her career than has previously been acknowledged.

Le système volcanique de La Réunion est formé de la coalescence des massifs du Piton des Neiges et du Piton de la Fournaise. Son édification, liée à l’activité d’un panache mantellique, est caractérisée par une phase de croissance sous-marine, puis subaérienne, suivie d’une période de dégénérescence, comme proposé classiquement pour les volcans boucliers océaniques d’Hawaii. De précédentes études ont montré que l’activité subaérienne de La Réunion aurait débuté il y a environ 2,2 Ma. Les analyses géochimiques menées jusqu’alors sur les produits associés à cette activité volcanique (subaérienne et sous-marine) ont montré un caractère chimique transitionnel avec une composition isotopique (87Sr/86Sr, 143Nd/144Nd et 176Hf/177Hf) particulièrement homogène pour un volcanisme de point chaud. Dans cette étude, nous montrons que des laves sous-marines récemment identifiées sous la série basique du Piton de la Fournaise (au sein de la sur Rift Zone Nord-Est) ainsi que des laves subaériennes affleurant à la base de canyons incisés dans le massif (Série Différenciée de la Rivière des Remparts), présentent des caractéristiques ne s’inscrivant pas dans le modèle d’évolution proposé précédemment pour ce volcan. Se pose donc la question de la nature et de l’origine de ces laves, ainsi que de leur place et appartenance dans l’édification du système volcanique réunionnais. De nouvelles investigations pétro-géochimiques et géochronologiques ont été menées sur la partie sous-marine de l’édifice de La Réunion. Elles révèlent l’existence d’un groupe de laves exceptionnel. Leur composition se distingue clairement de celle des échantillons communément analysés à La Réunion et montre (1) un enrichissement en éléments incompatibles couplé isotopiquement à (2) un rapprochement vers un pôle mantellique enrichi de type EM. Ces particularités géochimiques démontrent que le panache mantellique possède (1) une source hétérogène affectée par (2) des taux de fusion variables. De plus, deux échantillons de ce nouveau groupe datés à 3,77 (0,08) et à 3,34 (0,07) Ma étendent considérablement la période d’activité connue de l’édifice. Ces âges remarquables font de ces laves les plus anciennes jamais datées à La Réunion. La nature géochimique ainsi que la position stratigraphique des laves de cette étude (échantillons subaériens et sous-marins des massifs du Piton des Neiges et du Piton de la Fournaise) impliquent une réinterprétation du schéma d’évolution global de l’île. Contrairement aux études précédentes, nos résultats sur ces laves montrent que : (1) Les laves différenciées de la Rivière des Remparts, qui sont des laves subaériennes, de part leur position stratigraphique et géographique sous-jacente au Piton de la Fournaise et par analogie avec le Piton des Neiges, ne peuvent être reliées à l’activité de la Fournaise, (2) Le signal isotopique du groupe de laves sous-marines de la Rift Zone Nord-Est de la Fournaise, révèlent l’hétérogénéité de la source du panache mantellique sous La Réunion, source que nous identifions comme des enclaves d’éclogite contenues dans une lherzolite à spinelle, (3) L’âge plus ancien de ces laves sous-marines et leur localisation sous le flanc Est de la Fournaise remet en questions le schéma jusqu’alors admis pour l’édification de l’île de La Réunion reposant sur la construction du Piton des Neiges puis celle, adjacente, du Piton de la Fournaise. En conséquence, nos données géochimiques et géochronologiques sont de nouveaux arguments en faveur de l’élaboration d’un modèle d’évolution plus complexe, suggérant l’existence d’un troisième massif volcanique. Il est en accord avec les précédents travaux de pétrologie et de géophysique suggérant l’existence d’un troisième édifice à l’Est de La Réunion, communément appelé le Volcan des Alizés. / The volcanic system of La Reunion is made of the coalescent Piton des Neiges and Piton de la Fournaise edifices. Its formation, associated with the activity of a mantle plume, is characterized by phases of submarine and subaerial growth, followed by a period of destruction, as described in the classical model proposed for Hawaiian Island volcanoes. Previous studies showed that the subaerial activity of La Reunion would have started around 2.2 Ma ago. Geochemical analyses carried out on the products associated with subaerial and submarine volcanism revealed their transitional chemical nature and their peculiar homogeneous isotopic compositions (87Sr/86Sr, 143Nd/144Nd et 176Hf/177Hf) for a hotspot derived magmatism. In this study, we show that some unusual submarine lavas were recently identified below the basal series of Piton de la Fournaise volcano (dredged on the North-East Rift Zone of la Fournaise) and below the subaerial lavas outcropping at the base of the differentiated series of Rivière des Remparts, indicate that the evolution of La Reunion system is probably more complex than previously suggested. The question of the nature and origin of these lavas, together with their implication on the formation of La Reunion, is an issue of major interest in order to better constrain the global evolution of the volcanic system. As a consequence, new petrological, geochemical and geochronological investigations were conducted on the submarine part of La Reunion edifice. They revealed the existence of a geochemically exceptional group of lavas. Its composition is clearly different from common samples of La Reunion and presents (1) an enrichment in incompatible elements and (2) tends toward an enriched EM endmember. These chemical specificities reveal that the source of La Reunion magmatic products is (1) an heterogeneous source affected by (2) variable melting degrees. Moreover, two samples of this new group dated at 3.77 (0,08) and 3.34 (0,07) Ma extend considerably the period of activity of the island. These rocks are the oldest samples ever dated at La Reunion. The nature and stratigraphical location of subaerial and submarine samples from Piton des Neiges and Piton de la Fournaise imply a new interpretation of the global evolution of the island. Unlike previous studies, our results indicate that :(1) The differentiated subaerial lavas from Rivière des Remparts, due to their stratigraphical and geographical location underlying Piton de la Fournaise, and by analogy with the Piton des Neiges, cannot be linked to the activity of Piton de la Fournaise. (2) The isotope signature of the submarine lava group from the North-East Rift Zone of Piton de la Fournaise, reveals the heterogeneous character of the mantle source under La Reunion Island, that can be modelled as embedded eclogite in a matrix of spinel lherzolite, (3) The age of this submarine group and its location under the eastern flank of Piton de la Fournaise, imply a more complex model of evolution of La Reunion. Therefore, our geochemical and geochronological data are new arguments suggesting the existence of a third volcanic center on the island. This assumption confirms the previous petrological and geophysical evidence supporting the existence of this volcano at the East of La Reunion, commonly called Les Alizés volcano.