Gallart J. auteur aut IRD Driad L. auteur aut IRD Charvis Philippe auteur aut IRD Sapin M. auteur aut IRD Hirn A. auteur aut IRD Diaz J. auteur aut IRD Voogd B. de auteur aut IRD Sachpazi M. auteur aut IRD text journalArticle eng text/pdf reformatted digital access A 250 km long NE-SW lithospheric transect spanning the 40 km wide island of La Réunion and its submarine edifice is derived from lines of air gun shots at sea on either side, along the assumed hotspot trace. Seismic records were obtained from an array spanning the whole transect and including sea bottom and land receivers, providing a system of reversed and overlapping observations. Low seismic velocity, and hence density, is found on average for the whole edifice above the oceanic plate. We attribute high-velocity anomalies within the edifice to an intrusive core confined under the central northern quarter of the island-crossing segment. Unexpectedly, the main seismic interfaces, top and bottom of the prevolcanic crust, do not show significant flexural downwarping under the island. In addition, clear multipathing in the recorded wave field requires the presence of a body with a seismic velocity intermediate between the prevolcanic crustal material and the normal mantle. This lithospheric structure provides the first example where underplating occurs beneath an active volcanic island, suggesting a genetic relationship. The underplated body could represent residues of the evolution of primary picritic melts that yield erupted basalts. Evidence for reflectors deeper in the lithosphere may indicate further related heterogeneity. In the plate/hotspot model commonly assumed, the structural variation along the transect could be interpreted as a variation with time of the amount and physical state of underplated material. (Résumé d'auteur) specialized VOLCANISME POINT CHAUD LITHOSPHERE MANTEAU SISMOGRAMME PROFIL SISMIQUE GEOLOGIE STRUCTURALE INVERSION MODELISATION REUNION 064GEOREG 104 B2 2895-2908 1999 0148-0227 https://www.documentation.ird.fr/hor/fdi:010021654 10.1029/98JB02840 0148-0227 [F B010021654] https://www.documentation.ird.fr/hor/fdi:010021654 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/pleins_textes_7/b_fdi_55-56/010021654.pdf IRD - Base Horizon / Pleins textes 2000-06-07 2018-07-10 fdi:010021654 fre