Structure and morphology of submarine volcanism in the hotspot region around Réunion Island, western Indian Ocean

• Published in: Marine geology Vol. 148; no. 1; pp. 39 - 53
• Main Authors: Fretzdorff, S., Stoffers, P., Devey, C.W., Munschy, M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.1998
• Subjects: bathymetry; geophysics; hotspots; magmatism; tectonics; bathymetry; geophysics; magmatism; tectonics; hotspots
• ISSN: 0025-3227; 1872-6151
• DOI: 10.1016/S0025-3227(98)00022-X

The form of the Deccan-Maldives-Mascarene-Réunion hotspot trace suggests that it has, at least in part, been strongly controlled by crustal structures, especially fracture zones. This makes it difficult to assess the present-day or past location of the hotspot, and thus complicates the interpretation of African plate motion reconstruction. We present here results of a cruise to the Réunion area of which the aims were: (a) to determine the extent of present-day volcanism associated with the Réunion hotspot in the region; and (b) to examine the rôle of pre-existing oceanic crustal structures in controlling the location of present-day volcanism. Additionally, we examined the morphology and geology of the important extinct spreading centre southwest of Réunion abandoned when spreading jumped to separate Seychelles from India during the Deccan flood basalt episode some 60–65 Ma ago. The extensive bathymetrie, seismic and geological investigation shows that significant present-day hotspot volcanism is confined to the Piton de la Fournaise edifice on Réunion Island itself. Apparently, the location of recent Réunion volcanism has not been controlled by a crustal fracture and the major fracture zones on both sides of the island are not acting as magma conduits. For plate motion reconstruction and plume flux calculation purposes, Piton de la Fournaise must be taken as the present location of the Réunion hotspot. Accretion at the extinct spreading centre progressively ceased at the time of anomaly A27 (63 Ma), and was associated with marked propagation of the rift tips.