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The Comores archipelago in the western Indian Ocean: volcanology, geochronology and geodynamic setting

1986; Elsevier BV; Volume: 5; Issue: 2 Linguagem: Inglês

10.1016/0899-5362(86)90003-5

0731-7247

J. Nougier, J. M. Cantagrel, Julie Karche,

Geological and Geophysical Studies

New petrological and geochronological data on the Comores archipelago are presented. The K-Ar ages measured on subaerial volcanics range from 8 Ma in Mayotte Island to 0 in Grande Comore but the migration of the volcanic activity in the archipelago does not appear clearly. For each island the beginning of the volcanism remains unknown. The widespread volcanism of the western Indian Ocean is briefly reviewed and replaced in the geophysical framework of this region. The classical Seychelles-northern Madagascar-Mayotte-Grande Comore hot spot hypothesis is questioned. A more or less synchronous alkaline magmatism along old lithospheric fractures (from Madagascar continent toward Comores oceanic islands), periodically reactivated during Tertiary times, could be an alternative interpretation.