Construction and destruction rates of volcanoes within tropical environment: Examples from the Basse-Terre Island (Guadeloupe, Lesser Antilles)

In order to better constrain the construction and the erosion rate affecting the volcanic island of Basse-Terre Island (Guadeloupe, F.W.I.), an enlarged K–Ar age dataset has been combined with reconstruction of the paleo-topography. Two different methods of interpolation of the present topography have been cross-checked to better support the erosion rates obtained and their associated uncertainties. The present study focusses on the Monts-Caraïbes volcanoes and on the main geomorphic feature of the Piton de Bouillante volcano, the Beaugendre Valley. The Monts-Caraïbes volcanoes were constructed in 83 kyr at a rate of 0.12 ± 0.04 km3/kyr. During the last 450 kyr, they have experienced an erosion rate of 610 ± 550 t/km2/yr. In the Piton de Bouillante volcano eleven new K–Ar ages have been obtained, constraining the duration of its volcanic activity between 880 ± 14 and 712 ± 12 ka, and involving a construction rate of 0.70 ± 0.20 km3/kyr. For this volcano, an erosion rate of 1220 ± 700 t/km2/yr has been obtained for the last 700 kyr. Our study also shows, based on the contemporaneity of the ages in the entire Beaugendre Valley added to the mean erosion rate of 1350 ± 550 t/km2/yr, that the flank collapse hypothesis cannot explain the formation of this valley. Finally, the similarity of the erosion rates computed for different locations of the Basse-Terre Island shows that the time-integrated erosion appears independent to the trade wind effect and suggests that the barrier effect due to the relief is not present here.