Radiometric dating of three large volume flank collapses in the Lesser Antilles Arc |
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| Authors: | A Samper X Quidelleur G Boudon A Le Friant JC Komorowski |
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| Institution: | 1. Laboratoire de Géochronologie Multi-Techniques, UMR IDES 8148 CNRS-UPS, Dpt. Sciences de la Terre, Université Paris Sud 11, Bât. 504, 91405 Orsay, France;2. Institut de Physique du Globe de Paris, CNRS UMR 7154, Equipe de Géologie des Systèmes Volcaniques, 4 place Jussieu, 75252 Paris Cedex 05, France |
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| Abstract: | It is now recognised that flank collapses are a recurrent process in the evolution of the Lesser Antilles Arc volcanoes. Large magnitude debris-avalanche deposits have been identified off the coast of Dominica, Martinique and St. Lucia, with associated volumes up to 20 km3 Deplus, C., Le Friant, A., Boudon, G., Komorowski, J.-C., Villemant, B., Harford, C., Ségoufin, J., Cheminée, J.-L., 2001. Submarine evidence for large-scale debris avalanches in the Lesser Antilles Arc. Earth Planet. Sci. Lett., 192: 145–157.]. We present new radiometric dating of three major events using the K–Ar Cassignol–Gillot technique. In the Qualibou depression of St. Lucia, a collapse has been constrained by dome emplacement prior to 95 ± 2 ka. In Dominica, where repetitive flank collapse events have occurred Le Friant, A., Boudon, G., Komorowski, J.-C., Deplus, C., 2002. L'île de la Dominique, à l'origine des avalanches de débris les plus volumineuses de l'arc des Petites Antilles. C.R. Geoscience, 334: 235–243], the Plat Pays event probably occurred after 96 ± 2 ka. Inside the depression caused by this event, Scotts Head, which is interpreted as a proximal megabloc from the subsequent Soufriere avalanche event has been dated at 14 ± 1 ka, providing an older bound for this event. On Martinique three different domes within the Carbets structure dated at 337 ± 5 ka constrain the age of this high magnitude event. Finally, these results obtained from three of the most voluminous flank collapses provide constraints to estimate the recurrence of these events, which represent one of the major hazards associated with volcanoes of the Lesser Antilles Arc. |
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| Keywords: | Lesser Antilles flank collapse debris-avalanche deposits lava domes radiometric dating K/Ar Quaternary volcanism |
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