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Etude géochronologique, aspects géomorphologiques et géochimiques du volcanisme de l'île de Basse Terre (Guadeloupe), et datation des structures d'effondrement de flanc majeures de l'Arc des Petites Antilles

Abstract : The use of the K-Ar Cassignol-Gillot technique enabled us to define the temporal bounds of the sub-aerial effusive volcanism in Basse-Terre (Guadeloupe), and to constrain the active periods of the four main massifs that make the island, which were poorly defined so far. The Basal Complex [2.79 ± 0.04 – 2.68 ± 0.04 Ma], the Septentrional Chain [1.81 ± 0.03 – 1.15 ± 0.02 Ma], the Axial Chain [1023 ± 25 - 435 ± 8 ka] and the most recent volcanic complex of Grande-Découverte [205 ± 28 - actuel] illustrate the southwards migration of volcanism through time in Basse-Terre since 3 Ma, along a main N-S direction, at a rate of roughly 20 km/Ma. We propose magma extraction to be linked to the E-W striking graben and en-échelon normal fault systems that affect the Guadeloupe archipelago. Extrusion rates, on the basis of morphological observations and modeling spread from 1.4 10-5 (Basal Complex) to 4.5 10-4 km3/yr (Axial Chain). The main building stages of the most recent complex in Basse-Terre have been determined. The Trois Rivières – Madeleine Complex, located South of the Grande-Découverte Volcano has been constrained between 87 ± 5 ka and present time. For the first time K-Ar ages are provided for this area. These show that the various stages of effusive activity are contemporaneous with the Grande-Découverte volcano ones. The Trois-Rivières lava flows (87 ± 5 ka) and the subsequent emplacement of the E-W alignment of La Madeleine dome and Le Palmiste lava flow, between 70 and 45 ka, constrain the age of a Marie-Galante rift propagation phase. Recognition and dating of lava flows younger than 10 ka in the surroundings of the La Madeleine dome lead to extend the present time volcanic activity up to the extreme south of the island, hence to consider volcanic hazards in a larger zone spreading from La Soufrière area up to the La Madeleine -Trois Rivières volcanic complex. Finally, dating of major flank-collapse events in Basse-Terre (640 and 550 ka), Dominica (100 ka), Martinique (330 ka) and St. Lucia (100 ka) have been realized and we propose in this work a causal link between the recurrence of such catastrophic events and global climate changes.
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https://tel.archives-ouvertes.fr/tel-00398601
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Submitted on : Wednesday, June 24, 2009 - 3:11:21 PM
Last modification on : Wednesday, September 16, 2020 - 4:57:00 PM
Long-term archiving on: : Saturday, November 26, 2016 - 9:58:01 AM

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  • HAL Id : tel-00398601, version 1

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Agnes Samper. Etude géochronologique, aspects géomorphologiques et géochimiques du volcanisme de l'île de Basse Terre (Guadeloupe), et datation des structures d'effondrement de flanc majeures de l'Arc des Petites Antilles. Géologie appliquée. Université Paris Sud - Paris XI, 2007. Français. ⟨tel-00398601⟩

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