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Late Quaternary history of the Vakinankaratra volcanic field (central Madagascar): insights from luminescence dating of phreatomagmatic eruption deposits

Rufer, Daniel ; Preusser, Frank ; Schreurs, Guido ; Gnos, Edwin ; Berger, Alfons

In: Bulletin of Volcanology, 2014, vol. 76, no. 5, p. 1-20

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    Titre
    • Late Quaternary history of the Vakinankaratra volcanic field (central Madagascar): insights from luminescence dating of phreatomagmatic eruption deposits
    Auteur
    • Rufer, Daniel. Institute of Geological Sciences, Baltzerstrasse 1 + 3, University of Bern, 3012, Bern, Switzerland
    • Preusser, Frank. Department of Physical Geography and Quaternary Geology, Stockholm University, 10691, Stockholm, Sweden
    • Schreurs, Guido. Institute of Geological Sciences, Baltzerstrasse 1 + 3, University of Bern, 3012, Bern, Switzerland
    • Gnos, Edwin. Muséum d'histoire naturelle de Genève, route de Malagnou 1, CP 6434, 1211, Genève 6, Switzerland
    • Berger, Alfons. Institute of Geological Sciences, Baltzerstrasse 1 + 3, University of Bern, 3012, Bern, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Bulletin of Volcanology, 2014, vol. 76, no. 5, p. 1-20. Springer Berlin Heidelberg
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:325711
    Summary
    The Quaternary Vakinankaratra volcanic field in the central Madagascar highlands consists of scoria cones, lava flows, tuff rings, and maars. These volcanic landforms are the result of processes triggered by intracontinental rifting and overlie Precambrian basement or Neogene volcanic rocks. Infrared-stimulated luminescence (IRSL) dating was applied to 13 samples taken from phreatomagmatic eruption deposits in the Antsirabe-Betafo region with the aim of constraining the chronology of the volcanic activity. Establishing such a chronology is important for evaluating volcanic hazards in this densely populated area. Stratigraphic correlations of eruption deposits and IRSL ages suggest at least five phreatomagmatic eruption events in Late Pleistocene times. In the Lake Andraikiba region, two such eruption layers can be clearly distinguished. The older one yields ages between 109 ± 15 and 90 ± 11ka and is possibly related to an eruption at the Amboniloha volcanic complex to the north. The younger one gives ages between 58 ± 4 and 47 ± 7ka and is clearly related to the phreatomagmatic eruption that formed Lake Andraikiba. IRSL ages of a similar eruption deposit directly overlying basement laterite in the vicinity of the Fizinana and Ampasamihaiky volcanic complexes yield coherent ages of 68 ± 7 and 65 ± 8ka. These ages provide the upper age limit for the subsequently developed Iavoko, Antsifotra, and Fizinana scoria cones and their associated lava flows. Two phreatomagmatic deposits, identified near Lake Tritrivakely, yield the youngest IRSL ages in the region, with respective ages of 32 ± 3 and 19 ± 2ka. The reported K-feldspar IRSL ages are the first recorded numerical ages of phreatomagmatic eruption deposits in Madagascar, and our results confirm the huge potential of this dating approach for reconstructing the volcanic activity of Late Pleistocene to Holocene volcanic provinces.