LA-ICP-MS U/Pb zircon timescale constraints of the Pleistocene latest magmatic activity in the Sancy stratovolcano (French Massif Central) - Université Clermont Auvergne Accéder directement au contenu
Article Dans Une Revue Journal of Volcanology and Geothermal Research Année : 2019

LA-ICP-MS U/Pb zircon timescale constraints of the Pleistocene latest magmatic activity in the Sancy stratovolcano (French Massif Central)

Résumé

It has been demonstrated for several years that theU\\Pb zircon systemcan provide useful dating information for understanding the time-evolution of the volcanic systems. In addition, in situ techniques were successfully used for determining the formation age of young Pliocene and Pleistocene volcanic rocks and to record the spatial and temporal distribution and the lifetime evolution of the magma chambers, generally in the case of large volcanic domains. Herewe showthat it is possible to obtain a precision at the percent level on zircon froma short-size and late volcanic event from the Sancy stratovolcano (FrenchMassif Central). LA-ICP-MS dating of Pleistocenemagmatic zircons allowto distinguish the timescale of these latemagmatic eventswithin the complex volcanic activity of this large stratovolcano. A syenite xenolith enclosed into a trachyte pumice flow were dated at 277.6 ± 3.2 ka and 260.1±3.6 ka, respectively,whereas an earlier trachyandesite dome was emplaced at 284.4±4.2 ka. These different ages allowto propose aminimumevolution time of about 24±8 kyrs for a differentiatedmagma chamber, which corresponds to a short lifetime associated with lowmagma volumes. The duration of this discrete volcanic event should be compared to the hundreds of thousands of years reported for the large volcanic systems. Interestingly, the zircon crystals from the pumices were embedded into a thin layer of glass of trachytic composition, demonstrating that these zircons crystallized into the melt only a short time before eruption.
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Dates et versions

hal-02057053 , version 1 (10-12-2019)

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Jean-Louis Paquette, Etienne Médard, Justine Francomme, Patrick Bachèlery, Jean-Marc Hénot. LA-ICP-MS U/Pb zircon timescale constraints of the Pleistocene latest magmatic activity in the Sancy stratovolcano (French Massif Central). Journal of Volcanology and Geothermal Research, 2019, 374, pp.52-61. ⟨10.1016/j.jvolgeores.2019.02.015⟩. ⟨hal-02057053⟩
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