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An extensive K-bentonite as an indicator of a super-eruption in northern Iberia 477 My ago

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Gutiérrez-Alonso, Gabriel and Gutiérrez Marco, Juan Carlos and Fernández Suárez, Javier and Bernárdez Rodríguez, Enrique and Corfu, F. and López Carmona, Alicia (2019) An extensive K-bentonite as an indicator of a super-eruption in northern Iberia 477 My ago. IOP Conference Series: Earth and Environmental Science, 319 (1). pp. 1-8. ISSN 1755-1307, ESSN: 1755-1315

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Official URL: https://iopscience.iop.org/article/10.1088/1755-1315/319/1/012007



Abstract

Zircon and monazite ID-TIMS U-Pb dating of four Lower Ordovician altered ash-fall tuff beds (K-Bentonites) in NW Iberia provided coetaneous ages of 477.5±1, 477±1.3 Ma, 477.2±1.1 Ma and 477.3±1 Ma, with a pooled concordia age of 477.2±0.74 Ma. A conservative estimation of the volume and mass of the studied K-bentonite beds (using data from the Cantabrian Zone) returns a minimum volume for the preserved deposits of ca. 37.5 km3 (Volcanic Explosivity Index - VEI = 6, Colossal). When considering other putative equivalent beds in other parts of Iberia and neighbouring realms the volume of ejecta associated to this event would make it reach the Supervolcanic-Apocalyptic status (VEI=8, >1000 km3). Contrary to most cases of this kind of gargantuan eruption events, the studied magmatic event took place in relation to continental margin extension and thinning and not to plate convergence. We speculate that a geochronologically coincident large caldera event observed in the geological record of NW Iberia could be ground zero of this super-eruption.


Item Type:Article
Subjects:Sciences > Geology > Stratigraphic geology
Sciences > Geology > Mineralogy
Sciences > Geology > Petrology
ID Code:57319
Deposited On:10 Oct 2019 16:45
Last Modified:11 Oct 2019 07:51

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