Holocene marine tephra offshore Ecuador and Southern Colombia: First trench‐to‐arc correlations and implication for magnitude of major eruptions

Type Article
Date 2022-09
Language English
Author(s) Bablon MathildeORCID1, 2, Ratzov Gueorgui1, Nauret François3, Samaniego PabloORCID3, Michaud François4, Saillard MarianneORCID1, Proust Jean‐noëlORCID5, Le Pennec Jean‐luc6, 7, Collot Jean‐yvesORCID1, Devidal Jean‐luc3, Orange François8, Liorzou CelineORCID6, Migeon Sebastien4, Vallejo Silvia9, Hidalgo SilvanaORCID9, Mothes PatriciaORCID9, Gonzalez Miguel10
Affiliation(s) 1 : Université Côte d'Azur CNRS IRD Observatoire de la Côte d'Azur Géoazur Valbonne, France
2 : ISTerre IRD CNRS OSUG Université Grenoble Alpes Saint Martin d'Hères,France
3 : Laboratoire Magmas et Volcans Université Clermont Auvergne CNRS IRD OPGC Clermont‐Ferrand, France
4 : Université Côte d'Azur Sorbonne Universités CNRS Observatoire de la Côte d'Azur IRD Géoazur Valbonne, France
5 : Université Rennes 1 CNRS Géosciences Rennes Rennes, France
6 : Université de Bretagne Occidentale laboratoire Geo‐Ocean CNRS‐UBO‐Ifremer‐UBS IUEM Rue Dumont d'Urville29280 Plouzané ,France
7 : IRD Office for Indonesia & Timor Leste Jalan Kemang Raya n°4 Jakarta12730, Indonesia
8 : Université Côte d’Azur Centre Commun de Microscopie Appliquée Nice, France
9 : Instituto Geofísico Escuela Politécnica Nacional Ap. 17‐01‐2759 Quito ,Ecuador
10 : Escuela Superior Politecnica del Litoral (ESPOL) Grupo de Investigacion en Geociencias Marinas y Costeras (GEMAC) FIMCM‐FICT Campus Gustavo Galindo P.O. Box 09‐01‐5863 Guayaquil ,Ecuador
Source Geochemistry Geophysics Geosystems (1525-2027) (American Geophysical Union (AGU)), 2022-09 , Vol. 23 , N. 9 , P. e2022GC010466 (38p.)
DOI 10.1029/2022GC010466
Keyword(s) tephrochronology, volcanology, geochemistry, land-sea correlation, Ecuador
Abstract

Tephra layers preserved in marine sediments are strong tools to study the frequency, magnitude and source of past major explosive eruptions. Thirty-seven volcanoes from the Ecuadorian and Colombian arc, in the northern Andes, experienced at least one eruption during the Holocene. The volcanic hazard is therefore particularly high for the populated areas of the Andes and in particular cases for the coastal region, and it is crucial to document such events to improve hazard assessment. The age and distribution of deposits from major Holocene eruptions have been studied in the Cordillera, but no descriptions of distal fallouts have been published. In this study we focused on 28 Holocene tephra layers recorded in marine sediment cores collected along the northern Ecuador - southern Colombia margin. New lithological, geochemical and isotope data together with 14C datings on foraminifers allow us to determine the age and volcanic source of marine tephra, and to propose a first land-sea correlation of distal tephra fallouts. We show that at least seven explosive eruptions from Guagua Pichincha, Atacazo-Ninahuilca, Cotopaxi, and Cerro Machín volcanoes left tephra deposits recorded in marine cores over 250 km away from their source. Volume estimates of emitted tephra range between 1.3 and 6.0 km3 for the 10th century Guagua Pichincha, ∼5 ka Atacazo-Ninahuilca, ∼6.7 and ∼7.9 ka Cotopaxi events, suggesting that they were eruptions of Volcanic Explosivity Index of 5. The distribution of these deposits also brings new constraints for a better evaluation of the volcanic hazard in Ecuador.

Key Points

We propose a first land-sea correlation of distal Holocene tephra off Ecuador based on 14C age and geochemical data

Products from at least seven explosive Holocene eruptions in Ecuador and south Colombia reached the Pacific Ocean

Volumes of tephra emitted by largest eruptions vary between 1.3 and 6.0 km3, suggesting they were VEI-5 eruptions

Plain Language Summary

During major explosive eruptions, large volumes of gases and tephra (lapilli and ash particles) are thrown into the atmosphere and can be spread by winds over hundreds of kilometers and more. Tephra fallouts can impact the population, infrastructures and climate. It is therefore essential to document the age and magnitude of past major eruptions to better assess the volcanic hazards. In this study we use the minerology, glass shard morphology, and the geochemical composition of tephra settled in marine sediments off Ecuador and Colombia to investigate their source. Thickness of tephra layers and radiocarbon ages performed on under- and over-lying marine fauna allow us to determine the age of the eruptions, whereas the distribution of tephra yields constraints on the volume of fallout deposits. We show that the largest explosive eruptions from Ecuadorian and Colombian volcanoes reached the Pacific Ocean with a recurrence rate of about 1.5 events per millennium over the past 8 kyr.

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Publisher's official version 62 6 MB Open access
Supporting Information S1 15 KB Open access
Figure S1 14 27 MB Open access
Table S1 27 KB Open access
Table S2 214 KB Open access
Table S3 21 KB Open access
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How to cite 

Bablon Mathilde, Ratzov Gueorgui, Nauret François, Samaniego Pablo, Michaud François, Saillard Marianne, Proust Jean‐noël, Le Pennec Jean‐luc, Collot Jean‐yves, Devidal Jean‐luc, Orange François, Liorzou Celine, Migeon Sebastien, Vallejo Silvia, Hidalgo Silvana, Mothes Patricia, Gonzalez Miguel (2022). Holocene marine tephra offshore Ecuador and Southern Colombia: First trench‐to‐arc correlations and implication for magnitude of major eruptions. Geochemistry Geophysics Geosystems, 23(9), e2022GC010466 (38p.). Publisher's official version : https://doi.org/10.1029/2022GC010466 , Open Access version : https://archimer.ifremer.fr/doc/00791/90344/