Exceptional eruptive CO2 emissions from intra-plate alkaline magmatism in the Canary volcanic archipelago

Alkaline mafic magmas forming intra-plate oceanic islands are believed to be strongly enriched in CO2 due to low-degree partial melting of enriched mantle sources. However, until now, such CO2 enhancement has not been verified by measuring CO2 degassing during a subaerial eruption. Here, we provide evidence of highly CO2-rich gas emissions during the 86-day 2021 Tajogaite eruption of Cumbre Vieja volcano on La Palma Island, in the Canary archipelago. Our results reveal sustained high plume CO2/SO2 ratios, which, when combined with SO2 fluxes, melt inclusion volatile contents and magma production rates at explosive and effusive vents, imply a magmatic CO2 content of 4.5 ± 1.5 wt%. The amount of CO2 released during the 2021 eruptive activity was 28 ± 14 Mt CO2. Extrapolating to the volume of alkaline mafic magmas forming La Palma alone (estimated as 4000 km3 erupted over 11 Ma), we infer a maximum CO2 emission into the ocean and atmosphere of 10^16 moles of CO2, equivalent to 20% of the eruptive CO2 emissions from a large igneous province eruption, suggesting that the formation of the Canary volcanic archipelago produced a CO2 emission of similar magnitude as a large igneous province.

Mike Burton, Alessandro Aiuppa, Patrick Allard, María Asensio-Ramos, Ana Pardo Cofrades, Alessandro La Spina, Emma J. Nicholson, Vittorio Zanon, José Barrancos, Marcello Bitetto, Margaret Hartley, Jorge E. Romero, Emma Waters, Alex Stewart, Pedro A. Hernández, João Pedro Lages, Eleazar Padrón, Kieran Wood, Benjamin Esse, Catherine Hayer, Klaudia Cyrzan, Estelle F. Rose-Koga, Federica Schiavi, Luca D'Auria, Nemesio M. Pérez