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. This study presents evidence of highly CO2-rich gas emissions during the 86-day 2021 Tajogaite eruption of Cumbre Vieja volcano on La Palma Island. High plume CO2/SO2 ratios, combined with SO2 fluxes, melt inclusion volatile contents, and magma production rates, imply a magmatic CO2 content of 4.5 ± 1.5 wt%. The eruption released 28 ± 14 Mt CO2. Extrapolating to the volume of alkaline mafic magmas forming La Palma (estimated as 4000 km3 erupted over 11 Ma), the inferred maximum CO2 emission is comparable to 20% of emissions from a large igneous province eruption, suggesting significant CO2 release during Canary archipelago formation.

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