Equilibrium-disequilibrium textures and mineral chemistry of lavas from the Cumbre Vieja 2021 eruption, La Palma, Canary Islands, Spain: insights into magma plumbing systems under intraplate ocean islands

<p>La Palma is one of the youngest and the most active island of all the Canary archipelago, with a total of seven subaerial eruptions over the last 500 years. This magmatic activity is linked to the undergoing growth and development of the youngest volcanic complex in the island: the Cumbre Vieja edifice, a 20 km long and 1950 m high, north-south trending ridge with aligned volcanic cones and fissures forming its summit and flanks. The youngest of them is the Tajogaite volcanic vent, which is located in the western flank of the Cumbre Vieja ridge, and was built up by a mainly strombolian eruption from 19^th September to 13^th December 2021. The first erupted, clinopyroxene-amphibole-phyric tephrite lavas, are more evolved in composition than the subsequent clinopyroxene-olivine-phyric basanite flows, in a pattern resembling those described from the two former eruptions in Cumbre Vieja: Tenegu&#237;a (1971) and San Juan (1949). Furthermore, the detailed study of lava samples from the Tajogaite volcano reveals not only a drastic change in mineralogy, from amphibole-rich to olivine-rich lavas, but also the existence of complex textures and chemical zoning patterns including: 1) different olivine crystal populations, with and without disequilibrium textures (reverse zoning trends; reaction rims or coronae); 2) sodium-rich corroded clinopyroxene cores -with occasional titanite inclusions- overgrown by oscillatory zoned euhedral rims in equilibrium with groundmass; 3) a range of oxide mineral compositions from magnetite to chromite and spinel and, 4) the occurrence of early, nickel-bearing sulphides as inclusions in clinopyroxene. All these features record the interaction between ascending primitive mantle magmas and, at least, one shallow reservoir where differentiation had already taken place leading to iron, alkalis and water enrichment. This kind of interaction probably triggered the onset of the eruption, and could also be responsible for episodic phreatomagmatic activity pulses during the whole length of the volcanic process.&#160;&#160;&#160;</p>