Fecha: 9 junio 2026
Autores Ckelar: Álvaro Cárdenas, Alfredo Esquivel y Alexander Scheinost.
Otros autores: Verónica Oliveros, Pablo Salas, John M. Hanchar, Yoseline Muñoz, Philipp Ruprecht, Gary S. Michelfelder y Bruno Scaillet.
Revista científica: Bulletin of Volcanology
Abstract
Understanding how magma storage architecture and mafic recharge control eruptive behaviour is essential for interpreting explosive volcanism in thickened continental crust. We investigate the 1993 sub-Plinian eruption (VEI 4) of Lascar volcano, Andean Central Volcanic Zone, Chile, to constrain its crustal plumbing architecture and elucidate the role of magma mixing and mafic recharge. We integrate field observations, petrography, bulk-rock and mineral chemistry, to characterize five distinct eruptive products of the 1993 eruption: white pumice, green pumice, black scoria, banded pumice, and dome lithics, that range from basaltic trachyandesites to dacites (56–64 wt.% SiO2). Thermobarometric calculations reveal a multilevel plumbing system with at least two main storage domains at < 7 km and ~ 22–26 km, and two additional possible zones at ~ 11–15 km and ~ 41 km. Magma transfer among reservoirs was likely persistent and the shallower reservoir acted as buffer between deeper mafic inputs and eruptible silicic magmas. The 1993 eruption involved two geochemically distinct end-members: an evolved magma (white pumice) and mafic recharge (black scoria). Green pumice represents a hybrid magma produced by efficient mixing between hot, volatile-rich mafic recharge and cooler, evolved melts within the shallower reservoir, whereas banded pumice represents incomplete hybridization. Mineral zoning, disequilibrium textures, composition and thermal contrasts (~ 100ºC) indicate that mafic recharge supplied both heat and volatiles, promoting convection, hybridization, and volatile-driven overpressure before eruption. These findings highlight the importance of vertically connected magma storage, recharge efficiency, and volatile accumulation in controlling explosive eruptions at arc volcanoes emplaced above thick crustal segments.