Multiple melt bodies fed the AD 2011 eruption of Puyehue-Cordón Caulle, Chile

ALLOWAY, BRENT V.; PEARCE, N.J.G.; VILLAROSA, G.; OUTES, V; P.I. MORENO

NATURE SCIENTIFIC REPORTS

Nature Publishing Group

Año: 2015 vol. 5

Within thevolcanological community there is a growing awareness that many large- tosmallscale, point-source eruptive events can be fed by multiple melt bodiesrather than from a single magma reservoir. In this study, glass shard major-and trace-element compositions were determined from tephra systematicallysampled from the outset of the Puyehue-Cordón Caulle (PCC) eruption (~1 km3) insouthern Chile which commenced on June 4th, 2011. Three distinct but cogeneticmagma bodies were simultaneously tapped during the paroxysmal phase of thiseruption. These are readily identified by clear compositional gaps in CaO, andby Sr/Zr and Sr/Y ratios, resulting from dominantlyplagioclase extraction atslightly different pressures, with incompatible elements controlled by zirconcrystallisation.Our results clearly demonstrate the utility of glass shard major- andtrace-element data in defining the contribution of multiple magma bodies to anexplosive eruption. The complex spatial association of the PCC fissure zone withthe Liquiñe-Ofqui Fault zone was likely an influential factor that impeded theascent of the parent magma and allowed the formation of discrete melt bodieswithin the sub-volcanic system that continued to independently fractionate