title: Multiple melt bodies fed the AD 2011 eruption of Puyehue-Cordón Caulle, Chile.
abstract: Within the volcanological community there is a growing awareness that many large- to small-scale, point-source eruptive events can be fed by multiple melt bodies rather than from a single magma reservoir. In this study, glass shard major- and trace-element compositions were determined from tephra systematically sampled from the outset of the Puyehue-Cordón Caulle (PCC) eruption (~1 km(3)) in southern Chile which commenced on June 4(th), 2011. Three distinct but cogenetic magma bodies were simultaneously tapped during the paroxysmal phase of this eruption. These are readily identified by clear compositional gaps in CaO, and by Sr/Zr and Sr/Y ratios, resulting from dominantly plagioclase extraction at slightly different pressures, with incompatible elements controlled by zircon crystallisation. Our results clearly demonstrate the utility of glass shard major- and trace-element data in defining the contribution of multiple magma bodies to an explosive eruption. The complex spatial association of the PCC fissure zone with the Liquiñe-Ofqui Fault zone was likely an influential factor that impeded the ascent of the parent magma and allowed the formation of discrete melt bodies within the sub-volcanic system that continued to independently fractionate.
authors.affiliation: School of Geography, Environment and Earth Sciences, Victoria University of Wellington, Wellington 6140, New Zealand.
authors.forename: B V
authors.initials: BV
authors.lastname: Alloway
authors.affiliation: Department of Geography &Earth Sciences, Aberystwyth University, SY23 3DB Wales, United Kingdom.
authors.forename: N J G
authors.initials: NJ
authors.lastname: Pearce
authors.affiliation: INIBIOMA, CONICET-Universidad Nacional del Comahue, Bariloche, Argentina.
authors.forename: G
authors.initials: G
authors.lastname: Villarosa
authors.affiliation: INIBIOMA, CONICET-Universidad Nacional del Comahue, Bariloche, Argentina.
authors.forename: V
authors.initials: V
authors.lastname: Outes
authors.affiliation: Department of Ecological Sciences and Millennium Institute of Ecology and Biodiversity, Universidad de Chile, Santiago 7750000, Chile.
authors.forename: P I
authors.initials: PI
authors.lastname: Moreno