摘要：

The Lican Ignimbriteepresents large explosiveasalticndesite event inhe eruptiveistoryfhe Villarrica Volcano,nctivetratovolcanofheouthernndean Volcanic Zone.ineralogicaltudyfhis ignimbrite indicates important disequilibriumeatures.esoptionextures werebservedrounda-rich (An_(74-92); Group 1)ndoreodic (An_(35-44); Group 2) plagioclase phenocrystores.imsnhese phe-nocrystss wellsicrolites grew withn intermediateomposition (An_(47-63); Group 3). Low-ndigh-Mglinopyroxenendrthopyroxene phenocrysts werelso identified;ostfhemhowingeverseg zoning.asednheseineralogical datandhermodynamicodeling,n increasefbout 200 ℃ inemperature (from -900-1000°o -1100-1150 ℃), decompressionf-400ar (equivalento -1.5 km)nd decrease in_2Oontent inheeltf ~1.6wt.%re identified duringrystallization.dditionfotagmaromelow wouldaveausedeatingfheeservoir withheonsecutivescentfagma pulses,_2O exsolutionndonvectiveixing (compositionalnd/orhermalixing). numericalodelsingheinite Elementethod was developedossessheesponsefhe Lican Ignimbriteeservoirpononductiveeatingy 200 ℃yaficnderplating;hisodel indicatesapid (tensf years)emperatureo-mogenizationfhisystem, withscendingagma plumes with velocitiessighs 6/h.ecausehe Lican Ignimbrite eruptedthe endfhe Pleistocene glaciation, glacialnloadingouldavelsoontributedo depressurizationfheeservoir.

展开