Download The role of volcano-ice interactions in understanding

Theroleofvolcano-iceinteractionsinunderstandingsubductionzonemagmatism
WhitepapersubmissiontotheSZOWorkshopbyBenEdwards
ThevastmajorityoftheglacierizedvolcanoesonEarthareinsubductionzones(Fig.1
fromEdwardsandKochtitzky2015;IcelandandAntarcticaarethetwonotableexceptions),yet
littleworkhasbeendoneinthatsettingtounderstandhowinteractionsbetweeniceloading
andunloadingmayhaveaneffectonmeltgenerationprocessesorstabilityofcrustalmagma
storageareas(e.g.Gudmundsson,1986;Glazneretal.,Wattetal.2013).
Figure1.Globaldistributionofglacierizedvolcanoes(EdwardsandKochtitzky2015).
Whileitisdebatableastohowthickicemustbetoinfluencemantlemeltingprocesses,rapid
crustalloadingandunloadingofevenahundredmetersoficecanhaveimportanteffectson
localstressfields()andvolatilesaturation/vesiculation(Fig2;Edwardsetal.2015).Andgiven
manyrecentexamplesfromtheCascades(MSH),Alaska(Redoubt,Pavlov),Iceland
(Eyjafjallajokull),andSouthAmerica(NevadodelRuiz;Villarrica;Hudson),therealhazardsof
theseinteractionspotentiallyhaveamuchlongerreachduetothefluidityoflaharsandthe
potentialforthegenerationofextremelyfine
ashfrommagma-waterinteractions.Especially
inSouthAmerica,wherehighelevation
glaciovolcanoesareimportantforyear-round
watersuppliestomanycommunities,eruptions
fromglacierizedvolcanoesposemany‘nontraditional’threats.
Figure2.Relationshipbetweenfragmentation
processesasafunctionofmagmaH2O
concentrationandthicknessofoverlyingice.
Theroleofvolcano-iceinteractionsinunderstandingsubductionzonemagmatism
Whatisholdingbacksubductionzonesciencerelatedtoglaciovolcanism?
• Mainlyalargergroupofscientiststrainedintheknowledgeofglaciovolcanism,willing
andabletoworkinrelativelyextremefieldconditions;
• Extremelyhighaccuracygeochronologytechniquesthatcanresolveeruptiontimingon
thetime-scalesofclimatechange(1-10ky);and
• Moreaccuratemodelsforsaturationofacompletesetofvolatilegasesatrelevant
pressures(1-10MPa)
WhatgrandsciencerequiresanewSZOinitiativerelatedtoglaciovolcanism?
• Betterunderstandingoftheintegrated‘SZsystemscience’thatlinkslithospheric
dynamics,cryospheric/hydrosphericdynamics,andatmosphericdynamics,andthatwill
require:integratedresearchprojectsandteamsthatincludecrustal-andglacier-scale
geophysics(highfieldcosts),andhighprecisiongeochemicalstudies(e.g.,ionprobe
accessforCO2measurementsatconcentrationslessthan10ppm)thatwillalsohave
highcosts;and
• MainbenefitswillbeextractingamoredetailedclimaterecordfromSZvolcanoes(e.g.
Wattetal.2013;HuybersandLangmuir2009;SmellieandEdwards2016)tobetter
understandthefeedbackmechanismsbetweenclimateandvolcanism,aswellasbeing
abletomakemuchmoreaccuratehazardmapsforproximalanddistallocationsnear
glacierizedvolcanoes.
Whatisnew,excitinganddoable?
• Newistakingaholisticapproachtounderstandingglacierizedsubductionzone
volcanoesasanintegratedsysteminfluencedbymorethanmagmaticconditionsofmelt
generationandstorage;
• Excitingislinkingprocessesatvastlydifferenttime-scales(platetectonics[106yr],
Milankovichcycles[104-5yr],glaciermovements[104yr]anderuptiondynamics[101s]
tofullyunderstandlinkagesfromthemantletotheatmosphereclimatechange;also
understandinghowsuggestionsthatmoderndayclimatechangecontinuestoaffect
ratesofmagmaproductioninIceland(e.g.Sigmundssonetal.2010)yethasapparently
notleftascleararecordeveninactivesubductionzones(e.g.Wattetal.2013);
Theroleofvolcano-iceinteractionsinunderstandingsubductionzonemagmatism
•
Doableismakingafullaccountingofthelinkedclimate-eruptionhistoriesof
glaciovolcanoesinSZsettingswithdetailedfieldmappingandhighprecisionanalytical
methods(geochronology,micro-analysisofH2O/CO2andothervolatilesinmelt
inclusions,etc);
•
Glacierizedvolcanoeshavealonghistoryofhumaninteractionandmuchmorecanbe
donetoinvestigatelinkswithmodernandancientsocieties(e.g.sourcesofobsidianin
AK,Cascades,SA;religiousceremoniesofIncancultureand‘ice’mummies);and
Glaciersatthesevolcanoesmayhavelongtermrecordsoftephra,frozeninice,that
haveexperiencedlessdegradationfromsurficialweathering.
•
WhatformcantheSZOinitiativetakewithrespecttoglaciovolcanism?
• Makingsuretotargetvolcanoesthathavebeenorareglacierizedfordetailedfield
mappingandgeochronology;and
• Developingintegratedteamsacrossdisciplines(volcanologists–geochemists-
geochronologists–Quaternaryscientists–glaciologists)andestablishingageneric
rubrictosystematizeanalysisofglacierizedvolcanoes,whichcanbeadaptedtospecific
conditionsatlocationswithdifferentchallenges(e.g.volcanoesthatarepresently
heavilyglacierizedmayhavestratigraphythatismuchlessaccessible,andmayrequire
moregeophysicalsurveysoficeand/oricecoringtoquantifypresenticecoverandto
recovertephrarecordsfromice)
HowcantheSZOglaciovolcanismresearchreachscientists,studentsandthepublic?
• Glacierizedvolcanoesareofspecialinteresttothepublicbecausemanyarerecognized
ascriticalwatersourcesforcommunities(drinkingwaterforhumansandlivestock;
waterforagriculture);and
• Glacierizedvolcanoesarealsoofspecialinterestfortherecreationalopportunitiesthey
provide(skiareas,iceclimbing,etc)andtheirproximitytolargepopulationcenters(e.g.
Mt.RainierandSeattle;manyplacesinSouthAmerica).
Theroleofvolcano-iceinteractionsinunderstandingsubductionzonemagmatism
ReferencesCited
• Edwards,B.R.,Kochtitzky,W.2015.Assessingtheglobalpotentialforvolcano-glacier
interactions.GSAAbstractswithProgram,FallMeeting,Baltimore,MD.,Abst.#270455.
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Sigurdsson,H.,Houghton,B.,Rymer,H.,Stix,J.,McNutt,S.(Eds.),TheEncyclopediaof
Volcanoes,377–393.
• Glazner,A.F.,Manley,C.R.,Marron,J.S.andRojstaczer,S.1999.Fireorice:
anticorrelationofvolcanismandglaciationinCaliforniaoverthepast800,000years.
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Climateeffectsonvolcanism:influenceonmagmaticsystemsofloadingandunloading
fromicemassvariations,withexamplesfromIceland.PhilosophicalTransactionsofthe
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• Smellie,J.L.,Edwards,B.R.2016.GlaciovolcanismonEarthandMars:products,
processesandpaleoclimateimplications.CambridgeUniversityPress:Cambridge,ISBN
9781107037397,490p.
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