ARTÍCULO
Geostatistics and multivariate analysis as a tool to characterize volcaniclastic deposits: Application to Nevado de Toluca volcano, Mexico
N. Bellotti, L. Capra, D. Sarocchi, D'Antonio M.
Journal of Volcanology and Geothermal Research 191: 117-128., 2010.
ABSTRACT:
Grainsizeanalysisofvolcaniclasticdepositsismainlyusedtostudy flowtransportanddepositional processes,inmostcasesbycomparingsomestatisticalparametersandhowtheychangewithdistancefrom thesource. Inthisworkthegeospatialandmultivariateanalysesarepresentedasastrongadaptablegeostatisticaltool appliedtovolcaniclasticdepositsinordertoprovideaneffectiveandrelativelysimplemethodologyfortexture description,depositdiscriminationandinterpretationofdepositionalprocesses. WechoosethecaseofNevadodeTolucavolcano(Mexico)duetoexistingknowledgeofitsgeological evolution,stratigraphicsuccessionandspatialdistributionofvolcaniclasticunits.Grainsizeanalysesand frequencydistributioncurveshavebeencarriedouttocharacterizeandcomparethe28-kablock-and-ash flow depositassociatedtoadomedestructionepisode,andtheElMorraldebrisavalanchedepositoriginatedfrom thecollapseofthesouth-easternsectorofthevolcano.Thegeostatisticalinterpolationofsedimentologicaldata allowstorealizebidimensionalmapsdrapedoverthevolcanotopography,showingthegranulometric distribution,sortingand finematerialconcentrationintothewholedepositwithrespecttotopographic changes.Inthisway,itispossibletoanalyzeacontinuoussurfaceofthegrainsizedistributionofvolcaniclastic depositsandbetterunderstand flowtransportprocesses. Theapplicationofmultivariatestatisticanalysis(discriminantfunction)indicatesthatthismethodologycould beusefulindiscriminatingdepositswithdifferentoriginordifferentdepositionallithofacieswithinthesame deposit. Theproposedmethodologycouldbeaninterestingapproachtosustainmoreclassicalanalysisofvolcaniclastic deposits,especiallywhereaclear fieldclassificationappearsproblematicbecauseofahomogeneoustextureof thedepositsortheirscarceanddiscontinuousoutcrops.Ourstudyisanexampleofthestrongversatilityof geospatialanalysistoprovideaneffectiveandrelativelyclearmethodologyforthecharacterizationof volcaniclasticdeposits.