Volcanic products of Lipari (Aeolian islands, Italy): Multivariate analysis of petrographic and radiometric data

A petrographicandradiometricstudy,alongwithstatisticalmultivariateanalysisofvolcanicproductsof the islandofLipari(Aeolianislands,Italy)wascarriedout.ThevolcanologicalhistoryofLipariwas reconstructed defining twostages(pre-andpost-erosivestages)furtheronsubdividedinfourvolcanic phases,eachofwhichcharacterizedbyproductswithaparticularchemicalcompositionandseparated by stratigraphicunconformities.Thecorrelationsbetweenpetrographicfeatures,determinedbyX-ray fluorescence, andvolcanologicalhistoryoftheislandhighlightagradualdifferentiationwithyounger rocksshowingamoreacidchemicalcompositionthantheolderones.Radiometricfeatures,andin particularthecontentofprimordialradionuclides 238U, 232Th and 40K,havebeenmeasuredthrough gamma-rayspectrometrywithhyper-puregermaniumdetector. Thedifferentvolcaniclithologies,suchasbasalts,andesitesandrhyolites,havebeencharacterizedby petrographicdiagrams.Thecalculateddoseratehasalsobeenusedasanadditionalclassificationparameter. Olderproductsshowlowalkalicontentthantheyoungerones.Thisisrelatedwiththeincreasingof incompatibleelements,suchasuraniumandthorium,intheyoungerproducts. Principalcomponentsandhierarchicalclusteringstatisticalanalyseshaveprovidedadditionalinfor- mation onsampledifferentiationandsimilarities.