Petrogenesis of Late Cenozoic volcanic rocks from the Taupo Volcanic Zone, New Zealand, in the light of new lead isotope data

Ian J. Graham*, Brian L. Gulson, Jeffrey W. Hedenquist, Karen Mizon

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

68 Citations (Scopus)

Abstract

Lead isotopes and U Pb concentrations have been measured for a wide range of volcanic rocks from the Taupo Volcanic Zone (TVZ), New Zealand. Combined geochemical and isotope plots suggest that the majority of mafie-intermediate volcanic rocks result from contamination (AFC) of primitive basalt by Mesozoic metasedimentary basement. Lead isotope data indicate that some previously published petrogenetic models require modification, notably in the choice of parental magma and in the composition and proportion of the crustal assimilant. Evidence is also presented to show that the voluminous ignimbrites and rhyolites of the TVZ could be derived by melting of early-formed andesites (with accompanying minor crustal contamination) and rule out previous models such as direct melting of Mesozoic basement rocks or contamination of mantle derived melts.

Original languageEnglish
Pages (from-to)2797-2819
Number of pages23
JournalGeochimica et Cosmochimica Acta
Volume56
Issue number7
DOIs
Publication statusPublished - 1992
Externally publishedYes

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