The origin and crust/mantle mass balance of Central Andean ignimbrite magmatism constrained by oxygen and strontium isotopes and erupted volumes

Volcanism during the Neogene in the Central Volcanic Zone (CVZ) of the Andes produced (1) stratovolcanoes, (2) rhyodacitic to rhyolitic ignimbrites which reach volumes of generally less than 300 km 3 and (3) large-volume monotonous dacitic ignimbrites of up to several thousand cubic kilometres. We p...

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Bibliographic Details
Published in:Contributions to mineralogy and petrology 2015-06, Vol.169 (6), p.461, Article 58
Main Authors: Freymuth, Heye, Brandmeier, Melanie, Wörner, Gerhard
Format: Article
Language:English
Subjects:
Analysis
Continental dynamics
Crystallization
Earth and Environmental Science
Earth Sciences
Geology
Isotopes
Magma
Magmatism
Melting
Mineral Resources
Mineralogy
Neogene
Original Paper
Oxygen isotopes
Petrology
Porphyry
Strontium
Volcanic eruptions
Volcanism
Volcanoes
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Summary:Volcanism during the Neogene in the Central Volcanic Zone (CVZ) of the Andes produced (1) stratovolcanoes, (2) rhyodacitic to rhyolitic ignimbrites which reach volumes of generally less than 300 km 3 and (3) large-volume monotonous dacitic ignimbrites of up to several thousand cubic kilometres. We present models for the origin of these magma types using O and Sr isotopes to constrain crust/mantle proportions for the large-volume ignimbrites and explore the relationship to the evolution of the Andean crust. Oxygen isotope ratios were measured on phenocrysts in order to avoid the effects of secondary alteration. Our results show a complete overlap in the Sr–O isotope compositions of lavas from stratovolcanoes and low-volume rhyolitic ignimbrites as well as older (>9 Ma) large-volume dacitic ignimbrites. This suggests that the mass balance of crustal and mantle components are largely similar. By contrast, younger (
ISSN:0010-7999
1432-0967
DOI:10.1007/s00410-015-1152-5