Primitive andesites from the Taupo Volcanic Zone formed by magma mixing

Beitrag in einer Fachzeitschrift
(Originalarbeit)


Details zur Publikation

Autor(en): Beier C, Haase K, Brandl P, Krumm S
Zeitschrift: Contributions To Mineralogy and Petrology
Verlag: Springer Verlag
Jahr der Veröffentlichung: 2017
Band: 172
Heftnummer: 5
ISSN: 0010-7999


Abstract


Andesites with Mg# >45 erupted at subduction zones form either by partial melting of metasomatized mantle or by mixing and assimilation processes during melt ascent. Primitive whole rock basaltic andesites from the Pukeonake vent in the Tongariro Volcanic Centre in New Zealand’s Taupo Volcanic Zone contain olivine, clino- and orthopyroxene, and plagioclase xeno- and antecrysts in a partly glassy matrix. Glass pools interstitial between minerals and glass inclusions in clinopyroxene, orthopyroxene and plagioclase as well as matrix glasses are rhyolitic to dacitic indicating that the melts were more evolved than their andesitic bulk host rock analyses indicate. Olivine xenocrysts have high Fo contents up to 94%, δO of +5.1‰, and contain Cr-spinel inclusions, all of which imply an origin in equilibrium with primitive mantle-derived melts. Mineral zoning in olivine, clinopyroxene and plagioclase suggest that fractional crystallization occurred. Elevated O isotope ratios in clinopyroxene and glass indicate that the lavas assimilated sedimentary rocks during stagnation in the crust. Thus, the Pukeonake andesites formed by a combination of fractional crystallization, assimilation of crustal rocks, and mixing of dacite liquid with mantle-derived minerals in a complex crustal magma system. The disequilibrium textures and O isotope compositions of the minerals indicate mixing processes on timescales of less than a year prior to eruption. Similar processes may occur in other subduction zones and require careful study of the lavas to determine the origin of andesite magmas in arc volcanoes situated on continental crust.



FAU-Autoren / FAU-Herausgeber

Beier, Christoph PD Dr.
Lehrstuhl für Endogene Geodynamik
Brandl, Philipp
Lehrstuhl für Endogene Geodynamik
Haase, Karsten Prof. Dr.
Lehrstuhl für Endogene Geodynamik
Krumm, Stefan Dr.
Lehrstuhl für Endogene Geodynamik


Zitierweisen

APA:
Beier, C., Haase, K., Brandl, P., & Krumm, S. (2017). Primitive andesites from the Taupo Volcanic Zone formed by magma mixing. Contributions To Mineralogy and Petrology, 172(5). https://dx.doi.org/10.1007/s00410-017-1354-0

MLA:
Beier, Christoph, et al. "Primitive andesites from the Taupo Volcanic Zone formed by magma mixing." Contributions To Mineralogy and Petrology 172.5 (2017).

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Zuletzt aktualisiert 2018-16-10 um 22:40