Decoupled crystallization and eruption histories of the rhyolite magmatic system at Tarawera volcano revealed by zircon ages and growth rates

Show simple item record Storm, S en Shane, Philip en Schmitt, AK en Lindsay, Jan en 2018-10-10T20:29:37Z en 2012-03 en
dc.identifier.issn 0010-7999 en
dc.identifier.uri en
dc.description.abstract We obtained U–Th disequilibrium age data on zircons from each of the four rhyolite eruptions that built Tarawera volcano in the last 22 ka within the Okataina Volcanic Center (OVC), caldera, New Zealand. Secondary ion mass spectrometry analyses on unpolished euhedral crystal faces that lack resorption features show that crystal growth variously terminated from near-eruption age to ~100 ka prior to eruption. Age-depth profiling of crystals reveals long periods of continuous (~34 ka) and discontinuous growth (~90 ka). Growth hiatuses of up to ~40 ka duration occur, but do not all relate to obvious resorption surfaces. Age differences up to similar magnitude are found on opposing faces of some crystals suggesting episodes of partial exposure to melts. These features are best explained by periodic, complete, or partial, sub-solidus storage and/or inclusion in larger crystal phases, followed by rapid liberation prior to eruption. This is supported by high abundances of U and Th (~500 − >2,000 ppm) in some zircons consistent with periods of high crystallinity (>70%) in the magmatic system, based on crystal/melt partitioning. Contemporaneous but contrasting rim-ward trends of these elements within crystals, even in the same lava hand sample, require synchronous growth in separate melt bodies and little connectivity within the system, but also significant crystal transport and mixing prior to eruption. Many crystals record continuity of growth through the preceding ~60 ka OVC caldera-collapse and subsequent eruptions from Tarawera. This demonstrates a decoupling between eruption triggers, such as shallow crustal extension and mafic intrusion, and the crystallization state of the OVC silicic magmatic system. The data highlights the need to distinguish between the time for accumulation of eruptible magma and the long-term magma residence time based on the age of crystals with high closure temperatures, when assessing the potential for catastrophic eruptions. en
dc.publisher Springer en
dc.relation.ispartofseries Contributions to Mineralogy and Petrology en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights.uri en
dc.title Decoupled crystallization and eruption histories of the rhyolite magmatic system at Tarawera volcano revealed by zircon ages and growth rates en
dc.type Journal Article en
dc.identifier.doi 10.1007/s00410-011-0682-8 en
pubs.issue 3 en
pubs.begin-page 505 en
pubs.volume 163 en
dc.rights.holder Copyright: The author en
pubs.end-page 519 en
dc.rights.accessrights en
pubs.subtype Article en
pubs.elements-id 325916 en Science en School of Environment en
dc.identifier.eissn 1432-0967 en
pubs.number 3 en
pubs.record-created-at-source-date 2013-07-08 en

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