The 26·5 ka Oruanui Eruption, Taupo Volcano, New Zealand: Development, Characteristics and Evacuation of a Large Rhyolitic Magma Body

Wilson, C. J. N.; Blake, Stephen; Charlier, B. L.; Sutton, Andrew N.

doi:10.1093/petrology/egi066

Cited by 189 publications

(343 citation statements)

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“…pyroclastic material (see Miller and Wark 2008 for overview), and are often interpreted to result from a unique set of circumstances that lead to the accumulation and mobilisation of large amounts of magma (Caricchi et al 2014;Malfait et al 2014). It is now widely regarded that significant volumes of partly molten crystal-rich mush are required to generate the huge volumes of melt(s) required for supereruptions Bergantz 2004, 2008;Hildreth 2004;Glazner et al 2004;Wilson et al 2006;Hildreth and Wilson 2007;Lipman 2007;Girard and Stix 2009;Wilson and Charlier 2009;Allan 2013;Lipman and Bachmann 2015). Such studies often highlight the crucial interplay of this evolved crystal mush with a deeper-seated feeder system of less evolved mafic melts and their crystalline products (Hildreth 1981).…”

Section: Electronic Supplementary Materialsmentioning

confidence: 99%

Fine-scale temporal recovery, reconstruction and evolution of a post-supereruption magmatic system

Barker

Wilson

Allan

et al. 2015

Contrib Mineral Petrol

214

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eruption of 25 rhyolitic units starting at ~12 ka. The dacites show strongly zoned minerals and wide variations in meltinclusion compositions, consistent with early magma mixing followed by periods of cooling and crystallisation at depths of >8 km, overlapping spatially with the inferred basal parts of the older Oruanui silicic mush system. The dacites reflect the first products of a new silicic system, as most of the Oruanui magmatic root zone was significantly modified in composition or effectively destroyed by influxes of hot mafic magmas following caldera collapse. The first rhyolites erupted between 12 and 10 ka formed through shallow (4-5 km depth) cooling and fractionation of melts from a source similar in composition to that generating the earlier dacites, with overlapping compositions for melt inclusions and crystal cores between the two magma types. For the successively younger rhyolite units, temporal changes in melt chemistry and mineral phase stability are observed, which reflect the development, stabilisation and maturation of a new, probably unitary, silicic mush system. This new mush system was closely linked to, and sometimes physically interacted with, underlying mafic melts of similar composition to those involved in the Oruanui supereruption. From the inferred depths of magma storage and geographical extent of vent sites, we consider that a large silicic mush system (>200 km 3 and possibly up to 1000 km 3 in volume) is now established at Taupo and is capable of feeding a new episode or cycle of volcanism at any stage in the future.

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Section: Electronic Supplementary Materialsmentioning

confidence: 99%

Fine-scale temporal recovery, reconstruction and evolution of a post-supereruption magmatic system

Barker

Wilson

Allan

et al. 2015

Contrib Mineral Petrol

214

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“…[43] Weighing of phenocrysts and groundmass separated by heavy liquid separation, magnetic separation, elutriation, and handpicking from coarsely crushed samples can be used to determine phenocryst content by weight [e.g., Wilson et al, 2005].…”

Section: A42 Phenocryst Separationmentioning

confidence: 99%

Preeruptive magma viscosity: An important measure of magma eruptibility

Takeuchi

2011

J. Geophys. Res.

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[1] Using a compilation of melt compositions, meltwater contents, temperatures, and phenocryst contents, the preeruptive viscosities under magma reservoir conditions are calculated for 83 erupted magmas. The basaltic-to-rhyolitic magmas have preeruptive viscosities over the range 10 1 to 10 8 Pa s. Although bulk SiO 2 content has often been used as a qualitative measure of preeruptive magma viscosity, the bulk SiO 2 content shows a weak correlation with magma viscosity (correlation coefficient r = 0.5). Because of a wide range of phenocryst contents from 0 to ∼50 vol %, andesitic magmas have viscosities ranging from 10 2 to 10 7 Pa s, which are lower or higher than those of phenocryst-poor rhyolitic magmas with 10 5 to 10 6 Pa s. Focusing on andesitic to rhyolitic magmas, the r between bulk SiO 2 contents and magma viscosities changes to −0.1. In contrast, the melt-only SiO 2 content from a basaltic-to-rhyolitic melt shows a good linear correlation with melt-only viscosity (r = 0.9). Although most of the calculated viscosities of erupted magmas fall below ∼106 Pa s, as consistent with the previous compilation study, this paper describes 20 examples of highly viscous magmas with >106 Pa s, in most cases, composed of mixtures of high-silica rhyolitic melt (75-79 wt % SiO 2 ) and abundant phenocrysts (30-55 vol %). In these highly viscous magmas, 9 examples have erupted following the precursory eruption of less viscous magma, suggesting that precursory dike propagation and conduit formation by the less viscous magma with <10 6 Pa s induced the following eruption of less eruptible, highly viscous magmas.

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“…The caldera-forming Kawakawa or Oruanui eruption of Taupo volcano, one of the largest volcanic events of the late Quaternary (Wilson et al, 2006), resulted in the widespread distribution of an important chronostratigraphic marker for eLGM sequences in New Zealand (Pillans et al, 1993). Several different names have been applied to the various pyroclastic products of this eruption (Table 1).…”

Section: Kawakawa/oruanui Tephramentioning

confidence: 99%

“…Rampino and Self, 1993), although the extent of cooling and impact is debated (Zielinski et al, 1996;Oppenheimer, 2002). The Kawakawa/ Oruanui eruption is the largest known 'wet' eruption (explosive interaction between silicic magma and external water), generating $430 km 3 of fall deposits, $320 km 3 of pyroclastic density-current (mostly ignimbrite) deposits, and $420 km 3 of primary intracaldera material, approximately 1170 km 3 in total and equivalent to $530 km 3 of magma (Wilson, 2001;Manville and Wilson, 2004;Wilson et al, 2006). It is reasonable to postulate therefore that the apparent cooling trend inferred by the increasing levels of grass pollen in Kohuora, Pukaki and Mt Richmond pollen records commencing just after deposition of the Kawakawa/Oruanui tephra was triggered by volcanic cooling of the atmosphere.…”

Section: Comparison With Other Palynological Records From Aucklandmentioning

confidence: 99%

Vegetation and climate of Auckland, New Zealand, since ca. 32 000 cal. yr ago: support for an extended LGM

Newnham

Lowe

Giles³

et al. 2007

J Quaternary Science

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Auckland occupies a climatically sensitive position close to a major biogeographic boundary in the southern mid‐latitudes. A new pollen record from Kohuora maar crater, Auckland, displays vegetation and climatic changes for the past ca. 32 000 years. Of particular interest are the inferred climatic patterns for the first part of the interval, encompassing the Last Glacial Maximum (LGM). The Kohuora record corresponds closely with pollen records from other Auckland sites indicating that the patterns observed are at least regional in extent. It is also broadly consistent with a variety of palaeoenvironmental evidence from across New Zealand, including the glacial record from Westland, other palynological records from North Island, other palaeoecological records from the South Island, and aeolian quartz sequences from western North Island. These records show that glacial conditions prevailed across most, if not all, of New Zealand during the interval ca. 29–19 k cal. yr BP, longer and earlier than the LGM sensu stricto. We suggest that the term extended LGM (eLGM) may be more appropriate for the New Zealand region. Within this predominantly cold interval, the Auckland pollen records indicate a climatic amelioration for the interval ca. 26–24 k cal. yr BP, also consistent with other palaeocological data from Canterbury, that fall within a period of climate amelioration recognised between the first two eLGM glacial advances in Westland. We refer to this warming interval as the eLGM Interstadial. The ca. 27 k cal. yr BP Kawakawa/Oruanui tephra is instrumental in most of these inter‐site comparisons and occurs after the first peak of eLGM cooling in a short‐lived comparatively mild phase. A subsequent return to apparently colder climate in the Auckland records may indicate a volcanic cooling effect or, more likely, widespread landscape disturbance following this major eruption event. Strong correspondence between biotic responses, glacial fluctuations and aeolian quartz deposition linked to major shifts in strength and latitudinal extent of the southern westerlies suggest that both the eLGM and eLGM Interstadial may be more widely registered, at least across the Southern Ocean. Support for this assertion comes from parallel investigations in western and southernmost South America and isotopic and palaeoecological records from Southern Ocean marine cores. Recent reconstructions of the globally averaged ice‐equivalent sea‐level history are in line with this evidence from the Southern Hemisphere, suggesting that the eLGM may have a global registration. In light of these observations, we suggest a re‐examination of the defined timing of the LGM along with renewed effort to establish climatic patterns during this period and understand their causes. Copyright © 2007 John Wiley & Sons, Ltd.

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The 26·5 ka Oruanui Eruption, Taupo Volcano, New Zealand: Development, Characteristics and Evacuation of a Large Rhyolitic Magma Body

Cited by 189 publications

References 91 publications

Fine-scale temporal recovery, reconstruction and evolution of a post-supereruption magmatic system

Fine-scale temporal recovery, reconstruction and evolution of a post-supereruption magmatic system

Preeruptive magma viscosity: An important measure of magma eruptibility

Vegetation and climate of Auckland, New Zealand, since ca. 32 000 cal. yr ago: support for an extended LGM

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