The invisible hand: Tectonic triggering and modulation of a rhyolitic supereruption

Allan, Aidan S. R.; Wilson, C. J. N.; Millet, Marc-Alban; Wysoczanski, Richard J.

doi:10.1130/g32969.1

Cited by 125 publications

(189 citation statements)

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“…The Oruanui juvenile material was >99 % rhyolite, with a minor (<1 %) component of mafic magmas (Sutton et al 1995;Wilson et al 2006). Investigation of pumice compositions has shown that there was a complex range of rhyolite melts involved, with a dominant high-silica rhyolite (HSR), minor amounts of a low-silica rhyolite (LSR) and traces of an independent biotite-bearing (BtB) magma introduced via syneruptive diking from the contemporaneous NE dome magmatic system Allan et al 2012;Allan 2013;Fig. 1a).…”

Section: Electronic Supplementary Materialsmentioning

confidence: 98%

“…The young eruptive history of Taupo is exceptionally well constrained by field stratigraphy, radiocarbon dating and correlation with other young tephras from the Taupo Volcanic Zone (TVZ) (Wilson 1993;). Taupo's caldera was primarily formed in the catastrophic 25.4 ka Oruanui event, the world's youngest supereruption, which evacuated >530 km 3 of magma (>1100 km 3 of pyroclastic material) (Wilson 2001;Wilson et al 2006; Vandergoes et al 2013;Allan 2013;Allan et al 2012Allan et al , 2013Fig. 1).…”

Section: Electronic Supplementary Materialsmentioning

confidence: 99%

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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: 98%

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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“…We have not found any evidence that the different magma systems interacted during eruption. However, their close spatial and temporal proximity would seem to allow for the possibility (e.g., Allan et al, 2012).…”

Section: Continuity Of Magmatism and Peralkaline Versus Metaluminous-mentioning

confidence: 99%

Geology and evolution of the McDermitt caldera, northern Nevada and southeastern Oregon, western USA

et al. 2017

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The McDermitt caldera (western USA) is commonly considered the point of origin of the Yellowstone hotspot, yet until now no geologic map existed of the caldera and its geology and development were incompletely documented. We developed a comprehensive geologic framework through detailed and re connaissance geologic mapping, extensive petrographic and chemical analy sis, and highprecision Eruption of the McDermitt Tuff generated the irregularly keyholeshaped, 40 × 30-22 km McDermitt caldera. Collapse occurred mostly along a narrow ringfault zone of discrete faults with variable downwarp into the caldera be tween faults. Minor parallel faults locally widen the zone to as much as 6 km. We find no evidence that the McDermitt caldera consists of multiple nested calderas, as previously postulated. Total collapse was no more than ~1 km, and total erupted volume was ~1000 km 3 , of which 50%-85% is intracaldera tuff. Uncertainties in these estimates arise because an intracaldera tuff section is exposed only along the western edge of the caldera, and outflow tuff is not completely mapped. Megabreccia and mesobreccia are common in intracal dera tuff in the complete section. Intracaldera tuff is strongly rheomorphic, scrambling the compositional zoning, which is locally better preserved in out flow sections. However, outflow tuff is also strongly rheomorphic where it was deposited over steep topography.The caldera underwent postcollapse resurgent uplift driven by intrusion of icelandite magma, which also erupted from two major vents and as wide spread lavas. Major igneous activity around the McDermitt caldera lasted from before 16.7 to 16.1 Ma, although minor highalumina olivine tholeiite lavas were emplaced ca. 14.9 Ma in the youngest recognized igneous activity.Tuffaceous sediments as much as 210 m thick filled the caldera, although whether deposition preceded, followed, or spanned resurgence is unresolved. Although formed during regional extension, the caldera is cut only at its west ern and eastern margins by much younger, highangle normal faults that re sulted in gentle (~10°) eastward tilting of the caldera.Numerous hydrothermal systems probably related to caldera magmatism and focused along caldera structures produced Hg, Zrrich U (some along the western caldera ring fracture dated as 16.3 Ma), Ga, and minor Au mineral ization. Lithium deposits formed throughout the intracaldera tuffaceous sedi ments, probably ca. 14.9 Ma.Silicic central Snake River Plain, which also erupted voluminous rhyolitic tuffs. How ever, the Snake River Plain ignimbrites are metaluminous and homogeneous in bulk chemistry, with plagioclase, sanidine, and minor quartz as common phenocrysts, and rarely contain pumice or lithics.

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“…Wark et al 2007), when other, external factors may be important in causing both the recharge and the eruption (e.g. Allan et al 2012;..…”

Section: Introductionmentioning

confidence: 99%

Timescales of mixing and mobilisation in the Bishop Tuff magma body: perspectives from diffusion chronometry

Chamberlain

Morgan

Wilson

2014

Contrib Mineral Petrol

135

173

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Abstract:We present two-feldspar thermometry and diffusion chronometry from sanidine, orthopyroxene and quartz from multiple samples of the Bishop Tuff, California, to constrain the temperature stratification within the pre-eruptive magma body and the timescales of magma mixing prior to its eruption. Two-feldspar thermometry yields estimates that agrees well with previous Fe-Ti oxide thermometry and gives a ~80 °C temperature difference between the earlier-and later-erupted regions of the magma chamber. Using this thermometry, we model diffusion of Ti in quartz, and Ba and Sr in sanidine as well as Fe-Mg interdiffusion in orthopyroxene to yield timescales for the formation of overgrowth rims on these phenocryst phases. Diffusion profiles of Ti in quartz and Fe-Mg in orthopyroxene diffusion both yield timescales of <150 years for the formation of overgrowth rims. In contrast, both Ba and Sr diffusion in sanidine yield nominal timescales 1-2 orders of magnitude longer than these two methods. The main cause for this discrepancy is inferred to be an incorrect assumption for the initial profile shape for Ba and Sr diffusion modelling (i.e., growth zoning). Utilising the divergent diffusion behaviour of Ba and Sr, we place constraints on the initial width of the interface and can refine our initial conditions considerably, bringing Ba and Sr data into alignment, and yielding timescales closer to 500 years, the majority of which are then within uncertainty of timescales modelled from Ti diffusion in quartz. Care must be thus taken when using Ba-in-sanidine geospeedometry in evolved magmatic systems where no other phases or elements are available for comparative diffusion profiling. Our diffusion modelling reveals piecemeal rejuvenation of the lower parts of the Bishop Tuff magma chamber at least 500 years prior to eruption. Timescales from our mineral profiling imply either that diffusion coefficients currently used are uncertain by 1-2 orders of magnitude, or that the minerals concerned did not experience a common history, despite being extracted from the same single pumice clasts. Introduction of the magma initiating crystallization of the contrasting rims on sanidine, quartz, orthopyroxene and zircon was prolonged, and may be a marker of other processes that initiated the Bishop Tuff eruption rather than the trigger itself. 2 AbstractWe present two-feldspar thermometry and diffusion chronometry from sanidine, orthopyroxene and quartz from multiple samples of the Bishop Tuff, California, to constrain the temperature stratification within the pre-eruptive magma body and the timescales of magma mixing prior to its eruption. Twofeldspar thermometry yields estimates that agree well with previous Fe-Ti oxide thermometry and gives a ~80 °C temperature difference between the earlier-and later-erupted regions of the magma chamber. Using this thermometry, we model diffusion of Ti in quartz, and Ba and Sr in sanidine as well as Fe-Mg interdiffusion in orthopyroxene to yield timescales for the formation of overgrowth rims on th...

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The invisible hand: Tectonic triggering and modulation of a rhyolitic supereruption

Cited by 125 publications

References 18 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

Geology and evolution of the McDermitt caldera, northern Nevada and southeastern Oregon, western USA

Timescales of mixing and mobilisation in the Bishop Tuff magma body: perspectives from diffusion chronometry

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