Petrologic investigations of the 1995 and 1996 eruptions of Ruapehu volcano, New Zealand: formation of discrete and small magma pockets and their intermittent discharge

Nakagawa, Mitsuhiro; Wãda, Keiji; Thordarson, T.; Wood, C. P.; Gamble, J. A.

doi:10.1007/s004450050259

Cited by 101 publications

(65 citation statements)

References 42 publications

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“…3). Consistent with the rarity of andesitic melts generated by this mechanism in the lower crust, many andesite magmas show petrographic evidence of mingling/mixing; in these cases a simpler explanation for their genesis would be interaction between mafic and felsic magmas (Nakamura 1995;Murphy et al 1998;Nakagawa et al 1999;Frey & Lange 2010;Humphreys et al 2012;Jeffery et al 2013;Kilgour et al 2013).…”

Section: Magma Fluxes and Phase Equilibriamentioning

confidence: 79%

The temporal evolution of chemical and physical properties of magmatic systems

Caricchi¹,

Blundy

2015

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Exactly 100 years ago the great Canadian-born petrologist N. L. Bowen published two seminal works on the chemical differentiation of magmas in which he posed the basis for a physicochemical understanding of the fractionation of crystals from melts in molten rock. A subsequent century of research and technological advances has enhanced our understanding of the physics and chemistry of magmatic systems and their temporal evolution. The image of sub-volcanic magmatic systems has evolved greatly in that time, from a simple 'boiling vat' concept of molten rock in which bubbles, crystals and melt separate gravitationally to a recognition that magma vats are relatively rare and that most magmatic systems spend much of their lifetime in a partially molten, or mushy, state. Real magmatic systems appear to be organized into a series of storage regions periodically connected by feeding structures transferring magma (and heat) at different fluxes. Magma fluxes between the different portions of this plumbing system, and the variation of the chemical and physical properties of magma as it rises through the crust, exert essential controls on the eruptive modalities of volcanoes and the geochemistry of their products. This book presents a collection of contributions that use petrology, geochemistry, geochronology and numerical modelling to identify the processes operating at different depths within magmatic systems and to characterize the fluxes of magma between them.

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Section: Magma Fluxes and Phase Equilibriamentioning

confidence: 79%

The temporal evolution of chemical and physical properties of magmatic systems

Caricchi¹,

Blundy

2015

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“…9) show that these represent a suite of cogenetic igneous rocks that were generated by fractional crystallization of pyroxene, plagioclase, and titanomagnetite as a major phase. Nevertheless, it seems that this differentiation process cannot be explained by normal crystal fractionation and/or accumulation if compared with the morphometric age (Nakagawa et al, 1999). There are different sequential linear trends of elements in the Harker diagrams accompanied by the subsequent appearance of a low D.I.…”

Section: Interpretation Of Petrological Datamentioning

confidence: 95%

Morphometric age and petrological characteristics of volcanic rocks from the Bajawa Cinder Cone Complex, Flores, Indonesia

Sucipta

Takashima

Muraoka

2006

Journal of Mineralogical and Petrological Sciences

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The Bajawa Cinder Cone Complex consists of at least 78 cinder cones, which can be grouped into five morphometric ages. The oldest group, Bajawa 01, is dated between 0.53 and 0.73 Ma. The groups Bajawa 02, 03, and 04 have an age range from 0.41 Ma to 0.51 Ma, 0.32 Ma to 0.40 Ma, and 0.22 Ma to 0.31 Ma, respectively; the youngest cinder cone group, Bajawa 05, is aged between 0 and 0.20 Ma.Three batches of magma have contributed to the long eruptive episode of the complex. Magma mixing and fractional crystallization were important processes in differentiation. Magma mixing may have been caused by recharge of a mafic contributor to form a mixed magma in a temperature range of 836 °C 978 °C and at a pressure of less than 1.25 kbar before eruption.

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“…However, it is clear that ascending magma often interacts with other magmas or crystal mush zones (Nakamura, 1995;Nakagawa et al, 1999Nakagawa et al, , 2002Kilgour et al, 2013). Research into the dynamics of magma-magma and magma-mush interactions is ongoing, but a clear consequence of this process is the addition of foreign crystals along with more evolved melt into the rising magma.…”

Section: Rheological Impact Of Magma Interactionsmentioning

confidence: 99%

Rheological controls on the eruption potential and style of an andesite volcano: A case study from Mt. Ruapehu, New Zealand

Kilgour

Mader

Blundy

et al. 2016

Journal of Volcanology and Geothermal Research

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. AbstractThe evolving magma rheology of three recent Ruapehu eruptions (1969, 1977, and 1995) is estimated using a combination of thermodynamic models and rheological calculations, supported by textural observations of the erupted scoria. We use a well-established thermodynamic model to determine the composition of these representative Ruapehu magmas from 300 MPa to ∼ 30MPa. The outputs of the model provide the changing crystal and bubble content in a closed system (assuming no gas loss), as well as the fractionating melt compositions. We calculate the melt viscosity, and the effect of bubbles and crystals, to quantify the rheology of the magma during ascent (under assumed equilibrium conditions). The moderately high phenocryst content of Ruapehu scoria (∼ 30 %) means that only a small amount of additional microlite crystallisation (∼ 5 %) would result in a yield strength, which may lead the magma to stall. However, if the strain rates are high enough, more crystallisation would be possible without developing a yield stress. This suggests that microlite-rich magmas are almost certain to stall unless they encounter significant fluid addition from a source such as a hydrothermal system, groundwater, or surface water (i.e., Ruapehu's Crater Lake).Ruapehu magmas are initially H 2 O-undersaturated and as a consequence, crystallisation and bubble growth were suppressed until the magma achieved saturation, at ∼ 100 to 50 MPa.From this analysis, we suggest that Ruapehu magmas are more likely to erupt compared to magmas of a similar composition that are H 2 O-saturated. This partly explains the regular, albeit small-volume eruptions at Ruapehu and the propensity for phreatomagmatic eruptions when the magma:water ratio is low.

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Petrologic investigations of the 1995 and 1996 eruptions of Ruapehu volcano, New Zealand: formation of discrete and small magma pockets and their intermittent discharge

Abstract: Ruapehu volcano erupted intermittently be-

Cited by 101 publications

References 42 publications

The temporal evolution of chemical and physical properties of magmatic systems

The temporal evolution of chemical and physical properties of magmatic systems

Morphometric age and petrological characteristics of volcanic rocks from the Bajawa Cinder Cone Complex, Flores, Indonesia

Rheological controls on the eruption potential and style of an andesite volcano: A case study from Mt. Ruapehu, New Zealand

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