Magma Dynamics and Petrological Evolution Leading to the VEI 5 2000 bp Eruption of El Misti Volcano, Southern Peru

Tepley, F. J.; Silva, De; Salas, Guido

doi:10.1093/petrology/egt040

Cited by 17 publications

(19 citation statements)

References 78 publications

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“…1; Browne, 2005;Browne and Gardner, 2006;Buckley et al, 2006;Coombs et al, 2013;Daag et al, 1996;Devine et al, 1998;Garcia and Jacobsen, 1979;Humphreys et al, 2009;McCanta et al, 2007;Murphy et al, 2000;Plechov et al, 2008;Rutherford and Devine, 2003;Rutherford and Hill, 1993;Scott et al, 2012;Tepley et al, 2013). In addition to polycrystalline reaction rims, other studies have described amphibole mantled by or replaced by pseudomorphs of augite, formed as a single continuous crystal around the host amphibole (e.g., Holocene deposits of El Chichón; Andrews et al, 2008).…”

Section: Natural Amphibole Reaction Rim Classificationsmentioning

confidence: 99%

“…However, other factors also trigger amphibole breakdown (e.g., oxidation, fluxing of the melt with a CO 2 rich fluid, or heating; Rutherford and Hill, 1993). The role of heating is particularly important because many arc magmas display disequilibrium textures that record the heating of one magma by another during pre-eruptive mixing (e.g., Clynne, 1999;Devine et al, 2003;Eichelberger, 1975;Feeley and Sharp, 1996;Murphy et al, 2000;Ruprecht and Bachmann, 2010;Tepley et al, 2000;Venezky and Rutherford, 1999). This process may lead to the breakdown of amphibole as temperatures exceed its typical thermal stability boundary of ∼880-900 • C (Browne and Gardner, 2006;Henton de Angelis, 2013).…”

Section: Introductionmentioning

confidence: 99%

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Amphibole reaction rims as a record of pre-eruptive magmatic heating: An experimental approach

Angelis

Larsen

Coombs

et al. 2015

Earth and Planetary Science Letters

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Editor: T.A. MatherKeywords: amphibole reaction rim heating andesite Magmatic minerals record the pre-eruptive timescales of magma ascent and mixing in crustal reservoirs and conduits. Investigations of the mineral records of magmatic processes are fundamental to our understanding of what controls eruption style, as ascent rates and magma mixing processes are well known to control and/or trigger potentially hazardous explosive eruptions. Thus, amphibole reaction rims are often used to infer pre-eruptive magma dynamics, and in particular to estimate magma ascent rates. However, while several experimental studies have investigated amphibole destabilization during decompression, only two investigated thermal destabilization relevant to magma mixing processes. This study examines amphibole decomposition experimentally through isobaric heating of magnesiohornblende phenocrysts within a natural high-silica andesite glass. The experiments first equilibrated for 24 h at 870 • C and 140 MPa at H 2 O-saturated conditions and ƒO 2 ∼ Re-ReO prior to rapid heating to 880, 900, or 920 • C and hold times of 3-48 h. At 920 • C, rim thicknesses increased from 17 μm after 3 h, to 55 μm after 12 h, and became pseudomorphs after longer durations. At 900 • C, rim thicknesses increased from 7 μm after 3 h, to 80 μm after 24 h, to pseudomorphs after longer durations. At 880 • C, rim thicknesses increased from 7 μm after 3 h, to 18 μm after 36 h, to pseudomorphs after 48 h. Reaction rim microlites vary from 5-16 μm in size, with no systematic relationship between crystal size and the duration or magnitude of heating. Time-averaged rim microlite growth rates decrease steadily with increasing experimental duration (from 3.97 × 10 −7 mm s −1 to 3.1 to 3.5 × 10 −8 mm s −1 ). Time-averaged microlite nucleation rates also decrease with increasing experimental duration (from 1.2 × 10 3 mm −3 s −1 to 5.3 mm −3 s −1 ). There is no systematic relationship between time-averaged growth or nucleation rates and the magnitude of the heating step. Ortho-and clinopyroxene together constitute 57-90 modal % mineralogy in each reaction rim. At constant temperature, clinopyroxene abundances decrease with increasing experimental duration, from 72 modal % (3 h at 900 • C) to 0% (48 h at 880 • C, and 36 h at 900 and 920 • C). Fe-Ti oxides increase from 6-12 modal % (after 3-6 h) to 26-34 modal % (after 36-48 h). Plagioclase occurs in relatively minor amounts (<1-11 modal %), with anorthite contents that increase from An56 to An88 from 3 to 36 h of heating. Distal glass compositions (>500 μm from reacted amphibole) are consistent with inter-microlite rim glasses (71.3-77.7 wt.% SiO 2 ) within a given experiment and there is a weakly positive correlation between increasing run duration and inter-microlite melt SiO 2 (68.9-78.5 wt.%). Our results indicate that experimental heating-induced amphibole reaction rims have thicknesses, textures, and mineralogies consistent with many of the natural reaction rims seen at arc-andesite volcanoes. They are also texturally c...

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Section: Natural Amphibole Reaction Rim Classificationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Amphibole reaction rims as a record of pre-eruptive magmatic heating: An experimental approach

Angelis

Larsen

Coombs

et al. 2015

Earth and Planetary Science Letters

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“…The clear magmatic signature and high equilibrium temperature of the emitted gases, together with their high exit temperature (270-310°C), suggest a relatively shallow magmatic source (see model from Stevenson, 1993). While the current composition of the magmatic source is unknown it may be similar to either the rhyolitic or andesitic magmas that interacted during the ca 2050 BP eruption (Tepley et al, 2013). Tepley et al (2013) estimated the temperature of the andesitic magma at 940 ± 40°C using pyroxenes pairs thermometry and the temperature of the rhyolitic magma at 816 ± 30°C using groundmass ilmenite and magnetite thermometry.…”

Section: Discussionmentioning

confidence: 99%

“…While the current composition of the magmatic source is unknown it may be similar to either the rhyolitic or andesitic magmas that interacted during the ca 2050 BP eruption (Tepley et al, 2013). Tepley et al (2013) estimated the temperature of the andesitic magma at 940 ± 40°C using pyroxenes pairs thermometry and the temperature of the rhyolitic magma at 816 ± 30°C using groundmass ilmenite and magnetite thermometry. The temperature recorded by the gas composition (Eqs.…”

Section: Discussionmentioning

confidence: 99%

“…For instance, a change of the temperature or composition of the magma following a recharge event-such as inferred for the last Plinian eruption in ca 2050 BC (Tepley et al, 2013)-should produce a measurable change in the equilibrium temperature and oxidation state of the gases. A change in the established outgassing pathways by fracture healing (e.g.…”

Section: Implications For Hazards and Volcanic Monitoringmentioning

confidence: 99%

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Magmatic gas percolation through the old lava dome of El Misti volcano

et al. 2017

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The proximity of the major city of Arequipa to El Misti has focused attention on the hazards posed by the active volcano. Since its last major eruption in the fifteenth century, El Misti has experienced a series of modest phreatic eruptions and fluctuating fumarolic activity. Here, we present the first measurements of the compositions of gas emitted from the lava dome in the summit crater. The gas composition is found to be fairly dry with a H 2 O/SO 2 molar ratio of 32 ± 3, a CO 2 / SO 2 molar ratio of 2.7 ± 0.2, a H 2 S/SO 2 molar ratio of 0.23 ± 0.02 and a H 2 /SO 2 molar ratio of 0.012 ± 0.002. This magmatic gas signature with minimal evidence of hydrothermal or wall rock interaction points to a shallow magma source that is efficiently outgassing through a permeable conduit and lava dome. Field and satellite observations show no evolution of the lava dome over the last decade, indicating sustained outgassing through an established fracture network. This stability could be disrupted if dome permeability were to be reduced by annealing or occlusion of outgassing pathways. Continued monitoring of gas composition and flux at El Misti will be essential to determine the evolution of hazard potential at this dangerous volcano.

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Diagnosing open-system magmatic processes using the Magma Chamber Simulator (MCS): part I—major elements and phase equilibria

Bohrson

Spera

Heinonen

et al. 2020

Contrib Mineral Petrol

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The Magma Chamber Simulator (MCS) is a thermodynamic tool for modeling the evolution of magmatic systems that are open with respect to assimilation of partial melts or stoped blocks, magma recharge + mixing, and fractional crystallization. MCS is available for both PC and Mac. In the MCS, the thermal, mass, and compositional evolution of a multicomponentmultiphase composite system of resident magma, wallrock, and recharge reservoirs is tracked by rigorous self-consistent thermodynamic modeling. A Recharge-Assimilation (Assimilated partial melt or Stoped blocks)-Fractional Crystallization (R n AS n FC; n tot ≤ 30) scenario is computed by minimization or maximization of appropriate thermodynamic potentials using the family of rhyolite-and pMELTS engines coupled to an Excel Visual Basic interface. In MCS, during isobaric cooling and crystallization, resident magma thermally interacts with wallrock that is in internal thermodynamic equilibrium. Wallrock partial melt above a user-defined percolation threshold is homogenized (i.e., brought in to chemical potential equilibrium) with resident magma. Crystals that form become part of a cumulate reservoir that remains thermally connected but chemically isolated from resident melt. Up to 30 instances (n ≤ 30) of magma mixing by recharge and/or bulk assimilation of stoped wallrock blocks can occur in a single simulation; each recharge magma or stoped block has a unique user-defined composition and thermal state. Recharge magmas and stoped blocks hybridize (equilibrate) with resident melt, yielding a single new melt composition and temperature. MCS output includes major and trace element concentrations and isotopic ratios (Sr, Nd, Hf, Pb, Os, and O as defaults) of wallrock, recharge magma/stoped blocks, resident magma melt, and cumulates. The chemical formulae of equilibrium crystalline phases in the cumulate reservoir, wallrock, and recharge magmas/stoped blocks are also output. Depending on the selected rhyolite-MELTS engine, the composition and properties of a possible supercritical fluid phase (H 2 O and/or CO 2 ) are also tracked. Forward modeling of theoretical magma systems and suites of igneous rocks provides quantitative insight into key questions in igneous petrology such as mantle versus crustal contributions to terrestrial magmas, the record of magmatism preserved in cumulates and exsolved fluids, and the chronology of RASFC processes that may be recorded by crystal populations, melt inclusions, and whole rocks. Here, we describe the design of the MCS software that focuses on major element compositions and phase equilibria (MCS-PhaseEQ). Case studies that involve fractional crystallization, magma recharge + mixing, and crustal contamination of a depleted basalt that resides in average upper crust illustrate the major element and phase equilibria consequences of these processes and highlight the rich array of data produced by MCS. The cases presented here, which represent an infinitesimal fraction of possible RASFC processes and bulk compositions, show that the rec...

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Magma Dynamics and Petrological Evolution Leading to the VEI 5 2000 bp Eruption of El Misti Volcano, Southern Peru

Cited by 17 publications

References 78 publications

Amphibole reaction rims as a record of pre-eruptive magmatic heating: An experimental approach

Amphibole reaction rims as a record of pre-eruptive magmatic heating: An experimental approach

Magmatic gas percolation through the old lava dome of El Misti volcano

Diagnosing open-system magmatic processes using the Magma Chamber Simulator (MCS): part I—major elements and phase equilibria

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