Assimilation of Plutonic Roots, Formation of High-K ‘Exotic’ Melt Inclusions and Genesis of Andesitic Magmas at Volcán De Colima, Mexico

Reubi, Olivier; Blundy, Jon

doi:10.1093/petrology/egn066

Cited by 94 publications

(68 citation statements)

References 58 publications

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“…All investigated magmas are andesitic in composition with 59.0-61.4 wt% SiO 2 (H 2 O-free), as are all historical lavas (Luhr 2002;Carmichael 1980, 1990;Mora et al 2002;Reubi and Blundy 2008;Savov et al 2008). The 1998 andesites are petrographically homogenous with 30-38 % phenocryst-sized minerals (i.e.…”

Section: Previous Work On the Petrology Of 1998-2005 Andesitesmentioning

confidence: 92%

“…For the Vulcanian eruptions, bread-crust bombs collected on the caldera floor (El Playón) directly north of the active cone were used. The petrology and geochemistry of the samples, as well as the major and trace element chemistry of some of the melt inclusions are presented in detail in Reubi and Blundy (2008). Only a summary is given here.…”

Section: Previous Work On the Petrology Of 1998-2005 Andesitesmentioning

confidence: 99%

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Volatiles contents, degassing and crystallisation of intermediate magmas at Volcan de Colima, Mexico, inferred from melt inclusions

Reubi

Blundy

Varley

2013

Contrib Mineral Petrol

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In volatile-saturated magmas, degassing and crystallisation are interrelated processes which influence the eruption style. Melt inclusions provide critical information on volatile and melt evolution, but this information can be compromised significantly by post-entrapment modification of the inclusions. We assess the reliability and significance of pyroxene-hosted melt inclusion analyses to document the volatile contents (particularly H 2 O) and evolution of intermediate arc magmas at Volcán de Colima, Mexico. The melt inclusions have maximal H 2 O contents (B4 wt%) consistent with petrological estimates and the constraint that the magmas crystallised outside the amphibole stability field, demonstrating that pyroxenehosted melt inclusions can preserve H 2 O contents close to their entrapment values even in effusive eruptions with low effusion rates (0.6 m 3 s -1 ). The absence of noticeable H 2 O loss in some of the inclusions requires post-entrapment diffusion coefficients (B1 9 10 -13 m 2 s -1 ) at least several order of magnitude smaller than experimentally determined H ? diffusion coefficient in pyroxenes. The H 2 O content distribution is, however, not uniform, and several peaks in the data, interpreted to result from diffusive H 2 O reequilibration, are observed around 1 and 0.2 wt%. H 2 O diffusive loss is also consistent with the manifest lack of correlations between H 2 O and CO 2 or S contents. The absence of textural evidence supporting post-entrapment H 2 O loss suggests that diffusion most likely occurred via melt channels prior to sealing of the inclusions, rather than through the host crystals. Good correlation between the melt inclusion sealing and volcano-tectonic seismic swarm depths further indicate that, taken as a whole, the melt inclusion population accurately records the pre-eruptive conditions of the magmatic system. Our data demonstrate that H 2 O diffusive loss is a second-order process and that pyroxene-hosted melt inclusions can effectively record the volatile contents and decompression-induced crystallisation paths of vapoursaturated magmas.

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Section: Previous Work On the Petrology Of 1998-2005 Andesitesmentioning

confidence: 92%

Section: Previous Work On the Petrology Of 1998-2005 Andesitesmentioning

confidence: 99%

Volatiles contents, degassing and crystallisation of intermediate magmas at Volcan de Colima, Mexico, inferred from melt inclusions

Reubi

Blundy

Varley

2013

Contrib Mineral Petrol

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“…Hornblende was present in the 1913 magmas, but not in subsequent eruptions, and olivine exists as xenocrysts. The lavas generally contain ∼30 vol.% phenocrysts, 25-50 vol.% microlites and 14-45 vol.% "dry" rhyolitic glass (Reubi and Blundy, 2008;Savov et al, 2008;Lavallée et al, 2012;Kendrick et al, 2013) with a bimodal porosity distribution peaking at 12 and 26% . Geothermometry of pyroxenes suggests relatively deep magma storage at temperatures of 960-1020 • C (Savov et al, 2008), while melt inclusions verify this, indicating trapping conditions of 10-150 MPa and 959-1015 • C (Reubi et al, 2013).…”

Section: Historic Activity At Volcán De Colimamentioning

confidence: 99%

Blowing Off Steam: Tuffisite Formation As a Regulator for Lava Dome Eruptions

et al. 2016

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Tuffisites are veins of variably sintered, pyroclastic particles that form in conduits and lava domes as a result of localized fragmentation events during gas-and-ash explosions. Those observed in-situ on the active 2012 lava dome of Volcán de Colima range from voids with intra-clasts showing little movement and interpreted to be failure-nuclei, to sub-parallel lenses of sintered granular aggregate interpreted as fragmentation horizons, through to infilled fractures with evidence of viscous remobilization. All tuffisites show evidence of sintering. Further examination of the complex fracture-and-channel patterns reveals viscous backfill by surrounding magma, suggesting that lava fragmentation was followed by stress relaxation and continued viscous deformation as the tuffisites formed. The natural tuffisites are more permeable than the host andesite, and have a wide range of porosity and permeability compared to a narrower window for the host rock, and gaging from their significant distribution across the dome, we posit that the tuffisite veins may act as important outgassing pathways. To investigate tuffisite formation we crushed and sieved andesite from the lava dome and sintered it at magmatic temperatures for different times. We then assessed the healing and sealing ability by measuring porosity and permeability, showing that sintering reduces both over time. During sintering the porosity-permeability reduction occurs due to the formation of viscous necks between adjacent grains, a process described by the neck-formation model of Frenkel (1945). This process leads the granular starting material to a porosity-permeability regime anticipated for effusive lavas, and which describes the natural host lava as well as the most impervious of natural tuffisites. This suggests that tuffisite formation at Volcán de Colima constructed a permeable network that enabled gas to bleed passively from the magma. We postulate that this progressively reduced the lava dome's ability to seal and build pressure that drives explosions. Indeed, the time interval between explosions during 2007-2011 gradually increased before the onset of a period of quiescence starting in June 2011. We suggest that the permeability evolution during tuffisite formation has important consequences for modeling of gas-and-ash explosions, common at dome-forming volcanoes.

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“…2a) at Ludwig-Maximilians University in Munich (see Hess et al, 2007 for details of the apparatus). This investigation of bulk rock strength and associated mechanisms of deformation of tuffisite-bearing and tuffisite-free samples was carried out at 940 • C, as pre-eruptive temperatures were estimated at 960-1020 • C (Reubi andBlundy, 2008 andSavov et al, 2008). A heating rate of 1 • C min −1 was applied until the sample reached the target temperature.…”

Section: Strength Experimentsmentioning

confidence: 99%

Strength and permeability recovery of tuffisite-bearing andesite

Kolzenburg

Heap

Lavallée³

et al. 2012

Solid Earth

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Abstract. Tuffisites, the products of subsurface fragmentation, transport and deposition, are common in explosive volcanic environments. Their study provides direct insight to the mechanical processes operating within volcanic conduits. Here we document the influence of the presence of coherent tuffisite veins on the physical properties of andesitic rocks. We find that (1) compressive strength is unaffected by the presence and/or orientation of tuffisites, (2) permeability doubles when tuffisites are oriented favorably (at 45 • to the fluid flow direction), and (3) ultrasonic wave velocities show a continuous increase with depth, independent of vein presence and orientation. Although the influence of tuffisites on andesitic rock properties determined here is modest, we emphasize that the material tested represents the post-eruptive state of tuffisite. Thus, these results likely delineate the upper and lower boundaries of strength vs. permeability and porosity, respectively. Our evidence suggests that, via compaction and lithification, tuffisites may restore the strength of the volcanic host-rocks to that of their pre-tuffisite values.

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Assimilation of Plutonic Roots, Formation of High-K ‘Exotic’ Melt Inclusions and Genesis of Andesitic Magmas at Volcán De Colima, Mexico

Cited by 94 publications

References 58 publications

Volatiles contents, degassing and crystallisation of intermediate magmas at Volcan de Colima, Mexico, inferred from melt inclusions

Volatiles contents, degassing and crystallisation of intermediate magmas at Volcan de Colima, Mexico, inferred from melt inclusions

Blowing Off Steam: Tuffisite Formation As a Regulator for Lava Dome Eruptions

Strength and permeability recovery of tuffisite-bearing andesite

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