Hornblende- and Phlogopite-Bearing Gabbroic Xenoliths from Volcan San Pedro (36degreesS), Chilean Andes: Evidence for Melt and Fluid Migration and Reactions in Subduction-Related Plutons

Costa, Fidel; Dungan, M. A.; Singer, Brad S.

doi:10.1093/petrology/43.2.219

Cited by 70 publications

(38 citation statements)

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“…[1][2][3][4][5]. Most of the mafic xenoliths in volcanic rocks from island arc systems fall into one of three categories: cognate xenoliths that are indicative of magma mixing [e.g.…”

Section: Introductionmentioning

confidence: 99%

Two types of gabbroic xenoliths from rhyolite dominated Niijima volcano, northern part of Izu-Bonin arc: petrological and geochemical constraints

et al. 2017

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Abstract:We examined the petrography, petrology, and geochemistry of two types of gabbroic xenoliths (A-and Btype xenoliths) in olivine basalt and biotite rhyolite units among the dominantly rhyolitic rocks in Niijima volcano, northern Izu-Bonin volcanic arc, central Japan. A-type gabbroic xenoliths consisting of plagioclase, clinopyroxene, and orthopyroxene with an adcumulate texture were found in both olivine basalt and biotite rhyolite units, and B-type gabbroic xenoliths consisting of plagioclase and amphibole with an orthocumulate texture were found only in biotite rhyolite units. Geothermal-and barometricmodelling based on mineral chemistry indicated that the A-type gabbro formed at higher temperatures (899-955 ∘ C) and pressures (3.6-5.9 kbar) than the B-type gabbro (687-824 ∘ C and 0.8-3.6 kbar). These findings and whole-rock chemistry suggest different parental magmas for the two types of gabbro. The A-type gabbro was likely formed from basaltic magma, whereas the B-type gabbro was likely formed from an intermediate (andesitic) magma. The gabbroic xenoliths in erupted products at Niijima volcano indicate the presence of mafic to intermediate cumulate bodies of different origins at relatively shallower levels beneath the dominantly rhyolitic volcano.

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“…[1][2][3][4][5]. Most of the mafic xenoliths in volcanic rocks from island arc systems fall into one of three categories: cognate xenoliths that are indicative of magma mixing [e.g.…”

Section: Introductionmentioning

confidence: 99%

Two types of gabbroic xenoliths from rhyolite dominated Niijima volcano, northern part of Izu-Bonin arc: petrological and geochemical constraints

et al. 2017

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“…Pel6e, Lesser Antilles, Pichavant et al, 2002 andFichaut et al, 1989;Mt. St. Helens, Cascades, Medicine Lake, California, Arenal, Costa Rica, Costa et al, 2002; and several localities in Japan, Yagi andTakeshita, 1987 andCosta et al, 2002). Three xenolith samples with similar mineral assemblages have been studied for this project, in addition to previous studies done on several xenoliths (Abdollahi, 1990).…”

Section: 3d Gabbroic Xenolithsmentioning

confidence: 99%

“…Homblende is a common phase in gabbroic xenoliths in arc related lava (Yagi and Takeshita, 1987;Costa et al, 2002). These hornblende-bearing gabbros have been interpreted to reflect differentiation processes, specifically crystal fractionation (Costa et al, 2002), inside many volcanic systems including Calbuco .…”

Section: Hornblende Crystals In the Cumulate Xenolithsmentioning

confidence: 99%

“…These hornblende-bearing gabbros have been interpreted to reflect differentiation processes, specifically crystal fractionation (Costa et al, 2002), inside many volcanic systems including Calbuco . Yagi and Takeshita (1987) suggested that fractionation of approximately 40% of a hornblende gabbroic assemblage from hydrous, high-alumina basalt could produce calcalkaline andesitic magma.…”

Section: Hornblende Crystals In the Cumulate Xenolithsmentioning

confidence: 99%

“…The presence of hornblende in arc volcanics is not well understood. Questions as to whether it crystallizes from the magma or whether it forms due to later reactions have been posed by Costa et al (2002). Little is known about how andesites are actually formed despite the fact that the Earth's crust has an overall andesitic composition.…”

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confidence: 99%

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Determining magmatic processes from analysis of phenocrysts and gabbroic xenoliths contained in Calbuco andesites

Horst¹

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Interpretation of the provenance of small‐scale heterogeneity as documented in a single eruptive unit from Mt. Jefferson, Central Oregon Cascades

Üstünışık

Loewen

Nielsen

et al. 2016

Geochem Geophys Geosyst

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Mt. Jefferson is a large composite volcano located in the central Oregon Cascades that has erupted a diverse compositional suite of lavas from basalt to rhyodacite (50–72 wt. % SiO2). Individual eruptive units contain multiple populations of plagioclase, and a variety of mafic textural/mineralogical components often preserved as large centimeter to millimeter‐sized enclaves. Understanding the processes active in any volcanic center requires that we document the products of those processes. In this contribution, we documented the small‐scale compositional diversity within a single eruptive unit at Mt. Jefferson, the Whitewater Creek andesite, in order to answer three questions: (1) what are the characteristics and scale of diversity in a single eruptive unit, (2) what is the provenance of the observed components, and (3) how does that observed small‐scale diversity relate to the larger‐scale diversity observed between other flows at Mt. Jefferson. Our analyses are based on major, trace element concentrations for phenocrysts, and melt inclusions from a single eruptive unit, the Whitewater Creek andesite which is one of the most heterogeneous units erupted at Mt. Jefferson. We have identified at least four distinct components present at the centimeter scale. These components, identified on the basis of their mineralogy and composition, include three mafic (two pyroxene + plagioclase; plagioclase‐hornblende, and olivine‐orthopyroxene) and one silicic component (dacitic groundmass). To understand the relationship between the observed textural components and the magma types erupted at Mt Jefferson, equilibrium liquid compositions were calculated from the phenocryst compositions. The range exhibited by those calculated liquids covers much of the entire range represented by the lavas at Mt. Jefferson. However, it is difficult to directly connect them to specific magma types observed at Mt. Jefferson. We attribute our inability to directly link the textural components to the known magma types to post mixing diffusive reequilibration during storage and transport. These results suggest that great care should be taken in interpretation of whole rock data.

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Hornblende- and Phlogopite-Bearing Gabbroic Xenoliths from Volcan San Pedro (36degreesS), Chilean Andes: Evidence for Melt and Fluid Migration and Reactions in Subduction-Related Plutons

Cited by 70 publications

References 62 publications

Two types of gabbroic xenoliths from rhyolite dominated Niijima volcano, northern part of Izu-Bonin arc: petrological and geochemical constraints

Two types of gabbroic xenoliths from rhyolite dominated Niijima volcano, northern part of Izu-Bonin arc: petrological and geochemical constraints

Determining magmatic processes from analysis of phenocrysts and gabbroic xenoliths contained in Calbuco andesites

Interpretation of the provenance of small‐scale heterogeneity as documented in a single eruptive unit from Mt. Jefferson, Central Oregon Cascades

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