Effects of fO2 and H2O on andesite phase relations between 2 and 4 kbar

Martel, Caroline; Pichavant, Michel; Holtz, François; Scaillet, Bruno; Bourdier, Jean-Louis; Traineau, Hervé

doi:10.1029/1999jb900191

Cited by 198 publications

(192 citation statements)

References 36 publications

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“…700 MPa, 990 • C) to lower P -T magnesiohornblende (avg. 190 MPa, 840 • C), consistent with the compositional variations known for calcalkaline magmas from experiments (Gill, 1981;Martel et al, 1999;Müntener et al, 2001;Behrens and Gaillard, 2006).…”

Section: Temperature and Pressure From Amphibole Thermobarometrysupporting

confidence: 67%

Magma storage and plumbing of adakite-type post-ophiolite intrusions in the Sabzevar ophiolitic zone, northeast Iran

et al. 2015

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Abstract. Subduction-related adakite-type intrusive rocks emplaced into the late Cretaceous-Paleocene Sabzevar ophiolite zone, northeast Iran, range from Mg-andesite to rhyodacite in composition. Here we investigate the magma supply system to these subvolcanic intrusive rocks by applying thermobarometric mineral and mineral-melt equilibrium models, including amphibole thermobarometry, plagioclasemelt thermobarometry and clinopyroxene-melt barometry. Based on the results of these thermobarometric models, plagioclase crystallized dominantly at pressures of ∼ 350 (130 to 468) MPa, while amphiboles record both low pressures (∼ 300 MPa) and very high pressures (> 700 MPa) of crystallization. The latter is supported by the calculated pressures for clinopyroxene crystallization (550 to 730 MPa). The association of amphibole with clinopyroxene and no plagioclase in the most primitive samples (Mg-andesites) is consistent with amphibole fractionation from very hydrous magmas at deep crustal levels of the plumbing system, which may have been a key process in intensifying adakite-type affinities in this rock suite. Barometry, combined with frequent disequilibrium features such as oscillatory-zoned and sieve-textured plagioclase crystals with An-rich overgrowths in more evolved samples, implies that final magma differentiation occurred in an open upper crustal magma system that developed progressively stronger compositional modifications during high-level magma storage.

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Section: Temperature and Pressure From Amphibole Thermobarometrysupporting

confidence: 67%

Magma storage and plumbing of adakite-type post-ophiolite intrusions in the Sabzevar ophiolitic zone, northeast Iran

et al. 2015

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“…These rheological constraints are now used to evaluate how contrasted pairs of natural magmas may well mix together. We have selected basalt, andesite, dacite and rhyolite compositions whose phase equilibria are known in the pressure range 0.2-1 GPa [44][45][46][47][48][49][50] . This allows us to establish the temperature-dependent crystal fraction ( Supplementary Fig.…”

Section: Resultsmentioning

confidence: 99%

“…For more felsic reservoirs, dacitic or rhyolitic, the onset of mixing requires a larger mass fraction, , , Figure 4 | Evolution of magma viscosity with temperature. The melt fraction trends and compositions needed for viscosity calculations are derived from the phase equilibrium works 36,[44][45][46][47][48][49][50] . Melt viscosities (that is, the straight lines in the high temperature part of each curve) differ by o2 orders of magnitude of each other.…”

Section: Resultsmentioning

confidence: 99%

On the conditions of magma mixing and its bearing on andesite production in the crust

et al. 2014

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Mixing between magmas is thought to affect a variety of processes, from the growth of continental crust to the triggering of volcanic eruptions, but its thermophysical viability remains unclear. Here, by using high-pressure mixing experiments and thermal calculations, we show that hybridization during single-intrusive events requires injection of high proportions of the replenishing magma during short periods, producing magmas with 55-58 wt% SiO 2 when the mafic end-member is basaltic. High strain rates and gas-rich conditions may produce more felsic hybrids. The incremental growth of crustal reservoirs limits the production of hybrids to the waning stage of pluton assembly and to small portions of it. Large-scale mixing appears to be more efficient at lower crustal conditions, but requires higher proportions of mafic melt, producing more mafic hybrids than in shallow reservoirs. Altogether, our results show that hybrid arc magmas correspond to periods of enhanced magma production at depth.

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“…In hydrous, oxidized arc-magmas, magnetite is often the liquidus phase at 200 MPa (Martel et al, 1999). This magmatic magnetite is enriched in elements such as Ti, V, Mn, Al and Ga, consistent with Type 1 magnetite cores.…”

Section: A Combined Igneous and Magmatic-hydrothermal Model For Kirunmentioning

confidence: 95%

Trace elements in magnetite from massive iron oxide-apatite deposits indicate a combined formation by igneous and magmatic-hydrothermal processes

Knipping

Bilenker

Simon

et al. 2015

Geochimica et Cosmochimica Acta

220

104

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. data demonstrate that a saline magmatic-hydrothermal ore fluid will scavenge significant quantities of metals such as Cu and Au from a silicate melt, and when combined with solubility data for Fe, Cu and Au, it is plausible that the magmatic-hydrothermal ore fluid that continues to ascend from the IOA depositional environment can retain sufficient concentrations of these metals to form iron oxide copper-gold (IOCG) deposits at lateral and/or stratigraphically higher levels in the crust. Notably, this study provides a new discrimination diagram to identify magnetite from Kiruna-type deposits and to distinguish them from IOCG, porphyry and Fe-Ti-V/P deposits, based on low Cr (< 100 ppm) and high V (>500 ppm) concentrations. Trace elements in magnetite from massive iron oxide-apatite deposits indicate a combined formation by igneous and magmatic-hydrothermal processes

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Effects of f_O2 and H₂O on andesite phase relations between 2 and 4 kbar

Cited by 198 publications

References 36 publications

Magma storage and plumbing of adakite-type post-ophiolite intrusions in the Sabzevar ophiolitic zone, northeast Iran

Magma storage and plumbing of adakite-type post-ophiolite intrusions in the Sabzevar ophiolitic zone, northeast Iran

On the conditions of magma mixing and its bearing on andesite production in the crust

Trace elements in magnetite from massive iron oxide-apatite deposits indicate a combined formation by igneous and magmatic-hydrothermal processes

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