Control and monitoring of oxygen fugacity in piston cylinder experiments

Matjuschkin, Vladimir; Brooker, Richard A.; Tattitch, Brian; Blundy, Jon; Stamper, Charlotte C.

doi:10.1007/s00410-015-1105-z

Cited by 45 publications

(23 citation statements)

References 63 publications

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“…In nine cases, the reported experimental fO 2 values deviated by more than 1.0 log unit fO 2 from the values obtained via magnetite-ilmenite oxybarometry (Ghiorso and Evans, 2008; Fig. S-3), suggesting problems with the control of experimental fO 2 (Matjuschkin et al, 2015 The rationale behind this equation is depicted in Figure 1. The overall uncertainty of the FeTiMM model, calculated from the errors of the fits in Figure 1b,c propagated into Equation 1 (see Supplementary Information) increases from ±0.2-0.3 log units fO 2 at ≤∆FMQ+1.5, to ±0.3-0.5 log units fO 2 at ∆FMQ+4.5 (Supplementary Table S-1).…”

Section: Calibration Of the Fetimm Oxybarometermentioning

confidence: 90%

FeTiMM – A new oxybarometer for mafic to felsic magmas

Robert¹,

Audétat²

2017

Geochem. Persp. Let.

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The oxidation state of magmas is a key parameter that is notoriously difficult to reconstruct. The most common approach is via magnetite-ilmenite oxybarometry. However, many natural magmas do not contain ilmenite, preventing application of this technique. Here we present a new method that allows fO 2 to be reconstructed based on the partitioning of Fe and Ti between magnetite and silicate melt. The new method, which we call FeTiMM, is applicable to both ilmenite-free and ilmenite-bearing samples, and even to slowly cooled intrusive rocks such as granites. FeTiMM was calibrated on 109 experiments covering a wide range of oxygen fugacities, temperatures, pressures and silicate melts ranging from basaltic to rhyolitic composition, and returned fO 2 values that agree within 0.5 log units with independently constrained fO 2 values in all but five cases. A first test on 19 natural samples of dacitic to rhyolitic compositions was equally successful. FeTiMM thus opens the door for numerous new applications in various disciplines of Earth Sciences, including the fields of volcanology, igneous petrology, experimental geochemistry and ore geology.

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Section: Calibration Of the Fetimm Oxybarometermentioning

confidence: 90%

FeTiMM – A new oxybarometer for mafic to felsic magmas

Robert¹,

Audétat²

2017

Geochem. Persp. Let.

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“…The experimental runs were performed at temperature of 1250 -1300°C. Because the run duration was shorter than 48 hours which is necessary to reach oxygen fugacity equilibrium with a piston-cylinder double-capsule techniques of mineral buffer (Matjuschkin et al, 2015), the redox conditions in our kinetic experiments were controlled by the initial Fe 2+ /Fe 3+ ratios in the MORB glass and serpentinite, although more oxidized conditions were established during the runs due to the presence of water and partial H2 loss to Al2O3 pressure media. The Fe 2+ /Fe 3+ ratios in several quenched products were estimated using XANES (X-ray absorption near edge structure) at European Synchrotron Radiation Facility (ESRF) in Grenoble (France).…”

Section: Experimental Strategy and Methodsmentioning

confidence: 99%

Hydrated Peridotite–Basaltic Melt Interaction Part II: Fast Assimilation of Serpentinized Mantle by Basaltic Magma

et al. 2020

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The most abundant terrestrial lavas, mid-ocean ridge and ocean island basalt (MORB and OIB), are commonly considered to be derived from a depleted MORB-mantle component (DMM) and more specific, variably enriched mantle plume sources. However, findings of oceanic lavas and mafic cumulates issued from melts, enriched in chlorine and having a radiogenic 87 Sr/ 86 Sr ratio, can be attributed to an interaction between the asthenosphere-derived melts and lithospheric peridotite variably hydrated due to penetration of hydrothermal water down to and below Moho level. To constrain mechanisms and rates responsible for the interaction, we report results of 15 experiments of reaction between serpentinite and tholeiitic basaltic melt at 0.2 -1.0 GPa and 1250 -1300°C. Results show that the reaction proceeds via a multi-stage mechanism: (i) transformation of serpentinite into Cr-rich spinel-bearing harzburgite (Fo92-95 mol.%) containing pore fluid, (ii) partial melting and dissolution of the harzburgite assemblage with formation of interstitial hydrous melts (up to 57 -60 wt% of SiO2 contents at 0.5 GPa pressure), and (iii) final assimilation of the Cr-rich spinel-bearing harzburgite/dunite and formation of hybrid basaltic melts with 12 -13 wt.% of MgO and elevated Cr (up to ~500 ppm) and Ni (up to ~200 ppm) contents. Assimilation of serpentinite by basaltic melt may occur under elevated melt/rock ratios (>2) and may lead to chromitite formation. We show that hybrid magmas produced by the progressive assimilation of serpentinized lithospheric mantle may be recognized by high Mg-numbers and high Cr and Ni contents of olivine and pyroxenes, an excess of SiO2, H2O and halogens in the melts, and some unusual isotopic composition (e.g., radiogenic 87 Sr/ 86 Sr, non-mantle δ 18 O and low 3 He/ 4 He). Our experiments provide evidence that MORB and high-Mg-Cr orthopyroxene-rich cumulates depleted in incompatible elements can be produced from common mid-ocean ridge basaltic melts modified by reaction with hydrated lithospheric peridotite. We established that the rate of assimilation of serpentinized peridotite is controlled by silica diffusion in the reacting hydrous basaltic melt. Our study challenges 3 traditional interpretation of the variations in MORB and OIB chemical and isotopic composition in terms of deep mantle plume source heterogeneities or/and degrees of partial melting.

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“…The process of oxidation or reduction of starting materials primarily involves diffusion of H 2 , to which experimental capsules are effectively open. If the apparatus provides an environment that is reducing with respect to the oxidation state of the starting materials, H 2 will enter the capsule and may form H 2 O by reduction of iron oxides, constituting an increase in M H 2 O and decrease in M O (carbon, derived from graphite furnaces, may play a underacknowledged role in this process; see Brooker et al, 1998;Jakobsson, 2012;Matjuschkin et al, 2015). Finally, apparent loss or gain of both H 2 and O 2 , or possibly molecular H 2 O, has been reported in several piston cylinder studies (e.g.…”

Section: Calibration Strategymentioning

confidence: 99%

Activity–composition relations for the calculation of partial melting equilibria in metabasic rocks

Green

White

Diener

et al. 2016

Journal Metamorphic Geology

675

478

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A set of thermodynamic models is presented that, for the first time, allows partial melting equilibria to be calculated for metabasic rocks. The models consist of new activity–composition relations combined with end‐member thermodynamic properties from the Holland & Powell dataset, version 6. They allow for forward modelling in the system Na2O–CaO–K2O–FeO–MgO–Al2O3–SiO2–H2O–TiO2–Fe2O3. In particular, new activity–composition relations are presented for silicate melt of broadly trondhjemitic–tonalitic composition, and for augitic clinopyroxene with Si–Al mixing on the tetrahedral sites, while existing activity–composition relations for hornblende are extended to include K2O and TiO2. Calibration of the activity–composition relations was carried out with the aim of reproducing major experimental phase‐in/phase‐out boundaries that define the amphibolite–granulite transition, across a range of bulk compositions, at ≤13 kbar.

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Control and monitoring of oxygen fugacity in piston cylinder experiments

Cited by 45 publications

References 63 publications

FeTiMM – A new oxybarometer for mafic to felsic magmas

FeTiMM – A new oxybarometer for mafic to felsic magmas

Hydrated Peridotite–Basaltic Melt Interaction Part II: Fast Assimilation of Serpentinized Mantle by Basaltic Magma

Activity–composition relations for the calculation of partial melting equilibria in metabasic rocks

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