Water partitioning between mantle minerals from peridotite xenoliths

Grant, Kevin; Ingrin, Jannick; Lorand, Jean Pierre; Dumas, Paul

doi:10.1007/s00410-006-0177-1

Cited by 178 publications

(195 citation statements)

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“…Beran and Libowitzky (2006) and Grant et al (2007) note that the water content stored in olivine and mantle garnet is very low compared to that in pyroxenes, and Wang et al (2006) infer that the water content in the continental lithospheric upper mantle is <10 -3 wt%.…”

Section: Effect Of Hydrous Mineralsmentioning

confidence: 99%

Velocity–conductivity relationships for mantle mineral assemblages in Archean cratonic lithosphere based on a review of laboratory data and Hashin–Shtrikman extremal bounds

Jones

Evans

Eaton

2009

Lithos

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Can mineral physics and mixing theories explain field observations of seismic velocity and electrical conductivity, and is there an advantage to combining seismological and electromagnetic techniques? These two questions are at the heart of this paper. Using phenomologically-derived state equations for individual minerals coupled with multi-phase, Hashin-Shtrikman extremal-bound theory we derive the likely shear and compressional velocities and electrical conductivity at three depths, 100 km, 150 km and 200 km, beneath the central part of the Slave craton and beneath the Kimberley region of the Kaapvaal craton based on known petrologically-observed mineral abundances and magnesium numbers, combined with estimates of temperatures and pressures. We demonstrate that there are measurable differences between the physical properties of the two lithospheres for the upper depths, primarily due to the different ambient temperature, but that differences in velocity are negligibly small at 200 km. We also show that there is an advantage to combining seismic and electromagnetic data, given that conductivity is exponentially dependent on temperature whereas the shear and bulk moduli have only a linear dependence in cratonic lithospheric rocks.Focussing on a known discontinuity between harzburgite-dominated and lherzolitic mantle in the Slave craton at a depth of about 160 km, we demonstrate that the amplitude of compressional (P) wave to shear (S) wave conversions would be very weak, and so explanations for the seismological (receiver function) observations must either appeal to effects we have not considered (perhaps anisotropy), or imply that the laboratory data require further refinement. Jones et al.Velocity-conductivity relations of Archean lithospheric mantle

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Section: Effect Of Hydrous Mineralsmentioning

confidence: 99%

Velocity–conductivity relationships for mantle mineral assemblages in Archean cratonic lithosphere based on a review of laboratory data and Hashin–Shtrikman extremal bounds

Jones

Evans

Eaton

2009

Lithos

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“…In contrast, the incorporation of aluminum in orthopyroxene greatly increases the water solubility relative to that in the pure Al-free system [13,21,[24][25][26]. As a result, the partition coefficient of water between aluminous enstatite and olivine is very high: [13,[27][28][29][30]. Thus, the water content in the aluminous enstatite reaches values close to 1 wt.% at low pressures and temperatures.…”

Section: Citationmentioning

confidence: 98%

“…It is known that aluminum can greatly enhance water solubility in orthopyroxene [12,13,21,[26][27][28][29][30]38]; thus, one crucial factor in determining the solubility of water in orthopyroxene is likely to be the concentration of aluminum. According to previous studies [24,38,39], the most likely substitution mechanism for Al incorporation in aluminous orthopyroxene is through the Tschermaks-substitution reaction: Mg 2+ + Si 4+ = 2Al 3+ .…”

Section: Effects Of Temperature and Al Contentmentioning

confidence: 99%

“…Therefore, aluminous enstatite could be a more important host than olivine for water in the Earth's upper mantle, and it may be related to abnormal geophysical observations at the top of the asthenosphere [1,3,7,13,16]. The solubility of water as a function of temperature and pressure has been investigated to determine the mechanism and thermodynamics of the incorporation of water in orthopyroxene [13,21,24,25,[27][28][29]. However, it is worth noting that most studies were conducted using a pure MgSiO 3 system [21,24,[27][28][29] and single crystals of orthopyroxene.…”

mentioning

confidence: 99%

“…The solubility of water as a function of temperature and pressure has been investigated to determine the mechanism and thermodynamics of the incorporation of water in orthopyroxene [13,21,24,25,[27][28][29]. However, it is worth noting that most studies were conducted using a pure MgSiO 3 system [21,24,[27][28][29] and single crystals of orthopyroxene. Except for two studies [13,25], few data on water solubility have been systematically reported for the (Mg, Fe)SiO 3 -H 2 O-Al 2 O 3 system (Al-Fe-Mg orthopyroxene) that simultaneously consider the influences of temperature and Al content.…”

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confidence: 99%

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Water solubility in orthopyroxene: Dependence on temperature and Al content

Zhang

Matsuzaki

2013

Chin. Sci. Bull.

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The water solubility in Al-Fe-Mg orthopyroxene [(Mg,Fe,Al)(Si,Al)O 3 : X Fe = 0.1] was investigated as a function of temperature and Al contents. Experiments were performed at 10 kbar with temperatures ranging from 800 to 1200°C under water-saturated conditions. Water contents in the (Mg,Fe)SiO 3 -H 2 O-Al 2 O 3 system were determined using unpolarized Fourier transform infrared spectroscopy. The present results show that water solubility in Al-bearing orthopyroxene decreases systematically with temperature from approximately 1 weight % at 800°C to 568 ± 58 ppm at 1200°C and increase significantly with increasing Al 2 O 3 contents under the same annealing temperature and pressure. Combined with published results on the dependence of hydroxyl solubility on water fugacity and pressure, the present results can be described by the relationwhere A = 0.0024 ± 0.0015 ppm/bar 0.5 , 1bar H = −103.348 ± 9.768 kJ/mol, and solid V = 9.2 ± 1.1 cm 3 /mol. This equation implies that the incorporation mechanism of water in aluminous orthopyroxene involves the isolated OH groups. Based on the experimentally established solubility model used in this study, it is suggested that water solubility decreases with increasing temperature under typical upper mantle pressure. The predicted temperature dependence of water solubility is in good agreement with the previous experimental observations in Al-bearing orthopyroxene, but the opposite dependence is observed in Al-free systems. Moreover, our estimation of the water solubility in upper-mantle minerals as a function of depth for a typical oceanic geotherm might be of potential importance in interpreting the geophysical observations. orthopyroxene, water solubility, infrared spectroscopy, asthenosphere Citation:Zhang B H, Matsuzaki T, Wu X P. Water solubility in orthopyroxene: Dependence on temperature and Al content. Chin Sci Bull, 2013Bull, , 58: 38953902, doi: 10.1007 The presence of water or hydroxyl defects in nominally anhydrous minerals (NAMs) has a dramatical influence on their geophysical properties such as solidus temperature [1], electrical conductivity [2-6] and viscosity [7][8][9], as well as on mantle dynamics such as melt generation [10] and mantle convection [7]. Critical to understanding the role of water in the Earth's mantle, a key step is to estimate the distribution of water inside the mantle and the incorporation mechanism of hydrogen in mantle minerals by combining experimentally determined mineral properties with geophysical observations. Two principal approaches can provide significant constraints on the water content in the Earth's interior. One approach is water solubility experiments in mantle minerals [11][12][13], and the other infers the water content based on the electrical conductivity of the NAMs [2-6,14-19].Orthopyroxene is considered to be one of the main constituent minerals in the Earth's upper mantle and is believed to constitute approximately 20-40 vol% [20]. Previous studies indicate that the water solubility in pure MgSiO 3 enstatite increa...

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Pyroxenes as tracers of mantle water variations

2014

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The concentration and distribution of volatiles in the Earth's mantle influence properties such as melting temperature, conductivity, and viscosity. To constrain upper mantle water content, concentrations of H 2 O, P, and F were measured in olivine, orthopyroxene, and clinopyroxene in mantle peridotites by secondary ion mass spectrometry. Analyzed peridotites are xenoliths (Pali Aike, Spitsbergen, Samoa), orogenic peridotites (Josephine Peridotite), and abyssal peridotites (Gakkel Ridge, Southwest Indian Ridge, Tonga Trench). The comparison of fresh and altered peridotites demonstrates that low to moderate levels of alteration do not affect H 2 O concentrations, in agreement with mineral diffusion data. Olivines have diffusively lost water during emplacement, as demonstrated by disequilibrium between olivine and coexisting pyroxenes. In contrast, clinopyroxene and orthopyroxene preserve their high-temperature water contents, and their partitioning agrees with published experiments and other xenoliths. Hence, olivine water concentrations can be determined from pyroxene concentrations using mineral-mineral partition coefficients. Clinopyroxenes have 60-670 ppm H 2 O, while orthopyroxenes have 10-300 ppm, which gives calculated olivine concentrations of 8-34 ppm. The highest olivine water concentration translates to an effective viscosity of 6 × 1019 Pa s at 1250°C and~15 km depth, compared to a dry effective viscosity of 2.5 × 10 21 Pa s. Bulk rock water concentrations, calculated using mineral modes, are 20-220 ppm and correlate with peridotite indices of melt depletion. However, trace element melt modeling indicates that peridotites have too much water relative to their rare earth element concentrations, which may be explained by late-stage melt addition, during which only hydrogen diffuses fast enough for reequilibration.

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Water partitioning between mantle minerals from peridotite xenoliths

Cited by 178 publications

References 75 publications

Velocity–conductivity relationships for mantle mineral assemblages in Archean cratonic lithosphere based on a review of laboratory data and Hashin–Shtrikman extremal bounds

Velocity–conductivity relationships for mantle mineral assemblages in Archean cratonic lithosphere based on a review of laboratory data and Hashin–Shtrikman extremal bounds

Water solubility in orthopyroxene: Dependence on temperature and Al content

Pyroxenes as tracers of mantle water variations

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