Water in the Earth’s Interior: Distribution and Origin

Peslier, A. H.; Schönbächler, Maria; Busemann, H.; Karato, Shun‐ichiro

doi:10.1007/978-94-024-1628-2_4

Cited by 33 publications

(69 citation statements)

References 553 publications

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“…A major goal of previous work has been to determine the solubility of water in mantle NAMs at various pressures, temperatures, and oxidation states. There has been a reasonable agreement on research results for upper mantle and transition zone minerals (e.g., Karato, ; Ohtani, ; Peslier et al, ). However, water solubility in the lower‐mantle minerals, particularly for bridgmanite, has been poorly constrained.…”

Section: Introductionsupporting

confidence: 80%

Water Concentration in Single‐Crystal (Al,Fe)‐Bearing Bridgmanite Grown From the Hydrous Melt: Implications for Dehydration Melting at the Topmost Lower Mantle

Yang

Karato

et al. 2019

Geophysical Research Letters

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High‐quality single‐crystals of (Al,Fe)‐bearing bridgmanite, Mg0.88 Fe3+0.065Fe2+0.035Al0.14Si0.90O3, of hundreds of micrometer size were synthesized at 24 GPa and 1800 °C in a Kawai‐type apparatus from the starting hydrous melt containing ~6.7 wt% water. Analyses of synthesized bridgmanite using petrographic microscopy, scanning electron microscopy, and transmission electron microscopy show that the crystals are chemically homogeneous and inclusion free in micrometer‐ to nanometer‐spatial resolutions. Nanosecondary ion mass spectrometry (NanoSIMS) analyses on selected platelets show ~1,020(±70) ppm wt water (hydrogen). The high water concentration in the structure of bridgmanite was further confirmed using polarized and unpolarized Fourier‐transform infrared spectroscopy (FTIR) analyses with two pronounced OH‐stretching bands at ~3,230 and ~3,460 cm−1. Our results indicate that lower‐mantle bridgmanite can accommodate relatively high amount of water. Therefore, dehydration melting at the topmost lower mantle by downward flow of transition zone materials would require water content exceeding ~0.1 wt%.

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Section: Introductionsupporting

confidence: 80%

Water Concentration in Single‐Crystal (Al,Fe)‐Bearing Bridgmanite Grown From the Hydrous Melt: Implications for Dehydration Melting at the Topmost Lower Mantle

Yang

Karato

et al. 2019

Geophysical Research Letters

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“…A dry transition zone below Europe has already been suggested by Utada et al (2009) from joint inversion of electromagnetic and seismic tomographic models. Based on experimental evidence of the water storage capacity (see below) of transition zone minerals (wadsleyite and ringwoodite), transition zone water content is higher than that of the upper mantle (olivine) ranging from ∼0.1-1 wt % (Pearson et al, 2014;Peslier et al, 2017). Based on experimental evidence of the water storage capacity (see below) of transition zone minerals (wadsleyite and ringwoodite), transition zone water content is higher than that of the upper mantle (olivine) ranging from ∼0.1-1 wt % (Pearson et al, 2014;Peslier et al, 2017).…”

Section: Transition Zone Temperature and Water Contentmentioning

confidence: 99%

“…The origin of water in the transition zone is likely due to water carried down with subducting plates along cold geotherms (e.g., Ohtani et al, 2004;Peslier et al, 2017;Schmidt & Poli, 1998) and due to upward percolation of hydrous melts from the lower mantle (e.g., Hirschmann, 2006), whose storage capacity is believed to be extremely low (e.g., Bolfan-Casanova et al, 2002. The extent to which this actually results in a water-enriched region in the transition zone is unclear.…”

Section: Transition Zone Temperature and Water Contentmentioning

confidence: 99%

Stochastic Inversion of Geomagnetic Observatory Data Including Rigorous Treatment of the Ocean Induction Effect With Implications for Transition Zone Water Content and Thermal Structure

et al. 2018

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In this paper we estimate and invert local electromagnetic (EM) sounding data for 1‐D conductivity profiles in the presence of nonuniform oceans and continents to most rigorously account for the ocean induction effect that is known to strongly influence coastal observatories. We consider a new set of high‐quality time series of geomagnetic observatory data, including hitherto unused data from island observatories installed over the last decade. The EM sounding data are inverted in the period range 3–85 days using stochastic optimization and model exploration techniques to provide estimates of model range and uncertainty. The inverted conductivity profiles are best constrained in the depth range 400–1,400 km and reveal significant lateral variations between 400 km and 1,000 km depth. To interpret the inverted conductivity anomalies in terms of water content and temperature, we combine laboratory‐measured electrical conductivity of mantle minerals with phase equilibrium computations. Based on this procedure, relatively low temperatures (1200–1350°C) are observed in the transition zone (TZ) underneath stations located in Southern Australia, Southern Europe, Northern Africa, and North America. In contrast, higher temperatures (1400–1500°C) are inferred beneath observatories on islands, Northeast Asia, and central Australia. TZ water content beneath European and African stations is ∼0.05–0.1 wt %, whereas higher water contents (∼0.5–1 wt %) are inferred underneath North America, Asia, and Southern Australia. Comparison of the inverted water contents with laboratory‐constrained water storage capacities suggests the presence of melt in or around the TZ underneath four geomagnetic observatories in North America and Northeast Asia.

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“…Plate tectonics causes the largest recycling system on Earth, but the extent to which volatiles are coupled to this cycle is uncertain (e.g., Demouchy & Bolfan‐Casanova, ; Hirschmann, ; Peslier et al, ). Although the potential existence of water reservoirs in the Earth's mantle transition zone has been intensively investigated since the early experiments of Ringwood and Major (), its confirmation by means of geophysical observations is still a matter of debate.…”

Section: Introductionmentioning

confidence: 99%

A Subsolidus Olivine Water Solubility Equation for the Earth's Upper Mantle

Padrón‐Navarta

Hermann

2017

JGR Solid Earth

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The pressure and temperature sensitivity of the two most important point hydrous defects in mantle olivine involving Si vacancies (associated to trace amounts of titanium [TiChu‐PD] or exclusively to Si vacancies [Si]) was investigated at subsolidus conditions in a fluid‐saturated natural peridotite from 0.5 to 6 GPa (approximately 20–200 km depth) at 750 to 1050°C. Water contents in olivine were monitored in sandwich experiments with a fertile serpentine layer in the middle and olivine and pyroxene sensor layers at the border. Textures and mineral compositions provide evidence that olivine completely recrystallized during the weeklong experiments, whereas pyroxenes displayed only partial equilibration. A site‐specific water solubility law for olivine has been formulated based on the experiments reconciling previous contradictory results from low‐ and high‐pressure experiments. The site‐specific solubility laws permit to constrain water incorporation into olivine in the subducting slab and the mantle wedge, as these are rare locations on Earth where fluid‐present conditions exist. Chlorite dehydration in the hydrated slab is roughly parallel to the isopleth of 50 ± 20 ppm wt H2O in olivine, a value which is independent of the pressure and temperature trajectory followed by the slab. Hydrous defects are dominated by [Si] under the relevant conditions for the mantle wedge affected by fluids coming from the slab dehydration (slab‐adjacent low viscosity/seismic low‐velocity channel, P > 3 GPa). In cold subduction zones at 5.5 km from the slab surface the storage capacity of the mantle wedge at depths of 100–250 km ranges from 400 to 2,000 ppm wt H2O.

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Water in the Earth’s Interior: Distribution and Origin

Cited by 33 publications

References 553 publications

Water Concentration in Single‐Crystal (Al,Fe)‐Bearing Bridgmanite Grown From the Hydrous Melt: Implications for Dehydration Melting at the Topmost Lower Mantle

Water Concentration in Single‐Crystal (Al,Fe)‐Bearing Bridgmanite Grown From the Hydrous Melt: Implications for Dehydration Melting at the Topmost Lower Mantle

Stochastic Inversion of Geomagnetic Observatory Data Including Rigorous Treatment of the Ocean Induction Effect With Implications for Transition Zone Water Content and Thermal Structure

A Subsolidus Olivine Water Solubility Equation for the Earth's Upper Mantle

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