Experimental investigation of the electrical behavior of olivine during partial melting under pressure and application to the lunar mantle

Pommier, Anne; Leinenweber, Kurt; Tasaka, Miki

doi:10.1016/j.epsl.2015.05.052

Cited by 27 publications

(15 citation statements)

References 57 publications

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“…The measured resistance corresponds to the response of the sample and the contribution of the electrodes (molybdenum squares, metallic wires, and cables). The latter corresponds to a value of 7.6 Ω over the entire temperature range (Pommier et al, ), and this value was subtracted from all resistance values of the samples. The analytical error on electrical conductivity values is determined by accounting for uncertainties on the sample dimensions (diameter and thickness of the sample from the Scanning Electron Microscopy [SEM] images) and the electrical resistance value (Table ).…”

Section: Experimental Methodsmentioning

confidence: 99%

Electrical Investigation of Natural Lawsonite and Application to Subduction Contexts

et al. 2019

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We report an experimental investigation of the electrical properties of natural polycrystalline lawsonite from Reed Station, CA. Lawsonite represents a particularly efficient water reservoir in subduction contexts, as it can carry about 12 wt % water and is stable over a wide pressure range. Experiments were performed from 300 to about 1325 °C and under pressure from 1 to 10 GPa using a multi‐anvil apparatus. We observe that temperature increases lawsonite conductivity until fluids escape the cell after dehydration occurs. At a fixed temperature of 500 °C, conductivity measurements during compression indicate electrical transitions at about 4.0 and 9.7 GPa that are consistent with crystallographic transitions from orthorhombic C to P and from orthorhombic to monoclinic systems, respectively. Comparison with lawsonite structure studies indicates an insignificant temperature dependence of these crystallographic transitions. We suggest that lawsonite dehydration could contribute to (but not solely explain) high conductivity anomalies observed in the Cascades by releasing aqueous fluid at a depth (~50 km) consistent with the basalt‐eclogite transition. In subduction settings where the incoming plate is older and cooler (e.g., Japan), lawsonite remains stable to great depth. In these cooler settings, lawsonite could represent a vehicle for deep water transport and the subsequent triggering of melt that would appear electrically conductive, though it is difficult to uniquely identify the contributions from lawsonite on field electrical profiles in these more deep‐seated domains.

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Section: Experimental Methodsmentioning

confidence: 99%

Electrical Investigation of Natural Lawsonite and Application to Subduction Contexts

et al. 2019

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“…Using illustrative values, R m ¼ 40 v=1 cm=s ð ÞL=300 km ð Þσ=10; 000 S=m ð Þ . Therefore, for a silicate dynamo to operate the electrical conductivity must exceed 10,000 S/m, more than 100 times higher than the highest values measured in silicate liquids at low pressure and temperature 8,9 , although less than typical metallic conductivity (10 6 S/m for the Earth's outer core).…”

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confidence: 87%

A silicate dynamo in the early Earth

2020

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The Earth's magnetic field has operated for at least 3.4 billion years, yet how the ancient field was produced is still unknown. The core in the early Earth was surrounded by a molten silicate layer, a basal magma ocean that may have survived for more than one billion years. Here we use density functional theory-based molecular dynamics simulations to predict the electrical conductivity of silicate liquid at the conditions of the basal magma ocean: 100-140 GPa, and 4000-6000 K. We find that the electrical conductivity exceeds 10,000 S/m, more than 100 times that measured in silicate liquids at low pressure and temperature. The magnetic Reynolds number computed from our results exceeds the threshold for dynamo activity and the magnetic field strength is similar to that observed in the Archean paleomagnetic record. We therefore conclude that the Archean field was produced by the basal magma ocean.

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“…Allowing for upwelling of partial melt or infiltration of melt into grain boundaries or cracks, we should consider the porous flow governed by Darcy's law [McKenzie, 1984;Katz et al, 2007;Cagnioncle et al, 2007;Wilson et al, 2014] rather than the Stokes flow. However, it has yet to be studied whether numerical simulation allowing for the porous flow can cause the overturned flow in the mantle wedge and under which condition the overturn can occur.…”

Section: Overturn Of Electrically Conductive Plume and Back-arc Volcamentioning

confidence: 99%

Electrical image of subduction zone beneath northeastern Japan

et al. 2015

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We conducted long‐period magnetotelluric observations in northeastern Japan from 2010 to 2013 to investigate the three‐dimensional electrical resistivity distribution of the subduction zone. Incorporating prior information of the subducting slab into the inversion scheme, we obtained a three‐dimensional resistivity model in which a vertically continuous conductive zone is imaged from the subducting slab surface to the lower crust beneath the Ou Backbone Range. The conductive body indicates a saline fluid and/or melt pathway from the subducting slab surface to the lower crust. The lower crust conductor is less than 10 Ω m, and we estimate a saline fluid and/or melt fraction of at least 0.7 vol. %. Other resistivity profiles in the across‐arc direction reveal that the conductive body segregates from the subducting slab surface at 80–100 km depth and takes an overturned form toward the back arc. The head of the conducting body reaches the lower crust just beneath Mt. Gassan, one of the prominent back‐arc volcanoes in the system.

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Experimental investigation of the electrical behavior of olivine during partial melting under pressure and application to the lunar mantle

Cited by 27 publications

References 57 publications

Electrical Investigation of Natural Lawsonite and Application to Subduction Contexts

Electrical Investigation of Natural Lawsonite and Application to Subduction Contexts

A silicate dynamo in the early Earth

Electrical image of subduction zone beneath northeastern Japan

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