Geeth Manthilake

Laboratoire Magmas et Volcans

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D. Andrault

Laboratoire Magmas et Volcans

Julien Chantel

Unité Matériaux et Transformations

M. A. Bouhifd

Institut de Recherche pour le Développement

Nathalie Bolfan‐Casanova

Laboratoire Magmas et Volcans

Mainak Mookherjee

Florida State University

Tomoo Katsura

University of Bayreuth

Takashi Yoshino

Okayama University

D. J. Frost

University of Bayreuth

Tahar Hammouda

Laboratoire Magmas et Volcans

J. Monteux

Laboratoire Magmas et Volcans

Cooperative Institutions

Centre National de la Recherche Scientifique

Institut de Recherche pour le Développement

Laboratoire Magmas et Volcans

Université Clermont Auvergne

University of Bayreuth

Clermont Université

Sorbonne Université

Okayama University

Université Paris Cité

Institut de minéralogie, de physique des matériaux et de cosmochimie

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Editorial: High-pressure physical behavior of minerals and rocks: Mineralogy, petrology and geochemistry

Frontiers in Earth Science (2023)

Lidong Dai Haiying Hu Xi Liu Geeth Manthilake V. Saltas

EDITORIAL article Front. Earth Sci., 09 January 2023Sec. Solid Earth Geophysics Volume 10 - 2022 | https://doi.org/10.3389/feart.2022.1126463

Solid earth

10.3389/feart.2022.1126463

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Is There a Global Carbonate Layer in the Oceanic Mantle?

Goldschmidt Abstracts (2021)

Tahar Hammouda Geeth Manthilake Philippe Gonçalves Julien Chantel Jérémy Guignard

Previous modeling of carbonate subduction by high‐pressure experimentation has allowed to propose scenarios for bulk carbon return to the mantle, but the detailed transfer mechanisms have seldom been studied. We monitored carbonate–silicate reactions by combining high‐pressure experiments and synchrotron‐based X‐ray diffraction. Carbonates break down at moderate pressure and high temperature and CO2 is trapped at grain boundaries. Further isothermal compression yields melting, which may control continuous carbon introduction, first in the mantle wedge, and next, away from the wedge. Carbon presence has been discussed in a variety of magmatic contexts, under the oceanic lithosphere (hotspots, petit spots, and fossil ridges). We suggest the presence of a global carbon‐rich layer under the oceanic lithosphere that is steadily fed by subduction processes. This layer can be the source of mechanical weakening of the lithosphere–asthenosphere boundary under the oceans. Therefore, carbon‐induced compression melting may be a key mechanism of modern‐style plate tectonics.

10.7185/gold2021.5187

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A new multi-anvil press employing six independently acting 8 MN hydraulic rams

High Pressure Research (2012)

Geeth Manthilake N. Walte D. J. Frost

Abstract A new large volume multi-anvil system which employs six independently acting hydraulic rams with independent oil pressurization systems has been developed for high pressure and temperature experiments. The six 8 MN hydraulic rams approach at right angles inside a composite steel plate frame and can each advance a square faceted anvil of either hardened steel or tungsten carbide. The position of each anvil can be measured relative to the frame of the press to a precision of 0.1 μ m. The press is designed to perform both deformation experiments using cubic ceramic pressure media and experiments employing eight inner cubic anvils to compress an octahedral pressure medium. During compression, the position of each anvil relative to the press frame can be precisely measured and controlled independently, thus ensuring a high level of symmetry in the compressive stress environment. The highly cubic compressive regime provides an optimal environment for the use of inner sintered diamond cubic anvils, which can potentially obtain pressures above 50 GPa. The large loading capacity (24 MN) allows larger cubic pressure media to be used at higher pressures than conventional systems. Keywords: a six-axis multi-anvil apparatuspressure generationdeformation Acknowledgements The development and construction of six-ram multi-anvil presses for the Bayerisches Geoinstitut and the neutron diffraction beam-line at FRM-II, Garching, Germany has been funded by grants to H. Keppler from the Deutsche Forschungsgemeinschaft (DFG: INST 91/204) and Bundesministerium für Bildung und Forschung (BMBF Projekt 05K10WC2). We are grateful to Kurt Klasinski, Sven Linhardt, Heinz Fischer Stefan Übelhack and the firm of Max Voggenreiter Gmbh, Mainleus, Germany for technical support.

Diamond anvil cell

Hydraulic press

Tungsten Carbide

10.1080/08957959.2012.680450

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Citations (22)

Experimental evidence supporting a global melt layer at the base of the Earth’s upper mantle

Nature Communications (2017)

Damien Freitas Geeth Manthilake Federica Schiavi Julien Chantel Nathalie Bolfan‐Casanova

Abstract The low-velocity layer (LVL) atop the 410-km discontinuity has been widely attributed to dehydration melting. In this study, we experimentally reproduced the wadsleyite-to-olivine phase transformation in the upwelling mantle across the 410-km discontinuity and investigated in situ the sound wave velocity during partial melting of hydrous peridotite. Our seismic velocity model indicates that the globally observed negative Vs anomaly (−4%) can be explained by a 0.7% melt fraction in peridotite at the base of the upper mantle. The produced melt is richer in FeO (~33 wt.%) and H 2 O (~16.5 wt.%) and its density is determined to be 3.56–3.74 g cm −3 . The water content of this gravitationally stable melt in the LVL corresponds to a total water content in the mantle transition zone of 0.22 ± 0.02 wt.%. Such values agree with estimations based on magneto-telluric observations.

Peridotite

Seismic velocity

Discontinuity (linguistics)

10.1038/s41467-017-02275-9

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Citations (48)

Mesures simultanées de conductivité électrique et de vitesse d'ondes sismiques de matériaux géologiques partiellement fondus à haute pression et haute température : implication pour la fraction de liquide silicaté dans l'asthénosphère

HAL (Le Centre pour la Communication Scientifique Directe) (2016)

Damien Freitas Geeth Manthilake Julien Chantel D. Andrault

Un debat important existe actuellement sur les capacites des systemes partiellement fondus a augmenter la conductivite electrique et reduire la vitesse des ondes sismiques du materiel geologique, necessaires pour expliquer la presence de zones d’anomalies geophysiques dans le manteau terrestre (zone de faible vitesse : LVZ de l’asthenosphere entre 70 et 200 Km [1],[2],[3]). De nombreuses hypotheses alternatives ont ete proposees et sont basees sur des processus a l’etat solide [4] telles la diffusion de l’hydrogene dans la structure cristalline. Ces theories suggerent une asthenosphere sans fusion partielle. Alors que de fortes evidences physiques confirment la presence de fusion partielle du manteau asthenospherique, comme la decouverte de basaltes alcalins jeunes disposes sur la plaque oceanique indienne beaucoup plus ancienne [5], les mesures experimentales de conductivite electriques et de vitesse des ondes sismiques realisees en laboratoire sur les systemes partiellement fondus apportent des estimations antagonistes de la fraction de liquide silicate implique dans l’asthenosphere. De plus, la source du desaccord entre les deux techniques geophysiques (conductivite electrique et vitesse sismique) demeure toujours mal contrainte. Utilisant les nouvelles techniques experimentales developpees sur la presse multi-enclumes au Laboratoire Magmas et Volcans de Clermont-Ferrand, des mesures couplees de conductivite electrique et de vitesse des ondes acoustiques ont ete realisees de facon in situ et simultanee sur le meme echantillon. Nous avons alors etudie des systemes partiellement fondus en utilisant des echantillons composes d’un melange biphase d’olivine de San Carlos (standard petrologique) et d’un basalte de ride medio-oceanique hydrate provenant de la ride Est-Pacifique (issu d’un forage) dans des conditions de haute pression : 2.5 GPa et de haute temperature: jusqu’a 1650 K.

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Thermal expansion of liquid Fe-S alloy at high pressure

Earth and Planetary Science Letters (2021)

Fang Xu G. Morard Nicolas Guignot Attilio Rivoldini Geeth Manthilake

Liquidus

Supercooling

Temperature Gradient

10.1016/j.epsl.2021.116884

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Citations (9)

Argon behavior in basaltic melts in presence of a mixed H2O-CO2 fluid at upper mantle conditions

Chemical Geology (2016)

Alessandro Fabbrizio M. A. Bouhifd D. Andrault Nathalie Bolfan‐Casanova Geeth Manthilake

CO2 content

Argon gas

10.1016/j.chemgeo.2016.11.014

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Halogen Bearing Amphiboles, Aqueous Fluids, and Melts in Subduction Zones: Insights on Halogen Cycle From Electrical Conductivity

Journal of Geophysical Research Solid Earth (2021)

Geeth Manthilake Kenneth T. Koga Ye Peng Mainak Mookherjee

Abstract Amphiboles are hydrous minerals that are formed in the oceanic crust via hydrothermal alteration. The partial substitution of halogens for OH − makes amphibole one of the principal hosts of Cl and F in the subducting slab. In this study, we investigated the electrical conductivity of a suite of halogen bearing amphibole minerals at 1.5 GPa up to 1,400 K. The discontinuous electrical behavior indicates dehydration of amphibole at ∼915 K. This is followed by dehydration induced hydrous melting at temperatures above 1,070 K. We find that the released aqueous fluids have an electrical conductivity of ∼0.1 S/m. This high electrical conductivity is likely to explain anomalously high electrical conductivity observed in certain subduction zone settings. This high electrical conductivity of an order of magnitude greater than the electrical conductivity of pure aqueous fluids at similar conditions is likely due to the partitioning of the F and Cl into the aqueous fluids. We also noted that subsequent to the dehydration, secondary phases form due to the breakdown of the primary halogen bearing amphibole. Chemical analyses of these secondary phases indicate that they are repositories of F and Cl. Hence, we infer that upon dehydration of the primary halogen bearing amphibole, first the F and Cl are partitioned into the aqueous fluids and then the halogens are partitioned back to the secondary mineral phases. These secondary minerals are likely to transport the halogen to the deep Earth and may in part explain the halogen concentration observed in ocean island basalt.

Amphibole

10.1029/2020jb021339

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Citations (11)

Lattice thermal conductivity of lower mantle minerals and heat flux from Earth’s core

Proceedings of the National Academy of Sciences (2011)

Geeth Manthilake Nico de Koker D. J. Frost Catherine McCammon

The amount of heat flowing from Earth's core critically determines the thermo-chemical evolution of both the core and the lower mantle. Consisting primarily of a polycrystalline aggregate of silicate perovskite and ferropericlase, the thermal boundary layer at the very base of Earth's lower mantle regulates the heat flow from the core, so that the thermal conductivity (k) of these mineral phases controls the amount of heat entering the lowermost mantle. Here we report measurements of the lattice thermal conductivity of pure, Al-, and Fe-bearing MgSiO(3) perovskite at 26 GPa up to 1,073 K, and of ferropericlase containing 0, 5, and 20% Fe, at 8 and 14 GPa up to 1,273 K. We find the incorporation of these elements in silicate perovskite and ferropericlase to result in a ∼50% decrease of lattice thermal conductivity relative to the end member compositions. A model of thermal conductivity constrained from our results indicates that a peridotitic mantle would have k = 9.1 ± 1.2 W/m K at the top of the thermal boundary layer and k = 8.4 ± 1.2 W/m K at its base. These values translate into a heat flux of 11.0 ± 1.4 terawatts (TW) from Earth's core, a range of values consistent with a variety of geophysical estimates.

Silicate perovskite

Post-perovskite

Core–mantle boundary

10.1073/pnas.1110594108

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Citations (123)

Subducted slabs induce high heat flux at the core-mantle boundary

Goldschmidt Abstracts (2023)

Geeth Manthilake Chengcheng Zhao Ali Bouhifd Antoine Mathieu

Core–mantle boundary

Slab

10.7185/gold2023.14920

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