Abstracts of Poster presentation
International School March 7-10, 2019, Hida, Japan-Thermal evolution, energy sources and associated heterogeneity-

MEXT Grant-in-Aid for Scientiﬁc Research on Innovative Areas

Interaction and Coevolution of the Core and Mantle
Toward Integrated Deep Earth SciencePoster List <Poster Session : March 8th & 9th, 21:00- >1-min presentation 1 (March 7th, 18:10 ‒)1 Norikatsu Akizawa (The University of Tokyo)“Ancient, highly depleted mantle beneath French Polynesia archipelago constrained by rhenium-osmium
isotope and highly-siderophile element compositions of mantle xenoliths”
2 Irene Bonati (Tokyo Institute of Technology)“Modeling Ultralow Velocity Zones as a thin chemically distinct layer at the core-mantle boundary”
3 Hitoshi Gomi (Okayama University)“Electrical resistivity and thermal conductivity of fcc Fe: Implications for the Mercuryʼ s core”
4 Anselme Borgeaud (The University of Tokyo)“3-D S-velocity structure of the mantle transition beneath Central America using waveform inversion”
5 Yuuki Hagiwara (Hokkaido University)“Fluid inclusion as a potential geobarometer: Determination of the depth provenance of mantle xenoliths”
6 Li-Wei Chen (UC Berkeley)“An application of source stacking followed by cross-correlations for global waveform tomography using theSpectral Element Method”
7 Thibaut Clarté (ENS Lyon)“Thermo-Compositional Convection in Magma Oceans”
8 Shinnosuke Aoyama (Niigata University)“Sulfur isotopic signature of granitoids: link to the crustal evolution through Earthʼ s history”
9 Haruhiko Dekura (Ehime University)“Ab initio lattice thermal conductivity of ferropericlase”

1-min presentation 2 (March 8th, 20:30 ‒ )10 Nozomi Kondo (Ehime University)“Major element composition of the Hadean crust and mantle chemical evolution in the early Earth”
11 Xuejing He (The University of Tokyo)“Equation of State of Schreibersite Fe2.15Ni0.85P”
12 Wang Ran (Okayama University)“Electrical conductivity of diaspore, epsilon-FeOOH and delta-AlOOH”
13 Sebastian Ritterbex (Ehime University)“Ab-Initio Investigation of Iron Diﬀusion Properties with Implications for Inner Core Plasticity”
14 Adrien Morison (ENS Lyon)“Dynamics and evolution of the primitive mantle with magma oceans”
15 Atsuro Okamoto (The University of Tokyo)“Viscosity of lower mantle estimated from the common diﬀusivity of creep and grain growth”
16 Vancliﬀ Hengyi Su (National Central University)“The multi-fault rupture process of 1935 Hsinchu-Taichung Earthquake, Taiwan revealed from dynamic
modeling”
17 Yasuhiro Kuwayama (The University of Tokyo)“Density and sound velocity of iron in the Earthʼ s core conditions”
18 Shiori Morii (The University of Tokyo)“Distribution and formation of radiocesium in environment derived from Fukushima Dai-ichi nuclear disaster,
focusing on radiocesium-bearing micro particle”

1-min presentation 3 (March 9th, 20:30 ‒ )19 Yuki Suzuki (The University of Tokyo)“Anisotropy and ﬂows at the lowermost mantle beneath the Northern Paciﬁc revealed by waveform
inversion”
20 Ryo Tsuruoka (Osaka University)“Density measurement of liquid metal at high pressure using X-ray absorption method with externally heateddiamond anvil cell”
21 Lena Yokokura (Hokkaido University)“Is there substantial evidence for the big mantle wedge hypothesis?”22 Chikara Shito (Tohoku University)“In-situ X-ray diﬀraction study on beta-CrOOH at high pressure and high temperature”
23 Liang Yuan (Tohoku University)“Ultralow-velocity zones possibly explained by light element-enriched iron compounds”
24 Youyue Zhang (Okayama university)“Eﬀect of iron content on thermal conductivity of olivine with implications for cooling history of rocky
planets”
25 Ingrida Semenec (Queenʼ s University)“Geo-neutrinos at SNO+”
26 Laura Sammon (University of Maryland)“Improving geoneutrino predictions from jointly constrained local crustal models”

Ancient, highly depleted mantle beneath French Polynesia archipelago
constrained by rhenium-osmium isotope and highly-siderophile element
compositions of mantle xenoliths
Norikatsu Akizawa*1, Akira Ishikawa2, Katsuhiko Suzuki3, and Tetsu Kogiso4
1Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5

Kashiwanoha, Kashiwa, Chiba, 277-8564, Japan

2Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-

12-1 Ookayama, Meguro, Tokyo, 152-8550, Japan

3Research and Development Center for Submarine Resources, Japan Agency for

Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima,
Yokosuka, Kanagawa 237-0061, Japan
4Graduate School of Human and Environmental Studies, Kyoto University,
Yoshida-Nihonmatsu, Sakyo, Kyoto, 606-8501, Japan
E-mail address of the presenter: akizawa@aori.u-tokyo.ac.jp
Mantle xenoliths can provide lithological and geochemical information of theinaccessible mantle. In order to better characterize the lithological andgeochemical characteristics of the mantle, we conducted extensive sampling ofmantle xenoliths throughout French Polynesia archipelago: Tahiti, Moorea, andRurutu islands. We collected 42 mantle xenoliths: 1 lherzolite, 14 harzburgites,
22 dunites, 3 wehrlites, and 2 orthopyroxenites. Here, we present whole-rockrhenium-osmium isotope and highly-siderophile element (Os, Ir, Ru, Pt, Pd, andRe) compositions in addition to whole-rock major-element compositions.
Osmium isotope ratio (187Os/188Os) of the mantle xenoliths ranges from 0.1172
to 0.1464, where the harzburgites show a statistical bimodal distribution with
unradiogenic (187Os/188Os < 0.125) and radiogenic (187Os/188Os > 0.125)
compositions. The harzburgites with unradiogenic 187Os/188Os are depleted withregards to whole-rock major-element compositions (< 1.22 wt% Al2O3), andchondrite-normalized patterns of highly-siderophile elements. Considering thelithological variation of the mantle xenoliths used herein, the mantle isconsiderably heterogeneous beneath French Polynesia archipelago. In
particular, the contrasting isotopic compositions of the harzburgites suggest
different mantle reservoirs, from which the harzburgite xenoliths were derived.
We propose a possibility that the harzburgites with unradiogenic 187Os/188Os are
impinged mantle material beneath normal oceanic lithosphere due probably toascending plumes.

Modeling Ultralow Velocity Zones as a thin chemicallydistinct layer at the core-mantle boundary
Irene Bonati, John W. Hernlund
Earth-Life Science Institute, Tokyo Institute of Technology, 212-1 Ookayama, Meguro, Tokyo 152-8550, Japan
irene.bonati@elsi.jp
Seismically detected ultralow velocity zones (ULVZs) at thecore-mantle boundary (CMB) reflect the dynamical state andgeological evolution of the silicate-metal frontier of Earth's
deep interior. Modeling the evolution of ULVZs presents,
however, a number of difficulties, such as the necessity of finescale resolution and the treatment of large viscosity contrasts.
Here we extend the study of ULVZs using a lubrication theory
approach and apply it to numerical and analytical models ofmantle convection in the CMB region. A generic model of athin low viscosity ULVZ layer embedded between an overlying
convective viscous mantle and an underlying inviscid core can
explain several features that are consistent with seismic
inferences, such as the absence of ULVZs in some regions andan elongated shape where they are concentrated. The model
explains how the topography of ULVZs tends to saturate as
they become thicker, due to the non-linear feedback between
viscous aggregation beneath upwelling mantle currents andgravitational relaxation. Implementing the ULVZ equation in
mantle convection models indicates that ULVZs are
preferentially concentrated beneath long-lived plumes, andmay not exist below newly formed plume roots. The
presence/absence of ULVZs, as well as their shapes, may
provide important insights into the dynamical state of thelowermost mantle.

Electrical resistivity and thermal conductivity of fcc Fe:
Implications for the Mercury’s core
Hitoshi Gomi, Takashi Yoshino
Institute for Planetary Materials, Okayama University, Misasa,
Tottori 682-0193, Japan.
hitoshi.gomi@okayama-u.ac.jp
Electrical resistivity andthermal conductivity offace-centred cubic (fcc) Fe
are calculated by using the
Korringa-Kohn-Rostoker(KKR) method combinedwith the Kubo-Greenwood
formula. Two types ofscattering mechanisms are
considered: (1) phonon
scattering and (2) magnetic
scattering. The former isapproximated by means of
the alloy analogy model ofatomic displacements, andthe latter is represented by
the local magnetic disorder(LMD) approach. Both ofthese two effects are treatedwithin the coherent potential
approximation (CPA), which
is implemented in the
AkaiKKR package. The
contribution of the magnetic
scattering is important at

ambient pressure, andcalculated electricalresistivity and thermal
conductivity are consistent
with experimental data.
However, the local magnetic
moment is quenched at highpressure. Based on thepresent first-principles
calculations, we modelled
the depth increasing thermal
conductivity of Mercury’score, which is consistent withthe thin layered dynamo
model of the weak magnetic
fields.

3-D S-velocity structure of the mantle transition zone
beneath Central America using waveform inversion
Anselme F. E. Borgeaud1*, Kenji Kawai1, Robert J. Geller1
1
University of Tokyo*anselme@eps.s.u-tokyo.ac.jp

Abstract…………………………………………….
Travel-time tomography
studies have reported various
modalities of subduction of slabs
around the mantle transitionzone (MTZ), but the causes ofthis variability are still
controversial. In order to place
additional constraints on themodality of subduction in andnear the MTZ, we apply
waveform inversion to S-wave
triplications due to the 410 and
660 km discontinuities, and infer
the regional 3-D S-velocity
structure in the depth range 330–
820 km beneath Central America
and the Gulf of Mexico. We use~3,600 transverse component
records at epicentral distances
10–30˚ from 20 intermediate
focus earthquakes beneathCentral America recorded atstations of the USArray andother smaller networks. We filter
the records between 20–100 s,
and use the portions of the
waveforms from 10 s before to~40–80 s after the arrival of thedirect S-wave, thereby including
the S-wave triplications while
excluding the sS depth phase.
We correct the data for the
structure above our target region
using previous S-velocity
models; we show that the resultsof the inversion do not depend
heavily on which correction isused. Resolution tests confirm
that we can resolve small-scale
structure in the target region.
Our inferred models show that
the Cocos slab penetrates into
the lower-mantle, but with
important variations along the
Middle America Trench in the
subduction modality of the slab.
We suggest that this variability
could be due to the thermal
structure of the Cocos slab, andto the interaction of the slab witha lower-mantle plume.

Fluid inclusion as a potential geobarometer: Determination of the depth
provenance of mantle xenoliths
Yuuki Hagiwra*1 and Junji Yamamoto2
1

Graduate School of Science, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo,
Hokkaido 060-0810, Japan
2
The Hokkaido University Museum, Kita 10 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810,
Japan
E-mail address of the presenter: hagi@eis.hokudai.ac.jp
Fluid inclusions, if they satisfy several criteria, contain information about theenvironment prevailing at the time of formation of the fluid inclusions (Roedder, 1984).
Therefore, accurate measurements of the residual pressure of the fluid inclusions at a given
temperature can indicate the depth provenance of the rocks from the equilibrium temperatureof the rocks and the equation of state of the fluid. However, to assess re-equilibration processesof the fluid inclusions, one must obtain physicochemical information of fluid inclusions ofvarious sizes including very small ones because the fluid retentivity depends on the fluidinclusion size. Particularly with respect to the residual pressure, the most reliable size range of
fluid inclusions for density calculation is close to submicrometer order because higher pressure
retentivity is associate with smaller fluid inclusions. Therefore, in this study, we measured theresidual pressure of the fluid inclusions by Raman based barometer, which can be applied tosmall fluid inclusions. By using this method, we measured the residual pressure of fluidinclusions in submicron to 10 μm in mantle xenoliths from Ennokentiev, Sikhote-Alin, Far
Eastern Russia.
Raman spectra were acquired using excitation by a diode pumped solid-state laser(532 nm, Gem 532; Laser Quantum), and using a spectrometer with 75 cm focal length(Acton SP-2750; Princeton Instruments, Inc.) and a CCD camera (1650 × 200 pixels, 16 mwidth, iVac; Andor Technology). The laser power was ~10 mW at the sample. The respective
sizes of the fluid inclusions were measured using a 2000× objective (VH-ZST; Keyence Co.)
with a digital microscope (VHX-5000; Keyence Co.). The fluid inclusion size was measured
automatically by identifying the outline of a fluid inclusion using the brightness contrast.
The results show that the residual pressure of the fluid inclusion systematicallychanges depending on the diameter of the fluid inclusion, and the smaller the fluid inclusions
are, the higher the pressure retentivity is. The fluid density vary from 0.94 to 1.08 g/cm3. The
depth provenance calculated from EOS of CO2 and equilibrium temperature is 0.87–0.62 MPa.
To explain this variation, we calculated size dependence of thermoelastic equilibrium between
fluid inclusion and host mineral based on the formulation of Zhang (1998). However,thermoelastic equilibrium can not explain the large density variation (~10%) since its
contribution to the density variation is only on the order of 0.01%. Additionally, we assessed
the effect of size dependent brittle fracture on the fluid density. Although we can successfully
explain general fluid density trend, to explain the whole data, effect of plastic deformation andfluid diffusion should be added to the simple brittle fracture model.

An application of source stacking followed by cross-correlations for global
waveform tomography using the Spectral Element Method
Li-Wei Chen​1​, Barbara Romanowicz​1,2,3
1. UC Berkeley
2. Collège de France Paris
3. Institut de Physique du Globe, Paris
Accurate synthetic seismic wavefields can now be computed by using the spectral element
method (SEM), which helps constructing of 3D earth models by seismic waveform
tomography and has been shown to help improve resolution, However, the heavy
computational costs represent a challenge for further resolution improvements. These costs
can be reduced by implementing a source stacking method (Capdeville et al., 2005, GJI), in
which multiple earthquake sources are simultaneously triggered in only one teleseismic SEM
simulation. Thus, this method can potentially reduce the computational costs by several
orders of magnitude.
One issue with this approach is that the summed wavefield is dominated by the large
amplitude fundamental mode surface waves. The windowing and weighting schemes used inconventional waveform tomography cannot be applied and it could possibly lead the loss ofresolution at depth. Romanowicz et al. have addressed this issue in 2013 by computing thecross-correlation wavefield between pairs of stations before each inversion iteration.
Although the Green’s function between the two stations is not reconstructed as well as in thecase of ambient noise tomography, it is still possible to apply the same processing to the 3D
synthetics and to the data, and the source parameters are known to a good approximation.
By doing so, we can separate time windows with large energy arrivals corresponding tofundamental mode surface waves, and apply a weighting scheme to bring out thecontribution of overtones and body waves. Also, the normal mode perturbation theory isused for computing the gradient and Hessian rather than an adjoint approach, so there is nocross-talk effect in the inversion step.
Here we present the results of testing this approach for a synthetic global long period(400-60s) 3-component waveform dataset computed for 273 globally distributed events in a
toy 3D radially anisotropic upper mantle model which contains shear wave anomalies atdifferent scales. We demonstrate the results of inversion of 10,000 s stacked time series
using source stacking with and without noise, and cross-correlations. It is worth to mention
the comparisons of different parameters in global full-waveform tomography are practicallyunattainable using conventional SEM-based waveform tomography.

THERMO-SOLUTAL CONVECTION IN MAGMA OCEANS

Thibaut Clarté, Nathanaël Schaeffer, Stéphane Labrosse
ISTerre, Université Grenoble Aples, LGL, ENS de Lyon
thibaut.clarte@ens-lyon.fr

Because of giant impacts, the history of the Earth’s mantle may have begun
with a period during wich it is largely molten, the magma ocean era. We
should understand the cooling and freezing of such an ocean to obtain information about mantle differentiation and the beginning of plate tectonics.
Current models for magma oceans usually make the hypothesis of a compositionally well mixed isentropic liquid. Indeed the low viscosity of such an
ocean and the huge radiative heat flow at the top should lead to vigourous
convection. Nevertheless, fractionnal crystallization of liquid at the bottomof the liquid may produce a basal enrichement in FeO of the ocean (making
it denser) possibly ending up with the formation of a stably stratified layer.
Whether or not this happens depends on the competition between the destabilising thermal buoyancy and the stabilising compositional one. With thatquestion in mind, we have developed a model for direct numerical simulationsof rotating thermosolutal convection in a 3D spherical geometry.

We have decided to focus on the consequences of two physical processes–possibly underwent by magma oceans– on the dynamics and on the properties of heat and solute transports. These phaenomena are the fractional
crystallization of the liquid inducing basal enrichment in iron oxyde and theradiative equilibrium between the ocean and an atmosphere.

Considering the thermodynamics of crystallization at the bottom, we obtain a linear relationship between the heat and solute fluxes at the bottom,
a condition that we implemented in the numerical code. For the top boundary, radiative equilibrium is taken into account by imposing a linear relation
between temperature and heat flux (Robin condition).

An exploration of parameter space (mainly Rayleigh, Ekman and Biot
numbers) has been conducted. Influence of Robin boundary conditions andthermo-solutal coupling on convection is separately discussed.
1

Sulfur isotopic signature of granitoids: link to the crustal
evolution through Earth’s history
Shinnosuke Aoyama
Faculty of Science, Niigata University
aoyama@geo.sc.niigata-u.ac.jp
Sulfur is mainly present as oxidized sulfur (sulfate) andreduced sulfur (sulfide) in the ocean and crust, the surface
environments. The surface sulfur finally returns back to themantle through subduction process, but a part of sulfur isrecycled to the surface as dehydration and arc magmatism in
subduction zones. Sulfur isotopic signature of granitoids is
potentially a useful tracer for the origin of the recycled sulfur
in subduction zones, and linked to the crustal evolution throughEarth’s history. In the presentation, I report compiled sulfur
isotopic signature of granitoids through Earth’s history, from
Early Archean granitoids (aged ca. 4.0 Ga) to Phanerozoic
granitoids (aged ca. 100 Ma). Sulfur isotopic signature of
granitoids through Earth’s history is expected to show surface
sulfur isotopic signature and regime of the crustal formation.

TITLE: Ab initio lattice thermal conductivity offerropericlase
Authors: Haruhiko DEKURA* and Taku TSUCHIYA
Affiliation: Geodynamics Research Center, Ehime University
E-mail address of the presenter: dekura.haruhiko.mf@ehimeu.ac.jp
Abstract: Determination of lattice thermal conductivity (𝜅lat ) oflower mantle (LM) minerals is a key to understanding the
dynamics and evolution of the earth’s deep interior. Some
recent experimental studies have shown that 𝜅lat of MgO issubstantially reduced by Fe incorporation (Manthilake et al.,2012; Goncharov et al., 2015; Ohta et al., 2017; Hsieh et al.,2017). However, those experimental measurement remains
technically challenging at the deep mantle condition. In thisstudy, we investigate 𝜅lat of ferropericlase (FP) in the LM
pressure and temperature conditions, based on the ab initio
anharmonic lattice dynamics techniques with fully solving thephonon Boltzmann transport equation (Dekura and Tsuchiya,2017) combined with the internally consistent LDA+U
technique for more precisely describing the Fe-O bond (Wanget al., 2015). Calculations demonstrate strong negative solid
solution effects of low-spin Fe on 𝜅lat of FP, as a linear
decrease in log 𝜅lat with increasing the Fe concentration. Ourdetailed analyses indicate that such strong effects occur
primarily due to the substantial changes in harmonic properties.
The 𝜅lat of FP with 12.5% iron at the core-mantle boundary
condition (136 GPa and ~4000 K) is estimated to be ~12 Wm1 -1
K which is ~60% smaller than the Fe-free system (~30 Wm1 -1
K , Dekura and Tsuchiya, 2017).

TITLE

Major element composition of the Hadean crust and mantle chemical evolution in the
Early Earth

Author(s)Nozomi M. Kondo1,2, Tetsu kogiso1

Affiliation(s)12Graduate School of Human and Environmental Studies, Kyoto University
Geodynamics Research Center, Ehime University

E-mail address of the presenterkondo.nozomi.xg@ehime-u.ac.jp

Abstract

Introduction: The mantle composition and dynamics have been evolved through formation
and re-mixing of crust. Therefore, in order to understand the history of the mantle chemicaland dynamical evolution, we have to know the initial condition of the crustal formation andrecycling. Previous studies have investigated the crustal formation in the early Earth fromzircons <4.4 Ga, and from isotopic record in the Archean rocks (ex. Nebel et al. 2014; Rizo etal, 2013). These clues have suggested formation of the primary crust from mantle melting
before 4.4 Ga, formation of the evolved crust (secondary, …) from melting of pre-existing(primary, …) crust and re-mixing of these crusts. However, the rock record before 4.0 Ga(the Hadean) has never or scarcely found, and therefore, the major element composition of
the Hadean crusts have been unrevealed. The major element composition controls physicalproperties such as density and viscosity of melt and crust, and these physical properties inturns controls the formation and recycling of the crust. Therefore, in this study weconstrained the major element composition of the Hadean primary and secondary crust anddiscussed about the formation and fate of these Hadean crusts.
Strategy: We combined the Sm-Nd isotope systematics and high-pressure melting
experiments in order to constrain the major element composition of the Hadean primary andsecondary crust. For the primary crust, we firstly estimated melting condition of mantle at the
Hadean silicate (mantle and crust) differentiation from the Sm-Nd systematics in the earlyArchean rocks, that have higher and lower 142Nd/144Nd ratio than that of the present mantle.
The 142Nd/144Nd anomalies are distinct in the early Archean rocks, and diminish from the lateArchean to the present. Due to the short half-life of the 146Sm (68 Myr), the parent nuclide of
the 142Nd, the 142Nd/144Nd anomalies and diminishing of them have been interpreted as the
Sm/Nd fractionation at the Hadean silicate differentiation and re-mixing of the Hadean
depleted mantle (high Sm/Nd and 142Nd/144Nd ratio) and enriched crust (low Sm/Nd and142
Nd/144Nd ratio). Since the degree of the Sm/Nd fractionation depends on two variables, thetiming and melting condition of the Hadean silicate differentiation, we can constrain thesetwo variables from two Sm-Nd systematics, 146Sm-142Nd and 147Sm-143Nd systems. Then, we
estimated the major element composition of the melt generated at the Hadean silicate
differentiation from the melting condition constrained from the Sm-Nd systematics and dataof high-pressure melting experiments of a primitive mantle (Fallon et al. 2008; Hirose &Kushiro 1993; Walter 1998; Davis et al. 2011; Kondo et al. 2016) . For the secondary crust,
we conducted high-pressure melting experiments of synthesized starting material with thehydrous primary crust composition, using piston-cylinder high-pressure apparatus atGraduate School of Human and Environmental Studies, Kyoto University, and determined
the major element composition of melt.
Result and discussion: For the Hadean primary crust, the estimated melting condition at the
Hadean silicate differentiation was extremely small melt fraction at shallow upper mantle
pressures. Then, as the result, the major element composition of the melt was estimated to be
Ti-basaltic at 1 GPa, Ti-K-rich picritic at 3 GPa, and Ti-Fe-P-rich komatiitic at 7 GPa. Then,
we discussed the probable composition of the Hadean primary crust to be Ti-Fe-P-richkomatiitic by estimating the condition of the Hadean mantle (mantle potential temperature,tectonics, and thickness of lithosphere). We also discussed the formation of the Hadean
primary crust by estimating the density and viscosity of the Ti-Fe-P-rich komatiitic melt. For
the Hadean secondary crust, the solidus and melting phase relation of the hydrous Hadean
primary crust was determined from 1-3 GPa, and the major element composition of the melt
was revealed to be Ti-Fe-P rich mafic. Then, we discussed the subduction and melting of thehydrous Hadean primary crust by comparing the solidus and subduction P-T pass of the earlyArchean and the present subduction zones. We also discussed the formation of the Hadean
secondary crust by estimating the density and viscosity of the Ti-Fe-P rich mafic melt.
Summary: We constrained the major element composition of the Hadean primary andsecondary crust by combining the Sm-Nd systematics and high-pressure melting experiments.
The Hadean primary crust would have formed at extremely small melt fraction and had TiFe-P-rich komatiitic composition. The Hadean secondary crust would have formed
subduction-related melting of the hydrous Hadean primary crust and had Ti-Fe-P-rich mafic
composition.

Equation of State of Schreibersite Fe2.15Ni0.85P
Xuejing He1,*, Jiazeng Guo2, Xiang Wu3, Shengxuan Huang1,
Fei Qin1, Xiangping Gu4, Shan Qin1
1
Key Laboratory of Orogenic Belts and Crustal Evolution,
MOE, School of Earth and Space Sciences, Peking University,
Beijing 100871, P.R. China
2
Institute of Jewelry and Jade Carving, Nanyang Normal
University, Nanyang 473061, P.R. China
3
State Key Laboratory of Geological Processes and Mineral
Resources, China University of Geosciences, Wuhan 430074,
P.R. China
4
School of Geosciences and Info-Physics Institute, Central
South University, Changsha 410083, P.R. China
xuejinghe@pku.edu.cn
Abstract
Phosphorus is thought to be an important light element
existing in planetary cores. The phosphorus abundance isevaluated to be ~0.20 wt% in the Earth’s core, and ~0.32 wt%
in the Martian core. To fully understand its existence inplanetary cores, structural and physical properties of ironnickel phosphides should be investigated under high pressureand high temperature. (Fe,Ni)3P-schreibersite is observed as acommon accessory in the veinlet of iron and stony-ironmeteorites, so that it is of significance to discuss and constrain
the properties of planetary cores. The equation of state of anatural single-crystal schreibersite, Fe2.15Ni0.85P, has beenstudied up to ~50 GPa at room temperature in a diamond anvil
cell using in situ synchrotron-radiation X-ray diffraction. The
sample kept its tetragonal structure ( 𝐼𝐼4� ) up to the highest
pressure with no observation of phase transition. Experimental
results have shown that the magnetic collapse of Fe2.15Ni0.85P isweakened because of the substitution of nickel, leading to an
isotropic axial compressibility. The pressure-volume data werefitted by a third-order Birch-Murnaghan equation of state,yielding K0 = 184(4) GPa, 𝐾𝐾0′ = 4.1(2), V0 = 365.9(1) Å3, anda second-order Birch-Murnaghan equation of state, yielding K0= 185(1) GPa, 𝐾𝐾0′ = 4.0(fixed), V0 = 365.8(1) Å3. The densityof Fe2.15Ni0.85P, along with several iron sulfides and iron
phosphides has been calculated under relative pressuretemperature conditions of the Martian core. The comparison
with that of γ-Fe and a density model of the Martian coreevidences that nickel and phosphorus dopant would result in
density reduction of iron sulfides, suggesting that (Fe,Ni)3(S,P)
might be a possible compound existing in the Martian core.

Electrical conductivity of diaspore, δ-AlOOH and ε-FeOOH
Ran Wang*, Takashi Yoshino
Institute for Planetary Materials, Okayama University
Email address: ranwang @s.okayama-u.ac.jp

FeOOH and AlOOH are dominant hydrous phases in sedimentary rocks deposited in thesea or lake basins which were considered to be possibly related to the deep water cycle byslab subduction. Therefore, understanding of the electrical conductivity behaviors of thesephases are essential to explore the nature and dynamic process of the Earth’s interior. In thisstudy, electrical conductivity of diaspore (α-AlOOH), δ-AlOOH and ε-FeOOH was measured
by impedance spectroscopy with a frequency range from 10-1 to 106 Hz at pressures up to 15,
20 and 12 GPa and temperatures of 1200, 1200 and 1000 K well below the dehydration
temperatures of these phases under the relevant pressures. For diaspore at 8, 10, and 12 GPa,
the relationship between electrical conductivity and reciprocal temperature could be wellfitted by the Arrhenius formula: σ = σ0 exp[-(ΔE+PΔV)/kT] and shows the pre-exponential
factor (σ0), activation energy (ΔE) and activation volume (ΔV) of 55.94 ± 1.16 S/m, 0.547 ±
0.016 eV and 1.683 ±0.123 cm3/mol, respectively. However, data of diaspore obtained
below 6 GPa could not be fitted by the Arrhenius formula, which was thought to be due to theremnant of free water in the sample caused by heating to insufficient temperature to proceed
dehydration of interstitial water. Thus, it is quite difficult to measure the electricalconductivity of diaspore at low pressures. The electrical conductivity of diaspore increased
with pressures ranging from 8 to 12 GPa by half order of magnitude and then the
conductivity change with pressures from 12 to 15 GPa became negligibly small. The
dominant conduction mechanism of diaspore is regarded as proton conduction. δ-AlOOH andε-FeOOH show one and two orders of magnitude higher electrical conductivity than diaspore.
Due to isostructural CaCl2-type hydroxide structure, δ-AlOOH and ε-FeOOH display thenearly identical activation enthalpy (0.384 ±0.007 eV, 0.330 ±0.048 eV) which is relatively
lower than that of diaspore.

Ab-Initio Investigation of Iron Diffusion Properties with
Implications for Inner Core Plasticity
Author(s)Sebastian Ritterbex and Taku Tsuchiya
Affiliation(s)Geodynamics Research Center, Ehime University, Japan
E-mail address of the presenter
ritterbex.sebastian_arthur_willem.us@ehime-u.ac.jp
Abstract
The mechanical properties of the Earth’s inner core are essential forunderstanding its evolution and dynamics. However, little is known about themechanical properties of iron at inner core conditions. Therefore, long-standing
questions remain open about the viscous strength of the inner core (Yoshida etal., 1996; Karato, 1999), about the origin of its seismic anisotropy (Deuss, 2014)
and about its rotational dynamics (Buffett, 1997). All these issues rely on plastic
deformation of the inner core, which is barely constrained.
Under conditions of the Earth’s deep interior, the rate of plastic deformation is
expected be constrained by atomic diffusion. Experimental studies on diffusionin iron-nickel alloys all rely on extrapolation to inner core conditions (Yunker
and Van Orman, 2007; Reaman et al., 2012). Here, we investigate vacancy
diffusion in iron at the appropriate inner core conditions. We use a density
functional approach to calculate all quantities entering the diffusion coefficientand quantify the self-diffusion coefficient of hcp iron according to transition state
theory (TST).
Vacancy diffusion controls many deformation mechanisms such as dislocation
creep, an effective strain producing mechanism in metals. Here, we derived acreep model (Weertman, 1955; Nabarro, 1967) to quantify the rate limitingbounds of climb-controlled dislocation creep in hcp iron and provide the first
theoretical estimates of the viscosity of the inner core.

Dynamics of the primitive mantle in interaction withmagma oceans
A. Morison, S. Labrosse, D. Bolrão, A. Rozel, M. Ballmer, R.
Agrusta, R. Deguen, T. Alboussière, P. Tackley
ENS de Lyon, LGLTPE. ETH Zürich.
adrien.morison@ens-lyon.fr
Accretional energy and short-lived-elements radioactive
heating involved in planets formation is thought to be
sufficient to melt the primitive mantle entirely, resulting ina global magma ocean. Depending on how thetemperature profile in the magma ocean compares with thesolidus temperature, the crystallization of the magma
ocean might start from the bottom of the primitive mantle
or somewhere in the middle. At some point in its history,
the solid mantle might then have been surrounded bymagma oceans above and/or below it.
We propose here to study the dynamic and evolution of theprimitive solid mantle surrounded by magma oceans. We
solve numerically the equations of solid-state convectionin the solid part of the mantle. This model is coupled to
1D models of crystallization of the magma oceans to selfconsistently compute the thickening of the solid part asheat is evacuated from the mantle. We take into accountfractional crystallization at the phase change boundary.
Moreover, the boundaries between the solid and themagma oceans are phase-change interfaces. Convecting
matter in the solid arriving near the boundary or getting
away from it forms a topography which can be erased bymelting or freezing. Hence, provided the melting andfreezing occurs rapidly compared to the time needed tobuild the topographies by viscous forces, dynamical
exchange of matter can occur between the solid mantle andthe magma oceans. We take this effect into account in ourmodel with a boundary condition applied to the solid.
We find that the boundary condition allowing matter tocross the interfaces between the solid and the magma
oceans greatly affects the convection patterns in the solid
as well as its heat flux. Larger-scale convection patterns
are selected compared to the classical case with nonpenetrative boundary conditions; and the heat transfert in
the solid is more efficient with these boundary conditions.
This affects the long term thermal evolution of the mantle
as well as the shape of chemical heterogeneities that can bebuilt by fractional crystallization of magma oceans.

TITLE: Viscosity of lower mantle estimated from thecommon diffusivity of creep and grain growth
Author(s): Atsuro Okamoto*, Takehiko Hiraga
Affiliation(s): The University of Tokyo
E-mail address of the presenter: aokamoto@eri.u-tokyo.ac.jp
Abstract: Grain-size reduction caused by the post-spineltransformation and subsequent grain growth during the wholemantle convection should control viscosity of the lower
mantle, if it deforms by diffusion creep which is a grain-size
sensitive mechanism. Thus, to estimate viscosity of the lower
mantle, grain growth has to be taken into consideration.
We have recently conducted high-temperature creep andgrain growth experiments on forsterite + periclase aggregate,a good analog material of the lower mantle and found thatgrain boundary diffusivities extracted from both creep andgrain growth rates are essentially identical. This results
indicate that the creep and grain growth in polymineralicrocks are controlled by a common diffusion mechanism.
When creep and grain growth rates are determined by thecommon diffusivity, grain size and viscosity of the aggregate
can be described in terms of material constants, diffusivity
and time. We applied these relationships to the lower mantle
to calculate grain size and viscosity at each depth and age ofthe mantle during one cycle of the whole mantle convection.
Calculations show that grain size and viscosity indownwelling mantle are ~0.2 mm and 1018 ~ 1020 Pa·s while
those in upwelling mantle are ~0.2-7 mm and 1018 ~ 1023 Pa·s.
Thus, we predict a large viscosity variation within lower
mantle. The viscosity profile estimated from a joint inversionof convection and glacial rebound data is well within suchvariation.

TITLEThe multi-fault rupture process of 1935 Hsinchu-Taichung Earthquake, Taiwan revealed
from dynamic modeling
Author(s)Heng-Yi Su1, Ming-Hsuan Yen1, David Douglas Oglesby2, Kuo-Fong Ma1
Affiliation(s)1National Central University, Taiwan
2
University of California Riverside, CA, United States
E-mail address of the presenter
hengyi.vs@gmail.com
Abstract
The severe Hsinchu-Taichung Earthquake with local magnitude of 7.1 occurred on April
21st ,1935. Understanding the physical rupture process of this event can shed light on the future
identification on fault system from multiple faults for seismic hazard potential evaluation.
Historical data in geological investigation and modeling from geodetic leveling data suggests
this event involved two major faults: the Shihtan reverse fault and the Tuntzuchiao right-lateral
strike-slip fault, both with ruptures to the surface. The hypocenter, however, did not appear tohave been on either of these structures, suggesting the existence of unobserved blind fault. Yen(NCU, MS thesis, 2016) performed a finite-fault inversion that constructed a possible fault
model by comparing the synthetic and observed surface displacement, and leveling data. The
optimum model suggested the event was resulted from a fault system, which consists of four
segments, including both reverse and strike slip fault, with the rupture-jumping between two
blind faults that have opposite direction of dip, and thus increasing separation with depth. In
this study, we propose two possible fault models and both associated with a heterogeneous prestress designed to produce slip similar to that of the inversion result. First model is modified
from Yen’s study. We further assume a linking fault between two blind faults as our second
model. Through further refinement, the correlation between the slip pattern derived from the
dynamic model and inversion model, along with the jumping phenomenon, are used as criticalfactors in evaluating the reasonableness of our dynamic rupture model. The result shows both
two models can engender the comparable slip distribution and amount with the inversion result,and the comparable theoretical magnitude with historical record. However, two models yieldto very distinct difference in the moment rate functions, which might be keen to our further
examination of the historical 1935 Omori records. Our ongoing work includes the influence offault geometry, such as the location and connectivity of the blind faults, and simulating theseismogram combining the low frequency motions (frequency-wavenumber method) and highfrequency motions (EXSIM, Stochastic Finite-Fault Ground-Motion Simulation Algorithm) toreveal the source characteristics of the 1935 earthquake.

Density and sound velocity of liquid iron at Earth’s core
conditions
Y. Kuwayama1*, G. Morard2, Y. Nakajima3, K. Hirose1,4 et al.
1
U. Tokyo, 2IMPMC, 3Kumamoto Univ., 4ELSI Tokyo Tech.
*
kuwayama@eps.s.u-tokyo.ac.jp
Abstract…………………………………………….
The Earth’s core is composed
generate high P-T only along themostly of liquid iron but includes
Hugoniot path that intersects thesubstantial amounts of lightmelting curve of iron around 270
elements, in particular in its liquid
GPa (Brown & McQueen, 1986), it
outer part (Birch, 1952). The
is impossible to conduct
identification of core lightmeasurements of liquid iron atelements is of great importancelower pressures.
because it has wide implications
In this study, we measured the ρfor Earth building blocks, core
and Vp of liquid iron up to the coreformation process, thermalpressure, using a laser-heatedstructure, mechanism for corediamond-anvil cell combining withconvection and geodynamo, etc.
in-situ x-ray diffraction
While density (ρ) and soundmeasurements and high resolution
velocity (VP) are primaryinelastic x-ray scattering
spectroscopy at SPring-8.
observables of the outer core
Combining with previous shock(Dziewonski & Anderson, 1981)
compression data, its P–T–ρ–VP
and thus keys to constraining its
relation is obtained over entire
composition, they have not beenliquid core conditions. The results
examined for liquid pure iron bystatic compression experiments toshow that the outer core (with TCMB
high pressure and temperature= 4000 K (Lay et al., 2008))
relevant to the Earth’s core.
exhibits 7.5–7.6% lower ρ and 4.3–
3.7% higher VP than liquid pure
Earlier shock-wave experiments
iron, which will be an importantmeasured the ρ and VP (equivalent
to bulk sound velocity, VΦ, in aconstraint on the maximum amountliquid) of molten iron between 278
of light elements in the Earth’sand 397 GPa, corresponding tocore.
pressures near the bottom of theouter core (Anderson & Ahrens,
1994; Brown & McQueen, 1986).
Since the shock compression can

TITLE: Distribution and formation of radiocesiumin environment derived from Fukushima Dai-ichi nuclear
disaster, focusing on radiocesium-bearing micro particle…………………………………………
Author: Shiori Morii
Affiliation: Department of Earth and Planetary Science,
Graduate School of Science, The University of Tokyo
E-mail address of the presenter: morii@eqchem.s.u-tokyo.ac.jp
Abstract…………………………………………….
March 11th, 2011,
Fukushima Daiichi nuclear
power plant accident
happened. Radioisotopes ofcesium (134Cs, 137Cs) were
included in fall out.
The half-life of radio cesium
is relatively long (134Cs: 2.06
years, 137Cs: 30.2 years) andthose nuclides are still in theenvironment.
At first, those radioactive
materials are considered toexist in water-soluble state inaerosol (Kaneyasu et al., 2012).
However, it was revealed
that radio cesium is also
included in water-insoluble
glass particle (Adachi et al., 2012).
Those particles are called“Radiocesium bearing micro
particle.”
Because of its waterinsoluble characteristic, theparticle may be adsorbed to
the lung or cavitas nasi, theparticle may exist for longtime. This may cause topicalinternal exposure.
In this research, nonwoven fabric mask whichworn by general citizen in
Fukushima prefecture in thespring of 2012 wasinvestigated, especially
focused on cesium bearing
micro particle. Purpose ofthis research is to grasp
distribution and formation ofthis particle

Anisotropy and flows at the lowermost mantle beneath theNorthern Pacific revealed by waveform inversion
Yuki Suzuki1, Kenji Kawai1, Robert J. Geller1
1
School of science, The University of Tokyo
E-mail: yuki.s@eps.s.u-tokyo.ac.jp

Abstract
The D″ region is the lowermost
several hundred km of the mantle
immediately above the core-mantle
boundary (CMB) and its base is in contact
with the liquid outer core composed of ironalloy. Since the D″ region is the thermalboundary layer (TBL) at the base of the
Earth's mantle, and the solidus of its
constituent materials is thought to be close to
the mantle geotherm, vertical and lateralvariations of temperature and chemicalcomposition associated with the Earth's
thermal evolution are expected. Sincechemically and thermally distinct subductedslabs would interact with the hot TBL above
the CMB, and disturb the lowermost mantle,
understanding the thermal, chemical anddynamical evolution processes of the D″region under subduction zones is essential tobetter understand the Earth's evolution.
The D ″ region beneath thenorthern
Pacific
isofparticulargeodynamical interest, because the paleoIzanagi and present Pacific plates have been
subducting beneath the northwestern marginof Laurentia since ~250 million years ago(Müller et al. 2016), which implies that
paleo-slabs could have reached thelowermost mantle. Suzuki et al. (2016)
inferred the detailed three-dimensional Svelocity structure in the lowermost 400 kmof the mantle beneath the northern Pacific.
They hypothesized a prominent sheet-likelateral high-velocity, interpreted as paleoslabs, and a prominent low-velocity anomaly
block immediately above the CMB below
the high-velocity anomalies, which theyinterpreted as a TBL. In order to verify theabove hypothesis and obtain geodynamical
information, we infer 3D anisotropic

structure beneath the northern Pacific in thisstudy.
We conduct waveform inversion(Kawai et al. 2014, GJI) to infer the variationof the values of the TI (transverse isotropic,
i.e. radial anisotropic) elastic constants L and
N (Note that L is related to VSV and N isrelated to VSH when the shear wave
propagates horizontally) straightforwardly inthe lowermost mantle beneath the Northern
Pacific, using a total of ~18,000 (~9,000transverse and ~9,000 radial component)
broadband body-wave seismograms. We
used deep- and intermediate-focus events
recorded at epicentral distances 70˚≤Δ≤100˚at seismic stations of the USArray. The data
are filtered in the period range of 20 to 200 s(i.e. 0.005 to 0.05 Hz) using a Butterworth
bandpass filter. By using an S/ScS time
window which is sensitive to the D ″structure we could image small-scale
structure with finer resolution than previous
tomographic studies.
The observed anisotropy isinterpreted as due to deformation-inducedalignment of crystal caused by mantle flowfor either Mg-perovskite (Mg-Pv), Mg-postPerovskite (Mg-pPv), Ferro-periclase (Fp) or
a combination thereof. When we assume thedominant glide system of each mineral under
the lowermost mantle condition, the inferred
3D anisotropic structure is interpreted ashorizontal flow which would be related to
subducted paleo-slabs are dominant in thisregion, and we find vertical flow which
would be related to the plume induced byslab sinking.

Density measurement of liquid metal at high pressureusing X-ray absorption method with externally heateddiamond anvil cell
Ryo Tsuruoka*1, Hidenori Terasaki1, Seiji Kamada2, Fumiya Maeda3, Tadashi
Kondo1, Naohisa Hirao4
1
Department of Earth and Space Science, Graduate School of Science Osaka
University
2
Frontier Research Institute for Interdisciplinary Sciences, Tohoku University
3
Department of Earth and Planetary Materials Science Graduate School of
Science, Tohoku University
4
Japan Synchrotron Radiation Research InstituteE-mail address of the presenter: tsuruoka@ess.sci.osaka-u.ac.jp

Abstract
To understand compression behavior of a liquid metal and to determine its
equation of state (EOS), it is important to measure its densities at high pressuresand high temperatures. Gallium (Ga), which is easy to treat as liquid metal for
its low melting temperature (302.9 K at 1 atm) has been reported to have somethermodynamic anomalies. The densities of Ga at high pressures have beenreported based on the measurement of volume changes (Lyapin et al. 2008), thatof liquid structures (Yu et al. 2012), and that of sound velocity (Ayrinhac et al.
2015). However, its compression behavior has large differences between thesestudies. In this study, we measured densities of liquid Ga at high pressure using
an X-ray absorption method with an externally heated diamond anvil cell
(EHDAC).
High pressure was generated using a symmetric DAC with a lever-arm frame.
Diamond anvils with a culet size of 600 μm were employed. Ga sample andreference materials (KBr, RbBr) were placed in each hole drilled on a preindented Re gasket. The reference materials were used for the calibration of Xray absorption and for determination of experimental pressures (Takubo et al.
2018). The Re gasket was coated with Al2O3 to avoid a reaction with the Ga
sample. High temperature was generated using two heater cartridges which
consists of Pt-Rh wire coils and zirconia insulator. X-ray absorption
measurements were carried out with monochromatic X-ray of 30 keV at
BL10XU beamline in SPring-8. Intensities of incident and transmitted X-rays
were detected using an ion chambers and a photo-diode, respectively.
Experimental pressures were determined from XRD patterns of KBr and RbBr
collected using a flat panel detector.
The densities of liquid Ga were measured up to 4 GPa and 433 K. The densityof liquid Ga at 4 GPa and 433 K is obtained as 6.53(7) g/cm3. This density is
consistent with the density reported by Ayrinhac et al. (2015).

Is there evidence for big mantle wedge hypothesis?
…………………………………………
Lena Yokokura, Junji Yamamoto**, Junji Torimoto***,Takeshi Kuritani****, Naoto Takahata*****, Yuji Sano*****
Graduate School of Science, Hokkaido University, JapanThe Hokkaido University Museum, Japan***
Ore Genesis Research Unit, Project Team for Development of New-Generation*****Research Protocol for Submarine Resources, JAMSTEC, Japan****Department of Earth and Planetary Sciences, Graduate School of Science, Hokkaido

University, Japan******The University of Tokyo, Atmosphere and Ocean Research Institute, Japanl_yokokura@eis.hokudai.ac.jp
Abstract…………………………………………….
In northeastern Asia, seismic tomographic

3

images suggest the existence of a subducting

atmosphericPacific plate. However, this is not well

distinctively from convergent plate margins.

supported

Results suggest that both the radiogenic

byrheologicaldata.

He/4He ratios such as those below
value

have

been

found

Measurements of the noble gas isotopic

3

compositions are effective for differentiation

originated from the subduction-related fluidof the subducted slab and lithospheric mantle.

infiltrating into the backarc lithosphere. This

Peridotite xenoliths were collected fromsuggestion supports the big mantle wedge

northeastern China, which is regarded as

hypothesis that the subducted Pacific platebackarc in eastern Asia. Major element

which reaches the upper mantle lower mantle

compositions of constituent minerals of theboundary influences volcanos in backarc

xenoliths show typical of the lithosphericregions.

mantle. Noble gas results showed that the3

He/4Heand40

Ar/36Ar

ratiosare,respectively, 0.14–6.45 Ra and up to 1509.
Although3

He/4He and40

Ar/36Ar ratios

lower than those of mid-oceanic ridge basalt(MORB) are common for sub-continental
lithospheric mantle (SCLM), extremely low

He/4He and atmospheric 40Ar/36Ar ratios

In-situ X-ray diffraction study on β-CrOOH at highpressure and high temperature
Chikara Shito1*, Keitaro Okamoto1, Yuki Sato1, Ryuji
Watanabe1, Tomonori Ohashi1, Kazuhiro Fuchizaki2, Takahiro
Kuribayashi1 and Akio Suzuki1
1
Tohoku university 2Ehime university*
chikara.shito.r4@dc.tohoku.ac.jp
A distorted rutile-type M3+OOH is characterized by O-H⸱⸱⸱Ohydrogen bonds in a–b plane and an edge-sharing M3+O6
octahedral chain along the c-axis. Recently, pressure-induced
H-bond symmetrization was experimentally observed in δAlOOH. In addition, anisotropic stiffening behaviors, i.e.
changes in compression behaviors related to H-bondsymmetrization, were reported in distorted rutile-type M3+OOH(M = Al, Ga, In). However, the stiffening behavior was notobserved in β-CrOOH, which is already stiffened at ambientcondition.
An in-situ X-ray diffraction study of β-CrOOH wasconducted up to 6.2 GPa and 700 K to clarify temperatureeffects on compression behaviors of β-CrOOH. The P-V-T data
fitted to a second-order Birch-Murnaghan equation of stateyielded the following results: KT0 = 191(4) GPa, (∂KT/∂T)P =−0.04(2) GPa K−1 and α = 3.3(2) × 10−5 K−1. The values of αand (∂KT/∂T)P were similar to those of ε-FeOOH and RhOOH
under the P-T conditions of this study. At 300 K, a-axis becameless compressible at pressures between 1–2 GPa, where theslope of a/b and a/c turned to positive. Under high temperature
conditions, similar change in axial ratio was observed at higher
pressure than 1–2 GPa. We found that the pressure where theslope of axial ratio changes increases with temperature.

Ultralow-velocity zones possibly explained by light element-enriched iron compounds
Liang Yuan1, Eiji Ohtani1, Xiang Wu2, Shengxuan Huang3, Daijo Ikuta1, Tatsuya Sakamaki1,
Seiji Kamada1, Hiroshi Fukui4,5, Satoshi Tsutsui6, Hiroshi Uchiyama6, Daisuke Ishikawa5,6,
Naohisa Hirao6, and Alfred Q. R. Baron5
1

Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University, Sendai
980-8578, Japan
2
State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan
430074, China
3
Key Laboratory of Orogenic Belts and Crustal Evolution, MOE, Peking University and School of Earth andSpace Sciences, Peking University, Beijing 100871, China
4Center for Novel Material Science under Multi-Extreme Conditions, Graduate School of Material Science,
University of Hyogo, Hyogo 678-1297, Japan
5
Materials Dynamics Laboratory, RIKEN SPring-8 Center, Hyogo 679-5148, Japan
6
Japan Synchrotron Radiation Research Institute (JASRI), SPring-8, Hyogo, 679-5198, Japan
E-mail address of the presenter: Liang Yuan (yuan.liang.s4@dc.tohoku.ac.jp)

The core–mantle boundary (CMB) is the most fundamental chemical discontinuity in the Earth.
Recent experiments showed that, when water meets iron at the CMB, hydrogen-bearing ironperoxide FeO2Hx can be produced. The results indicate that water can interact with iron metalvery differently than it does on the surface of the earth. Seismic waves speeds in this hydrogenbearing iron peroxide are much slower compared with lower-mantle silicate solid phases, andtherefore it may help explain the seismic anomalies at the CMB. Given the steep geothermal
gradient across the CMB, the hydrogen-bearing iron peroxide FeO2Hx likely undergoes hightemperature decomposition into anhydrous iron oxides (e.g., Fe2O3 ) and fluids. We measured
the sound velocity of Fe2O3 post-perovskite (ppv) through inelastic X-ray scattering up to 132
GPa and 1,800 K, relevant to the lowermost mantle. Combined with first-principles
investigations, we are able to show that Fe2O3 ppv has very low sound velocities and strong
anisotropy with respect to lower-mantle silicates. Therefore, both hydrogen-bearing ironperoxide FeO2Hx and post-perovskite Fe2O3 are candidate phases for ultralow-velocity zones
at the CMB.
Funding acknowledgment: This work was supported by the JSPS Japanese–German Graduate
Externship.

Effect of iron content on thermal conductivity of olivine with
implications for cooling history of rocky planets
Youyue Zhang*1, Takashi Yoshino1, Akira Yoneda1, Masahiro Osako2.
1

Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan

2

Division of Physical Sciences, National Museum of Nature and Science, 3-23-1, Hyakunincho, Shinjuku-ku, Tokyo

169-0073, Japan*Presenter E-mail address: zhangyouyue@s.okayama-u.ac.jp

Abstract:
Knowledge of thermal transport properties of mantle materials is essential for understanding thethermal state and dynamics of the Earth and planetary interiors. Previous studies have suggested
that temperature and pressure dependences of thermal conductivity can affect mantle convection
and plate tectonics involving subduction dynamics. Olivine is the most abundant mineral in the
Earth’s upper mantle and chemical composition of olivine in the Earth’s upper mantle ischaracterized by high forsterite content around Fo90. For other terrestrial planets, Mercury is
believed to have a FeO-poor mantle along with end member silicates, whereas olivine in theMartian mantle would be more Fe-rich, speculated to be Fo67. Recent studies suggested that surface
of some asteroids is dominated by olivine of composition from Fo49 to Fo70. Hence, the effect of
Fe content in olivine on thermal conductivity could be significant for understanding the thermal
structure and cooling history of these terrestrial planets and asteroids.
In this study, thermal conductivity and diffusivity of olivine were determined simultaneously by
combining multi-anvil high pressure experimental technique and pulse heating method. Thermal
properties of olivine with six different Fe contents (Fo, Fo90, Fo70, Fo50, Fo31, Fo0) were measured
under the Earth’s upper mantle condition in a 5000-ton Kawai type multi-anvil press. The
minimum λ was found to be at composition near Fo31; the absolute λ value of Fo31 is about 65%
lower than that of Fo. Small amounts of minor elements can strongly reduce the thermal
conductivity at low temperature; λ value of Fo90 is about 50% of Fo at room temperature. As
temperature increases, the difference in λ among olivine samples with various Fe contents tends
to become smaller. Thermal conductivities of polycrystalline olivine have smaller absolute values
and weak pressure and temperature dependences, compared with those of natural single crystal
olivine determined by previous studies. Heat capacity of olivine calculated from λ and κ isindependent of pressure and is controlled by nearly constant thermal expansion coefficient of Fo70
and Fo50 with increasing temperature. Smaller λ of olivine aggregate with high Fe content would
produce thicker crust in the Fe-rich Mars, while heat in the Fe-poor Mercury can escape faster thanthe other terrestrial planets. Olivine-dominant asteroids with high Fe concentration could have
longer cooling history and lower thermal inertia on the surface.

Geo-neutrinos at SNO+
Ingrida Semenec
Queen’s University, SNO+ collaborationi.semenec@queensu.ca
SNO+ is a multipurpose liquid scintillator neutrino detector. It
is located 2km underground at SNOLAB in Sudbury, Canada.
The primary objective of SNO+ is to search for 0νββ decay in
Te-130. However, studies into other physics topics will be
performed, including geo-neutrinos.
Geo-neutrinos are antineutrinos that are generated in the
Earth’s crust and mantle from β-decaying isotopes. SNO+ can
observe geo-neutrinos coming from Uranium and Thorium
decay chains via inverse beta decay reaction with protons inliquid scintillator. The expected geo-neutrino event rates at
SNO+ are ~19.7 events/year for neutrinos originating from 238U
and ~5.5 events/year for neutrinos originating from 232Th, forthe 20TW Earth composition model.
Measured geo-neutrino flux will be compared with
KamLAND and Borexino results for global analysis. The
combined measurements will hopefully help to distinguishbetween current Earth composition models.

Improving geoneutrino predictions from jointly constrained
local crustal models
Laura Sammon*1, William F. McDonough1,2
1. Geology Department, University of Maryland, College Park, MD 20742,
USA
2. Research Center for Neutrino Science and Department of Earth Sciences,
Tohoku University, Sendai 980-8578, Japan*lsammon@umd.edu

Radioactive decay of U and Th produce geoneutrinos, electron
antineutrinos (𝜈̅𝑒 ). Detection of these particles can constrain theamount of radiogenic heat production in Earth and Earth’s
abundance of heat producing elements (HPE). About half of thegeoneutrino signal comes from the crust surrounding thedetector. In order to constrain the signal coming from Earth’s
mantle, we predict the signal coming from the crust and apply acorrection. Amphibolite and granulite facies xenoliths andterrains serve as analogues to the deep crust, which we cannot
sample directly. By applying thermodynamic principles togeochemical observations from these samples, we can predict
seismic wave speeds in the deep crust. Comparing predictions tohigh resolution seismic inversions, we determine the SiO2
content as a function of depth and temperature within the crust.
Trends among SiO2, U, and Th allow us to infer HPE content
near geoneutrino detectors and produce more accurate
geoneutrino flux predictions.