Joint symposium of Misasa 2019 &Core-Mantle Coevolution
Origin, Evolution & Dynamics of the Earth &Planetary Interiors

Brancart Misasa Room 401 & 403

18th to 21st March

Program
18th March
9:30-9:35

X. Xue (IPM, director)

Opening remarks from IPM

9:35-9:40

T. Tsuchiya (CMC leader)

Opening remarks from Core-Mantle Coevolution

Session 1: Geoneutrino
Chairman: H. Kagi
9:40-10:20

O. Šrámek (Charles Univ.)

Invited talkGeoneutrinos and radiogenic power in the Earth: recent advances and future prospects
10:20-10:40

W.F. McDonough (Tohoku Univ.)

W.F. McDonough*, B. Roskovec, O. Šrámek
In search of recycled continental crust in the Mantle Transition Zone using geoneutrino measurements
10:40-11:00

H. Tanaka (ERI, U. Tokyo)

Restriction of the Core-Mantle Chemical Composition with Neutrino Observations

Coffee break
Chairman: J-.F. Lin
11:20-11:40

M. Yamano (ERI, U. Tokyo)

M. Yamano*, H. Hamamoto, A. Tanaka, S. Goto, T. Matsumoto
Re-evaluation of surface heat flow data in Japan for better estimation of the temperature distribution in the crust.
11:40-12:00 H. Watanabe (Tohoku Univ.)
Development of New Technology for Geo-neutrino Directional Measurement

Lunch and Poster

Session 2: Geochemistry and Petrology
Chairman: E. Takahashi
14:00-14:40

M.J. Walter (Geophys. Lab. Carnegie Inst.) Invited talk

M. Walter*, J. Drewitt, H. Zhang, S. McMahon, D. Edwards, B. Heinen, O. Lord, S. Anzellini, A. Kleppe
The fate of carbonate in oceanic crust subducted into earth’s deep mantle
14:40-15:00

S. Aoyama (Niigata Univ.)

S. Aoyama*, T. Oneyama, W. Ouchi, Y. Ueno, M. Satish-Kumar
Multiple sulfur isotopes constraints on the origin of sulfide sulfur in Archean granitoids from Dharwar craton, SouthernIndia
15:00-15:20

M. Satish-Kumar (Niigata Univ.)

M. Satish-Kumar*, S. Aoyama
Recent developments in stable isotope measurements on high-pressure high-temperature experimental run products andnatural samples
15:20-15:40

K. Fukuyama (Univ. Tokyo)

K. Fukuyama*, H. Kagi, T. Inoue, Y. Sano, T. Shinmei, S. Kakizawa, N. Takahata, S. Hishita
Investigation of nitrogen incorporation into stishovite using implanted sample and outlook on deep nitrogen cycle

Coffee break

Chairman: R. Nomura
16:00-16:20

S. Tateno (ELSI, Tokyo Tech.)

S. Tateno*, H. Ozawa, K. Hirose, T. Suzuki
Fe2S: the most iron-rich Fe-S compound at pressures of the inner core
16:20-16:40

K. Suzuki (JAMSTEC)

A. Takamasa, K. Suzuki*, Y. Fukami, T. Iizuka
High precision tungsten isotope of ocean island and LIPS basalts from deep mantle
16:40-17:00

H. Sumino (Univ. Tokyo)

H. Sumino*, T. Tanaka, H. Kuwahara, S. Kishi, R. Nomura, K. Mibe, C. Jackson, S. Tateno, H. Kagi
Noble gas partition between metal-silicate melts
17:00-17:20

T. Tsuchiya (GRC, Ehime Univ.)

T. Tsuchiya*, A. Ohba, Z. Xiong
Ab Initio Applications to the Element Partitioning between Core and Mantle

19th March
Chairman: T. Okuchi (IPM)
9:00-9:40

T. Nakagawa (Univ. Hong Kong)

Invited talkOn theoretical and numerical modeling of the core-mantle thermal-chemical coupling: Review and perspective view
Session 3: water
9:40-10:00

X. Xue (IPM, Okayama Univ.)

Hydrogen incorporation mechanisms in nominally anhydrous mantle minerals: NMR spectroscopy andfirst-principles calculation
10:00-10:20

N. Prevjav (IPM, Okayama Univ.)

N. Purevjav*, T. Okuchi, N. Tomioka, X. Wang, C. Hoffmann
Probing hydrogen by single-crystal neutron diffraction in deep mantle hydrous minerals

Coffee break

Chairman: A. Suzuki
10:40-11:00

J. Tsuchiya (GRC, Ehime Univ.)

J. Tsuchiya*, K. UmemotoFirst principles determination of the dissociation boundary of phase H (MgSiO4H2) and possible existence of ice VII atlower mantle conditions
11:00-11:20

H. Fei (BGI)

H. Fei*, T. Katsura
High water solubility of ringwoodite at mantle transition zone temperature
11:20-11:40

S. Yamashita (IPM, Okayama Univ.)

In situ vibrational spectroscopy of the dehydration of talc in the system MgO-SiO2-H2O
11:40-12:00 T. Ohashi (Tohoku Univ.)
T. Ohashi*, T. Sakamaki, K. Funakoshi, M. Muranushi, C. Shito, Y. Shibazaki, A. Suzuki
Structures of hydrous sodium silicate melts under high pressure and high temperature

Lunch and Poster
Headquarter business meeting (Room 503 Juraku)

Session 4: Transport properties
Chairman: K. Kawai

14:00-14:40

A.R. Thomson (UCL)

Invited talk

A.R. Thomson*, S.A .Hunt, J. Van Driel, J.P. Brodholt, D.P. Dobson
Simultaneous deformation of Calcium Perovskite and Pyrope
14:40-15:00

Y. Nishihara (GRC, Ehime Univ.)

Y. Nishihara*, S. Doi, D. Yamazaki, N. Tsujino, T. Yoshino, T. Kubo, M. Imamura
D111-type apparatus for high-pressure deformation experiments and its application to a rheological study of hcp-iron
15:00-15:20 N. Tsujino (IPM, Okayama Univ.)
N. Tsujino*, D. Yamazaki, Y Nishihara
Creep strength of bridgmanite
15:20-15:40

S. Azuma (ELSI, Tokyo Tech.)

S. Azuma*, R. Nomura, K. Uesugi, Y. Nishihara, S. Doi, T. Arimoto, T. Irifune
Update of the rotational diamond anvil cell and deformation microstructures of lower mantle materials

Coffee break

Chairman: Y. Nishihara
16:00-16:20

S. Ritterbex (GRC, Ehime Univ.)

S. Ritterbex*, T. Tsuchiya
Ab-Initio Investigation of Iron Self-Diffusion: Implications for the Plasticity of Earth’s Inner Core
16:20-16:40

K. Kawai (Univ. Tokyo)

K. Kawai*, A. Borgeaud, Y. Suzuki
Imaging subducted slabs in the mantle from inversion of seismic waveforms
16:40-17:00

H. Gomi (IPM, Okayama Univ.)

H. Gomi*, T. Yoshino
Electrical resistivity and thermal conductivity of fcc Fe: Implications for the Mercury's core
17:00-17:20

K. Miyanishi (Osaka Univ.)

K. Miyanishi*, N. Ozaki, S. Ohmura, M. Harmand, A. Krygier, T. Nishikawa, Y. Umeda, K. Shigemori, Y. Sakawa, T.
Sano, R. Kodama
Study on transport properties of liquid iron and iron alloy under high temperature and high pressure using the laser
shock technique

17:40-18:00

Signing ceremony

Agreement of cooperation between the Geophysical Laboratory Carnegie Institution for Science andInstitute for Planetary Materials, Okayama University

18:30-20:30

Banquet (entry required)20th March
Session 5: Seismic observation and properties
Chairman: K. Ohta
9:00-9:40

D. Mainprice (Univ. Montpellier)Invited talkDeformation, crystal preferred orientations, and seismic anisotropy in the Earth’s D" layer
9:40-10:00

S. Tanaka (JAMSTEC)

Azimuthal anisotropy in the lowermost mantle beneath Philippine from ScS–S travel times
10:00-10:20

N. Takeuchi (ERI, Univ. Tokyo)

S.K. Roy, N. Takeuchi*, D. Srinagesh, M. Ravi Kumar, H. Kawakatsu
Topography of the western Pacific LLSVP constrained by S wave multipathing

Coffee break

Chairman: H. Terasaki
10:40-11:00

K. Ohta (Tokyo Tech.)

K. Ohta*, A. Hasegawa, T. Yagi, Y. Okuda, K. Onga, K. Hirose, Y. Ohishi
Measurements of high pressure-temperature thermal conductivity of the Earth’s lower mantle minerals in a laser-heateddiamond anvil cell
11:00-11:20 H. Terasaki (Osaka Univ.)
H. Terasaki*, I. Yamada, A. Kamiya, R. Tsuruoka, T. Kondo, Y. Higo, A. MachidaSound velocity of liquid Fe-Ni-S-Si under pressure
11:20-11:40

Y. Nakajima (Kumamoto Univ.)

Y. Nakajima*, D. Kinoshita, Y. Kuwayama, K. Hirose, A. Iwamoto, S. Tateno, D. Ishikawa, A.Q.R. Baron
Sound velocity of liquid Fe-P alloy under high pressure based on inelastic X-ray scattering measurements
11:40-12:00

T. Irifune (GRC, Ehime Univ.)

Sound velocities of CaSiO3 perovskite (“breyite”) and some implications for chemical compositions around the 660 km
discontinuity.

Lunch and Poster

Misasa joint-use research Session 1
Chairman: T. Katsura
14:00-14:40

J.F. Lin (Univ. Texas)

Invited talkInternally-consistent multiple constraints on the mineralogy and seismology of Earth’s lower mantle
14:40-15:00

T. Okuchi (IPM)

Nanoscale texture and transformation timescale of dense Mg2SiO4 polymorphs in shocked meteorites: comparison
between natural occurences by high-resolution TEM and experimental results by fast XFEL diffraction
15:00-15:20

M. Kanzaki (IPM)

Low-frequency micro-Raman spectroscopy: applications to mineral sciences

Coffee break

Chairman: D. Yamazaki
15:40-16:00

B. Zhang (CAS)B. Zhang*, T. Yoshino, C. Zhao
The effect of water on Fe-Mg interdiffusion rates in ringwoodite and implications for the electrical conductivity in the
mantle transition zone
16:00-16:20

N. Chertkova (GRC, Ehime Univ.)

N. Chertkova*, S. Yamashita, H. Ohfuji, T. Irifune, H. Kadobayashi, Y. Yamamoto
Probing basalt–5.75H2O–CH4 system by in situ vibrational spectroscopy
16:20-16:40

Y. Zhang (IPM)

Y. Zhang*, T. Yoshino, A. Yoneda, M. Osako
Effect of iron content on thermal conductivity of olivine with implications for cooling history of rocky planets
Session: Development of high-pressure technique
16:40-17:00

I.C. Ezenwa (IPM, Okayama Univ.)

I. C. Ezenwa*, T. Yoshino
Measurement of T -dependent electrical resistivity of solid and liquid Fe and Pt at fixed P

21st March
Misasa joint-use Session 2
Chairman: T. Yoshino
9:00-9:40

E. Takahashi (GIG)

Invited talkE. Takahashi*, S. Gao, J. Wang, L. Li
Melting process in Hawaii plume: Report from large volume multi-anvil laboratory in Guangzou Institute ofGeochemistry
9:40-10:00

N. Tsuchiya (Iwate Univ.)

N. Tsuchiya*, D. Yamazaki
Silicic melt formed by a partial melting experiment of mantle peridotite reacted with slab melt
10:00-10:20 Y. Nakamura (AIST)
Y. Nakamura*, T. Yoshino, M. Satish-Kumar
Pressure dependence of graphitization: Implications for rapid recrystallization of carbonaceous material in Earth’s crust

Coffee Break

Chairman: H. Gomi
10:40-11:00

K. Fujita (Osaka Univ.)

Y. Haraguchi, T. Yoshino, S. Yamashita, M. Nakamoto, M. Suzuki, K. Fuji-ta*, T. Tanaka
Electrical Conductivity Measurement of rhyolite and andesite glasses
11:00-11:20

Y. Mori (Okayama Univ. Sci.)

Y. Mori*, N. Nakano, T. Yoshino
The Measurement of Seebeck coefficient under Pressure using Six-axis Multi-Anvil Press
11:20-11:40

C. Zhao (IPM)

Redox kinetics of olivine revealed by diffusion profile of oxygen fugacity and its implication to the redox evolution of
the uppermost mantle
11:40-12:00

T. Yoshino (IPM)

T. Yoshino*, W. Sun, C. Zhao, N. Sakamoto, H. Yurimoto
Electrical conductivity of hydrous olivine: revisited by various approaches

Lunch and Poster

Misasa joint-use Session 3

Chairman: N. Tsujino
14:00-14:40

T. Katsura (BGI, Univ. Bayreuth)

Invited talkT. Katsura*, H.-F. Fei, D. Druzhbin
H2O-enhanced ionic conductivity of olivine
14:40-15:00

L. Xie (BGI, Univ. Bayreuth)

L. Xie*, K. Nishida, T. Ishi, C. Artem, B. Dimitry, T. Katsura
Simultaneously generation of ultra-high pressure and high temperature by combining boron-doped diamond heater andsintered diamond anvils.
15:00-15:20

D. Yamazaki (IPM)High pressure generation in the Kawai-type multianvil apparatus
15:20-15:30

X. Xue (IPM, director)

16:30-17:30

A. Yoneda (IPM)

Closing remarks

The last lecture (in Japanese with English slides)

Poster
A01
1. A. Okamoto*, T. Hiraga
Viscosity of Lower Mantle Estimated from the Common Diffusivity of Creep and Grain Growth
2. T. Kubo*, M. Imamura
Grain growth textures and kinetics in pyrolitic and basaltic materials under lower mantle conditions
3. R. Sinmyo
Technical development toward understanding the melting temperature of the materials at high pressure using ultra-fast
spectroradiometry
4. T. Sakai
Pressure scales at multi-megabar pressure
5. M. Nishi*, K. Yamamoto, Y. Zhou, T. Irifune
Polycrystalline diamond sintered from ultradispersed nanodiamonds
6.

Y Higo*, T Irifune

Development of ultrasonic measurement technique toward whole lower mantle conditions
7. T. Inoue*, M. Noda, S. Kakizawa, T. Kuribayashi, A. Sano, T. Hattori
Importance of various Al substitutions in bridgmanite
8. A. Suzuki
Stability field of hydrous aluminosilicates from the mantle transition zone to the shallow part of the lower mantle
9. H Kagi*, T. Kubo, A. Shinozaki, T. Okada, H. Ohfuji, A. Nakao
Reaction between forsterite and nitrogen fluid at high pressure and high temperature

A02
10. R. Iizuka-Oku*, H. Gotou, K. Fukuyama, H. Kagi
Behavior of light elements in the early stage of Earth’s evolution: In-situ high-pressure and temperature
11. T. Kuribayashi*, Y. Zhou, T. Irifune, H. Ohfuji
Structural study on new high-pressure forms of Al2SiO5
12. S. Tateno*, T. Komabayashi, K. Hirose
Static compression of B2 KCl to 230 GPa and its P-V-T equation of state
13. S. Itoh
Quantitative analysis from stigmatic isotope imaging of SIMS
14. T. Kogiso*, N. Akizawa
Controlling factor of whole-rock PGE concentrations in mantle peridotite

15. F. Maeda, Y. Horioka, S. Kamada*, S. Aoyama, S. Ozawa, M. Satish-Kumar, A. Suzuki
Sulfur and carbon isotope fractionation under mantle conditions
16. N.M. Kondo*, T. Kogiso
Major element composition of the Hadean crust: constraints from Sm-Nd isotope systematics and high-pressure melting
experiments

A03
17. S. Tanaka*, W. Siripunvaraporn, S. Boonchaisuk, S. Noisagool, K. Kawai, Y. Suzuki, T. Kim, Y. Ishihara, H.
Kawakatsu, N. Takeuchi, K. Miyagawa, R. Iritani
Completion of the seismic observation with Thai Seismic Array (TSAR)
18. S Kaneshima
S-to-P scattering in the lower mantle near subduction zones
19. M. Matsushima
Core-mantle interaction inferred from a core surface flow model
20. Y. Yamamoto*, H. Fukami, W. Taniguchi, P.C. Lippert
Variation of the intensity of the paleomagnetic field during 38-50 Ma deduced from the marine sediments
recovered from the northwest Atlantic
21. M. Obayashi*, T. Miyoshi, J. Yoshimitsu1
Toward adjoint tomography of the large low seismic velocity provinces beneath the western Pacific Ocean
22. G. Hao
Using S-P wave search the depth of mantle 660-discontinuity beneath Kuril Region where subduction slab do not exist
23. R. Iritani*, H. Kawakatsu, N. Takeuchi
Sharpness of the hemispherical boundary in the inner core beneath the northern Pacific
24. K. Minami, K. Ueki*, T. Iizuka, S. Enomoto, H.K.M. Tanaka
Sample-scale geochemical variation of the Inada granitic body, Ibaraki, Japan -toward the reduction ofgeoneutrino flux estimation errors-

A04
25. H. Dekura*, T. Tsuchiya
Ab initio anharmonic lattice dynamics for Fe-bearing lower mantle minerals

Misasa26. T. Moriguti*, A. Yoneda, E. Ito
Melting phase equilibrium relations in MgSiO3-SiO2 system under high pressures
27. M. Sakurai*, N. Tsujino
Pressure effect on IR spectra of anhydrous minerals
neutron diffraction measurements on iron-silicate-water-sulfur system
28. L. Guan*, D. Yamazaki
Lattice preferred orientation of akimotoite and mid-mantle anisotropy in subduction zones
29. H. Yusa*, N. Hirao, Y. Mori, Y. Ohishi
Latest remodeling of multi-axis DAC system for radial XRD experiments
30. Y. Yachi*, T. Kunihiro, E. Nakamura
DREAM & Its applications: Software for Management of Samples and Data
31. M. Osako*, A. Yoneda
Measurement of thermal conductivity and thermal diffusivity for mantle minerals by the pulse heating method
32. A. Yoneda*, S. Kobayashi, S. Kamada
Low-frequency micro-Raman spectroscopy and its application to mineral sciences
33. N. Noguchi*, Y. Fujii, T. Saitoh, H. Okamura
High-pressure synthesis of doped black phosphorous
34.

R. Wang*, T. Yoshino

Electrical conductivity of diaspore, δAlOOH and εFeOOH
35.

C. Liu*, T. Yoshino1

Intrinsic attenuation factor Q of partially molten Fe–S–O system

Geoneutrinos and radiogenic power in the Earth: recent advances and future prospects
O Šrámek1* 1Department of Geophysics, Charles University, Prague, Czech Republic.
*email:ondrej.sramek@gmail.com
which translates to radiogenic power of 21±10 TW
in the Silicate Earth (Fig.1) [7].
6050

Total geonu in TNU

Introduction: The Earth’s engine is driven by
unknown proportions of primordial and radiogenic
energy, with the former being left over after
accretion and core formation, while the latter is
produced in radioactive decay of K, Th & U.
Competing models of Earth’s composition reveal anorder of magnitude uncertainty in the amount ofradiogenic power driving mantle convection andplate tectonics. This gross level of uncertainty
weakens our models of the composition anddynamics of the Earth, including its thermal
evolution, style and planform of mantle convection,and energetics of the core.
Measurements of the flux of geoneutrinos,
electron antineutrinos emitted inside the Earthduring β− decays, reveal the amount of U and Th in
the Earth and define its amount of radiogenic power.
Flux measurements at large underground neutrino
detectors confronted with geological predictions ofgeoneutrino emission from the Earth’s crust
constrain the radiogenic power deeper in the Earth.
Earth’s energy budget: The secular loss of heatfrom the deep Earth has been reasonably wellconstrained at 46±3 TW [1] from careful analyses ofland and sea-floor heat flow measurements. Much
uncertainty remains in attempts to separate the total
surface heat loss into the two major contributions,the secular cooling and ongoing differentiation(inner core growth) of the planet on one hand, andthe power of radiogenic heat sources (radionuclidesof U, Th, K) on the other [1]. Our current
understanding offers a rather accurate estimate ofradiogenic heat production in the Earth’s crust of
7±1 TW [2] and argues for negligible to very limited
radiogenic power in the Earth’s core [3]. The
uncertainty of a factor of ~3 in geochemical andcosmochemical estimates of Silicate Earth’s
abundances of K, Th & U, translates, after
subtracting the crustal component, into an order ofmagnitude uncertainty in radiogenic power
available in the convecting mantle [4].
Measuring geoneutrino flux: The highest
energy antineutrinos, emitted in β− decays of natural
232Th and 238U decay chains, can be detected via
inverse beta decay reaction with energy threshold of
1.8 MeV, in large underground liquid scintillator
neutrino experiments. Detectors in Japan(KamLAND) [5] and Italy (Borexino) [6] havemeasured geoneutrino flux and have begun to put
limits on Earth models of U & Th abundances. A
simple combined analysis of KamLAND and
Borexino results indicates a mantle geoneutrinosignal of 8.8±6.4 TNU (Terrestrial Neutrino Units)

Borexino

40

KamLAND
30
TW radiogenic
power in BSE

20

30
10

20
10

0
0

10

20

30

40

50

60

Lithospheric flux in TNU

Figure 1 Measured geoneutrino total flux (vertical axis)
vs. predicted lithospheric flux (horizontal axis). The yintercept of slope 1 line fit (red dashed) indicates the
mantle signal, and translates into the Silicate Earth’s
radiogenic power (purple).

Three more detectors are expected to havemeasured geoneutrinos by year ~2020: SNO+ in
Canada, and JUNO and Jinping in China. The
combination of data from all five experiments has
the potential to provide much tighter limits onradiogenic power in the Earth’s mantle [8].
Synergy between neutrino physics andgeoscience: Extracting the mantle signal from themeasurement of total Earth’s geoneutrino emission
requires an independent accurate prediction ofcrustal signal which must come from geoscience.
Ongoing dedicated efforts are invested in improving
both the global and the regional (near detectors)
models of crustal structure and composition, hence
prediction of crustal geoneutrino emission.
Measuring geoneutrinos at oceanic locations,distant from nuclear reactors and continental crust,
would best reveal the mantle geoneutrino flux.
Performing a coarse scale geoneutrino tomography
could even test hypotheses of large heterogeneous
structures enriched in heat-producing elements
located in the shallow [9] or in the deep mantle [4].
References: [1] Jaupart, C. et al., Treatise Geophys.,vol. 7, ch. 6 (2015). [2] Huang, Y. et al., Geochem.
Geophys. Geosyst., 14, 2003 (2013). [3]McDonough, W.F., Treatise Geochem., vol. 3, ch.
16 (2015). [4] Šrámek, O. et al., Earth. Planet. Sci.
Lett., (2013). [5] Gando, A. et al., Phys. Rev. D, 88,
033001 (2013). [6] Agostini, M. et al., Phys. Rev. D,
92, 031101 (2015). [7] https://tinyurl.com/y2hj7psv[8] Šrámek, O. et al., Sci.Rep., 6, 33034 (2016). [9]Roskovec, B. et al. arXiv:1810.10914.

In search of recycled continental crust in the Mantle Transition Zone using geoneutrino
measurements
William F. McDonough1 , Bedřich Roskovec2 , and Ondřej Šrámek3 1 Department of Earth Sciences andResearch Center of Neutrino Sciences, Tohoku University, 6-3, Aramaki Aza Aoba, Aobaku, Sendai, Miyagi,
3980-8578, JAPAN wfm@tohoku.ac.jp Instituto de Fı́sica, Pontificia Universidad Católica de Chile, Santiago,
4
Chile Departmentt of Geophysics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2,
18000 Praha 8, Czech Republic

Plate tectonics provides the framework forunderstanding the modern evolution of the crustand mantle system, with subduction zones linking these two major domains of the silicate Earth.
Sediment recycling into the mantle at subduction zones is well established, although unknowns(e.g., past and present-day rates, amounts, depthof recycling, etc) remain significant. The present
day subduction zone settings include ocean-ocean,
ocean-continent, and continent-continent collisions
and each of these likely have differing degrees
of efficiencies of sediment recycling, as evidenceby distinct differences in the remnants of metasediments exposed in fossil forearc regions of different collision zones. The retrieved metamorphic
record of ocean-ocean and ocean-continent collision zones documents meta-sediments experiencing high-grade (granulite to eclogite facies) metamorphism. In contrast, continent-continent collisions return meta-sediments having experienced
ultra high-grade (up to diamond facies) metamorphism. What is not known is the effectiveness ofdeep sediment recycling, past the magmatic zone,
in each of these three different convergent margins.
Models that envisage successful subduction
channel transport of upper crustal materials below
300 km depth, past a critical phase transition in
buoyant crustal lithologies, are capable of accumulating and assembling these materials into so-called
Jinping“second continents” that are gravitationally stabilized at the base of the Transition Zone, at some 600
to 700 km depth [Kawai et al., 2013]. Global scale,
Pacific-type subduction (ocean-ocean and oceancontinent convergence), which lead to super continent assembly, were hypothesized to produce second continents that scale to about the size of Australia, with a maximum potential of continental upper crustal concentration levels of radiogenic power.
Seismological techniques are incapable of imaging
these second continents because of their negligible
difference in seismic wave velocities with the surrounding mantle. We can image the geoneutrino
flux linked to the radioactive decays in such hypothesized continental lithologies with land and/or
ocean-based detectors. We present predictions of
the geoneutrino signal for these continental lithologies, assuming different scaled models and showthat the combination of the KamLAND-JUNOJinping neutrino experiments are strategically positioned to discover or constrain a predicted second
continent beneath eastern China. The power emissions from such second continents were proposed tobe drivers of super continental cycles. Thus, testingmodels for the existence of continental lithologies in
the Mantle Transition Zone will place constraints
on mantle and plate dynamics when using landand ocean-based geoneutrino detectors deployed at
strategic locations.
g

JinpinKamLAND

JUNO

JUNO

KamL

AND

0

Depth (km)Continental Moho
200

subducted
oceanic crust

400

oceanic
lithosphericmantlesubducted
upper crust

Upper Mantle

410 km seismic discontinuity

ontinent
Second c

Lower Mantle

Transition Zone
600

800

660 km seismic discontinuity

Second Continent

Lower Mantle

Core

Figure 1: Left panel shows cartoon illustration of a second continent that formed under eastern China due to Pacific-type
subduction occurring along the western margin of the Pacific basin. Picture is an adaptation of Fig. 5 in Kawai et al.,(2013). The proximity of 3 geoneutrino experiments to this proposed second continent are shown as being underground inJapan (KamLAND) and China (JUNO and Jinping). These 3 detectors see approximately the same mantle volume andsimilar global crust, see right panel, which results in a major reduction in the predicted uncertainties. Local differences in
the geoenutrino signals for each of these detectors are due to geological differences in the nearby lithosphere (closest 500km) surrounding the detector; this region contributes approximately half of the detected signal.

Kawai, K., S. Yamamoto, T. Tsuchiya, and S. Maruyama (2013) The second continent: Existence of granitic
continental materials around the bottom of the mantle transition zone. Geoscience Frontiers, 4(1), 1-6.

Low-frequency micro-Raman spectroscopy and its application to mineral sciences
H.K.M. Tanaka1* 1Earthquake Research Institute, University of Tokyo, Bunkyo, Tokyo 113-0032, Japan.
Introduction: Neutrinos originated in decay ofradionuclide inside the Earth (geoneutrinos) weredetected by the Japanese group for the first time, andthe detection accuracy has been improved bypurifying the liquid scintillator of the detector andreduction of the nuclear reactor background. Since
the observational data at a surface of the Earth canbe converted to the radiogenic power, i.e., the heatproduction density, this new information provides
us a new vision to understand the core-mantle
dynamics including the heat source of the mantle
convection. The objective of this research is tocreate a new academic region that transversely
support particle physicists and earth scientists bydeveloping
advancedneutrino-based
earth
observation technologies.
The geoneutrino flux in the vicinity of
KamLAND detector was modeled in 2005.
However, this modeling has been done by utilizing
the globally averaged crustal structures andradioactive isotope concentrations. The newmodelling method that incorporates the local
information is underdevelopment in order to apply it
to the KamLAND data. Furthermore, proof-ofprinciple studies are currently conducted to realize
the idea of directional-sensitive detection ofgeoneutrinos in the future. The fundamental studies
are ongoing to clarify the technologicalrequirements for the actual implementation of thistechnique.
Modeling: The rock chemical composition
database and underground thermal structure
database have been generated and the probability
density function was evaluated based on these(Figure 1). For the rock chemical composition
database, 96 published papers and Geological
Survey Japan database (including 10862 rocksamples) have been used [1]. In addition, 215 rocksamples have been collected from Oki, Shimane
Prefecture, Megata, Akita Prefecture, andTakashima, Saga Prefecture and analyzed to study
the chemical composition of the lower crust [1]. The
seismic database [2] was utilized to compare thegenerated database with the seismic tomography
results in order to model the underground lithology.
By expressing the lithology at a deep undergroundin a form of the probability density function, and by
developing all of the modules that are required to
calculate the neutrino flux, the objective
geoneutrion flux based on the probability model has
been derived for the first time [1]. It is anticipatedthat the objective radiogenic heat production will bederived by subtracting the geoneutrino flux

observed with the KaMLAND by the neutrino flux
modeled by this objective geoneutrino flux.

Figure 1 Uranium concentrations in different tocks(Mantle, Gavvro, Granite and Shale) fitted by different
distribution functions (gamma. log-normal and normal).

Developments of the directionally sensitive
geoneutrino detector: A small-sized test detector
was developed for demonstration of this concept.
The post signal generated by geoneutrino wassimulated by using a neutron beam, and this signal
was successfully imaged by this test detector (Figure2). It is anticipated that 3 dimensional structures ofpseudo-geoneutrino signals will be imaged by thefurther developments of the data analysis algorithmand data taking electronics for detecting events withlower energies.

Figure 2 Imaging results of the pseudo-geoneutrinosignals generated by the neutron beam with the currently
developed test detector [3].

References: [1] N. Takeuchi, K. Ueki1, T. Iizuka, J.
Nagao, A. Tanaka, S. Enomoto, Y. Shirahata, H.
Watanabe, M. Yamano and H. K. M. Tanaka,
Physics of the Earth and Planetary Interiors, in press.
[2] Christensen and Mooney (1995). [3] Watanabe,
H. private communications

Re-evaluation of surface heat flow data in Japan for better estimation of the temperature distribution in
the crustM Yamano1*, H Hamamoto2, A Tanaka3, S Goto3, and T Matsumoto4
1
Earthquake Research Institute, the University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan, 2Center for
Environmental Science in Saitama, 3Geological Survey of Japan, AIST, 4National Research Institute for Earth
Science and Disaster Resilience, *email:yamano@eri.u-tokyo.ac.jp
Introduction: We have been studying the
subsurface temperature structure of the Japaneseislands as part of a research project to assess geoneutrino flux originating from U and Th in the crust.
Seismic velocity structure has been used to infercomposition of the crust, and information on thecrustal thermal structure is important in thisprocedure since seismic velocity depends on
temperature as well.
Surface heat flow is the most fundamental
geophysical data for estimation of subsurface
temperature structure. However, heat flow data onland in Japan had been rather sparse and not evenly
distributed owing to the limitation of boreholes
available for temperature measurement. Thissituation was improved by temperature profile dataobtained in observation wells for the Hi-net
seismograph network, which are densely and evenly
distributed over the Japanese islands.
Analysis of borehole temperature data: Mostof the Hi-net observation wells are shallow andsubject to influence of ground surface temperature(GST) variation. We selected temperature profile
data in relatively deep wells, over 150 m, in thecentral part of Honshu, close to the geo-neutrino
observation station, KamLAND. After eliminating
data apparently affected by ground water flow, wereconstructed GST history in the past at each wellthrough inversion analysis of the temperature profile
data. All the results show recent GST increase due
to global warming and/or the heat island effect. The
amplitude of GST increase in the last 100 years

Figure 1 GST history reconstructed from boreholetemperature data at Hi-net Yokohama station comparedwith surface air temperature (SAT) variation observed ata nearby meteorological station.

varies by site from 1.5 to 4 K. The results of GST
history reconstruction will be used for analysis oftemperature profiles in shallow wells.
We have also been conducting continuous
temperature measurement in the upper 100 m of twoboreholes located in central Tokyo and on the coastof the Lake Biwa. The obtained data demonstrate
downward propagation process of the influence of
surface thermal environment variation attributableto human activity.
Measurement of thermal conductivity: For
determination of heat flow values, we need to know
thermal conductivity of formations through which
temperature gradient is measured. At many stations,however, it is difficult to obtain rock/sediment
samples for thermal conductivity measurement,
which is a major source of uncertainty in heat flowdata.
Aiming for better evaluation of surface heat flow,
we started measurement of thermal conductivity ofcore samples collected from Hi-net wells andboreholes drilled for volcano observation. We use an
optical scanning instrument, which enables nearlycontinuous measurement along the core, as well as aconventional box-type probe. High-density datawith the optical scanning instrument provide
valuable information on small-scale heterogeneity
in thermal conductivity. New data for Hi-net
borehole samples can be included in GST history
reconstruction analysis to determine more reliable
heat flow values.
Compilation of geothermal data: We havebeen compiling heat flow data in the northwest
Pacific area (0 to 60 °N, 120 to 160 °E), which
includes the whole Philippine Sea, Japan Sea, andSea of Okhotsk. We have just updated the data set
for publication as part of a CD-ROM. It contains
3670 data, while 3184 values were collected in theprevious version published in 2004. We alsocollected thermal conductivity values measured onrock samples from boreholes in Japan. The compiled
data will also be published in the above-mentioned
CD-ROM together with geothermal gradient data inand around the Japanese islands. These databases, in
combination with data from Hi-net boreholes, serve
as a basis for modeling thermal structure of
subduction zones around Japan.

(Template for Misasa2017 & Core-Mantle Coevolution symposium. Remove this before upload.)
Development of New Technology for Geoneutrino Directional Measurement
H. Watanabe1* 1Research Center for Neutrino Science, Tohoku University, 6-3, Aramaki Aza Aoba, Aobaku,
Sendai, Miyagi, 980-8578, Japan.
*email:hiroko@awa.tohoku.ac.jp
Introduction: Neutrino is an elusive particle
and it can penetrate even astronomical objects.
While neutrino experiments continue to explore theneutrino properties, e.g. oscillation nature ofneutrino flavor transformation, mass-squaredifferences and mixing angles, we have began toutilize neutrino as a tool to look into the Earth.
Ant-neutrinos emitted from radioactive isotopes,
geo-neutrinos, bring unique and direct informationof the Earth’s interior and thermal dynamics.
Experimental
Studyof
Geoneutrino:
KamLAND, Kamioka Liquid-scintillator Antineutrino Detector, has 1 kton ultra pure liquid
scintillator. They reported the first experimental
study of geo-neutrino in 2005 [1]. Later the geoneutrino signals were used to estimate the Earth’s
radiogenic heat production and constrain thecomposition models of the bulk silicate Earth [2].
Following the Fukushima reactor accident in March
2011, the entire Japanese nuclear reactor industry
has been subjected shutdown. This unexpected
situation allows us to improve the sensitivity for
geo-neutrinos [3], because anti-neutrinos fromreactors, reactor neutrinos, are most serious
background for geo-neutrino measurement.
Directional Measurement : The liquid scintillator
detectors have the sensitivity for measuring total
amount of geo-neutrinos from the Earth’s crust andmantle. However, we do not have the technology
to track the direction of incoming geo-neutrinos atpresent due to the high miss-identification in aneutrino’s track reconstruction. The directionsensitive detector can map out the U and Th
distribution inside the Earth and this technic is also
applicable to resolving crust versus mantle
contributions.
Low energy anti-neutrinos are detected by the+
chargedcurrent
reaction ⌫¯e + p ! e + n(inverse beta decay reaction). This is tagged by thedelayed coincidence based on the prompt positron
signal and delayed neutron capture signal.
Although the positron in emitted almost
isotopically, the recoil neutron retains theinformation of the coming neutrino direction. We
have developed 6Li-loaded liquid scintillator (Fig. 1)
to (1) minimize thermal diffusion of the neutron
before it is captured by other nuclei and (2) get
point-like delayed signal for precise vertexes. To
separate prompt and delayed signals, optical
discrimination of energy deposit point by highresolution imaging devices is required.

Figure 1 Anti-neutrino detection with 6Li-loaded liquid
scintillator.

Developments : Recent progress in studying the
new technology confirmed that a signify
improvement in possible in neutrino tracking
identification with a combination of 6Li-loaded
liquid scintillator and imaging detector. Aa shownin Fig 2, the scintillation light is collected by the
mirror array and measured by pixelated photon
sensor to achieve high vertex resolution, ~2 cm.

Figure 2 Schematic view of directional measurement
detector.

(1) Mirror array
We have tried to increase the reflectance to get
more photons. In FY 2017, we developed themirror array with Al.
It had about 60% ofreflectance. We have developed the method ofaluminum evaporation on acrylic mirror andachieved about 95% of reflectance. Since there are
two refraction points between scintillator andphoton sensor, the expected photons is increased bya factor of 2.5. This achievement arrows us to get
more statistics of the image data and increase theresolution of separating vertexes.
(2) Photon sensor
In FY 2017, we studied about specificperformance of MCCP (Multi Pixel Photon
Counter).
We developed cooling system todecrease noise level to use our experiment. In thisFY, 3D measurement of scintillation light by two
imaging detector with MCCP was started. The 3D
images taken by MCCP and multi anode PMT will
be compared and reported.
References: [1] T. Araki et al., Nature 436, 499(2005) [2] A. Gando et al., Nature Geosci. 4, 647(2011) [3] A. Gando et al., Phys. Rev. D 88,
033001 (2013)

The fate of carbonate in deeply subjected oceanic crust
M Walter1, J Drewitt2, H. Zhang3, S. McMahon2, D Edwards2, B Heinen2, O Lord2, S Anzellini4 and A Kleppe41Geophysical Lab, Carnegie Institution of Washington, Washington D.C., 20015, USA
2
School of Earth Sciences, University of Bristol, Queens Road, BS8 1RJ, UK
3
School of Earth and Space Sciences, USTC, 96 Jinzhai RD, Hefei, Anhui 230026, P. R. China
4
Diamond Light Source Ltd, Diamond House, Chilton, OX11 0DE, UK*email: mwalter@carnegiescience.edu
Introduction: Knowledge of how carbon cancycle through exterior and interior reservoirs isfundamental for understanding its evolution throughgeological time and the habitability at earth’s
surface. The H/C ratio in earth’s exosphere is higher
than in the source region of primitive basalts,suggesting an enriched carbon reservoir in the
mantle [1]. One possible explanation is that
subduction of carbon enriched the mantle overgeological time. On average basaltic crust contains~ 2.5 wt.% CO2 [2], and modeling of slab
devolatilization processes indicates that subductedcarbonate may survive past the volcanic front to betransported deeper into the mantle [3].
Experimental evidence shows that carbonatedoceanic crust should melt in the transition zone
along most subduction geotherms (Fig. 1) due to a
deep depression in the carbonated basalt solidus [4].
Mineral inclusions in superdeep diamonds havetrace element signatures that testify to carbonate
melt in their formation providing direct evidence forthis process [4]. However, along cool subduction
geotherms carbonate may be transported into thelower mantle, potentially enriching the deep mantle
reservoir in carbon. Here we report on laser-heateddiamond anvil cell (LHDAC) experiments in the
CaO-MgO-SiO2-CO2 (CMSC) and FeO-MgO-SiO2CO2 (FMSC) systems at lower mantle pressures. We
investigate the stability of carbonate in basaltic
oceanic crust and test for decarbonation reactions
involving carbonate and coexisting silica [5].
Methods: We report on LHDAC experiments
and analysis of recovered run products bysynchrotron x-ray diffraction and micro-Raman
spectroscopy.
Starting
compositions
were
synthesized in the CMSC and FMSC systems by
mixing carbonates with silica glass. Experiments
were made in symmetric DACs with pressed discs
of starting material sandwiched between discs of
NaCl as a pressure medium. Samples were heatedusing a double-sided laser geometry andtemperatures measured by spectroradiometry.
Samples were held at temperature for up to 1 hour.
Samples were analyzed using angle-dispersive Xray diffraction at beamline I15 of the Diamond Light
Source for phase identification. The presence of
diamond in run products was determined by Raman
spectroscopy at the University of Bristol.

Results: We find that carbonate reacts withsilica to form bridgmanite ± Ca-perovskite + CO2 atpressures in the range of ~40 to 70 GPa (Fig. 1).
Decarbonation reactions have a negative Clapeyron
slope and present a final barrier to subduction ofcarbonate beyond ~1500 km depth. For somegeotherms solid CO2-V may be present in subductedcrust over a limited depth range but will eventually
breakdown to form diamond and free oxygen as
slabs heat up to ambient mantle temperatures [6].
We find that the fate of carbonate in subductedoceanic crust is ultimately diamond at conditions of
the deep lower mantle where it potentially may be
stored on long timescales, possibly being returned tothe surface in upwelling plumes. We investigate
whether the deep lower mantle may become
enriched in carbon in the form of diamond overgeological time due to subduction of carbonate andits eventual dissociation to form diamond plus
oxygen and whether release of oxygen during
diamond formation can provide a mechanism for
locally oxidizing the deep mantle.

Figure 1. Pressure-temperature diagram showing
generalised carbonate phase relations in subducted,
carbonated oceanic crust [5].

References: [1] Hirschmann, M. and Dasgupta,
R. (2009). Chemical Geology 262 4–16. [2] Alt, J.
& Teagle, D. (1999). Geochim. Cosmochim. Acta
63, 1527–1535. [3] Gormon et al. (2006) G-Cubed
doi:10.1029/2005GC001125 [4] Thomson et al(2016). Nature 529, 76-79. [5] Drewitt et al (2019).
Earth and Planetary Science Letters 511, 213-222.
[6] Katsura et al (2010). Physics of the Earth andPlanetary Interiors 183, 212-218.

Multiple sulfur isotopes constraints on the origin of sulfide sulfur in Archean granitoids from Dharwar
craton, Southern India
S Aoyama1*, T Oneyama1, W Ouchi1, Yuichiro Ueno2 and M. Satish-Kumar1
1Faculty of Science, Niigata University, 2-8050 Ikarashi, Nishi-ku, Niigata, 950-2181, Japan
2Department of Earth and Planetary Science, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan*email: aoyama@geo.sc.niigata-u.ac.jp
Introduction: Sulfur is ultimately derived fromthe mantle through magmatic activity. In the surface,sulfur is mainly present as sulfate (S6+) and sulfide(S2-) in the ocean and crust. A part of these sulfur
finally return back to the mantle through subduction
process, however, there are little evidences ofsubduction of sulfur in the Archean (>2.5 Ga) period.
Mass Independent Fractionation (MIF) of sulfur
isotopes is found in the Archean supracrastal rocks
such as sedimentary sulfide and sulfate deposits,
thus MIF signatures of granitoids potentially exhibit
subduction of surface sulfur in the depth of granitoid
formation. Because intensive MIF signals are foundin sedimentary rock records between late Archean toearly Proterozoic [1], multiple sulfur isotopes ofsulfide sulfur in granitoids from Dharwar craton,
Southern, India were studied to understand whether
sulphur has been recycled or not.
Experimental: From powder samples of about
80 Dharwar granitoids, sulfide sulfur was extractedby Cr(II) methods and converted into Ag2S. The
product Ag2S was fluorinated into SF6 gas by using
Kurie-point Pyrolyzer [2]. Multiple sulfur isotopes(ratios of 32S, 33S & 34S) of SF6 was analyzed byhigh-precision isotopic ratio mass spectrometer(MAT253, Thermofisher Scientific).
Results and Discussion: Eleven granitoid
samples with sulfide sulfur from Dharwar were
measured, d34S were mostly positive, ranging from
−1.4‰ to +30.4‰ (with analytical errors of ±1.5‰),

D33S ranged from −0.089‰‰ to +0.071‰ (withanalytical errors of ±0.05‰). Sulfur in the mantle(d34S = − 1.28‰ & D33S = 0.003‰, [3]) alone
cannot explain these variations, suggesting
incorporation of other source of sulfur such as
sedimentary sulfide and seawater sulfate. Based on
the chemical compositions, Na/K ratios and ASI(Aluminium Saturation Index) values of granitoids
tend to have little relationships with D33S values. On
the other hand, granitoids having high Sr/Y ratios
are prone to have negative D33S values. Because
high Sr/Y ratios are the signals of melting of mafic
rocks (e.g., altered oceanic crust) under the presenceof garnet and/or hornblende in residue, the result
implies that seawater sulfate component within theoceanic crust is subducted and partially melted to berecycled into granitoids. Such D33S signals of thesegranitoids, however, shows much smaller variations
compared to those of simultaneous surface rockrecords, suggesting high contributions of primordial
sulfur from the mantle in the late Archean period.
References:[1] Johnston, D. T. (2011). "Multiple sulfur isotopes
and the evolution of Earth's surface sulfur cycle."
Earth-Science Reviews 106(1-2): 161-183. [2] Ueno,
Y., Chemical geology, 419 (2015) 29–35 [3] Labidi,J., et al. (2013). "Non-chondritic sulphur isotope
composition of the terrestrial mantle." Nature
501(7466): 208s-+.

Recent developments in stable isotope measurements on high-pressure high-temperature experimental
run products and natural samples
M. Satish-Kumar1, S. Aoyama1
1
Department of Geology, Faculty of Science, Niigata University, Nishi-ku, Niigata 950-2181, Japan.
*email: satish@geo.sc.niigata-u.ac.jp
For constraining the light element contents oflower mantle and core, stable isotope composition
can be effectively used as an independent proxy [1,2]. Although isotope fractionation in the deep earth
occur in a narrow range, the volume of light element
content in the mantle and core are extremely high,which can effectively cause significant natural
isotopic compositional variations. It is necessary toaccurately measure the isotope composition
accurately in micro to nanomole scales, because thehigh-pressure experimental run products are small involume. Recent studies have predicted the presenceof isotope fractionation even at lower mantle andcore P-T conditions, especially in magma ocean
environment and during the core segregation [2, 3, 4].
Despite the necessity of the micro-volume stable
isotope measurement, there is always a tradeoff
between the accuracy and the sample size.
At Niigata University, a MAT-253 mass
spectrometer (Thermo Fisher Scientific) was
installed through the MEXT Grant-in-Aid for
Scientific Research on Innovative Areas. Carbon andoxygen isotopic compositions are measured using
CO2 and multiple sulfur isotopic composition aremeasured using SF6 gas. A new micro-volume inlet
system was installed and fundamental parameterssuch as pressure effect and capillary flow effect were
tested. Using the micro-volume inlet system theminimum volume required for analysis is 1
micro-mole sample gas, and the precession for
carbon and oxygen isotopic composition are better
than 0.1‰. The precession for sulfur isotopes is±0.3‰ and ±0.01‰ (1σ) for δ34S and Δ33S,
respectively, based on the repeated analyses ofstandard Ag2S (IAEA S-1). Multiple sulfur isotope
measurement system consists of 1) curie point
pyrolyzer for rapid conversion of small volume
samples to SF6 gas [5], 2) vacuum line system forpumping out non-condensable gasses, 3) gas
chromatograph for purifying the SF6 gas and 4)
micro-volume inlet system for introduction ofsample gas to ionization chamber.
Multiple sulfur isotope ratios experimental run
products were measured using the new system.
Metal phases were separated and sulfur was
extracted using Cr(II) reduction method [6].
Preliminary results indicate that S isotope
fractionations occur in the pressure range of 3−5
GPa,
under
high-temperature
conditions
corresponding to the magma ocean environment.
The negative δ34S of mantle [7], can hence be

explained by sulfur isotope fractionation in a magma
ocean environment.
Sulfur isotope measurements were also carriedout on granitoid samples from the Archean withsulfide sulfur showing positive δ34S values. Mass
independent isotope fractionation, expressed as Δ33S,
was also observed, suggesting that sulfur in the
mantle alone cannot explain these variations. The
incorporation of surface sulfur from sedimentaryrocks and seawater is proposed.
Carbon isotopic compositions of experimental
run products were also measured using the mass
spectrometer. We could measure isotopic
compositions of carbonate and diamond separately
for high-pressure samples up to 15 GPa. Further
refinements are underway for ultra small volume
measurements.
References: [1] Wood et al., Reviews in
Mineralogy & Geochemistry, 75, 231-250, (2013).
[2] Satish-Kumar M, et al., Earth and Planetary
Science Letters, 310, 340-348 (2011). [3] Shahar, A.
et al., Science, 352, 580-582, (2016). [4] Labidi et al.,Geochimica et Cosmochimica Acta, 175, 181–194,(2016). [5] Ueno Y., Chemical Geology, 419, 29–35(2015). [6] Canfield D.E. et al., Chem. Geol., 54,
149-155. (1986) [7] Labidi J. et al., Nature, 501,
208-211. (2013)

Investigation of nitrogen incorporation into stishovite using implanted sample and outlook on deep
nitrogen cycle
Ko Fukuyama1*, Hiroyuki Kagi1, Toru Inoue2, 3, Yuji Sano4, Toru Shinmei3, Sho Kakizawa3, Naoto Takahata4,
Shunichi Hishita5
1
Geochemical Research Center, Graduate School of Science, The University of Tokyo, 2Department of Earth andPlanetary Systems Science, Hiroshima University, 3Geodynamics Research Center, Ehime University,
4
Atmosphere and Ocean Research Institute, The University of Tokyo, 5National Institute for Materials Science
Tokyo 113-0033, Japan.
*email: ko.fukuyama@eqchem.s.u-tokyo.ac.jp
Introduction: Nitrogen occupies about 80% of
the Earth 's atmosphere and is an essential elementof life. Moreover, it is suggested that nitrogen had
an impact on the climate in the early Earth (e.g.
Goldblatt et al., 2009; Wordsworth and
Pierrehumbert, 2013). Therefore, nitrogen is an
important volatile element in the early Earthevolution process and origin of the life. However,
we still cannot fully understand the behavior of
nitrogen in the deep Earth. For example, nitrogen isdepleted compared to other volatile elements in deep
mantle (Marty et al., 2012). The "missing" nitrogenis an important subject in Earth Science.
Experimental: In this study, we comparednitrogen incorporation into lower-mantle minerals(bridgmanite, stishovite) by high-pressure and hightemperatureexperimentsusing
multi-anvil
apparatus installed at Geodynamics Research Center,
Ehime University under the conditions of 27 GPaand 1400 ˚C-1700 ˚C. In these experiments, we used
Fe-FeO buffer in order to reproduce the redox stateof the lower mantle. Two types of starting materials:
a powder mixture of SiO2 (quartz) and MgO and a
powder mixture of SiO2, MgO, Al2O3 and Mg(OH)2
were used for starting materials. Nitrogen inrecovered samples was analyzed using NanoSIMS
installed at Atmosphere and Ocean ResearchInstitute, The University of Tokyo.
We prepared implant standard samples in orderto estimate nitrogen solubility in stishovite at
National Institute for Materials Science. Implant
standards were quartz glass and we used N+ as
implant ion species.
Results and Discussion: A series ofexperimental results revealed that stishovite canincorporate 39-418 ppm nitrogen which is larger
than bridgmanite nitrogen solubility (5-50 ppm
nitrogen solubility reported by Yoshioka et al.
(2018)). Stishovite is formed by the transition of the
SiO2-rich oceanic crustal sedimentary rocks orcontinental crusts transported to the lower mantle
via subducting slabs. From these reasons, Our study
suggests that nitrogen would continue to be supplied

to the lower mantle via subducting slabs sinceapproximate 4 billion years ago when the plate
tectonics had begun, forming a “Hidden” nitrogen
reservoir in the lower mantle. Furthermore, this“Hidden” nitrogen reservoir may play a role indecreasing high-concentration nitrogen which
enhanced greenhouse effect in the early atmosphere(Goldblatt et al., 2009) to the present nitrogenconcentration level.
Thus, our experimental results support the young
faint Sun paradox explained by high-concentration
nitrogen in the early earth (e.g. Goldblatt et al.,2009; Wordsworth and Pierrehumbert, 2013) andsuggest “Missing” nitrogen has been caused byforming a “Hidden” nitrogen reservoir in the lower
mantle.

Figure 1 Nitrogen solubility in stishovite under different
temperatures

References:[1] Goldblatt et al. (2009) Nat Geosci 2, 891-896[2] Li et al. (2013) Earth. Planet. Sci. Lett. 377, 311323. [3] Marty (2012) Earth. Planet. Sci. Lett. 313,
56-66. [4] Wordsworth and Pierrehumbert (2013)
Science 339, 64-67. [5] Yoshioka et al., (2018) Earth.
Planet. Sci. Lett.

Fe2S: the most iron-rich Fe-S compound at pressures of the inner core
S Tateno1,2*, H Ozawa2,3, K Hirose1,4, T Suzuki5 1Earth-Life Science Institute, Tokyo Institute of Technology,
Tokyo 152-8550, Japan, 2Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan,
3Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Tokai-mura, Ibaraki 319-1195, Japan,
4Department of Earth and Planetary Science, The University of Tokyo, Tokyo 113-0033, Japan, 5Geochemical
Research Center, The University of Tokyo, Tokyo 113-0033, Japan.
*email: tateno@elsi.jp
Introduction: Sulfur is considered to be one of
the light elements in the Earth’s core as iron sulfides
are universally found in iron meteorites. The phase
diagram of the Fe–FeS system at the high-pressureand high-temperature (P–T) conditions of the corehas particular importance to understand thecomposition and state of the Earth’s core. Because
Fe3S is known as the most iron-rich Fe–S compoundat > 20 GPa, the iron–sulfur core model has been
discussed considering Fe and Fe3S in the solid core.
However, our previous experiment reveals that
Fe3S decomposes into S-bearing hcp-Fe and CsCl
(B2)-type phase above ~250 GPa from X-ray
diffraction measurements (XRD) [1]. Furthermore,
TEM analysis on the recovered sample exhibits that
S-poor phase, likely to be a former hcp-Fe, coexistedwith S-rich phase with >33.5 atm% S. Hence, the Srich end-member compound has not been
constrained under pressure more than 250 GPa. In
order to re-investigated the phase relations in FeFeS system, we studied phase relations in Fe2S at
multi-megabar pressure range.
Experimental: High P–T conditions weregenerated in a laser-heated diamond-anvil cell using
double-beveled diamond anvils with 40 or 60μm
culets. We used the Fe2S phase as the starting
material, which was synthesized beforehand at highpressures in a multianvil apparatus and confirmed
by microprobe analysis. SiO2 glass and MgO wereused for thermal insulation and pressure calibration.
We loaded such sample assembly as MgO/SiO2glass/Fe2S/SiO2-glass so that MgO was detachedfrom an iron sample, in order to avoid possible
chemical reaction at high temperature. Angledispersive XRD measurements were conducted at
BL10XU, SPring-8. Heating was performed fromboth sides of the sample by employing a pair of 100
W Yb fiber lasers.
Results and Discussion: We performed three
separate sets of experiments at pressures at 120-310
GPa and temperature up to 3000 K. When we heatedthe Fe2S sample being mostly amorphous bycompression to 300 GPa at 300 K, the 20 new peaks
appeared in a few minutes and became spotty withfurther heating. All peaks are assigned to theorthorhombic structure, which agrees well withPnma symmetry phase proposed by the theoreticalprediction [2]. This observation indicates that Fe2S

composition crystallizes as a single phase. In thefollowing decompression and re-heating the sample,
its stability was confirmed to be 150-310 GPa.
Our previous study [3] reported that hcp-Fe andB2 phase crystallizes in Fe-6wt% S bulk
composition at 270 GPa and 2400 K. Then, thepeaks from the B2 phase become weak at further
hearting. We re-analyzed the series of XRD datum,and found that such apparent weakening was caused
due to the appearance of Fe2S phase. Indeed, in the
XRD pattern collected at 3500 K, we confirmed that
additional weak peaks from Pnma-Fe2S were clearlyvisible and the reflection from the coexisting hcp-Fe
phase became intense simultaneously. This indicatesthat stable phase assemblage in Fe-6wt% S bulk
composition changes from hcp-Fe + B2-FeS into
hcp-Fe + Pnma-Fe2S. Hence, Fe2S is the sulfur-rich
end-member compound after the decomposition of
Fe3S at 250 GPa. The slope of eutectic melting
curve should have kink at the decomposition of Fe3S.
Also, pressure evolution of the eutectic composition
should change as well. Since the extrapolation fromlower pressure data is not applicable beyond 250
GPa, higher P-T experiments are necessary toestablish the phase diagram at the pressure of innercore boundary.

Figure 1 Composition-temperature diagrams in thesystem Fe-FeS, inferred from the present study and Moriet al. [3].

References: [1] Ozawa, H. et al., Gephys. Res. Lett.
40, 4845 (2013). [2] Bazhanova, Z. et al. Phys.
Uspekhi, 60, 1025 (2017). [3] Mori, Y. et al., Earth
Planet. Sci. Lett., 464, 135 (2018).

High precision tungsten isotope of ocean island and LIPS basalts from deep mantle
Asako Takamasa1, Katsuhiko Suzuki1*, Yusuke Fukami1, Tsuyoshi Iizuka2
1Research and Development Center for Submarine Resources, JAMSTEC, Natsushima, Yokosuka 237-0061,
Japan, 2Graduate School of Science, The University of Tokyo, Hongo, Bunkyo, Japan.
*email:katz@jamstec.go.jp
Introduction: Among five W isotopes, 182W isa product of b-decay of 182Hf with the relatively
short half life of 8.9 m.y. As Hf and W are lithophileand siderophile, respectively, the 182Hf-182W
radiometric system could constrain metal-silicate(core-mantle) differentiation, especially coresegregation, in the very early Earth system becauseof its large fractionation between metal-silicate andthe short half life of 182Hf. Recent improvements ofanalytical techniques of W isotope analyses using
TIMS and MC-ICP-MS equipped with a desolvating
device allow to obtain highly precise 182W/184W
ratios of terrestrial rocks. These led to findings ofµ182W anomalies (mostly positive) in old komatiites(2.4 – 3.8 Ga) and young volcanic rocks withpositive anomalies of 12 Ma Ontong Java Plateau
and 6 Ma Baffin Bay [1] and with negative
anomalies of those such as the Loihi and Samoa
basalts [2]. Recently, Kruijer and Kleine [3]proposed that the 182W excesses for an OJP sample
by Rizo et al. [1] may result from the nuclear field
shift effect leading to defect of 183W, as the NTIMS
analyses utilized a double normalization involving
the 183W/184W ratio.
Experimental: High-precision W isotope ratio
measurement with MC-ICP-MS (Thermo co. Ltd.,NEPTUNE PLUS) equipped with desolvating
nebulizer (ARIDAS II) following the chemical
separation using both cation and anion exchange
resin has been developed. We have measured the W
standard solution (SRM 3163) and obtained theisotopic compositions with a precision of ± 5ppm.
However, the standard solution, which wasprocessed by the cation or anion exchange chemistry
in the same way as for rock samples, has systematic

182W/184W drift of -5ppm, which was also observedby [4] and Kruijer and Kleine [3]. This shift likely
resulted from the nuclear field shift effect as
mentioned by Kruijer and Kleine [3]. Therefore, we
corrected the measured W isotope ratios of samples
with the standard solution processed by the same
method as that of the samples. This technique led toobtaining of the W isotopic compositions withreproducibility of several ppm.
Results and Discussion: We have obtained
negative µ182W for the basalts with the high 3He/4He
isotopic composition from the Loihi, Hawaii,
through the developed analytical method. This result
is consistent with that of Mundl et al., [2]. As the
Earth’s core should have a negative µ182W value ofca. -210, the Loihi sample we analyzed probably
contains a component with a signature of coremantle interaction. We have obtained the highprecision W isotope data for the fresh drilled basalts
from Louisville. Louisville is known to have beenoriginated from the primordial deep mantle source.
We will discuss the obtained results and the early
evolution of the deep mantle.
Acknowledgement – JSPS Grant-in-Aid has
supported this project. We are grateful to M.
Kawamura for experimental help and Y. Orihashi, T.
Hanyu, M. Tejada for providing samples.

References: [1] Rizo H. et al. Science, 352, 809(2016). [2] Mundl A. et al. Science, 356, 66 (2017).
[3] Kruijer T.S. and Kleine T. Chem. Geol., 485, 24(2018). [4] M. Willbold, et al. Nature, 477, 195(2011).

Noble gas partition between metal-silicate melts
H Sumino1*, T Tanaka1, H Kuwahara2, S Kishi1, R Nomura3, K Mibe4, C Jackson5, S Tateno6, H Kagi7
1
Department of Basic Science, University of Tokyo, Tokyo 153-8902, Japan. 2Geodynamics Research Center,
Ehime University, Ehime 790-8577, Japan. 3Hakubi Center, Kyoto University, Kyoto 606-8501, Japan.
4
Earthquake Research Institute, University of Tokyo, Tokyo 113-0032, Japan. 5Geophysical Laboratory,
Carnegie Institution of Washington, Washington, DC 20015-9801, USA. 6Earth-Life Science Institute, Tokyo
Institute of Technology, Tokyo 152-8550, Japan, 7Geochemical Research Center, University of Tokyo, Tokyo
113-0033, Japan. *email:sumino@igcl.c.u-tokyo.ac.jp
Introduction: Analyses of ocean island basalts
reveal a geochemical reservoir characterized byunradiogenic, “primordial” noble gas signatures(e.g., high 3He/4He and low 40Ar/36Ar ratios), likely
residing in the deep mantle. There has been muchdebate about the area holding the “primordial” noble
gases deep in the Earth [1], including that the“primordial” noble gasses have been retained in the
deepest region of the mantle since 4.4 Ga [2], or in
the core since the core-mantle separation [3,4].
However, the validity of latter strongly depends on
the quantity of noble gases the core incorporates
during accretion and can hold in the present day.
Experimental: In order to investigate noble gas
partitioning behavior between the core and mantle,
noble gases were dissolved into metal-silicate melts
under high temperature and pressure conditions, andthen the samples were quenched, recovered, andanalyzed for noble gas concentrations.
At the Geophysical Laboratory, Carnegie
Institute of Washington, argon partitioning
experiments at 1 GPa and 2000 K were conductedusing a piston cylinder apparatus. Argon was added
as a liquid to a Pt (outer)-graphite (inner) double
capsule containing a Fe metal-silicate mixture, andthe capsule was welded shut while held in a bath ofliquid N2.
The other two series of samples were synthesized
at the Geodynamics Research Center, Ehime
University. Noble-gas doped silicate glass and iron
were melted and equilibrated under high pressure
and temperature (8-70 GPa, 1700-1900 K) using a
multianvil apparatus (2000~2300 K, 3-8 GPa) and alaser-heated diamond anvil cell (2000-4000 K, 10-70
GPa).
The sample capsule was cut and the polishedsurface of the section was investigated with scanningelectron microscope and Raman spectroscopy. The
chemical compositions of silicate and metal phases
were determined with electron microprobe. And
then, the noble gases in the samples were extracted
by an ultraviolet laser ablation apparatus andanalyzed using a noble gas mass spectrometer at the
University of Tokyo.
Results and Discussion: The partition
coefficient D, where D = (noble gas in metal
phase)/(noble gas in silicate phase), of argon at 1
GPa varied widely from orders of 10–4 to to 10–1.
This resulted from heterogeneous argon distribution

in the metal phase, which seems significantly
controlled by contaminant phases, such as silicate
inclusions and micro- or nano-argon bubbles.
Therefore the lowest D so far determined would
yield the best estimate, 7 × 10–5, which is threeorders of magnitude lower than the values reportedby the previous work [5].
On the other hand, D for neon, argon, krypton
and xenon at 8 GPa obtained with the samples
synthesized with multianvil apparatus were in theorder of 10–3, which is consistent with the previous
work [5]. However, it was revealed from the Raman
spectra that crystallization of clinopyroxene had
occurred in the samples synthesized at pressures of 6
GPa or higher, suggesting that the obtained D values
are significantly underestimated because a previous
study showed that noble gas content in pyroxene
crystal is smaller than those in glass (melt) by about
10–4 [6].
At present, we have not determined helium
partition coefficient in the all pressure range as it
was difficult to retain enough amount of helium inhigh-pressure and temperature apparatus during theexperiments. We confirmed that the silicate phaseobtained with laser-heated diamond anvil cell
contained a sufficient amount of noble gas.
However, we have not determined amount of thenoble gas contained in the metal phase because it
was too small to be selectively analyzed with thelaser ablation system for noble gas extraction.
Further experiments are necessary to obtain thenoble gas concentration contained in the metal phasein order to determine the partition coefficients at
higher pressure, at least 30 GPa with which theelemental partition between iron and silicate melt
would have occurred during core formation [7].
References:[1] Porcelli, D. and Ballentine, C.J., Rev. Mineral.
Geochem., 47, 411 (2002). [2] Mukhopadhyay, S.,
Nature. 486, 101 (2012). [3] Trieloff, M. andKunz, J., Phys. Earth Planet. Inter., 148, 13 (2005).
[4] Bouhifd, M.A., Jephcoat, A.P., Heber, V.S. and
Kelley, S.P., Nature Geo., 6, 982 (2013). [5]Matsuda, J., Sudo, M., Ozima, M., Ito, K., Ohtaka,O. and Ito, E., Science, 259, 788 (1993). [6] Heber,
V.S., Brooker, R.A., Kelley, S.P. and Wood, B.J.,
Geochim. Cosmochim. Acta, 71, 1041 (2007). [7]Righter, K., Earth Planet. Sci. Lett. 304, 158 (2011).

Ab Initio Applications to the Element Partitioning between Core and Mantle
T Tsuchiya, A Ohba, Z Xiong Ehime University, Japan*email: tsuchiya.taku.mg@ehime-u.ac.jp
Metal-silicate element partitioning is a key tounderstanding the chemical interaction between thecore and mantle and their evolution. We areparticularly interested in the liquid-liquid
partitioning under high P,T condition to consider the
early-Earth differentiation processes. From thetheoretical point of view, element partitioning isdetermined based on free energy balance inexchange reactions. However, determination of freeenergy in particular of liquids is not easy because theevaluation of entropy of liquids is not easy. In thisstudy we employ the thermodynamic integration(TI) method, which is funded by statisticalmechanics (Kirkwood, 1935) and enable us tocompute free energy differences between reference
and target systems. The TI routine is implemented
into our ab initio molecular dynamics (AIMD)
simulation program, and our TI-AIMD code can beapplicable not only to liquids but also to solids,
where ideal gas and Einstein crystal are chosen for
the reference systems respectively, and the reference
systems are directly switched to the ab initio (target)
systems (Taniuchi and Tsuchiya, 2018). This
technique has successfully been applied to predictthe melting temperature of MgO up to 4 TPa(Taniuchi and Tsuchiya, 2018). Metal-silicate
potassium partitioning, helium partitioning, andargon partitioning have also been studied (Xiong etal. 2018).
Calculated results imply that the potassium
partitioning behavior strongly depends on thecomposition of liquid iron. Potassium basically
prefers silicate melt associated with the its usual
lithophilic behavior, but this feature was found tochange if liquid iron contains oxygen. The solubilityof potassium in liquid iron increased with increasing
the oxygen content there. In contrast, thepartitioning behaviors of noble gases were found todepend strongly on pressure. This can be understoodby the size of vacant spaces in the melt structures.
Helium and argon were both partitioned into silicate
melt under low pressure primarily due to larger
vacant spaces, but they changed to prefer liquid iron
under high pressure because the vacant spaces insilicate melts were rapidly compressed with pressure(Xiong and Tsuchiya, in prep.). The technique isfurther extended to compute the water partitioning
between liquid iron and molten silicate. So far we
consider only a simple exchange reaction of water(H2O) with no oxidation-reduction reaction.
Calculations are yet to be converged and stillongoing, but in the moment water prefers liquid ironto silicate melt at 135 GPa and 5000 K (Ohba,
diploma thesis, Ehime Univ. 2018). This behavior isconsistent with some experiments conducted atmuch lower pressures (e.g., Iizuka-Oku et al., 2017).
Water was found to dissociate to atomic states inliquid iron without formation of molecular H2O.
Some preliminary simulations of metal-silicate
element partitioning suggest that the outer core
could be a reservoir of several geochemicallyinteresting elements. Our TI-AIMD might be a very
useful technique but very careful attention has to be
paid for the numerical accuracy of free energy
integration to obtain reliable results of element
partitioning. Also, since the TI processes need huge
computations, so far simple compositions of silicate
and iron only can be taken for practical reasons

On the core-mantle thermal and chemical coupling: Review and perspectives
T Nakagawa1* 1Department of Earth Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong.
*email: ntakashi@hku.hk
Introduction: On the core-mantle thermal andchemical coupling in terms of the long-term
evolution of Earth’s mantle and core, there aremainly two approaches for explaining the magnetic
evolution provided from paleomagnetic data [1] andheat budget across the Earth [2]. They are based on
numerical mantle convection simulations andparameterized mantle convection model imposing
the bottom thermal and chemical boundary
conditions at the core-mantle boundary.
Parameterized approach: Owing to the great
progress on the heat transfer in the deep planetaryinterior so that may include the heat transport bypartial melting [3], it is available to access the coremantle evolution wit semi-analytical approachrather than to use a massively parallel computing.
Recent, investigations have been pointed out that theheat transfer across the core-mantle boundary could
range up to 20 TW and the age of the inner core
seems to be around 500 Myrs or younger, which
seems to be consistent with interpretations of
paleomagnetic data [4].
Massively parallel computing of mantle
convection
simulations:However,theparameterized approach could not be addressed forvarious complicated processes expected in the
global-scale mantle dynamics modeling. For
instance, the mantle dynamics associated with phasetransition and extremely variable viscosity can be
only addressed in numerical mantel convection
models. In this modeling approach, the coupled
core-mantle evolution seems to be influenced fromthe onset timing of plate-like behavior that is
generated by the yield criteria of oceanic lithosphere[5].
Incorporating into the chemical evolution ofEarth’s core: In the recent accomplishment of semianalytical model of thermal and chemical evolutionof the Earth’s core [6], the chemical diffusive
processes may be played for the significant role inthermal and magnetic evolution of the Earth’s core.
Moreover, the chemical evolution associated with
the inner core growth may also be greatly important
for the thermal and magnetic evolution of Earth’s
core [7]. Regarding the recent mineral physics
accomplishments, the dissolution processes ofmagnesium or silicon seem to have a great impact tothe dynamo actions in the early Earth [8] [9] andpointed out by thermal evolution model [10].
Synthesis and perspectives: In this presentation,
I would provide the current status of core-mantle
coupling research in terms of long-term evolution ofthermal, chemical and magnetic evolution so thatcan be explained for the geophysical observations,paleomagnetic and mineral physics interpretations
using two modeling approaches: 1. Semi-analyticalparameterized mantle convection and 2. Massively
parallel computing of mantle convection
simulations. At the end of presentation, I will
provide the future direction of coupled evolution ofcore-mantle dynamics with both mantle convection
and geodynamo simulations that has been provided
for the preliminary results [11].
References: [1] Biggin, A. J., et al., Nature 526(2015). [2] Jaupart, C., et al. Treatise on Geophysics
7 (2007). [3] Driscoll, P., and D. Bercovici, Phys.
Earth Planet. Int. 236 (2014). [4] Biggin, A., J.,
Nature Geoscience 1 (2008). [5] Nakagawa, T., andTackley, P. J., G-cubed 16 (2015). [6] [7] Labrosse,
S., C. R. Geoscience 346 (2014). [8] Badro, J., et al.,Nature 536 (2016). [9] Hirose, K., et al., Nature 543(2017). [10] O’Rourke, J., and Stevenson, D.,
Nature 529 (2016). [11] Olson, P., et al., Phys. Earth
Planet. Int. 214 (2013).

Hydrogen incorporation mechanisms in nominally anhydrous mantle minerals: NMR spectroscopy andfirst-principles calculation
Xianyu Xue1* 1Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan.
*email:xianyu@okayama-u.ac.jp
Introduction. Water, even when present in trace amounts in ‘nominally anhydrous’ major mantle minerals,
could have significant effects on mantle properties. As the effects of water on mineral properties strongly dependon how it is incorporated in the crystal structure, a fundamental understanding of the structure is indispensable.
Most of the studies on hydrogen incorporation in ‘nominally anhydrous’ minerals have been carried out using
infrared spectroscopy, which revealed a number of bands in the 3300~3700 cm-1 region due to O-H stretchingvibrations that have been interpreted in terms of presence of H in Mg vacancies, and/or Si vacancies and/orinterstitial sites. However, the spectral interpretations are often controversial. Solid-state NMR spectroscopy, in
combination with first-principles calculations, on the other hand, has proven to be unique in unravelling detailed
local structural information, including defect structures.
We have been applying a combined solid-state NMR and first-principles calculation approach to studyhydrogen defects in major mantle minerals, such as olivine, pyroxene and garnet, and have gained much new
insight that could not be readily obtained from other techniques. The information also shed light onto theinterpretation of the corresponding infrared spectra. Here, I review some of our findings on Mg2SiO4 forsterite(Xue, X., Kanzaki, M., Turner, D., and Loroch, D. 2017 Am. Mineral., 102, 519-536) and MgSiO3 enstatite (Xue
X., Kanzaki M., Jiang J., Djirar A-E & Gregson C., in preparation), both synthesized at high pressures andtemperatures.
Experimental & Calculation Methods. A Mg2SiO4 forsterite sample containing about 0.5 wt% H2O wassynthesized at 12 GPa, 1200°C, and several MgSiO3 enstatite samples with 0.1 to 0.3 wt% H2O were synthesized
at a range of pressures between 7 and 14 GPa and 1200°C, all in a Kawai-type multi-anvil press. The recovered
samples (to ambient condition) were confirmed to be nearly pure target phase.
1
H MAS and static NMR spectra were obtained at ambient condition using a Varian 9.4 T Unity-Inova NMR
spectrometer. First-principles calculations of NMR parameters were performed with the GIPAW method using
the Quantum-ESPRESSO package. A number of model structures of 2x1x2 supercell for Mg2SiO4 forsterite and1x1x2 supercell for MgSiO3 enstatite, with one Si replaced by 4H ((4H)Si defect) or one Mg replaced by 2H((2H)Mg defects) were studies. The structures were first fully relaxed before NMR calculation.
Results and Discussions
Mg2SiO4 forsterite. 1H static and MAS NMR spectra were obtained at spinning rates up to 30 kHz. The 1H
static NMR spectrum contains both a broad and a narrower component. The 1H MAS NMR spectra also revealed
two main components, a broader peak near 2.4 ppm that has extensive spinning sidebands and a narrower peak at
1.2 ppm with much less prominent spinning sidebands. There is also a very weak narrow peak near 7.3 ppm in
the MAS NMR spectra.
First-principles calculation revealed that the lowest-energy structures for forsterite with a (4H)Si defect arecharacterized by having one H point away from the center of the tetrahedron and the rest near the vacant tetrahedra,
which may account for the experimentally observed two main components in the 1H static and MAS NMR spectra,with the differences in peak width due to different extent of dipolar couplings; whereas the lowest-energy (2H)Mg
defects matches well with the observed very weak narrow 1H NMR peak near 7.3 ppm. Thus, most of thehydrogen defects observed for forsterite synthesized at 12 GPa and 1200˚C are in the form of (4H)Si defects, with
only minor (2H)Mg defects.
MgSiO3 enstatite. The 1H MAS NMR spectra for the enstatite samples synthesized at different pressures show
systematic differences. The spectra for both orthoenstatite and clinoenstatite at 7 GPa are dominated by two
narrow peaks near 5.8-5.9 and 7.8-7.6 ppm of equal intensities, whereas those of clinoenstatite (14 GPa) are muchbroader with peak maxima (or shoulders) recognized near 0.3, 3, 5.8, 8 and 12 ppm. The spectra for theintermediate pressure (12 GPa) contain both sets of components.
First-principles calculation suggests that the 1H NMR spectra for both orthoenstatite and clinoenstatite at 7
GPa are consistent with (2H)Mg defects; those of clinoenstatite (14 GPa) are consistent with (4H)Si as the
predominant hydrogen defects, with broad 1H NMR peak width resulting from strong 1H-1H dipolar interactions
from clustering of the 4H in the Si vacancy. The presence of 1H NMR peak of large chemical shift (12 ppm) forthe latter suggests that some of the protons have strong hydrogen bonding, which is different from (4H)Si defects
in forsterite that are characterized by weak hydrogen bonding and small 1H chemical shifts. This difference is
explainable by the difference in connectivity of SiO4 tetrahedra between forsterite and enstatite.
Acknowledgements. This study has been supported by Kakenhi No. 17H01174 to X.X. The work reviewed
here is the result of collaboration with M. Kanzaki, J. Jiang and participants of Misasa International Student
Program ((2015: D. Turner & D. Loroch: forsterite project; 2016: A-E. Djirar & C. Gregson: enstatite project).

Probing hydrogen by single-crystal neutron diffraction in deep mantle hydrous minerals
N Purevjav1*, T Okuchi1, N Tomioka2, X Wang3 and C Hoffmann3
1Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan.
2Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Nankoku,
Kochi 783-8502, Japan.
3Chemical and Engineering Materials Division, Neutron Sciences Directorate, Oak Ridge National Laboratory,
Tennesee, TN 37831, USA.
*email: narangoo@s.okayama-u.ac.jp
Introduction: Water in Earth’s deep mantle
minerals presents as structurally bound hydroxyls
within their crystal lattices. Studying such water in thehydrous minerals provide significant information forunderstanding water inventory and transportation as
well as its related geochemical and geophysicalevolutions within the deep Earth. To obtain better
understanding of the effects of such hydroxyls within
the hydrous minerals, it is essential to thoroughly
investigate hydrogen position, its occupancies andbonding geometries in the relevant mineral’s crystal
lattice. Single crystal neutron diffraction is the mostsuitable probe for investigating such hydrogen in theminerals with high precession, where the neutron issensitive for light atoms such as hydrogen. Thus, weapplied the method for the first time for the majorwater reservoirs of the deep mantle, which are mantle
transition zone minerals hydrous wadsleyite[b - Mg2SiO4]
andhydrousringwoodite[g - Mg2SiO4]. These studies are the first applicationsof single crystal neutron diffraction for the deep
mantle hydrous minerals and aimed to investigate
their hydrogen positions, occupancies and bonding
geometries with high precision.
Experimental: Single crystals of hydrous
wadsleyite and hydrous ringwoodite were synthesized
by using a scaled-up Kawai type cell combining with
our pre-established a slow-cooling method at theirrelevant pressure and temperature conditions of the
deep mantle [1]. Synthesized crystals were confirmed
to be chemically, physically and optically uniform byspectroscopic and diffraction techniques. The wellcharacterized single crystals of these minerals were
measured by neutron time of flight single-crystal
Laue diffraction at Spallation Neutron Source, Oak
Ridge National Laboratory. This state-of-the-art
instrument was used to obtain datasets with a superior
spatial resolution, even from the tiny crystal volumeof these studies. The crystals were separately
measured at 100 K, in different experimental periods.
Each dataset was obtained over durations of two or
three days.
Results and Discussion: Positions of hydrogen in
wadsleyite and ringwoodite crystal lattices were
contrasted by their negative scattering length density
distributions in the observed difference Fourier maps.
Such negative scattering lengths of hydrogen provides
good contrast to accurately determine its position
from the surrounding positive scattering lengthdensity distributions of the other atoms (Mg, Si and
O). We successfully determined atomic positions,occupancies, and temperature factors of the all theatoms without any constraints for these minerals
crystal lattices. The determined H-O bond distanceswere 0.999(5) Å and 1.10(4) Å for wadsleyite andringwoodite, respectively.
In wadsleyite, we investigated that there is only
one hydrogen site within its crystal lattice and it was
exchanged by the Mg cations at one of the specificM3 octahedra. From its refined hydrogen site
occupancy, we calculated 1.36 wt.% of H2O in thecurrent wadsleyite sample. By deducing therefinement result, we determined the maximum
allowable H2O concentration in wadsleyite lattice,which was 3.33 wt.% [2]. There are no other hydrogensites. In ringwoodite, we investigated that there werecharge vacancies in both octahedral and tetrahedral
sites, meanwhile the total charge vacancy was fullycompensated by single hydrogen site locating only atoctahedra. The calculated H2O was 1.9 wt.% in thecurrent ringwoodite sample. The current structurerefinement result suggests that H2O concentrationin ringwoodite lattice is not explicitly constrained by
the occupancy limitation of the hydrogen site itself.
It suggests that the ringwoodite may contain evenlarger amount of H2O than that has been reported
previously (max ~ 2.7 wt.% , by Ye et al., 2012).
Therefore, determined H2O concentrations inhydrous wadsleyite and hydrous ringwoodite bysingle crystal neutron diffraction were consistent withthose of the estimated amounts by combination of IR,
SIMS and x-ray diffraction works [2, 3]. Thus ourstudies suggest that single crystal neutron diffraction
is potential choice for quantitatively analyzing thewater in the minerals, even at level of a few wt.%
concentrations.
By following the studies, we also applied thesingle crystal neutron diffraction for dense hydrous
magnesium silicate phase E, which is the major
reservoir of the water in the subducting slab. The
details will be introduced in the talk.
References: [1] Okuchi, T. et al., Am. Mineral., 100,
1483 (2015). [2] Purevjav, N., Okuchi, T., Tomioka,N., Wang, X. and Hoffmann, C. Sci. Rep. 6, 34988(2016). [3] Purevjav, N., Okuchi, T., Wang, X.,
Hoffmann, C. and Tomioka, N. Acta Cryst. B74, 115(2018).

First principles determination of the dissociation boundary of phase H (MgSiO4H2) and possible existence of ice VIIat lower mantle conditions.

J. Tsuchiya1* and K. Umemoto2 1Geodynamics Research Center, Ehime University, Japan. 2Earth-Life Science
Institute, Tokyo Institute of Technology, Japan*email:junt@ehime-u.ac.jp
Introduction: It is believed that water is carried into
the Earth’s deep interior by hydrous minerals such as
dense hydrous magnesium silicates (DHMSs) in thedescending cold plate. A number of studies have been
conducted to determine the high-pressure behaviorsof DHMSs. In recent years, we discovered a new
DHMS, phase H, stable at lower mantle pressure
condition above ~ 40 GPa and the solid solution
formed by phase H and δ-AlOOH has been proposedas the most important carrier of water to the deepest
part of Earth’s mantle [1-3]. However, the MgSiO4H2
phase H has been reported to decompose into H2O andMgSiO3-bridgmanite at relatively low pressure
condition about 52 GPa at 0 K by first principles
calculation [1]. High temperature dissociation phaseboundary between phase H and MgSiO3+H2O has notbeen determined so far, since the hydrogen disordered
ice VII phase is stabilized above ~100 K. Here we
report the dissociation phase boundary of phase H athigh pressure and temperature condition bydetermining the free energies of H2O ice-VII [4] andMgSiO3 Bridgmanite and discuss the stability of H2O
ice-VII in the mantle which is recently identified in
the natural diamond inclusion [5] and possible
scenario of the transportation of water into deep Earthinteriors.
Experimental: Umemoto et al. 2010 successfully
calculated the phase boundary of order-disorder phasetransition between ice VII and VIII. Here we follow
the same method to calculate Gibbs free energy of ice
VII. The calculation of ice VII was modeled using
supercell (2 × 2 × 2 unit cells) containing 16 H2Omolecules. This supercell has 90×90 = 8100 possiblehydrogen configurations, satisfying the ice rule.
However, the number of the hydrogen configurations
can be reduced to 52 after considering symmetry.
The first principles calculation is based on thedensity functional theory with the generalized
gradient approximation (GGA) to the exchangecorrelation
functional.
Norm
conserving
pseudopotentials were used and those potentials wereextensively tested in previous studies. All structuralparameters are fully relaxed at a static 0 K at 0, 10, 20,
30, 40, 50, 60, 80, 100 and 120 GPa using damped
variable cell shape molecular dynamics implemented
in the Quantum-Espresso codes.
In this study, 144 phonon frequencies of the ice
supercell are calculated based on density functional
perturbation theory (DFPT). Zone-center phononmode (Γ point) is sampled for the calculation ofpartition function ZQHA.

For the determination of dissociation phaseboundary, we used the Gibbs free energy of phase H,
MgSiO3 perovskite
CaCl2-type SiO2, anddetermined based on DFPT and QHA.
Results and Discussion: The present result
indicates that the dissociation phase boundary ofphase H intersects with cold geotherm around 60 GPa.
Several previous melting temperatures of ice arehigher than that of cold geotherm. Therefore, there isa possibility that the dissociation of phase H produces
superionic ice phase at the middle of lower mantle
around 1500 km depth. The crystal chemical reactions
between superionic ice and surrounding minerals
have not been solved yet. But high diffusivity ofhydrogen in superionic ice may produce reaction
faster than that in solid ice but different from water,
liquid phase of H2O.

References: [1] Tsuchiya, J., Geophys. Res. Lett., 40,
4570. [2] Nishi, M. et al., (2014), Nature Geosci. 7,224 (2013). [3] Ohira, I. et al., Earth Planet. Sci. Lett.,
401, 12 (2014) [4] Umemoto, K., et al., Chem. Phys.
Lett., 499, 236 (2010). [5] Tschauner, O. et al.,Science, 359, 1136 (2018).

High water solubility of ringwoodite at mantle transition zone temperature
Hongzhan Fei*, Tomoo Katsura
Bayerisches Geoinstitut, University of Bayreuth, Bayreuth, D95447, Germany*email:Hongzhan.fei@uni-bayreuth.dewater contents in ringwoodite were analyzed by
The mantle transition zone, a potential water

Fourier transformation infrared spectroscopy withreservoir in the Earth’s interior, is suggested to

Koch-Muller and Rhede (2010) calibration.

contain more than 1 wt.% of water, at least locally,by the natural water-rich ringwoodite inclusion

The experimental results show that, although the(Pearson et al. 2014), electrical conductivity (e.g.

water solubility in ringwoodite decreases with

Kelbert et al., 2009), and mineral viscosity data

increasing temperature, even at 2000 K, both Fe-(Fei et al. 2017). However, laboratorial mineralfree and Fe-bearing ringwoodite can still store

physics experiments showed that the water

more than 1.0 wt.% H2O, much higher than thosesolubility in ringwoodite significantly decreases

reported by Ohtani et al. (2000). The waterwith

Althoughsolubility has negligible Fe-content dependence

ringwoodite can store up to 2.6 wt.% water at

at 2000 K, whereas that in Fe-free ringwoodite isrelatively low temperatures (~1600 K), under thehigher than Fe-bearing one at lower temperatures.

realistic mantle transition zone condition at ~2000

The high water solubility at 2000 K agrees to theK, the water solubility is less than 0.3 wt.% (e.g.,water-rich mantle transition zone inferred from

Ohtani et al. 2000), which is against themineral viscosity and the natural inclusion. The

conclusion of water rich mantle transition zone.

relatively low water content in ringwoodite

This argument implies that the water solubility inreported in previous studies is probably due toringwoodite at transition zone temperatures might

disequilibrium with SiO2 buffers or insufficient

have been under estimated.

H2O in the starting materials.

increasing

temperature.

To clarify the water storage capacity of
ringwoodite in the mantle transition zone, werevisited the water solubility in both Fe-free andReferences:

Fe-bearing ringwoodite. Mixtures of MgO, SiO2,

Pearson et al. (2014), Nature 507, 221.

FeO,

and

Mg(OH)2

powders

with

bulk

compositions of Fo100, Fo90, and Fo75 plus 1.5

Kelbert et al. (2009), Nature 460, 1003.

to 22 wt.% H2O were used as starting material.

Fei et al. (2017), Sci. Adv. 3, E1603024.

The mixtures were loaded in a PtRh capsule andannealed at 23 GPa, 1600-2000 K, for 0.7 to 6
hours. The run products appeared as coexisting of
ringwoodite, hydrous melt, and akimotoite. The

Ohtani et al. (2000), PCM 27, 533.
Koch-Muller and Rhede (2010), Am. Min. 97,
770.

In situ vibrational spectroscopy of the dehydration of talc in the system MgO-SiO2-H2O
Shigeru Yamashita1*
1Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan.
*email:shigeru@misasa.okayama-u.ac.jp

Results: Upon heating to 800 °C, the sample
chamber became thinner while the gasket deformed,
which let the sample pellet in contact with both theupper and the lower diamond anvils. At 800 °C and
2.4 GPa, the talc NIR (Fig. 1) and Raman bands
both monotonously decreased in the intensity withtime while Raman bands due to the fundamental
Si-O stretch of enstatite (~660, ~690, ~1010, and~1040 cm-1, Huang et al., 2000) appeared and grew.
No phase other than talc, forsterite, enstatite, andH2O fluid was observed during the experiment,
which indicates that the dehydration reaction, talc +forsterite = 5 enstatite + H2O, was successfully
reproduced. The time decay of the intensities of thetalc NIR bands was adequately fitted by an Avrami(JMAK)-type sigmoidal curve with the exponent of

ambient, after

2.0
2.0

1.5
1.5

1.0
1.0

0.5
0.5

H2O ﬂuid
Talc
H-O-H
Mg-O-H
comb.
comb.

Talc
H2O ﬂuid O-H
O-H
str. o.t.
str. o.t.

291
253
211
182
151
122
90
60
42
26
0

min@800 C

Experimental: A pellet of 50/50 mixture (inweight proportion) of natural, stoichiometric-pureMg-talc (<38 µm grain size) and synthetic
forsterite together with distilled H2O was loaded in
the Ir gasketed sample chamber of an externallyheated hydrothermal diamond anvil cell (HDAC)
fitted to micro-FTIR and micro-Raman
spectrometers. Pressure in the HDAC wasmonitored with the pressure- andtemperature-dependent Raman shift of thefundamental Si-O stretch vibration of forsterite(~857 cm-1 at ambient condition, Gillet et al., 1991;
Wang et al., 1993). To ensure the highest precisionof the Raman shift, the 557 nm Kr line was
acquired simultaneously as reference. Temperature
was controlled to ±1 °C with chromel-alumel
thermocouples in contact with the diamond anvils
near the sample chamber. Near infrared (NIR)
bands assigned to the combination modes of thefundamental Mg-O-H bending + stretch vibrations(~4200 to ~4400 cm-1, Madejova et al., 2011) and
Raman band assigned to the fundamental Mg-O-H
bending (~680 cm-1, Madejova et al., 2011) wererecorded as a scale of the talc abundance.

2 and the rate constant of 2.1 ± 0.2 x 10-5 min-2.
This translates into a half-lifetime of ~180 min for
the talc (a half of the talc disappears in that time).
This half-lifetime differs only a small factor fromthose obtained by previous works for theforsterite-deficient (silica-saturated) reaction, talc =3 enstatite + quartz + H2O, under similar
temperature conditions (e.g., Bose and Ganguly,
1994; Chollet et al., 2009).

Absorbance

Dehydration kinetics of talc is important tounderstand transport of H2O into the mantle wedge
during subduction processes. Experimental resultsfrom in-situ observation of the dehydration of talc
at 800 °C and 2.4 GPa under the presence of excess
amounts of forsterite are presented.

ambient, before
4000
4000

5000
5000

6000
6000

7000
7000

Wavenumber, cm-1

8000
8000

Figure 1. Time decay of the talc NIR bands of thesample pellet at 2.4 GPa and 800 °C. The NIR
beam was aimed at 100 x 100 µm sample spot.
Spectra are offset from each other in absorbancefor clarity.
References: Bose and Ganguly, Amer. Mineral.,79, 692-699, 1994; Chollet et al., Earth Planet. Sci.
Lett., 284, 57-64, 2009; Gillet et al., J. Geophys.
Res. Lett., 96, 11,805-11,816, 1991; Huang, et al.,Amer. Mineral., 85, 473-470, 2000; Madejova et al.,EMU Notes, Mineral., 9, 171-226, 2011; Wang etal., Amer. Mineral., 78, 469-476, 1993.

Structures of hydrous sodium silicate melts under high pressure and high temperature
T Ohashi1*, T Sakamaki1, K Funakoshi2, M Muranushi1, C Shito1, Y Shibazaki3 and A Suzuki1 1 Department ofEarth Science, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan. 2Neutron
Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS), Tokai
319-1106, Japan. 3National Institute for Materials Science (NIMS), Tsukuba 305-0044, Japan.
*email: tomonori.ohashi.s8@dc.tohoku.ac.jp
Introduction: The behaviors of high-pressure
silicate melts, which is controlled by their physicochemical properties, are important to understand themagma activity in the deep Earth. Particularly, theH2O content significantly affects the properties,
such as density (e.g., [1]) and viscosity (e.g., [2, 3]).
Since such macroscopic properties are known to belargely determined by the microscopic structure,
there are considerable interests in revealing how thestructures change with increasing pressure.
Experimental: We performed structuralinvestigations of hydrous Na2O∙8/3SiO2 (NS8/3)
melts containing 5 wt% (NS8/3_H5) and 9 wt% H2O(NS8/3_H9) were determined under high pressure
and temperature conditions by the in-situ
synchrotron X-ray diffraction (XRD). The dry
NS8/3 glass was prepared by quenching a molten
mixture of reagent powders SiO2 and Na2CO3, andH2O was added as distilled water. The in-situ XRD
study was conducted by using a cubic-type multianvil apparatus named MAX80 at the AR-NE5C
beamline of PF-AR at KEK, Japan. The
experimental pressure and temperature conditions
were about 1.5–3.0 GPa and 550–970 °C,
respectively. The design of our high-pressure cell
assembly is based on the idea developed by Yamada
and coworkers [4].
Results and Discussion: The total structure
factors, S(Q) of both liquids show that the positionof the first sharp diffraction peaks (FSDP) shift tohigher-Q with pressure. This positional shift
indicates the intermediate-range order structure ofpresent melts become compact. The obtained
reduced radial distribution functions, G(r) aredepicted in Fig. 1, and indicate different pressure
evolutions in the average Si-O bond lengths (rSi-O)
depending on their water contents. The rSi-O in theNS8/3_H9 liquid shows the monotonic decrease
with increasing pressure, however, the rSi-O of theNS8/3_H5 liquid hardly changes after its
contraction below 1.6 GPa. The structure of theNS8/3_H9 melt is assumed to be slightly more
depolymerized than the NS8/3_H5 melt at ambientpressure [5]. This difference might be due to aphenomenon that the number of strongly hydrogenbonded SiOH groups, which are favored in thevitreous and molten sodium silicates [6], increase
more significantly during pressure-induced…SiOSi… network breakage in the molten
NS8/3_H9 than in the NS8/3_H5 melt. This
increases Si(-NBO)/Si(-BO) ratio (NBO: nonbridging oxygen, BO: bridging oxygen), so that therSi-O gets shorter.

Figure 1 The reduced radial distribution functions, G(r),of the present melts at various pressure and temperature.

References: [1] Sakamaki, T., Suzuki, A. andOhtani, E., Nature, 439, 192 (2006). [2] Suzuki, A.,
Ohtani, E., Terasaki, H., Nishida, K., Hayashi, H.,
Sakamaki, T., Shibazaki, Y. and Kikegawa, T., Phys.
Chem. Miner., 38, 59 (2011). [3] Poe, B.T., Romano,
C., Liebske, C., Rubie, D.C., Terasaki, H., Suzuki A.
and Funakoshi, K., Chem. Geol., 229, 2 (2006). [4]Yamada, A., Inoue, T, Urakawa, S., Funakoshi, K.,
Funamori, N., Kikegawa, T., Ohfuji, H. and Irifune,T., Geophys. Res. Lett., 34, L10303 (2007). [5]Zotov, N. and Keppler, H., Am. Mineral., 83, 823(1998). [6] Xue, X. and Kanzaki, M., Geochim.
Cosmochim. Acta, 68, 5027 (2004).

Simultaneous deformation of Calcium Perovskite and Pyrope
AR Thomson1*, SA Hunt1, J Van Driel1, JP Brodholt1 and DP Dobson1
1
Department of Earth Sciences, University College London, UK.
*email: a.r.thomson@ucl.ac.uk
The DT cup apparatus: The DT-cup [1,2] is aunique high-pressure deformation apparatus thatuses a modified 6-8 split-cylinder geometry, and iscapable of generating pressures of ~ 25 GPa. At
high-pressure conditions, modified wedges allow
uniaxial shortening of the experimental assembly
using differential actuators incorporated into mainram. This setup permits controlled strain-rate
experiments to be performed to large total-strains.
Housed in a modified V6 Paris-Edinburgh load
frame, the DT-cup is small enough to be easilytransported for in-situ diffraction experiments at
European synchrotron sources. Beam-line I12(JEEP), a multi-functional engineering beamline, atDiamond Light Source (DLS) is one suchdestination well-equipped to perform deformation
experiments using monochromatic and/or whitebeam X-rays. Here we present recent experiments
performed at DLS to study the relative deformation
behaviour of CaTiO3 perovskite and pyrope garnet
samples.
Background: Calcium perovskite and garnet areboth major mineral components of the Earth’s
mantle that are particularly abundant in subducting
assemblages. Subducting oceanic crust converts into
eclogite and/or garnetite assemblages throughout
upper mantle, and consists of up to 90% garnet by
500 km depth [3]. Subsequently calcium perovskitestabilises beyond ~ 600 km, becoming the third mostabundant mineral throughout the lower mantle,
composing up to ~ 30% of slab assemblages.
Previous studies have suggested that garnet can beboth stronger [4] or weaker [5] than olivine at upper
mantle conditions, and that calcium perovskite is
likely to develop the strongest seismic anisotropy
due to LPO amongst common phase assemblages of
the upper/lower mantle boundary region [6].
However, despite their high abundances andpotential importance in understanding subduction
dynamics, relatively little is known about therheological properties of either calcium perovskite
or garnet throughout mantle conditions. In-situ
deformation experiments provide simultaneous
measurements of stress and strain-rate, enabling aquantitative determination of rheological properties
at mantle conditions.

Figure 1. X-ray radiographs of CaTiO3 (upper sample)
and pyrope (lower sample) before (left) and during (right)
deformation at high pressure-temperature conditions.

Experimental
techniques:
Fine-grained
powders of synthetic CaTiO3 and natural pyrope
garnet (Dora Maira) were loaded into 7/3 multi-anvil
assemblies. Thin Au marker foils were placed ateither end of each sample to monitor strain
throughout the experiments and Molybdenum
furnaces were used to generate high temperatures,
which were monitored using radial thermocouples
terminating near the sample position. During initial
experiments, conditions of up to ~ 6 GPa andtemperatures up to ~ 1600 K were investigated.
Angle dispersive diffraction patterns, generated by
the diffraction of monochromatic x-rays (λ ~ 0.22Å)from each sample in turn, were collected using a
Pilatus 2M CdTe detector. Diffraction patterns werecollected alternately with radiographic images of thesample lengths (Figure 1). Combining bothmeasurements allows simultaneous monitoring ofboth stress, strain and in-situ texture development incalcium perovskite and pyrope garnet samples,
which deformed at strain rates between 2x10-6 and1x10-5 s-1.
References: [1] Hunt, S.A. et al. (2014) Reviews of
Scientific Instruments. 85, 085103. [2] Hunt, S.A. &Dobson, D.P. (2017) Reviews of Scientific
Instruments, 88, 126106. (2017). [3] Stixrude, L.,
and Lithgow-Bertelloni, C. (2012) Annual Review
of Earth and Planetary Sciences, 40, 569–595. [4] Li,
L. et al. (2006) American Mineralogist, 91, 517–525.
[5] Hunt, S.A. et al. (2010) Physics of the Earth andPlanetary Interiors, 179, 87–95. [6] Kawai, K., andTsuchiya, T. (2015) Geophysical Research Letters,
42, 2718–2726.

D111-type apparatus for high-pressure deformation experiments and its application to a rheological studyof hcp-iron
Y. Nishihara1*, S. Doi1, D. Yamazaki2, N. Tsujino2, T. Yoshino2, T. Kubo3, and M. Imamura3
1
Geodynamics Research Center, Ehime University, Matsuyama, Ehime 790-8577, Japan.
2
Institute of Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan.
3
Department of Earth and Planetary Sciences, Kyushu University, Fukuoka 819-0395, Japan.
*email: yunishi@sci.ehime-u.ac.jp
Introduction: To study rheological properties ofmaterials in the Earth’s deep interior, high-pressure
deformation experiments have been carried out using
various deformation devises including rotational
Drickamer apparatus [1] and deformation-DIA
apparatus [2]. A new type apparatus, deformation TCup (DT-Cup), which is based on Kawai-type multianvil apparatus, was developed by Hunt et al. [3]. In
the DT-Cup, by driving two second-stage anvils using
differential actuators, well-controlled deformation
experiments can be conducted up to confiningpressure of 18 GPa. However, more improvement wasneeded to achieve experiments at the condition of the
Earth’s lower mantle (P >23 GPa).
To study the rheological properties at the lower
mantle condition experimentally, we have installed a“D111-type apparatus” that is an improved version of
DT-Cup with larger dimension. This apparatus has
been used to study rheological behavior of the deep
Earth materials including hcp-iron, bridgmanite andringwoodite. In this presentation, we introduce
specification of the D111-type apparatus and recent
results obtained by using this apparatus.
Experimental: A D111-type guide-block (Fig. 1)
was installed on a synchrotron beamline NE7A at PFAR, KEK, Tsukuba, Japan in 2017. Combining thisguide-block with the MAX-III press, it acts as adeformation apparatus “D111-type apparatus”. The
D111-type apparatus can be used under maximum
press load of 700 tonf which enables us to conduct
quantitative deformation experiments at the lower
mantle pressures.

conducted by advancing top and bottom differentialrams (D-ram) at high pressure and high temperature
conditions. Sample stress was measured by twodimensional
X-ray
diffraction
using
monochromatized synchrotron X-ray (50 − 60 keV)
and CMOS X-ray detector (Dexela 2923). Sample
strain was measured by X-ray radiography.
Results and Discussion: Well-controlled
deformation experiments with constant strain rate wasachieved at press load up to 350 tonf. Maximum
pressure and temperature in deformation experimentsare ~27 GPa and ~1700 K, respectively. Maximum
pressure exceeds 30 GPa at room temperature before
heating. These clearly show capability of deformation
experiments at the lower mantle conditions.
Based on the uniaxial deformation experiments of
hcp-iron (Fig. 2), steady state stresses were
determined under conditions up to 22.6 GPa and 873
K. A preliminary analysis of these data suggests thatpower-law dislocation creep with stress exponent of~5 is dominant at >700 K whereas power-law
breakdown occurs at lower temperatures. However,more experimental data are required to give an
accurate constraint on the inner core viscosity.
We have also carried out deformation experimentson the other deep Earth materials including
bridgmanite and ringwoodite. Results from theseexperiments will be briefly given in presentation.

Figure 2 Stress-strain relationship in a temperature-step
deformation experiment of hcp-iron at P = 16.3−-16.5 GPa,
T = 723−823 K and uniaxial strain rate of ~2 × 10−5 s−1.
Figure 1 Schematic illustration of D111-type guide-block.

High-pressure was generated using Kawai-type
assembly with octahedral pressure medium and eight
second stage anvils. Deformation experiments wereReferences: [1] Yamazaki, D. et al., Rev. Sci. Inst.,
72, 4207 (2001). [2] Wang, Y. et al., Rev. Sci. Inst.,
74, 3002 (2003). [3] Hunt, S. et al., Rev. Sci. Inst., 85,
085103 (2014).

Creep strength of bridgmanite
N Tsujino1*, D Yamazaki1, Y Nishihara2
1Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan.
2Geodynamics Research Center, Ehime University, Matsuyama, Ehime 790-8577, Japan.
*email:tsujino@okayama-u.ac.jp
Introduction: One dimensional viscosity
models of the Earth’s mantle proposed bygeophysical observations [e.g., 1] suggested thatthe lower mantle had the largest viscosity in the
Earth’s mantle. In order to understand mantle
dynamics in the Earth’s interior, it is important toknow the viscosity of the Earth’s lower mantle.
However, there are large variations of viscosity inthe lower mantle between suggested models
because of limitation of locations for geophysicalobservations. Therefore it is important to determine
viscosity of lower mantle minerals by high pressure
experiments in order to discuss mantle dynamics.
Bridgmanite would be the most abundant mineralin the lower mantle. This mineral could dominate
the lower mantle viscosity. In this study, we
conducted in-situ stress-strain measurements ofuniaxial deformation experiments of bridgmanite
aggregate using D-111 type high pressure
apparatus.
Experimental: In-situ measurements wereconducted using MAX III with D111 type guideblock at PF-AR NE7A beam line. Mg-purebridgmanite aggregates were used as starting
material. Experimental conditions are 1473-1673 K
and 24-27 GPa. Strain of bridgmanite wasmeasured by X-ray radiographies taken using an
imaging system composed of a YAG crystal and a
CMOS camera. WC second cubic anvils with cone
(6.5°) to take 2D X-ray diffraction, was used along
X-ray path. Two-dimensional X-ray diffraction
patterns were corrected for 240 s using flat panel
detector. To calculate pressure and the stressmagnitude of bridgmanite, (112) X-ray diffraction
peaks were used.
Results and Discussion: Largest strain wasreached to approximately 20 %. It is confirmed thatstrain rate can be well controlled using stroke speedof differential rams. Steady state creep wereobserved at 1473 K – 1673 K and 5 × 10-6 – 3.8 ×
10-5 /s. The creep strength of bridgmanite in thisstudy is the largest in constituent mantle minerals
reported by D-DAI apparatus at 10-5 /s.

Figure 1 X-ray radiographs of (a) before deformationand (b) after deformation.

Figure 2 Strain versus time for deformation experiments.
This experiment consists of the tests with three different
strain rates

References: [1] [1] A.M. Forte & J.X. Mitrovica,
Nature, 410, 1049-1056, 2001.

Ab-Initio Investigation of Iron Self-Diffusion:
Implications for the Plasticity of Earth’s Inner Core
1,*

S. Ritterbex and 1Taku Tsuchiya,
Geodynamics Research Center, Ehime University 2-5 Bunkyo-cho, Matsuyama, Ehime 7908577, Japan, *email: ritterbex.sebastian_arthur_willem.us@ehime-u.ac.jp

The mechanical properties of Earth’s innercore are essential for understanding theevolution and dynamics of the core.
However, little is known about themechanical properties of iron at inner core
conditions.
Therefore,
long-standing
questions remain open about the viscousstrength of the inner core (Yoshida et al.,
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.
16

H (eV)

10high pressure

8

4

VA,hcp = 1.8 cm3 mol-1
VA,fcc = 1.7 cm3 mol-1

fcc

0

50

−2

10-14 s-1

10

10−4

10−8
3000

VA,fcc = 2.9 cm3 mol-1

6100

10-14 s-1
10-16 s-1
10-18 s-1

pure climb creep

hcp iron
P=360 GPa

10-16 s-1
10-18 s-1

hcp

VA,hcp = 3.1 cm3 mol-1

12

102

10−6

low pressure

14functional approach to calculate allquantities entering the diffusion coefficient,including the role of pressure (Fig. 1) andtemperature, and quantify the self-diffusion
coefficient of hcp iron according totransition state theory (TST).

σ (MPa)1

100 150 200 250 300 350 400 450
P (GPa)Figure 1: Defect energetics as a function ofpressure for hcp and fcc iron. The tangentsto the curves represent the activation
volume of vacancy diffusion at theappropriate pressures.
Under conditions of the Earth’s deep
interior, the rate of plastic deformation is
expected be constrained by atomic
diffusion. Experimental studies on
diffusion in iron-nickel alloys at elevatedpressure and temperature conditions finally
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

recovery-controlled creep

4000

5000
6000
T (K)

7000

8000

Figure 2: Deformation mechanism map
including the rate-limiting bounds for
climb-controlled dislocation creep in hcp
iron at 360 GPa. The blue rectangle
suggests the most likely mechanism tooperate under conditions of the inner core.
Vacancydiffusion
controls
many
deformation
mechanisms
suchas
dislocation creep, an effective strain
producing mechanism in metals. We
derived a creep 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 inner coreviscosity (Fig. 2).

Imaging subducted slabs in the mantle from inversion of seismic waveforms
Kenji Kawai1*, Anselme Borgeaud1, Yuki Suzuki1 1Department of Earth and Planetary Science, University ofTokyo, Tokyo 113-0033, Japan *email:kenji@eps.s.u-tokyo..ac.jp
Introduction: Seismic tomographic studies
have inferred the three-dimensional seismologicalstructure in the Earth’s deep interior [e.g., 1, 2].
Some subducted slabs are found to be stagnant
above or below 660 km discontinuity, while others
fall through the lower mantle and reach thelowermost mantle (see [3] for details), suggesting
the whole-mantle convection rather than the layered
mantle convection. Recent waveform inversion
studies with better resolution especially for the low
velocity anomaly have found vertically continuous
low-velocity columns in the lower mantle andsuggested that the thermochemical plumes rooted in
the D" region are associated with the prominent
hotspots [4]. Hence, seismic tomographic studies
have contributed to understanding the mantle
convection.
It has been, however, difficult to estimate howlong it takes for the Earth’s mantle to migrate
between the Earth’s surface and the core-mantle
boundary (CMB) since the seismic tomographic
studies provide information on the current Earth’s
deep interior. In order to better understand theEarth’s evolution and dynamics dating inside theEarth is essential. Therefore, we try to infer thedetailed seismic velocity structure in the mantle
transition zone and D" region beneath Central
America and the Northern Pacific because
continuous subduction of oceanic plates beneath theNorth and South American plates has been taking
place since more than 200 Myr ago [5] andinvestigate the fate of subducted oceanic lithosphereand the thermal and chemical evolution of the Earth.
Data and Method: The used events are deepand intermediate-focus events recorded atbroadband seismic stations of the USArray,
Canadian Northwest Experiment (CANOE), Global
Seismographic
Network(GSN-IRIS/USGS),Southern California Seismic Network (SCSN),
Pacific Northwest Seismic Network (PNSN),
Berkeley Digital Seismic Network (BDSN), andCanadian National Seismograph Network (CNSN).
The data are filtered in the period range of 8 or 12.5
to 200 s using a Butterworth bandpass filter. The 3Dmodel is obtained by linearized inversion withrespect to a spherically symmetric initial model.
We formulated the inverse problem of waveform
inversion for localized 3-D seismic structure,computing partial derivatives of waveforms withrespect to the elastic moduli at arbitrary points inspace for anisotropic and anelastic media [6, 7] andapplied our method to the assembled dataset toinvert for 3-D shear wave structure
Results and Discussion: The inferred model
showed the presence of two distinct slabs at the
CMB beneath Central America and Venezuela andone prominent slab beneath the Northern Pacific due
to subduction 200 Myr ago [5], and how these slabs
possibly modulate the formation of passive
upwelling (called “passive plume”) of hot basal
mantle material [8, 9]. It then showed how such
plumes interact with slabs subducting in the upper
mantle and tearing of the subducted slab takes place
based on high-resolution seismic images [10].
The inferred imaging enables us to date the slab
at some depth taking into account the geologicalevents investigated based on plate reconstructionand estimate a viscosity contrast between the upperand lower mantle of 9-12, which is about 5 times
smaller than that estimated from post-glacial
rebound [11, 12]. Also, it implies that subduction
from the Earth’s surface down to the base of the
mantle affects the surface environment in two ways:
1) intermittent and localized subduction to the baseof the mantle cools down the CMB, influencing
convection in the outer core, and thus thegeodynamo and geomagnetic field. Increased heat
flux from the core to the mantle can trigger
geomagnetic reversal; 2) Subduction to the CMB
modulate the formation of passive plumes, which ifthey reach the Earth’s surface lead to volcanism that
can affect the composition of the atmosphere andtemperature of the Earth’s surface. This study
suggests the coupling between Earth’s deep mantle
and Earth’s surface.
References: [1] Romanowicz, B., Annu. Rev. Earth
Planet. Sci., 31, 303–28, 2003. [2] Dziewonski, A.M.
et al., EPSL, 299, 69–79, 2010. [3] Fukao, Y. et al.,Annu. Rev. Earth Planet. Sci., 37, 19-46, 2009. [4]French, S.W., & Romanowicz, B., Nature, 525, 95–
99, 2015. [5] Müller, R.D. et al., Annu. Rev. Earth
Planet. Sci., 44, 107–138, 2016. [6] Kawai, K. et al.,
GJI, 197, 495–524, 2014. [7] Konishi, K. et al., GJI,
199, 1245–1267, 2014. [8] Suzuki, Y. et al., EPS,
68:198, 2016. [9] Borgeaud, A.F.E., et al., Sci. Adv.
3, e1602700, 2017. [10] Borgeaud, A.F.E., PhD
Thesis, Univ. Tokyo, 2019. [11] Hager, B., JGR, 89,
6003–6015, 1984. [12] Forte, A. M., & Mitrovica, J.
X., Nature, 410, 1049–1056. 2001.

Electrical resistivity and thermal conductivity of fcc Fe: Implications for the Mercury’s core
H Gomi1*, T Yoshino1 1Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan.
*email:hitoshi.gomi@okayama-u.ac.jp
Introduction: The Mercury’s magnetic field may
be sustained by the geodynamo motion in the liquid Fe
core. However, its strength is about 1% of that of Earth.
This weak magnetic field may implies a partly stratified
core [1, 2]. Gomi et al. [3] pointed out that the geometryof the thermal stratification depends critically on thedepth dependency of the thermal conductivity. In thisstudy, we conducted first-principles calculations on theface-centered cubic (fcc) Fe to constrain the electricalresistivity and the thermal conductivity of the Mercury’s
core.
Methods: We calculated the electrical resistivity
and the thermal conductivity of fcc Fe by means of the
Korringa-Kohn-Rostoker method combined with thecoherent potential approximation (KKR-CPA) [4]. The
CPA was adopted to treat the disorder effects due to theatomic vibrations and the magnetic fluctuations on theelectronic band structure [5-7]. Within the alloy analogy
model, the thermal atomic displacements wererepresented by a discrete set of Nv displacement vectors
ΔRv(T), where |ΔRv(T)|=√〈u2〉 is the root mean squaredisplacement of atoms, which is based on the Debye
model without zero point vibration. The lattice parameterand the Debye temperature are obtained from theequation of state of fcc Fe [8]. In addition to thenon-magnetic state, the magnetic disorder was simulatedby the local magnetic disorder (LMD) approach. The
conductivity was calculated by the Kubo-Greenwood
formula with the vertex correction.
Results and Discussion: The calculated electricalresistivities and thermal conductivities with LMD state
are consistent with the literature data at 0 GPa [9, 10],whereas the non-magnetic results show smaller
resistivity and larger thermal conductivity. This suggests
the importance of the magnetic scattering at low
pressures. However, our calculation predicts that themagnetic contribution banishes at higher pressures than
20 GPa. Figure 1 compares the present results andprevious experiments [11-14] on the electrical resistivity
at ~5 GPa. Note that, within the fcc stability field,
previous measurements have a large variation. Our
calculated resistivity values are between Secco and
Scholoessin [11] and Silber et al. [14].
We further calculated the electrical resistivity and thethermal conductivity of fcc Fe up to 50 GPa and 3000 K.
The thermal conductivity increases with increasingpressure and temperature (Figure 2). This means that, if
the inner core is absent, the thermal stratification starts
from the bottom, and, after the onset of the inner core, athick thermal stratified layer may develop at the top of
the fluid core [3].

Figure 1 Electrical resistivity of Fe at ~5 GPa. Red solidline indicates the present calculations of fcc Fe with
LMD. Gray broken line, gray squares, open diamonds,
and black circles are previous experiments by Secco and
Schloessin [11], Deng et al. [12], Pommier [13] andSilber et al. [14], respectively.

Figure 2 Thermal conductivity of fcc Fe at high pressure
and temperature. Thermal conductivity increases withincreasing pressure and temperature.

References: [1] Christensen, U. R., Nature, 444, 1056
(2006). [2] Stanley, S., et al., Earth Planet. Sci. Lett., 234,
27, (2005). [3] Gomi, H., et al., Phys. Earth Planet. Inter.,
224, 88, (2013). [4] Akai, H., J. Phys.: Cond. Matt., 1,8045, (1989). [5] Glasbrenner, et al., Phys. Rev. B, 89,174408, (2014). [6] Ebert, H., Phys. Rev. B, 91, 165132,(2015). [7] Kou, S., and Akai, H., Solid Stat. Commun.,
276, 1, (2018). [8] Tsujino, N., et al., Earth Planet. Sci.
Lett., 375, 244, (2013). [9] Ho, C. Y., et al., J. Phys.
Chem. Ref. Data, 1, 279, (1972). [10] Ho, C. Y., et al., J.
Phys. Chem. Ref. Data, 12, 183, (1983). [11] Secco, R.
A., Schloessin, H. H., J. Geophys. Res., 94, 5887, (1989).
[12] Deng, L., et al., Geophys. Res. Lett., 40, 33, (2013).
[13] Pommier, A., Earth Planet. Sci. Lett., 496, 37,(2018). [14] Silber, R. E., et al., Sci. Rep., 8, 10758,(2018).

Study on transport properties of liquid iron and iron alloy under high temperature and high pressure using
the laser shock technique
K Miyanishi1*, N Ozaki1, 2, S Ohmura3, M Harmand4, A Krygier5, T Nishikawa2, Y Umeda2, K Shigemori1, Y
Sakawa1, T Sano1 and R Kodama1, 2
1Institute of Laser Engineering, Osaka University, 2Graduate school of engineering, Osaka University, 3Facultyof Engineering, Hiroshima Institute of Technology, 4IMPMC, Sorbonne Université, 5LLNL*email:miyanishik@ile.osaka-u.ac.jp
Introduction: Information on the thermal andelectrical transport properties of iron alloys underhigh-pressure and high-temperature conditions
corresponding to the earth’s outer core is necessary
to clarify the convection phenomena of the earth andthe cooling history. In particular, the transport
properties in the outer core–mantle boundary
condition strongly influence the mantle convection,
the outer core convection generating the earth's
magnetic field, the growth and inner flow of theinner core, and so on. However, there are very few
experimental examples concerning high-pressureand high-temperature liquid iron/iron-alloy whichcorrespond to the outer core conditions, and only a
few cases have been reported for pure iron [1]. It is
required to investigate transport coefficients ofliquid iron alloys containing light elements tosimulate actual outer core, experimentally. The laser
shock technique has several advantages to exploringiron-alloys under high-pressure and hightemperature condition. As there is no mechanicalrestriction on pressure generation, producing thepressure of even TPa is easy, and high heating rate
exceeding 1015 K / s is possible, and it is a closed
system that is not affected by surroundings.
Therefore the technique is effective for generationand observation of high-pressure and hightemperature liquid iron-alloys. In this research, wereport electrical conductivity deduced from opticalreflectivity, pressure and temperature measurementsof laser shock compressed iron and iron-silicon (FeSi) alloy at and above the earth's outer core
conditions.
Experimental: Target assemblies containing
polypropylene (CH), aluminum, quartz, iron or iron-silicon alloy and magnesium oxide (MgO) window
were shock compressed by the laser shock techniqueat the GEKKO XII laser facility, the Institute ofLaser Engineering, Osaka University. Iron and ironsilicon alloy were formed by electron beam
evaporation on the MgO window. Laser beams witha wavelength of 527 nm were focused onto the target.
A focal spot was 1 mm in diameter with a flat-top
spatial intensity distribution resulting in a planar
shock front. Temporal shape of the laser pulse wasapproximately a flat-top with a full-width at halfmaximum of 2.5 ns. The velocity interferometersystem for any reflector (VISAR) measures aparticle velocity and a reflectivity at the interface
between iron or iron-silicon alloy and MgO. The
pressure was evaluated using measured particle
velocity and a known equation of state of MgO[2].
The optical pyrometer measures the temperature at
the interface through the MgO window.
Results and Discussion: The pressuresdetermined from the measurement results werefrom 200 to 400 GPa, and the temperatures were up
to 15000 K. We observed, in the case of iron, adecrease in reflectivity as the pressure increased,
whereas in the case of the iron-silicon alloy, acontinuous increase following a discontinuous
decrease at around 250 GPa in the reflectivity.
These results suggest that the trends in change ofelectrical conductivity in iron and iron-silicon alloy
are significantly different in the pressure and thetemperature conditions.
References: [1] K. Ohta, Y. Kuwayama, K.
Hirose, K. Shimizu, Y. Ohisi: Nature, 534, 95(2016). [2] S. Root, L. Shulenburger, R. W. Lemke
et al.: Phys. Rev. Lett, 115, 198501 (2015).

Deformation, crystal preferred orientations, and seismic anisotropy in the Earth’s D" layer
D. Mainprice*Geosciences Montpellier, CNRS & Université de Montpellier, F-34095 Montpellier cedex 5,
France.
*email: david.mainprice@umontpellier.fr
We use a forward multiscale model that couples
atomistic modeling of intracrystalline plasticity
mechanisms (dislocation glide ±twinning) in
MgSiO3post-perovskite (PPv) and periclase (MgO)
at lower mantle pressures and temperatures topolycrystal plasticity simulations to predict crystal
preferred orientations (CPO) development andseismic anisotropy in D″. We model the CPO
evolution in aggregates of 70% PPv and 30% MgO
submitted to simple shear, axial shortening, andalong corner-flow streamlines, which simulatechanges in flow orientation similar to those
expected at the transition between a downwellingand flow parallel to the core–mantle boundary(CMB) within D″ or between CMB-parallel flow
and upwelling at the borders of the large low shear
wave velocity provinces (LLSVP) in the lowermost
mantle. Axial shortening results in alignment of
PPv [010] axes with the shortening direction.
Simple shear produces PPv CPO with a monoclinic
symmetry that rapidly rotates towards parallelism
between the dominant [100](010) slip system andthe macroscopic shear.
These
predictions
differfrom
MgSiO3post-perovskite textures formed indiamond-anvil cell experiments, but agree withthose obtained in simple shear and compression
experiments
using
CaIrO3post-perovskite.
Development of CPO in PPv and MgO results inseismic anisotropy in D″. For shear parallel to the
CMB, at low strain, the inclination of ScS, Sdiff,and SKKS fast polarizations and delay times varydepending on the propagation direction. At
moderate and high shear strains, all S-waves arepolarized nearly horizontally. Downwelling flow
produces Sdiff, ScS, and SKKS fast polarization
directions and birefringence that vary gradually as
a function of the back-azimuth from nearly parallel
to inclined by up to 70◦ to CMB and from null to∼5%. Change in the flow to shear parallel to the
CMB results in dispersion of the CPO, weakeningof the anisotropy, and strong azimuthal variation of
the S-wave splitting up to 250 km from the corner.

Evolution of the PPv CPO and of the S-waves
polarization anisotropy predicted for the 70% PPv+30% MgO aggregate along a corner flow line
simulating the change in flow direction associatedwith the transition from a downwelling to shearing
parallel to the CMB (cf. sketch at the bottom left of
the figure).

Evolution of the PPv CPO and of the S-waves
polarization anisotropy predicted for the 70% PPv+30% MgO aggregate along a corner flow line
simulating the change in flow direction associatedwith the transition from shearing parallel to the
CMB to upwelling at the border of a LLSVP (cf.
sketch at the bottom right of the figure)Transition from horizontal shear to upwellingalso produces weakening of the CPO and complex
seismic anisotropy patterns, with dominantly
inclined fast ScS and SKKS polarizations, overmost of the upwelling path. Models that take into
account twinning in PPv explain most observationsof seismic anisotropy in D″, but heterogeneity of
the flow at scales <1000 km is needed to comply
with the seismological evidence for low apparent
birefringence in D″. account twinning in PPv
explain most observations of seismic anisotropy inD″, but heterogeneity of the flow at scales <1000
km is needed to comply with the seismologicalevidence for low apparent birefringence in D″
Reference: Tommasi A. et al. Earth and Planetary
Science Letters 492 (2018) 35–46.

Azimuthal anisotropy in the lowermost mantle beneath Philippine from ScS–S travel times
S Tanaka1* 1D-Earth, JAMSTEC, 2-15 Natsushima-cho, Yokosuka, 237-0061, Japan.
*email:stan@jamstec.go.jp
Introduction: Seismic anisotropy in thelowermost mantle has been detected by splitting ofdiffracted S and ScS phases, the discrepancy of shear
wave splitting of SKS and SKKS, to date. In manycases, the propagation direction of such seismic
waves is restricted due to the combination of sources
and receivers. Thus, the azimuthal anisotropy using
ray paths passing in multi-directions has been rarely
discussed. Now, seismic networks and large-scale
seismic arrays have been increasing especially in theeastern Asia where there are also many earthquakes.
It is a good opportunity to examine an azimuthal
variation of travel times passing through the outsideof the Pacific Large Low Shear Velocity Province,
where the existence of anisotropy in the lowermost
mantle is expected.
Data and Method: I used the seismograms ofearthquakes occurred in Mariana, east China,
Indonesia, and Vanuatu that are record with theseismic stations belonging to IRIS GSN and
PASSCAL, Thai Metrological Department, F-net,
JISNET, NECESSArray (Fig.1). This geometry gives
a good condition that the mid-points of seismic raypaths are located near Philippine with various
azimuths.

Figure 1 Distribution of hypocenters (sold stars) andstations (green triangles).

I measured ScS–S differential travel times using a
waveform cross-correlation method, which caneffectively cancel the heterogeneity in the crust andupper mantle and the uncertainty of hypocenters. The
differential travel times are compared with theoreticaltravel times by PREM [1] with correction of physicaldispersion due to anelasticity for the typical period of
10 s, that for ellipticity of the Earth [2], finally I
obtained about 500 residuals. Even though I used thedifferential travel times, the ScS–S residuals show thelarge scattering and the correlation with the residualsof S travel times are much larger than that of ScS
phases. This means that the raw ScS–S residuals areaffected by heterogeneity in the upper part of thelower mantle where only S waves are propagated.
Thus, we applied the further corrections using 3D
mantle heterogeneity models.
Results and Discussion: We used S-wave 3Dmodels of S16U6L8 [3], S4BL16 [4], S40RTS [5],SEMUCB-WM [6], and a P-wave 3D model of GAPP4 [7] with conversion rate dlnVs/dlnVp=1.7 [8]. I
found that the scatter of the ScS–S residuals are much
improved and that the correlation coefficient between
the residuals of ScS–S and ScS are increased and thatbetween ScS–S and S are much reduced when the
GAP-P4 model are used for the correction, probably
due to its high spatial resolution in the upper lower
mantle. As a result, only the ScS–S residuals
corrected with the modified GAP-P4 can be used toinfer seismic anisotropy in the lowermost mantle.
Then I fitted cos 2q and cos 4q curves with leastsquare to obtain the characteristics of the azimuthal
variation of the ScS–S residuals, clearly indicatingthat cos 2q component is significant with the fastest
direction (the minimum ScS–S) is along ESE-WNW.

Figure 2 Azimuthal variation of ScS–S residual correctedwith the modified GAP-P4. Red, blue, and green lines are
the fitted curve composed of cos 2q and cos 4q, 2q, 4q
components, respectively.

References: [1] Dziewonski, A.M. and Anderson,
D.L., Phys. Earth Planet. Inter., 25, 297 (1981).
[2] Kennett, B.L.N. and Gudmundsson, O., Geophys.
J. Int., 127, 40 (1996). [3] Liu, X.F. and Dziewonski,
A.M., In: The Core-Mantle Boundary Region, 21(1998). [4] Masters, G., et al., In: Earth's DeepInterior: Mineral Physics and Tomography from theAtomic to the Global Scale, Geophysical Monograph
17, 63 (2000). [5] Ritsema, J., et al., Geophys. J. Int.
184, 1223 (2011). [6] French, S.W. and Romanowicz,
B., Nature 525, 95 (2015). [7] Obayashi, M., et al.,Geophys. Res. Lett. 40, 5652 (2013). [8] Karato, S.,
Geophys. Res. Lett., 20, 1623 (1993).

Topography of the western Pacific LLSVP constrained by S wave multipathing
Sunil K. Roy1,2, Nozomu Takeuchi1* , D. Srinagesh2, M. Ravi Kumar2,3 and Hitoshi Kawakatsu1 1Earthquake
Research Institute, University of Toyo, Bunkyo-ku, Tokyo 113-0032, Japan 2CSIR-National GeophysicalResearch Institute, Hyderabad, 500007, India 3Institute of Seismological Research, Gandhinagar, 382009, India.
*email:takeuchi@eri.u-tokyo.ac.jp
Summary of Our Finding: We found that
SHdiff phases generated by earthquakes in the FijiTonga, recorded in India, are accompanied bysecondary pulses. We interpreted them as aconsequence of multipathing of S waves caused by
the Pacific Large Low-Shear-Velocity Province(LLSVP). We analyzed the differential travel
times between SHdiff and the secondary pulse,
together with the absolute SHdiff arrival times, toconstrain the thickness and velocity perturbations in
the western end of the Pacific LLSVP. Our preferredmodel shows a lateral variation in the thickness of
the LLSVP; the southern part of our study region
revealing a thicker (300 km) low velocity region
compared to the northern part (200 km). However,the velocity perturbations of the LLSVP appear to
be comparable (-1.5%). The results are consistent
with a scenario that the LLSVP is a chemicallydistinct pile with significant surface topography.
Discussion: In this study, we showed that theobserved waveforms can be explained without muchalteration of the existing tomography models [1].
Our observations suggest that the western edge ofPacific LLSVP extends in the NE-SW direction
from 129.5°E to 136.5°E and has a smaller-scale
topography. There is a variation in the topographyof the western edge of the Pacific LLSVP from 300
km to 200 km, from south to north. The observations
also suggest that the edge of the LLSVP (i.e., ourstudy region) has both significant thickness andsurface topography, which favors the LLSVP as achemically distinct pile. The existence of
topography whose scale length is much smaller than
the whole Pacific LLSVP suggests some dynamic
process at the western edge such as a regional plume,
instability of dome-like structure, or push due todownwelling from the outside [2,3].
Sharpness of the top of LLSVP is important toconstrain the origin of this large anomaly. The
amplitude of the secondary phase decreases if the

thickness of the transition zone is greater than ~60
km. Although precise quantification is difficult,considering the observed amplitudes of thesecondary pulses being more than ~30% of the first
pulse for most of the cases, a gradual transition fromthe ambient mantle to the LLSVP is unlikely and the
LLSVP should be a distinct region.
It is debated whether the origin of the LLSVP isthermal or chemical [4-6]. Our results favor a
chemical origin because of the following reasons. If
the thermal anomalies were the origin, we expect
predominance of smaller scale anomalies withcomplex geometry that compose plume clusters [6].
Such smaller scale features were required to explain
the sharp sides observed in previous seismologicalstudies [7,8]. However, to explain the secondary
pulses observed in this study, we need quasihorizontal upper boundary of the lower velocity
region, otherwise we hardly expect phases withsimilar apparent velocity and arrival time as thosefor the SHdiff phase. To further constrain the origin,
we probably need to analyze Pdiff and its post- or
pre-cursors, which is a future research topic.
References: [1] Takeuchi, N., Earth Planet. Sci.
Lett., 319-320, 55–64, (2012). [2] Tan, E. & Gurnis,
M., J. Geophys. Res.: Solid Earth, 112(B6), (2007).
[3] Tan, E., Leng,W., Zhong, S., & Gurnis, M.,
Geochem. Geophys. Geosyst., 12(7) (2011). [4]McNamara, A. K. & Zhong, S., Nature, 437, 1136–
1139 (2005). [5] Bull, A. L., McNamara, A. K., &Ritsema, J., Earth Planet. Sci. Lett., 278, 152–162(2009). [6] Davies, D. R., Goes, S., Davies, J.,
Schuberth, B., Bunge, H.-P., & Ritsema, J., Earth
Planet. Sci. Lett., 353-354, 253–269 (2012). [7] Ni,
S., Tan, E., Gurnis, M., & Helmberger, D., Science,
296(5574), 1850–1852 (2002). [8] To, A.,
Romanowicz, B., Capdeville, Y., & Takeuchi, N.,
Earth Planet. Sci. Lett., 233(1), 137–153 (2005).

Measurements of high pressure-temperature thermal conductivity of the Earth’s lower mantle minerals ina laser-heated diamond anvil cell
K Ohta1*, A Hasegawa1,2, T Yagi2, Y Okuda1, K Onga1, K Hirose3,4, & Y Ohishi51
Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan,
2
National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology,
Tsukuba, Ibaraki 305-8563, Japan, 3Earth-Life Science Institute, Tokyo Institute of Technology, Meguro, Tokyo
152-8551, Japan, 4Department of Earth and Planetary Science, The University of Tokyo, Bunkyo, Tokyo 1130033, Japan, 5Japan Synchrotron Radiation Research Institute, Sayo, Hyogo 679-5198, Japan.
*email:k-ohta@geo.titech.ac.jp
As given by the Fourier’s law, heat conduction
in material is characterized by thermal conductivity,
a function of thermal diffusivity, density, andisobaric heat capacity. The thermal transport
properties of the Earth’s constituents are important
information to understand thermal evolution and theheat budget of the Earth. Thus, the experimental
determination of thermal conductivity of deep Earthmaterials are required.
The diamond anvil cell (DAC) is capable ofaccessing the pressure-temperature conditions of the
Earth’s deep interior, and is compatible with laser
optical techniques. The pulsed light heating
thermoreflectance (TR) method has been applied toa DAC in order to measure thermal conductivity anddiffusivity of condensed material [1,2]. This TR
with DAC method successfully obtained the thermal
conductivity of the Earth’s lower mantle minerals tothe pressure condition equal to the Earth’s coremantle boundary (135 GPa) but at room temperature[3,4]. To extend measurable temperature range, theTR method may be combined with a laser-heated
DAC (LHDAC) technique that is able to generate
the pressure-temperature condition equivalent to thecenter of the Earth.
We recently developed a new instrument tomeasure the thermal diffusivity (and thus thermal
conductivity) of sample in-situ at high pressure andtemperature based on the combination of the TR
method and the LHDAC system (Fig. 1). A
symmetric-type DAC is used for high-pressure
generation. The sample is loaded into a sample hole
drilled at the center of preindented rhenium gasket.
We use a double-sided high-power CW laser heating
technique to generate stable high temperature
conditions of sample in a DAC. Temperature
generated by the CW lasers is determined fromthermal radiation spectra from the heated sample. A
pulsed pump laser and a CW probe laser are also
irradiated to the sample to determine heat diffusion
time through the sample via the thermoreflectancephenomena. Details of the thermoreflectancetechnique in a DAC may be found in our previous
studies [2-4].

CW heating
laser

CW heating
laser

CW Probe
laser
Pulsed pumplaser

SampleRe gasket

Figure 1 Schematic illustration of the cross section of the
DAC and the arrangement of four laser beams for TR
pump laser, TR probe laser and heating CW lasers.

As a performance test of the developed system,
we examined thermal conductivity of Pt at 40 and 56
GPa and high temperatures up to 1910 K. We foundpositive pressure and temperature dependence of the
conductivity of Pt, which is in good agreement withthe previous study employing the flash heating
method in a LHDAC [5].
We also measured the thermal conductivity ofthe major minerals in the Earth’s lower mantle, MgO
periclase, MgSiO3 bridgmanite, post-perovskite and
CaSiO3 perovskite in-situ at high pressures and hightemperatures. These are the first experimental
demonstrations of thermal conductivity of the lower
mantle minerals at the conditions below the mid-partof the Earth’s lower mantle. The new thermal
conductivity measurement system will shed light on
the controversial thermal transport properties of the
Earth’s deep interior [6].
References: [1] Hsieh, W.-P. et al., Phys. Rev. B, 80,
180302 (2009). [2] Yagi, T. et al., Meas. Sci.
Technol., 22, 024011 (2011). [3] Imada, S. et al.,Geophys. Res. Lett., 41, 4542–4547 (2014). [4]Okuda, Y. et al., Earth Planet. Sci. Lett., 474, 25–31(2017). [5] McWilliams, R. S. et al., Phys. Earth
Planet. Inter., 247, 17–26 (2015). [6] Kavner, A. andRainey, E.S.G., Deep Earth: Physics and Chemistryof the Lower Mantle and Core, 31–42 (2016).

Sound velocity of liquid Fe–Ni–S–Si under pressure
H Terasaki1*, I Yamada1, A Kamiya1, R Tsuruoka1, T Kondo1, Y Higo2, A Machida3
1
Department of Earth and Space Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan. 2Japan
Synchrotron Radiation Research Institute, Sayo, Hyogo, 679-5198, Japan. 3National Institute for Quantum andRadiological Science and Technology, Sayo, Hyogo, 679-5148, Japan.
*email:terasaki@ess.sci.osaka-u.ac.jp
Introduction: Most of the terrestrial planets has
a liquid core, which mainly consists of Fe-Ni andalso contains possibly some light elements. Siliconhas been considered as a major candidate of the lightelement in Mercury core since Si tends to dissolve
into Fe in reduced condition and Mercury interior is
expected to be reduced due to its large metallic core.
However, it is found from recent X-ray spectroscopyof the MESSENGER spacecraft that surface on
Mercury contains 1–4 wt% of sulfur [1]. The S
content on the surface suggests that certain amountsof S and Si are likely to dissolve into liquid ironbased on partitioning of S and Si between metal andsilicate melts [2]. This indicates that both S and Si
are likely to be contained in the Mercury core. Thus,
elastic properties of liquid Fe–Ni–S–Si areimportant to understand the interior structures ofMercury and properties of its liquid outer core. In
this study, we measured sound velocity of liquid Fe–
Ni–S–Si under pressure to obtain their elastic
properties.
Experimental: The experiments were carriedout at BL04B1 and BL22XU beamlines, SPring-8
synchrotron facility. High pressure was generatedusing 1500 ton Kawai-type or 180 ton cubic
multianvil press. Used size for truncated edge
lengths were 5 mm for Kawai-press and 6 mm for
cubic press. We used two Fe–Ni–S–Si sample
compositions (Fe-11wt%Ni-6wt%S-4wt%Si andFe-11wt%Ni-3wt%S-8wt%Si). The sample pellet
was sandwiched by single crystal sapphire buffer
rods. High temperature was generated using
cylindrical graphite or TiC resistive heater.
The P-wave velocity was measured using thepulse-echo overlap method. The LiNbO3 transducer,
which generated the ultrasonic wave, was attachedon the backside of the tungsten carbide anvil. The
echo signals from the sample interfaces weredetected using a high resolution digital oscilloscope
to measure the P-wave travel time in the sample. The
sample length was determined from X-ray
radiography image of the sample. The P-wave
velocity (VP) was measured up to 16.3 GPa and 2010
K in this study.

Results and Discussion: The effect oftemperature on the VP of both Fe–Ni–S–Si
compositions are quite small in the range of present
conditions. The VP of both compositions increase
mildly with increasing pressure. Compared to thereported VP of liquid Fe–Ni [3], the VP of liquid Fe–
Ni decreases approximately 1.6% by addition of
6wt%S and 4wt%Si and 3.1% by addition of 3wt%S
and 8wt%Si. Therefore, addition of S reduces the VP
effectively whereas that of Si increases the VP in the
Fe–Ni–S–Si system. The elastic data obtained in thisstudy is applicable to estimate the core size andcomposition of the Mercury Fe–Ni–S–Si core.
References: [1] Nittler, L.R. et al., Science, 333,
1847 (2011). [2] Chabot, N.L. et al., Earth Planet.
Sci. Lett., 390, 199 (2014). [3] Kuwabara, S. et al.,Phys. Chem. Mineral., 43, 229 (2016).

Sound velocity of liquid Fe-P alloy under high pressure based on inelastic X-ray scattering measurements
Y. Nakajima1,2*, D. Kinoshita1, Y. Kuwayama3, K. Hirose3,4, A. Iwamoto1, S. Tateno4, D. Ishikawa2,5, A.Q.R.
Baron2
1
Department of Physics, Kumamoto University, 2Materials Dynamics Laboratory, RIKEN SPring-8 Center,3
Department of Earth and Planetary Science, The University of Tokyo, 5Earth and Life Science Institute, Tokyo
Institute of Technology, 5SPring-8/JASRI*email:yoichi@kumamoto-u.ac.jp
Introduction: The Earth’s liquid outer core iscomposed mainly of iron with several wt.% nickel.
The density and velocity of the outer core are 10%less and 4% higher, respectively, than that of Fe-Ni
alloy, indicating that the core contains lighter
components [1]. The nature of the light elements inthe core is key to understanding the Earth’s building
blocks, planetary accretion and core formation
processes, and subsequent chemical and thermal
evolution of the core. The influence of possible
lighter elements on the elastic parameters of liquid
Fe under high-pressure and -temperature relevant tothe core conditions is fundamental to constrain thelight elements in the core.
Phosphorous is one of the candidates for lightelements in the core because it is found in ironmeteorites [2] and depleted in the silicate mantle
relative to chondrites [3]. In this study, we
determined the P-wave velocity of liquid Fe-P alloy
under static high-pressure conditions to 80 GPa
based on inelastic X-ray scattering (IXS)
measurements in a laser-heated diamond-anvil cell
LH-DAC.
Experimental: We performed high-pressure
IXS measurements at the beamline BL43LXU of theSPring-8 synchrotron facility [4]. The sample was
Fe3P (hereafter called Fe75P25), which was packed
into the sample chamber of a rhenium gasket
together with two single-crystal sapphire discs that
acted as both thermal and chemical insulators. The
sample was compressed with 300 µm culet diamondanvils and heated up from both sides by using acouple of Yb3+-doped YAG fiber lasers. The
pressure was determined based on diamond Ramanshift and the temperature was measurand by aspetroradiometric method.
During heating, X-ray diffraction measurements
performed. Sample melting was judged from thedisappearance of diffraction peaks from solids andthe appearance of diffuse signals from liquid using.
IXS spectra of liquid sample were collected by ahigh resolution IXS spectrometer with an energy
resolution of ~2.8 meV using a Si(999)backscattering geometry at 17.79 keV. The incident
X-ray beam size was ~5 µm [5]. Scattered X-rays
were collected in an energy range of ±30 meV by anarray of 12 of 24 Si analyzers at different momentum

transfers (Q) between 3−6 nm-1. The collected IXS
data was analyzed for the excitation energy (E) of
longitudinal acoustic (LA) phonon mode of theliquid sample. From the obtained E-Q dispersion
relation, we determined the P-wave velocity of thesamples. We performed IXS measurements on
liquid Fe75P25 at 34−80 GPa and 2450−2800 K.
Results and Discussion: The P-wave velocity(VP) data obtained for liquid Fe75P25 are plotted as afunction of pressure in Figure 1. The Murnaghan
equation of state (EoS) was fitted to the P-VP data,with an assumption of no temperature effect on VP
of liquid Fe75P25 under the present high-pressure
conditions and 1 bar density data. The VP of liquid
Fe75P25 is almost identical to that of liquid Fe [6],whereas the bulk modulus and density derived fromthe EoS fitting are slightly lower. This exhibits that
phosphorus has negligible effect on VP of Fe, which
can be by cancelling out each effect of P on the bulk
modulus and density of liquid Fe.

Figure 1 Sound velocity of liquid Fe75P25. The solidline is a fitting to the obtained P-wave velocity of liquid
Fe75P25, which is compared with that for pure Fe based onshock-compression data [6].

References: [1] Birch, J. Geophys. Res., 57, 227(1952). [2] Skála and Císařova, Phys. Chem. Mine.,
31, 721 (2005) [3] McDonough, Treatise on
Geochem., Vol.2, 547 (2003) [4] Baron, SPring-8
Inf. Newsl., 15, 14 (2010). [5]. Baron et al., AIP Conf.
Proc., 2054, 020002 (2018) [6] Anderson andAhrens, J. Geophys. Res., 99, 4273 (1994)

Sound velocities of CaSiO3 perovskite (“breyite”) and some implications for chemicalcompositions around the 660 km discontinuity.
T Irifune1,2* and S Gréaux1,2 1Geodynamics Research Center, Ehime University, Matsuyama, Japan; Earth-Life
Science Institute, Tokyo Institute of Technology, Tokyo, Japan.
*email:irifune@dpc.ehime-u.ac.jp
Introduction: Precise measurements of soundvelocities of high-pressure minerals at high pressureand high temperature are important to constrain thechemical compositions of the deep mantle (e.g. [1]).
The GRC + JASRI group has been developing
techniques for such measurements using ultrasonicpulse-echo interferometry, and has enabled toperform sound velocity measurements under thepressure and temperature conditions of theuppermost region of the lower mantle, by a
combination of Kawai-type multianvil apparatus
and synchrotron in situ X-ray observations (e.g. [2],[3], [4]) . The group has made such measurements
on a number of important mantle minerals, such as
garnets with various chemical compositions,wadyleite, ringwoodite, akimotoite, stishovite, etc.,
as well as rocks such as pyrolite and MORB.
However, the velocity measurements on CaSiO3perovskite (CaPv) have not been made because ofunavailability of adequate sintered polycrystalline
samples of CaPv, as this phase is known to become
amorphous at the ambient pressure upon release ofpressure. Meanwhile, CaPv was recently discovered
as an inclusion in natural diamond of ultra-deep
origin [5], and named as “Breyite”, after the name ofProf. Gerhard Brey of Goethe University, which has
been approved by the IMA.
Experimental: Sound velocity measurements
were conducted at the BL04B1, SPring-8, using
SPEED-1500. The basic technique is similar to
those reported earlier ([2], [3]), but we expanded thepressure and temperature conditions toward theuppermost region of the lower mantle. A bulk glass
starting material of CaSiO3 composition was loadedin the cell, and first converted to CaPv at 21 GPa,
1300 K in 1 hour. The ultrasonic and in situ X-ray
observations were made upon decreasing
temperature at fixed press loads. We made fiveindependent such runs to see the mutual consistencyof the results. Further details of the present soundvelocity measurements on CaPv have been reported
in [6].
Results
andDiscussion:
Successful
measurements of sound velocities of cubic CaPv
have been made at pressures up to about 23 GPa andtemperatures between 600 K and 1700 K.
Significant decreases in both Vp and Vs wereobserved at temperatures below 600 K, suggesting
the cubic to tetragonal transition of CaPv at thelower temperatures. We obtained elastic moduli of
cubic CaPv as K0 = 248(3) GPa and G0 = 126(1) GPa.
The present shear modulus is substantially lower
than those predicted based on ab initio calculations(e.g. [7], [8]), while the bulk modulus is consistent
with those theoretically predicted. The present resultshows that the subducted oceanic crust of basaltic
compositions, which have 20-30 vol.% of CaPv inthe uppermost lower mantle, would have soundvelocities significantly lower than those of thesurrounding mantle, suggesting that the presence ofa basalt rich layer may be responsible for the lowvelocity signature recently found in some regions
atop of the lower mantle [9].
References: [1] Li, B and Liebermann, R. C., Phys.
Earth Planet. Inter., 233, 135 (2014). [2] Higo, Y.
et al., Phys. Earth Planet Inter., 166, 167 (2008).
[3] Irifune, T. et al., Nature, 451, 814 (2008). [4]Higo, Y et al., Rev. Sci. Instrum., 89, 014501 (2017).
[5] Nestola et al., Nature, 555, 237 (2018), [6]Gréaux et al., Nature, 565, 218 (2019). [7] Stixrude,
L. et al., Phys. Rev. B, 75, 024108 (2007), [8]Tsuchiya, T., Phys. Earth Planet. Inter. 188, 142(2011), [9] Schmandt, B. et al., Science, 344, 1265
(2014).

Internally-consistent multiple constraints on the mineralogy and seismology of Earth’s lower mantle
JF Lin1* 1Department of Geological Sciences, The University of Texas at Austin, Austin, TX78712, USA*email: afu@jsg.utexas.edu
Introduction: The mineralogical model,
seismic observations and thermal state of the
Earth’s lower mantle are key parameters tounderstand chemistry and dynamic processes ofplanet. However, it remains much debated on thechemical composition and origins of seismic
observations of the lower mantle even after decadesof experimental and theoretical efforts [1]. Directcomparison on the velocity and density profiles
between seismic observations, such as PREM andAK135, and mineral physics modeling fromlaboratory elasticity data has been widely used toconstrain the composition of lower mantle.
However, many previous studies used limited range
and/or number of physical parameters with highuncertainties for the comparison [1]. It’s thus
crucial to obtain reliable and multiple physicalparameters such as VP, VS, and ρ of singl-ecrystal(Al,Fe)-bearing bridgmanite and ferropericlase atrelevant lower mantle P-T conditions in order toderive reliable geophysical and geochemical
models of the region.
Experimental: Here we have synthesizedhigh-quality single-crystal and polycrystalline
bridgmanite and ferropericlase crystals using
5000-ton Kawai apparatus at Misasa. We have used
these well-characterized crystals such as
bridgmanite(Mg0.93Fe0.08Al0.10Si0.90O3(Fe8-Al10-Bgm) with Fe3+/∑Fe=~0.6), to measure
their VS, VP and ρ at high pressures using
combined Brillouin light scattering (BLS),
impulsive stimulated light scattering (ISLS) and
X-ray diffraction (XRD) techniques in a diamondanvil cell (DAC) [2-3].
Results and Discussion: VS, VP, and ρ ofpolycrystalline and single-crystal ferropericlase and(Fe,Al)-bearing bridgmanite crystals have beenmeasured at lower-mantle pressures. Single-crystal
results are used to derive full elastic constants offerropericlase and bridgmanite at lower-mantle
pressures. Specifically, velocity profiles of
Fe8-Al10-Bgm increase monotonically withpressure up to 83 GPa [2-3]. However, the spintransition of iron in ferropericlase and Fe-bearing
bridgmanite causes a significant drop in the VP athigh pressures. Our results also show significant Fe
and Al effects on the velocity of bridgmanite: VS of
Fe8-Al10-Bgm is slightly lower than that of
MgSiO3 and Al-bearing bridgmanite at highpressures, while its VP is significantly decreased
when compared with the extrapolation of MgSiO3
and Al-bearing bridgmanite [1-3].
We used the measured elasticity of bridgmanite
and ferropericlase, together with literature reports
on high pressure and temperaturedata of theseminerals, to quantitatively evaluate the effects ofthe temperature, spin transition as well as Fe andAl substitution on the elasticity of ferropericlase
and/or bridgmanite. These results are then used to
calculate their adiabatic bulk and shear moduli (KSand μ) [3, 4].
The elasticity data of bridgmanite andferropericlase are then used to model aninternally-consistent one-dimensional seismic andadiabatic temperature profile of lower mantle bytaking into account of the Fe/Al partitioning andthe spin transition [4]. Following thethermodynamic and elastic modeling, we derive aninternally-consistent mineralogical model andadiabatic temperature profile of lower mantle, thatcan reproduce consistent seismic profiles in VP, VS,and ρ at the whole lower-mantle pressures ranging
from 28 to130 GPa [4]. We will present theseresults and their implications in the workshop to
address the forefront scientific questions in our
understanding of the mineralogy and seismic
profiles of the lower mantle.

Figure Representative experimental Brillouin lightscattering (BLS), impulsive stimulated light scattering(ISLS), and X-ray diffraction (XRD) spectra of
single-crystal (Al,Fe)-bearing Bgm at 25 GPa. Inserts in(c) show photos of two Fe6-Al4-Bgm crystals loaded insample chambers with helium medium at 25 GPa.

References: [1] Lin, J.F. et al., Nature, 564, E18,
(2018). [2] Fu, S. et al., Geophys. Res. Lett., 45,(2018). [3] Fu, S. et al., Earth Planet. Sci. Lett.,
503, 1 (2018). [4] Fu, S. et al., in prep. (2019).

Nanoscale texture and transformation timescale of dense Mg2SiO4 polymorphs in shocked meteorites:
comparison between natural occurrences by high-resolution TEM and experimental results by fast XFEL
diffraction
T Okuchi1* 1Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan.
*email:okuchi@misasa.okayama-u.ac.jp
Introduction: Primitive meteorites often show
significant features of impact metamorphism. Oneof such features are occurrence of dense highpressure polymorphs of silicate minerals in heavily
shocked portions of the meteorites. By transmission
electron microscopy, it was discovered that somefraction of olivine (a-(Mg,Fe)2SiO4) crystals in suchmeteorites were transformed into its variety ofdenser polymorphs, which even include a recentlydiscovered new structure (e-(Mg,Fe)Mg2SiO4) thathas a unique nano-scaled microtexture (Figure 1).
While the impact events that induced suchtransformations must have played essential roles inearly history of planetary evolutions 4.5 billion
years before, there has been no successful study totransform olivine crystals into its denser polymorphs
by means of shock-compression experiments in alaboratory. Thus, temperature and stress conditionsof the impact events were still left ambiguous andcontroversial.

Figure 1 Microtexture of e-(Mg,Fe)2SiO4 occurring

within g-(Mg,Fe)2SiO4, which was observed byhigh-resolution TEM at Kochi JAMSTEC (Tomioka
and Okuchi, 2017).
Experimental: Here we experimentally reproduced
a part of such transformation processes of αMg2SiO4 forsterite olivine into its denser
polymorphs, which was successfully observed with
sub-nanosecond time resolution, by means ofultrafast x-ray diffraction scheme using x-ray freeelectron laser source at SACLA, SPring-8 (Figure 2).
The single crystals of forsterite were shockcompressed by irradiation of strong visible laser
beam of nanoseconds of pulse length, which was
focused into ~200 μm in diameter. Then its structure
was then immediately analyzed by free electron
laser beam of femtoseconds of pulse length, which
was focused into even smaller dimension where thestrongest shock compression was occurring.

Figure 2 Experimental setup for laser-driven shockcompression experiments coupled with fast XFEL
diffraction analysis (e.g., Albertazzi et al., 2017).

Results: The olivine crystals were compresseduniaxially along the a-axis until its dimension was
reduced down to ~90% of its original, and thenrapidly transformed into a denser structure having a
different space group, most possibly that of εMg2SiO4 or γ-Mg2SiO4 by means of an ultrafast slip
deformation process which completed only within a
few nanoseconds. Our current results havesignificant implication on the growth process andreaction kinetics of the olivine's dense polymorphs
naturally occurring within the meteorites, as well ason the nature of ancient impact events in the earlysolar system.
Acknowledgment: The author thanks MEXT X-ray
Free Electron Laser Priority Strategy Program,
SACLA Priority Strategy Proposal Program for"Ultrafast Processes under Extreme Conditions",
and JSPS Grant-in-Aid for Scientific Research.
References:
Tomioka, N. & T. Okuchi, A new high-pressure
form of Mg2SiO4 highlighting diffusionless phasetransitions of olivine. Sci. Rep. 7, 17351 (2017).
Albertazzi, B., N. Ozaki, V. Zhakhovsky, A. Faenov,
H. Habara, M. Harmand, N. J. Hartley, D. K.
Ilnitsky, N. Inogamov, Y. Inubushi, T. Ishikawa, T.
Katayama, H. Koyama, M. Koenig, A. Krygier, T.
Matsuoka, S. Matsuyama, E. McBride, K. Migda, G.
Morard, H. Ohashi, T. Okuchi, T. Pikuz, N.
Purevjav, O. Sakata, Y. Sano, T. Sato, T. Sekine, T.
Seto, K. Takahashi, K. A. Tanaka, Y. Tange, 16 T.
Togashi, K. Tono, Y. Umeda, T. Vinci, M. Yabashi,
T. Yabuuchi, K. Yamauchi, H. Yumoto & R.
Kodama, Dynamic fracture of tantalum under
extreme tensile stress, Sci. Adv. 3, e1602705 (2017).

Low-frequency micro-Raman spectroscopy and its application to mineral sciences
M Kanzaki1* 1Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan.
*email:mkanzaki@okayama-u.ac.jp
Introduction: Because of advent of simple andcheap Raman system with single monochromatorplus CCD detector, low-frequency Raman (below~200 cm-1) becomes nearly obsolete in last two
decades. This is due to lower frequency limit ofRaman filters (+ dichroic filter) used for those
spectrometers. However, this situation has changed
in last few years, as Ondax Inc. introduced new
Raman filter which allows measurement down to ~5
cm-1. Simultaneously, terahertz spectroscopy(corresponding far-infrared region) is now available
to non-specialists. Therefore, new era of terahertzregion spectroscopy has arrived.
Although low-frequency region is not quite
necessary for phase identification of materials (oneof most used applications), it contains richinformation of dynamics and local structure ofmaterials. Boson peak in glasses and soft mode ofphase transition are a few well known examples. In
the talk, a few examples of applications to minerals
are given to demonstrate ability of low-frequency
Raman spectroscopy.
Experimental: For micro-Raman measurement,a home-build spectrometer with singlemonochromator and CCD detector was used. Two
Ondax SureBlock filters are adopted to the system
to obtain low-frequency Raman spectra. We also
employed a Ondax NoiseBlock filter, which works
as a dichroic mirror. 488 nm solid laser with laser
power of 80 mW was used. See [1] for details of the
instrument.
For high-temperature measurements, a wireheater was used, and temperature was calibrated
against 5~6 standard materials with known melting
points [2].
Results and Discussion: First example is softmode of a-AlPO4-moganite. This is a high-pressure
phase synthesized at 5 GPa, 1500 ˚C [3]. Similar to
SiO2-moganite and other silica phases such as quartz,
temperature-induced phase transition is expected.
This supposed transition was studied using present
micro-Raman system up to 600 ˚C. Two lowfrequency modes (60 and 74 cm-1) were detected atroom temperature. The 74 cm-1-mode significantly
shifted toward 0 cm-1 with temperature as shown in
Fig. 1. This behavior is well fitted with an orderparameter equation as shown in Fig. 1, confirmingthat the mode is soft mode. The transition
temperature (Tc) was determined as 415 ˚C. Firstprinciples calculation of vibrational modes of aAlPO4-moganite predicted two low-frequency
modes, and atomic displacements for the 74 cm-1-

mode matched well toward to route for the expected
high-temperature structure.

Figure 1 Soft mode Raman shift of a-AlPO4-moganite
versus temperature (sold circles). The solid line
represents curve fitting using an order parameterequation (ws = A|Tc-T|b).

Second example is low-frequency peak observedin natural minerals. We found a very intense (andbroad) low-frequency Raman peak in a CO2containing melanophlogite as shown in Fig. 2 [4].
Melanophlogite is one of rare silica minerals with aclathrate structure. Heating study of this sample
revealed that this feature is due to CO2 in the
structure and is likely due to librational andtranslational modes of CO2 molecules in cages, asdegassing reduced its intensity. Degassing behavior
which is related to diffusion of CO2 in cages of thestructure, can be studied by observing this and also
CO2 vibrational peaks [4]. Low-frequency peaks arealso found in several zeolites which are likely
originated from molecular H2O clusters in the large
cages of zeolites.

Figure 2 Raman spectrum of CO2-containing
melanophlogite from Fortunillo, Italy at ambientconditions.

References:[1] http://www.misasa.okayamau.ac.jp/pukiwiki/index.php?Micro-Raman
spectroscopy [2] Kanzaki, M., J. Mineral. Petrol.
Sci., 113, 126 (2018). [3] Kanzaki, M. and Xue, X.
Inorg. Chem., 51, 6164 (2012). [4] Kanzaki, M., J.
Mineral. Petrol. Sci., 114 (2019) in press.

The effect of water on Fe–Mg interdiffusion rates in ringwoodite and implications for the electricalconductivity in the mantle transition zoneB H Zhang1*, T Yoshino2, C C Zhao2, 1Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081,
China; 2Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan.
*zhangbaohua@vip.gyig.ac.cn
Introduction: Ringwoodite [γ-(Mg,Fe)2SiO4] isthe major component of the lower mantle transitionzone (MTZ), which can contain significant amountof water in its crystal structure. Therefore, the MTZ
is considered to be a large water reservoir in deep
Earth [1, 2]. It has been demonstrated that theincorporation of even tens of wt. ppm water could
significantly affect physical properties of
ringwoodite including seismic wave velocity andelectrical conductivity [3].
Among various atoms in ringwoodite, Fe-Mg isthe fastest diffusing species, providing the upper
limit of related processes and the effect of water on
its DFe–Mg might be larger than that in olivine [4]. To
verify this speculation, we determined the water
effect on DFe–Mg of synthetic Fe-free (Mg2SiO4) andFe-bearing (Fe0.2Mg1.8SiO4) ringwoodite aggregates
under high temperature and high pressure in thisstudy. The role of water in homogenization ofchemical heterogeneities in the MTZ was discussed
and the possible MTZ water storage was estimatedby means of the inferred conductivity of
ringwoodite from present DFe–Mg data.
Experimental: We determined the kinetics of
Fe-Mg interdiffusion in ringwoodite aggregates as afunction of water content (up to ~6000 wt. ppm
H2O) at 20 GPa and 1373-1673 K by the diffusion
couple method. Element maps and diffusion profilesof ringwoodite diffusion couple were analyzed by
EPMA. The dependence of Fe-Mg interdiffusivity(DFe-Mg) on Fe concentration was determined using
a Boltzmann-Matano method.
Results and Discussion: The experimentally
reported DFe-Mg in ringwoodite within 0 ≤XFe ≤ 0.1
could
be
fittedbytherelation
2nr
DFe-Mg (m /s) = D0 X FeCH2O exp[-( E * +a CH2O ) / RT ], where E* = (1- XFe)EMg + XFeEFe (EMg = 140 ± 5
kJ/mol, EFe = 4 ± 2 kJ/mol), D0 = 5.59 +-2.90
× 10-101.91
m2/s, n = -0.21 ± 0.10, r = 0.25 ± 0.03, , and α = -24± 4. The water content exponent r of 0.25 suggests a
non-negligible role of water in enhancing Fe–Mg
interdiffusion in ringwoodite.
The length scale over which the chemical
heterogeneities are homogenized by Fe-Mg
interdiffusion in the MTZ is estimated to be only a
few hundred meters even assuming the whole Earthage.

Figure 1 Arrhenius plot of the variation of DFe–Mg for XMg= 0.94 in the nominally dry and wet ringwoodite diffusion
couples displayed as a function of inverse temperature at
20 GPa.

Comparison between the conductivities
predicted from Fe-Mg interdiffusion and thoseobtained from magnetotelluric surveys suggest thataround 0.1 wt.% water can account for the highconductivity anomalies (~10-0.6‒10-1 S/m) observedin the lower part of the MTZ.

Figure 2 Ringwoodite electrical conductivity as a functionof inverse temperature and H2O content. Calculations areshown for dry ringwoodite [3] as well as hydrous (thisstudy). The light blue and purple regions denote ranges ofconductivity values observed in the global average model[5] and in the North Pacific Ocean [6], respectively.

References: [1] Inoue et al., GRL, 22, 117 (1995).
[2] Ohtani et al., PEPI, 143, 255 (2004). [3] Yoshino
et al., Nature, 451, 326 (2008). [4] Hier-Majumder
et al., JGR, 110, B02202 (2005). [5] Kelbert et al.,Nature, 460, 1003 (2009). [6] Shimizu et al., GJI,
180, 1030 (2010).

Probing basalt–5.75H2O–CH4 system by in situ vibrational spectroscopy
N Chertkova1*, S Yamashita2, H Ohfuji1, T Irifune1, H Kadobayashi1, Y Yamamoto3
1Geodynamics Research Center, Ehime University, 2-5 Bukyo-cho, Matsuyama, 790-8577, Japan
2Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan
3National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8569, Japan*email:chertkova.nadezda.sj@ehime-u.ac.jp
Introduction: Volatile components released
from sediments in subduction zones are involved inmelting, island-arc volcanism, and the chemicalalteration of the mantle wedge above subducting
plates. Increase of melt fraction triggered by thepresence of volatile components has a major effecton seismic velocities [1-3] and should be consideredin
constructionofgeodynamic
models.
Experimental data on fluid and rock interaction can
provide essential information for understanding ofthese processes and interpretation of observed
seismic parameters.
Experimental: Experiments were carried out inan externally heated Mao-type diamond anvil cell[4] with modified cell assembly and increased
opening angle. Doubly-polished MORB glass pieces
were loaded into the sample chamber of DAC
together with methane hydrate fluid source [5],pressurized, then heated in the temperature range to1000 °C. Phase relationships were monitored during
heating under the optical microscope, employing insitu micro-Raman and infrared spectroscopy [4,6].
During experiments temperature was measured by
the thermocouple, attached to the gasket, andpressure was determined using the Raman spectrumof optical pressure sensor [4,7].
Results and Discussion: Microphotographs
taken during experiments are shown on Fig. 1.
During heating above 100 ˚C, a decomposition ofsolid methane hydrate into methane and water took
place (Fig. 1b). Upon further heating to 700 ˚C,crystallization of coesite crystals in the fluid wasobserved (Fig. 1c). At temperatures above 800 ˚Cclinopyroxene and garnet crystals were coexistingwith homogeneous fluid phase (Fig. 1c).

Figure 1 Microphotographs of the phases observed
during DAC experiments in the system basalt–5.75H2O–
CH4: (a) starting basaltic glass with solid methane
hydrate at room temperature; (b) basaltic glass withdecomposed methane hydrate; (c) crystallization ofcoesite crystals during heating; (d) fine-grained
clinopyroxene and garnet, surrounded by supercriticalfluid.

Observed mineral phases are in consistency withthe subsolidus association described in the drybasaltic system with the similar MORB composition[8]. Though previous studies, which employed
quenching techniques, reported the presence ofimmiscibility gaps in the basaltic systems with C-OH components at temperatures below 1600 ˚C andpressures below 6 GPa [9,10], results of this study
showed stability of homogeneous silica-rich fluid
phase at temperatures above 800 ˚C and pressures
above 3.2 GPa, with separation of supercritical fluid
into several components during quenching.
References: [1] Hammond, W.C. and Humphreys,
E.D., J. Geophys. Res., 105, 10975 (2000). [2]Wiens, D.A. and Smith, G.P., Geophysical
Monograph -AGU, 138, 59 (2003). [3] Chantel, J.,
Manthilake, G., Andrault, D., Novella, D., Yu, T.
and Wang, Y., Science advances, 2, e1600246(2016). [4] Chertkova, N., Ohfuji, H., Nomura, R.,
Kadobayashi, H. and Irifune, T., High Pressure Res.,38, 337 (2018). [5] Kadobayashi, H., Hirai, H.,
Ohfuji, H., Ohtake, M. and Yamamoto, Y. J. Chem.
Phys., 148, 164503 (2018). [6] Chertkova, N. andYamashita, S. Chem. Geol., 409, 149 (2015). [7]Chertkova, N., Yamashita, S., Ito, E. and Shimojuku,
A. Mineral. Mag., 78, 1677. [8] Yasuda, A., Fujii,
T. and Kurita, K. J. Geophys. Res.: Solid Earth, 99,
9401. [9] Zhang, P. F., Tang, Y. J., Hu, Y., Zhang,
H. F., Su, B. X., Xiao, Y. and Santosh, M. Int.
Geology Rev., 54, 1443-1455 )(2012). [10]Litasov, K. D., Shatskiy, A. and Ohtani, E.
EPSL, 391, 87 (2014).

Effect of iron content on thermal conductivity of olivine with implications for cooling history of rocky
planets
Youyue Zhang1*, Takashi Yoshino1, Akira Yoneda1, Masahiro Osako2.
1Institute for Study of the Earth's Interior, Okayama University, Misasa, Tottori 682-0193, Japan
2Division of Physical Sciences, National Museum of Nature and Science, 3-23-1, Hyakunincho, Shinjuku-ku,
Tokyo 169-0073, Japan*email: zhangyouyue@s.okayama-u.ac.jp
Introduction: Knowledge of thermal transport
properties of mantle materials is essential forunderstanding the thermal state and dynamics of the
Earth and planetary interiors. Previous studies havesuggested that temperature and pressure dependencesof 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 is characterized by highforsterite content around Fo90. For other terrestrial
planets, Mercury is believed to have a FeO-poor
mantle along with end member silicates, whereas
olivine in the Martian mantle would be more Fe-rich,speculated to be Fo67. Recent studies suggested that
surface of some asteroids is dominated by Fe-richolivine of composition from Fo49 to Fo70. Hence, theeffect 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.
Experimental: In this study, by combining multianvil high pressure experimental technique and pulse
heating method, thermal conductivity and diffusivityof olivine were determined simultaneously. 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. For Fo90, Fo70, Fo50 and Fo31,
we measured thermal conductivity and diffusivity up
to 10 GPa and 1000 K. For fayalyite (Fo0), taking into
consideration of the relatively low transition
temperature to spinel phase under high pressure, themeasurement condition was limited up to 8 GPa and700 K. And for Forsterite, we took data up to 5 GPa
and 1000 K.
Results and Discussion: Thermal conductivity ofolivine was varied by different Fe contents and thelowest value appeared at composition about Fo31 atroom temperature. The thermal conductivity of Fo31
was about 70% of Fo90 and 35% of Fo. For olivine,
the temperature dependence of thermal conductivity
and diffusivity can be described by an empirical form
as A + B / T. The pressure dependence can be
expressed by a linear function as a + bP. As
temperature increases, the difference in λ among
olivine samples with various Fe contents tends tobecome smaller. According to the fitting equation, theabsolute λ value of Fo31 at 800 K correspond to 72, 74
and 77% of the value of Fo90 at 6, 8 and 10 GPa,

respectively. Meanwhile, at temperatures higher than
500 K, the minimum value appears at composition of
Fa.

Figure 1 Compositional dependence ofconductivity λ of olivine at room temperature.

thermalCompared with single crystal olivine, the grainboundary scattering of polycrystal olivine lowered theabsolute value of thermal conductivity and reduced
the pressure dependence of thermal conductivity atroom temperature and temperature dependence ofthermal conductivity under high temperature.

Figure 2 Comparison of thermal conductivity of olivine
single crystal λsingle and polycrystal λpoly with models’
predictions.

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.
The composition dependent thermal conductivityof olivine suggests a warmer upper mantle and thicker
crust of Mars than expected. The Fe-poor mantle ofMercury indicates a much higher speed of heat loss
than other terrestrial planets. Olivine dominant
asteroids with high Fe content have longer coolinghistory and smaller thermal inertia on the surface.

Measurement of T-dependent electrical resistivity of solid and liquid Fe and Pt at fixed P
Innocent C. Ezenwa1*, Takashi Yoshino1
1Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan.
*email: iezenwa@okayama-u.ac.jp
Introduction: Knowledge of the thermal andelectrical conductivity of solid and liquid Fe and its
relevant alloys at P and T conditions is essential forunderstanding the cooling history of planetary coresand modelling their dynamo. The general
understanding of the electrical transport propertiesof the transition metals at lower P will perhaps giveinsight in understanding Fe behavior at the
inaccessible planetary core conditions. Theoreticalinvestigation has suggested that the electrical andthermal conductivity of solid and liquid Fe at Earth’s
core conditions are similar in value [1]. At ambientT, experimental investigation showed that hcp εphase of Fe becomes paramagnetic at ~18 GPa while
Pt is paramagnetic and crystalize fcc at ambientconditions. Since Fe and Pt have an unfilled d-band
electronic structure and at high P both exhibits
closed packed crystal structures, experimental
determination of the transport properties of molten
Pt at lower P conditions is important forunderstanding the behavior of molten Fe preceding
ε-phase at ~80 GPa.
Experimental: We develop a technique and cell
design for the investigation of the electricalresistivity of metals that keeps it free fromcontamination in the multianvil press. And, we

report measurements on Fe and Pt. The sample was
kept pure by making the electrodes and the sample
the same composition while the thermocouple (TC)is placed close to the sample and taking through thegasket. The major challenge of TC breakage during
compression and/or heating was overcome byshielding the TC with a cylindrical hollow coilingring made of the same composition as the TC leads.
The use of current polarity reversal to eliminate
biased voltage as deployed in previous studies was
adopted.
Results and Discussion: The resistivity of both
Fe and Pt increases and decreases with T and P
respectively, was observed. On melting, Fe result at
3 GPa agrees with very recent data by Silber et al.
[2] which showed an increasing difference in theresistivity value of solid and liquid with increasing
P. While, Pt resistivity on melting at 3 GPa appears
constant comparable to its 1 atm value. Experimentis on-going to measure resistivity of liquid Fe and Pt
at higher P.
References: [1] Wagle, F., Steinle-Neumann, G.,
Geophys J. Int., 213, 237, (2018). [2] Silber, R.E.
et al., Sci. Rep., 8, 10758 (2018).

Melting process in Hawaii plume: Report from a large volume multi-anvil laboratory in Guangzhou
Institute of Geochemistry
E.Takahashi1,2* S.Gao1,2, J.Wang1 and Li Li1 1Guangzhou Institute of Geochemistry, Chinese Academy of
Sciences, 510640, China, 2Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo Japan*email: takahashi@gig.ac.cn
Introduction: Mantle plumes originate either
from the bottom of the mantle (CMB; core-mantle
boundary, Davies, 1990) or the base of the upper
mantle (600-700 km depth, White and McKenzie,
1995). In order to produce large amount of tholeiitemagma in the shield building stage of the Hawaiian
plume its potential temperature is considered to be atleast 300°C higher than asthenosphere judging fromthe peridotite dry solidus at 3 GPa (base of the Pacificplate).
However, if large amount of recycled eclogite
component is involved in the genesis of LIP magmas,
estimated PMT of the plumes based on peridotite drysolidus should be overestimated in great amount.
Based on melting study of the Columbia River basalts,
Takahashi [1] proposed that temperature of the
Yellowstone plume may be only ~100°C higher thannormal asthenosphere. In order to evaluate the role ofrecycled eclogite in magma genesis of Hawaiian
plume, we carried out high-P and high-T melting
experiments.
Experimental: High-pressure experiments at 2.9,
5 and 8 GPa were carried out using a Boyd-Englandtype piston cylinder and a 2500 ton cubic-type multianvil press recently moved from EPS Tokyo Instituteof Technology to Guangzhou Institute of Technology.
Under both dry and hydrous conditions, layered
basalt/peridotite starting materials were used. Fertilelherzolite KLB-1 (Takahashi [2]) was employed as
peridotite component, and two basalt components
were used as recycled crust component:
1)
Columbia River basalt (CRB72-180, Takahashi [1])which is relatively enriched in K, Ti and LREE(K2O≈1wt%, TiO2=3.15wt%), N-type MORB
(NAM-7, Yasuda [3]).
Results: Melts formed by reactive melting ofdry eclogite and peridotite changes dramatically in thetemperature range across the solidus of peridotite
KLB-1 from basalt (below dry solidus) to picrite (2040°C above dry solidus). Basaltic melts are notsaturated with olivine both at 2.9, and 5 GPa andtherefore they are separated by peridotite matrix by
Opx film. Chemical reaction between the basalt melt
and the peridotite matrix proceeds only slowly bysolid-diffusion across the Opx film. In hydrous
experiments, solidus of peridotite decreases
significantly and therefore the reaction betweenhydrous melt and the partially molten peridotite
matrix proceeds at temperatures below peridotite drysolidus.

Melting study of alkali-basalt/peridotite layered
sample showed much lower solidus temperature than
MORB/peridotite sample mainly due to K2O. Melting
starts as deep as 200km depth and composition of
initial melts at pressures higher than 120km are
similar to K-rich alkali acidic rocks (phonolite,
hawaiite) as long as melting is limited in basalt layer.
On the other hand, silica-poor alkali magmas(basanite, nephelinite) are produced in the presence ofvolatiles which widen partial melting of peridotite aswell as mafic component.
Genesis of Hawaiian tholeiite magma: Iron richnature of Hawaiian tholeiite is difficult to reproduce
by reaction melting of MORB/peridotite but isreproduced by CRB72-180/peridotite. Recycled
mafic component in Hawaii plume, therefore, may behigher in FeO than modern MORB which isconsistent with Fe-rich nature of mafic rocks in early
Earth and estimated model recycle time of Hawaii
plume (>2Ga). Based on present experiments, we
propose that potential temperature of the Hawaii
plume may be only 100-150°C above that of normal
asthenosphere. Tholeiite magma in the shield building
stage may be formed slightly under hydrous condition
near the dry solidus of peridotite (1450-1500°C at
about 3 GPa). Our model predicts lower plumetemperatures than most previous estimates. Change inplume flux of Hawaii hot spot through time may berelated to the amount of entrained eclogite thanpotential temperature.
Origin of alkali magma: Post shield stage
phonolite and hawaiite magmas in Hawaii wereconsidered to be fractionation product of alkali basalts
under crustal magma chambers (e.g., Frey et al, 1990).
However, our experimental results revealed analternative scenario that phonolite and hawaiite
magma were derived from partial melting of alkali
basaltic blocks at deeper part (150-200km) of theplume. On the other hand, basanite and nephelinite
which appears in rejuvenated stage may represent
partial melt of peridotite portion of the plume beneathpacific plate. We discuss magma genesis in Hawaii
plume based on our melting experiments andoccurrence of diverse magma types both
geographically and in growth history of a given shield
volcano.
References: [1] Takahashi et al, Earth Planet. Sci.
Lett. (1998) [2] Takahashi, J.Geophys. Res.,(1986),[3] Yasuda et al., J.Geophys. Res. (1994)

Silicic melt obtained from the melting experiments of mantle peridotite reacted with slab melt
N. Tsuchiya1*and D. Yamazaki2
1
Department of Geology, Iwate University, Morioka 020-8550, Japan. 2Institute for Planetary Materials,
Okayama University, Misasa, Tottori 682-0193, Japan. *email: tsuchiya@iwate-u.ac.jp
Introduction: Island arc magmatism along
convergent plate margins is one of the major
processes of continental crust generation, and the
net flux from mantle to crust is considered to bebasaltic [1]. On the other hand, Archeantrondhjemite-tonalite-granodiorite (TTGs) areconsidered to have formed during subduction by
partial melting of hydrated oceanic crusttransformed into garnet amphibolite to eclogite(slab melting), slab melting is of particularimportance to crust-forming processes in the planet
Earth [2-4]. In this study, the partial melting of
peridotite modified by reaction with felsic slab
melts, was experimentally investigated at 1.5 GPa
for H2O saturated conditions in the relatively low
temperature range from 1000 to 1075˚C, and thegeneration of andesitic melts is discussed.
Results and Discussion: Starting materials are1) synthesized peridotite (H2O: 12.59%), 2)
synthesized peridotite plus 40%, 20%, and 5% ofslab melt (H2O: 0.7 to 12%), and 3) Ichinomegata
lherzolite plus 40% of adakitic granite (H2O: morethan 10%). All the experiments were carried out
using a piston cylinder apparatus and Au capsules.
In the case of starting materials 1), no glass wereobserved both at 1000 and 1050˚C. Starting
materials 2) to 3), the quenched glasses obtained at
1000˚C were dacitic in composition (SiO2 =67-68%, MgO = 0.5-1.1%), and the volume of melt
was 18 to 32%. The quenched glasses obtained at
1050˚C were andesitic in composition (SiO2 =57-64%, MgO = 1.5-4.5%), and the volume of melt
was 20 to 34%. The quenched glasses obtained at
1075˚C were andesitic in composition (SiO2 =56-61%, MgO = 3-4%). All of those glasses arecoexistingwitholivine(Fo
89-91%),
orthopyroxene, and clinopyroxene.
These results indicates the possibility thatcalk-alkaline dacitic to andesitic melts can begenerated by the reaction of slab melts with mantle
peridotite.
Moreover,thissuggeststhatcalk-alkaline dacites to andesites can be formed bydirect partial melting of the hydrous upper mantle
contaminated with slab melts. These results were
not consisting with the previous results [5, 6],
which probably resulted from higher SiO2 content
in starting peridotite.

Figure 1 AFM diagram of glass compositions obtained
from this study. Data from [5, 6], and experimental slab
melt compiled by [7] are also plotted for comparison.

Figure 2 MgO-SiO2 diagram of glass compositions
obtained from this study. Data from [5, 6] are alsoplotted for comparison.

References: [1] Kay, R. W., and Kay, S. M.,
Geological Society Special Publication 24,
147-159 (1986). [2] Martin, H., Geology, 14,753-756 (1986). [3] Defant, M.J. and Drummond,
M.S., Nature, 347, 662-665 (1990). [4] Rollinson,
H., Nature, 389, 173-176 (1997). [5] Hirose, K.,
and Kawamoto, T., Earth and Planetary Science
Letters, 133, 463-473 (1995). [6] Hirose, K.,
Geology, 24, 44-46 (1997). [7] Tsuchiya, N.,
Kimura, J.-I. and Kagami, H., Journal ofVolcanology and Gerthermal Research, 167,
134-159 (2007).

Pressure dependence of graphitization: Implications for rapid recrystallization of carbonaceous
material in Earth’s crust
Y. Nakamura1,*, T. Yoshino2, and M. Satish-Kumar3
1
Geological Survey of Japan, National institute of Advanced Industrial Science and Technology, AIST,
Tsukuba Central 7, 1-1-1 Higashi, Tsukuba 305-8567, Japan
2
Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan3
Department of Geology, Faculty of Science, Niigata University, 2-8050 Ikarashi, Nishi-ku, Niigata 9502181, Japan *E-mail:yoshi-nakamura@aist.go.jp
Introduction: Graphitization of carbonaceous
material (CM) to graphite is one of the most importantand sensitive thermal indicators for very low-grade toamphibolite facies metamorphism (150–650 °C) [1].
Although there are many reasons for investigating
natural graphitization, most studies ultimately focus
on its application as a user-friendly thermal indicatorduring metamorphism, independent of bulk chemistry
and the mineral assemblage. Hence, many researchers
have widely investigated natural graphitization inmetamorphic rocks. On the other hand, the kinetics ofgraphitization has been debated for several decades.
Laboratory experiments have shown that the synthesisof graphite from amorphous carbon at 1 atm requiresa very high activation energy of ~1000 kJmol–1 [2].
For example, previous experimental kinetic datasuggest that, even at 700 °C, synthesizing graphitefrom amorphous carbon would require a duration of~1040 min (~1.9 ´ 1034 years) [3]. Thus, besides
temperature, further extrinsic factors such as pressureand deformation during metamorphism should also be
considered.
Experiment: HPHT experiments for the kineticsof graphitization were performed at the Institute forPlanetary Materials (IPM). Three different highpressure apparatuses were used in this experiment: (1)a piston-cylinder (PC) high-pressure apparatus, (2) a
DIA-type high-pressure apparatus (AMAGAEL), and(3) a Kawai-type multi-anvil high-pressure apparatus.
Results and Discussion: Natural carbonaceous
material from sedimentary rocks in the Shimanto
accretionary complex and the Hidaka metamorphic
belt, underwent systematic changes in crystallinity
and morphology with increasing pressure (0.5 to 8.0
GPa) and durations (10 min to 24 h) at 1200 °C. To
assess the pressure dependence of graphitization, we
adopt two approaches for formulating thegraphitization kinetics using a power law rate model(Fig. 1A) and a Johnson–Mehl–Avrami–Kolmogorov
model (Fig. 1B). Activation volumes of –21.7 ± 3.0 to–33.7 ± 17.3 cm3 mol–1, and –1.5 ± 0.3 to –4.0 ± 1.7
cm3 mol–1 are obtained for pressures from 0.5 to 2.0
GPa and 2.0 to 8.0 GPa, respectively (Fig. 1). Suchnegative activation volumes are closely related tonanostructural reorganization in the precursor
material based on TEM observations. The
experimental data are applied to the Arrhenius-type
equation of graphitization, extrapolated to geological

P–T–t conditions. Our model predicts thatcarbonaceous material undergoing metamorphism for~10 Myr at pressures of 0.5–1.0 GPa will begin to
crystallize at 380–500 °C and will transform to fullyordered graphite at 480–700 °C, depending on thepeak pressure. Thus, natural graphitization in Earth’s
crust might proceed much more rapidly thanpreviously estimated, owing to the large negative
activation volumes of the reaction. Our model isapplicable to a wide range of P–T–t conditions andprovides a new pathway not only for more precise
geothermometry, but also geospeedometry andgeobarometry.

Figure 1. Log-linear plots of pressure (GPa) andlnkpower (A) and lnkJMAK (B) for both samples. The
lnka,p as a function of pressure are fitted by power rateand linear regressions.
Reference: [1] Buseck, P. and Beyssac, O. Elements,
10, 421 (2014). [2] Fischbach, D.B. Nature, 200, 1281
(1963). [3] Bustin, R.M., Rouzaud, J.-N., and Ross,
V., Carbon, 33, 679 (1995).

Electrical conductivity measurement of rhyolitic and andesitic glasses
Y Haraguchi1, T Yoshino2, S Yamashita2, M Nakamoto1, M Suzuki1, K Fuji-ta1* and T Tanaka1
1Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan.
2Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan.
*email: fujita@fsao.eng.osaka-u.ac.jp
Introduction: Magneto-Telluric (MT) soundings
have been developed to seek electrical conductivity
structure of volcanic body and its undergroundstructures. In particular, to interpret melt process
and properties of rock and/or mineral beneath thevolcano, it is crucial to obtain electrical conductivity
data of rock and mineral in the laboratory. To
compare with results from MT observation andthose of laboratory measurement, we can have muchknowledge of subsurface electrical conductivity
structure of volcanic region. Despite theaccumulation of much MT data and laboratory data,
the interpretation for electrical conductivity
structure and conductivity variation in the laboratory
remainunknown.
Particularly,
electricalconductivity behavior of volcanic rock in the melt
region and glass transition zone is not elucidated yet.
In the present work, our studies examine andfocus on electrical conductivity change of rhyolite
and andesite glasses.
Experimental: We synthesized rhyolite glasses
using the piston cylinder apparatus. Glass samples
were synthesized at 1GPa.
Electrical conductivity measurements wereconducted at 1 to 3 GPa using a DIA-type cubic
anvil press with maximum load of 2000 ton and 6axis apparatus. In our experiments, the sample
assembly was designed to have high insulation
resistance as shown in Figure 1. The cell assembly
mainly consists of pyrophyllite, ZrO2, Al2O3 andMgO to keep high insulation [1]. Before starting
conductivity measurement, the assembly was preheated below 500-600 K to exclude the containedwater and moisture. The glass sample withdimensions of 1.0-1.6 mm in diameter and 1.0 mm
in thickness was surrounded by single crystal quartz.
To avoid chemical reaction between sample andsurrounded quartz, we conducted preparatory
experiments and carefully inspected reactivity inhigh temperature range using the SEM.
Results and Discussion: After conducting preheating to purge contained water and moisturearound the assembly, stable conductivity data wereobtained. Between 500 and 1600 K, the conductivityof rhyolite (Water contents: 0 wt% and 4 wt%)
seemed to stabilize and show linear trend as
expected from Arrhenius equation. We succeeded inelectrical conductivity measurement to have stable
and reversible values up to 1600 K. The conductivity
linearly increased with increasing temperature.
Using the linear trend of Arrhenius law, theactivation energy of rhyolite was estimated. We also
examined conductivity behavior of andesitic glasses.
From the specific data, we observed minuteelectrical conductivity variation around the glasstransition temperature which were estimated fromviscosity [2] for rhyolite and andesite glasses. Our
results suggest that the relation between the changeof electrical conductivity and glass transition
temperature estimated electrical conductivity can beused for prediction such as explosive event involcanic region.

Figure 1 Construction of cell assembly for electricalconductivity measurements of rhyolitic and andesitic
glasses.

References:[1] Fuji-ta, K., et al., Tectonophysics, 504, 116–121(2011).
[2] Giordano, D., et al., Journal of Volcanology andGeothermal Research, 142, 105-118 (2005).

The Measurement of Seebeck coefficient under Pressure using Six-axis Multi-Anvil Press
Y Mori1*, N. Nakano1, T. Yoshino2
1
Department of Science, Okayama University of Science, Ridai 1-1, Kita-ku, Okayama 700-0005, Japan.
2
Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan.
*email:mori@das.ous.ac.jp

Figure 1 Schematic image of high-pressure cell for themeasurement. Two sheet heaters of graphite were put thecenter position and the off-set position to make thetemperature gradient in the sample.

Thermal Electro Motive Force / V

Magnesium silicide (Mg₂Si) is a semiconductor
with the promising because the thermoelectricmaterial because of a harmless to the human bodyand a large deposit. The phase diagram of thematerial is very simple however it is difficult tosynthesize the high purity Mg2Si, because themelting point of Mg2Si is close to the boiling pointof Mg at high temperature region. Therefore wehave studied the high-pressure synthesis by means ofa piston cylinder method and a hot pressing method
to synthesize to the stoichiometric compound [1]. As
a result, the high quality Mg2Si without theunreacted starting materials was synthesized, but thethermoelectric performance never improved
dramatically. Morozova et al. reported that thePower factor of Al-doped Mg2Si at 2 GPa increasedby 10 times of the ambient pressure [2]. In order tounderstand the behavior under high-pressure, it isnecessary to develop the measurement technique ofthe Seebeck coefficient and the electric resistanceunder high-pressure and high-temperature.
In this paper, we developed the thermoelectricmeasurement system at high-temperature andhigh-pressure using six-axis multi-anvil press.
The pressure was generated by the six-axis
multi-anvil press, which was installed in the Institutefor Planetary Materials, Okayama University.
High-pressure cell consists of a pyrophyllite body asa pressure medium, zirconia tube as heat insulator.
Two graphite sheets as a heater were put the center
position and the off-set position in the high-pressure
cell to make the monotonous temperature gradient asshown in Fig. 1. The temperature on the both
surfaces of sample was controlled, individually by
the heaters, and measured by two thermocouples
made of W-Re. There were 4-leads for the electricalconductivity and 2-leads for the thermal electro
motive force. The sample which size was 2.25 mm
in height and 3.0 mm in diameter was formed by an
ultrasonic machining.
The pressure experiment was carried out from 1.0
GPa to 2.5 GPa. The temperature condition wasfrom 472 K to 873 K with 50 K intervals and thetemperature difference for the temperature gradientwas from minus 20 K to plus 10 K.
Figure 2 shows the results of thermal electro
motive force at 1 GPa under several temperature.
The value of Seebeck coefficient under pressure was
evaluated by an inclination of the line, and theabsolute value of that was decreased with increasingpressure.

0.005

472 K
523 K
573 K
623 K
673 K
723 K
773 K
823 K
873 K

0.000

-0.005-0.010-0.015-0.020
-20

-15

-10

-5

0

5

10

15

20

Differential Temperature / K

Figure 2 Thermal electro motive force of Mg2Si as afunction of differential temperature at various
temperatures under 1 GPa. The seebeck coefficient iscalculated by the inclination.

Acknowledgement: The study was performed by“Joint Usage / Research Centre” program by MEXT at theInstitute for Planetary Materials, Okayama University. The
work was supported by JSPS KAKENHI Grant Number
17K06847 and 26420731, and Foundation for “Okari
GAP”, Okayama University of Science.
References:[1]Y. Mori, Y. Kaihara, S. Nakamura, T. Yoshino
and K. Takarabe., phys. stat. solidi. (c), 2013, 10,
1847-1849.

[2]N. V. Morozova, S. V. Ovsyannikov, I. V.
Korobeinikov, A. E. Karkin, K. Takarabe, Y.
Mori,S. Nakamura, V. V. Shchennikov, J.
Appl. Phys., 2014, 115, 213705 1-9.

Redox kinetics of olivine revealed by diffusion profile of oxygen fugacity and its implication to the redox
evolution of the uppermost mantle
C Zhao1* T Yoshino1 1Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan.
*email:zhaocc@s.okayama-u.ac.jp
Introduction: The evolution of the redox state of
the mantle through time has been a focus of hot debate.
Recent study implies that the redox state of the slab
may not significantly be changed during subduction[1]. Thus, ferric iron transported by oxidized slab is
expected to change the redox state of the upper mantle.
However, concentrations of Cr, V, and the V/Sc ratioof the oldest known rocks indicate that the upper mostmantle has remained at approximately FMQ over the
past 3.5 Gyrs [2, 3]. Therefore, it seems that althoughoxidized slab is continuously subducted into mantle,
the redox state of the upper mantle does not changesystematically.
It is possible that the mantle represents an almost
infinite buffer reservoir and renders the addition ofoxidized slab ineffective. On the other hand, thepossible extremely slow reaction speed between slab
and the uppermost mantle materials might disable theoxidized component to be an effective redox changer.
However, the mechanism of the interaction between
them remains unclear, which is of great urgent toinvestigate.
Experimental: Olivine (MgO, SiO2 and Fe2O3oxide mixture) with 5 wt% Pt powder used as oxygen
sensor was first synthesized using gas mixture furnace
at iron-wustite (IW) buffer and Ni-NiO (NNO)
buffered condition at 1300 oC. Diffusion couple
method is adopted to investigate the redox kinetics ofolivine, within which pre-sintered piece of oxidized
and reduced olivine was stacked face to face.
Diffusion experiments were conducted for different
durations at 1 GPa, 1100-1300 oC using piston
cylinder apparatus.
After recovery, oxygen fugacity profiles were
calculated from iron fraction in Pt alloy and ironcontent in olivine measured by EPMA [4]. Diffusion
coefficients were obtained using Boltzmann-Matano
method through fitting and calculation of iron content
in Pt alloy as a function of distance from Matanointerface. Water content after diffusion was measured
using FTIR.
Results and Discussion: Except one couple, thewater content of all the other couples shows < 10 wt.
ppm. Redox process in olivine could be viewed as adiffusion-controlled process. Diffusion coefficient inoxidized olivine shows obvious oxygen fugacity
dependence, while that in reduced one shows small
dependence (Fig. 1).
The activation enthalpy is calculated to be 235
kJ/mol, which is comparable with that for Fe-Mg
diffusion in olivine. However, the magnitude is 2-4
orders higher. Since the activation enthalpy andmagnitude are comparable with that of diffusion ofhydrous defects related to Mg-vacancies [5], it ispossible that even extremely small amount of water
could dominate redox kinetics in olivine.

Figure 1 Diffusion coefficient Diffusion coefficient as afunction of iron content in Pt alloy. Unfilled and filled
symbols are data from Pt capsuled and MgO capsuled
samples, respectively. Blue star line is diffusion coefficientfrom magnetite-containing couple.

The diffusion length calculated indicate that the
influence exerted by slab on the reduced mantle isvery limited (< 4 km at 1600 oC even for 4500 Ma’s
stagnation in the upper mantle) (Fig. 2). Therefore, it
is possible that the extremely slow redox process
prevents subducted slab to change the redox state of
the upper mantle. Once subducted more, the oxidizedslab can bring redox budget to deep mantle as it keeps
dry condition.

Figure 2 Diffusion length calculated for subducting slab
stagnated at the upper mantle for different durations.

References: [1] Lee, C.A., et al., Nature, 468, 681(2010). [2] Canil, D., Earth Planet. Sci. Lett., 195, 75(2002). [3] Li, Z.A. and Lee, C.A., Earth Planet. Sci.
Lett., 228, 483 (2004). [4] Faul, U.H., et al., Phys.
Chem. Mineral., (2017). [5] Padron-Navarta, J.A., etal., Earth Planet. Sci. Lett.,392, 100 (2014).

Electrical conductivity of hydrous olivine: revisited by various approaches
T. Yoshino1*, W. Sun1,2, C. Zhao1, N. Sakamoto3, H. Yurimoto3,4
1Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan. 2Earth-Life Science
Institute, Tokyo Institute of Technology, Tokyo, Japan. 3Isotope imaging laboratory, Creative Research Institute,
Hokkaido University, Japan. 4Department of Natural History Sciences, Hokkaido University, Sapporo, Hokkaido
060-0810, Japan.
*email:tyoshino@misasa.okayama-u.ac.jp
Introduction: Magnetotelluric (MT) studies haveconstructed the profiles and structures of electricalconductivity in the mantle up to the uppermost lower
mantle. A major conductivity anomaly is found in theoceanic upper mantle at ~100 km depth near the midocean ridge. It shows high conductivity about 10–2 to10-1 S/m and is characterized by strong anisotropic
feature [1]. The origin of the conductivity anomalies
is still in debate. One of major hypotheses to explain
this anomaly is olivine hydration.
Many researchers have studied effect of water onelectrical conductivity of olivine. Although several
groups have measured the electrical conductivity ofmantle materials at high pressure, they have provided
inconsistent results with regard to the effect of water.
Some studies suggested that olivine with the
maximum soluble H2O content at the top of theasthenosphere has lower conductivity less than 0.1
S/m, which is a typical value of conductivity anomaly
observed in the oceanic mantle, and has weakanisotropic feature [2-4]. In contrast, more recently,
electrical conductivity measurement of single crystal
olivine at relatively high temperature have shownhigher conductivity with high activation energy [5],suggesting that small amounts of water account forthe conductivity anomaly.
In this study, we revisit the effect of water onelectrical conductivity of olivine based on H-D interdiffusion in olivine single crystal and conductivity
measurement of buffered sintered samples.
Experimental: Hydrogen in octahedral site vacancy
has thought to be a main charge carrier to link latticehydrogen diffusion and proton conduction. Recent
FTIR and NMR investigation and first principle
calculation indicated that concentration of hydrogenin M site was negligibly small. The other candidate ofelectric carrier for hydrous olivine is [2H]XMg
diffusion. The activation enthalpy obtained forhydrogen self-diffusion in olivine is 1.1-1.8 eV, whilethat for proton conduction is around 0.7 eV. To
investigate H-site specific effect on electricalconductivity of hydrous olivine, we have performed
the conductivity measurements for the forsterite
aggregates buffered by MgO and SiO2. To estimate
electrical conductivity at higher temperatures,hydrogen self-diffusion coefficients determined frominter-diffusion in H- and D-doped olivine single
crystal couples at the upper mantle conditions (3-13
GPa and 1000–1300 K).
Results and Discussion: FTIR spectra of MgObuffered forsterite aggregates shows strong sharp
absorption peaks at high wave numbers, while thoseof SiO2 buffered samples are characterized by smaller
water content and broad absorption bands at low wave
numbers. Thus, this broad band seems to be related to
H in Mg site. The activation enthalpy of SiO2 bufferedsample is higher than MgO-buffered one, suggestingthat the main charge carrier is different between them.
Low activation energy (~0.7 eV) is comparable to theprevious results by conductivity measurements atlower temperatures. Hydrogen in Si site vacancy inassociation with proton shows dominant conduction
mechanism at low temperatures and in MgO bufferedcondition.
Hydrogen self-diffusion is highly anisotropic withhighest mobility along [100] orientation. The
geometric average hydrogen self-diffusion coefficientis showed as a function of temperature and water
39*±3' :;/=>?
𝐷" = 10&'.'±*.+ (𝐶./0 )*.23±*.*3 exp (−) mC /s . This@A
activation energy is consistent with conductivity
measurement for the SiO2-buffered sample and single
crystal [6] determined at high temperatures.
Combined with the Nernst-Einstein relation, thepresent results suggests that the most of literature data
overestimate effect of water on conductivity ofhydrous olivine because of sample heterogeneity.
Although previous studies used single crystal
synthesized by diffusion, the single crystals used inthese experiments have not reached equilibrium fromthe viewpoint of hydrogen diffusion. At hightemperatures to relevant mantle condition, a mainelectrical charge carrier of hydrous olivine seems tobe [V]”Mg in association with migration of [2H]XMg.
References: [1] Evans et al., Nature, 437, 249 (2005).
[2] Yoshino et al., Nature, 443, 973 (2006). [3] Poe etal., Phys. Earth Planet. Inter., 181, 103 (2010). [4]Yang et al., Earth Planet. Sci. Lett., 317-318, 241(2012). [5] Dai and Karato, Earth Planet. Sci. Lett.,
408, 709 (2014).

H2O-enhanced ionic conductivity of olivine
T. Katsura1,2*, H.-F. Fei1, D. Druzhbin1 1Bayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth,
Germany, 2 Center for High Pressure Science & Technology Advanced Research, 100094 Beijing, China.
*email: tomo.katsura@uni-bayreuth.de
Introduction: A magnetotelluric study showeda high-conductivity (10-1-10-2 S/m) layer (HCL) at
70~120 km depths in the asthenosphere beneathyoung plates near the East Pacific Rise [1], which
is higher than dry olivine conductivity by morethan one order of magnitude. Although manystudies attributed this high conductivity to olivine
proton conduction, which is driven by migration ofHi⦁, its magnitude in this region should be small
because of the small amounts of H2O in thedepleted MORB mantle [2]. Furthermore, therelatively small activation enthalpy of the proton
conduction does not agree to the HT location of the
HCL.
Although the olivine conduction mechanismthat dominates at asthenospheric temperatures willbe the ionic conduction (σVMg"), which is driven by
migration of VMg", conductivity measurements atambient pressure demonstrated its small
magnitudes. Our diffusion study, however, showedthat the olivine Mg self-diffusivity (DMg) almost
linearly increases with increasing H2O content(CH2O) [3]. This result implies enhancement of σVMg"
by H2O incorporation, which may interpret the
HCL. To prove this hypothesis, σVMg" was measured
as a function of CH2O in this study [4].
Experimental: Samples for conductivity
measurement were discs of natural-olivine single
crystals with initial CH2O = 50 wt. ppm. They weresurrounded by single-crystal MgO, and sandwichedby Mo foils, which were loaded in a multi-anvilcell. When a higher H2O content was intended, atiny amount of brucite was added next to the Mo
foils. Impedance spectroscopy in the frequency
range of 107 to 102~0 Hz was conducted in the threedifferent crystallographic orientations at P = 2 − 10
GPa. The T conditions were up to 2200 and 1700 K
for low- (CH2O = ~20 wt. ppm) and high-CH2O
samples, respectively. Several heating and coolingcycles were repeated to confirm essentially nochange in conductivity after the first cooling. The
CH2O’s were measured by means of FT-IR
spectroscopy with the Withers’ calibration [3] after
recovery.
Results and Discussion: Results ofconductivity measurement show that slopes of thelogarithmic conductivity (log σ) to the reciprocal
temperature (1/T) increase with increasing T due tomixed contribution of the σVMg" and hopping
conductivity. These two mechanisms werenumerically separated by assuming their parallel
contributions. The activation energy and volume ofσVMg" were obtained as Ea = 250 − 450 kJ/mol. andVa = 3.2 − 5.3 cm3/mol,, which are identical tothose of DMg within the errors (Ea = 200 − 400
kJ/mol. and Va = 1.0 − 4.3 cm3/mol.) [3, 6].
Significant anisotropy was found in σVMg", whichis σ[001] ≫ σ[100] ≈ σ[010]. This characteristic is
identical to those of σVMg" under dry conditions [7]and of DMg [6].
The CH2O’s with and without brucite were 20 −40 and 200 − 500 ppm wt. ppm, respectively. By
assuming a proportionality to a power of CH2O, theCH2O exponent was found r = 1.3 ± 0.2. This
exponent is identical to that of DMg (r = 1.2 ± 0.2).
These results suggest that σVMg" increases withincreasing CH2O. Since the increase in DMg with
CH2O starts at least at CH2O of 1 ppm, the increase inσVMg" will start at this CH2O as well. Hence, anincrease in CH2O from 1 to 100 wt. ppm, forexample, is expected to increase σVMg" by 2.5 ordersof magnitude. Thus, H2O incorporation will
tremendously enhance σVMg".
Under the P-T conditions at the top of theasthenosphere under a 5-Ma old plate, namely 3
GPa and 1650-1700 K [1], the isotropic σVMg" ofolivine with CH2O = 100 wt. ppm will be 4×10-2
S/m. This conductivity is identical to or evenhigher than that of the top of the asthenosphere in
the isotropic model (1~4×10-2 S/m). Ref [2] also
reported by a half order of anisotropy, which canbe duplicated by the higher conductivity in the[001] direction than the [100] and [010] direction.
Thus the HCL can be attributed to the H2O
enhanced σVMg".
References: [1] Katsura, T. et al. Tectonophys. 717,
162 (2017). [2] Baba, K. et al., J. Geophys. Res.
111, B02101 (2006). [3] Fei, H.-Z. et al., Earth
Planet Sci. Lett., 484, 204 (2018). [4] Fei, H.-Z. etal., submitted. [5] Withers, A. et al. Chem. Geol.,
334, 92 (2012). [6] Chakraborty, S. et al., Phys.
Chem. Min. 21, 489 (1994) [7] Constable, S. et al. J.
Geophys. Res. 83, 3397 (1992).

Simultaneously generation of ultra-high pressure and high temperature by combining boron-doped
diamond heater and sintered diamond anvils
L Xie1*, K Nishida1, T Ishi1, C Artem1, B Dimitry1, T Katsura1
1 Bayerisches Geoinstitut, Univ. of Bayreuth, 95440 Bayreuth, Germany.
*email:Longjian.Xie@uni-bayreuth.de
Introduction: The Kawai-type multi-anvil press(MAP) is one of the most widely used highpressure-temperature (P-T) apparatus. It generates
uniform and stable high-pressure-temperature
conditions in a relatively large volume. However,traditional MAPs has limited P-T conditions.
Recently, significant efforts have been made fordevelopment of pressure generation technique using
sintered diamond (SD) anvils and of temperature
generation technique using boron-doped diamondheater.
Thanks to these efforts, the maximum pressureof MAPs exceeds 100 GPa [1], which is close to thecore mantle boundary. The temperature range has
been expanded to 4000 K at pressures to 15 GPausing boron-doped diamond (BDD) heater [2].
However, simultaneous generation of ultrahighpressure (UHP) and ultrahigh temperature (UHT) is
still difficult. The BDD heater was quite recently
developed, and has not been implemented in cell
assemblies for SD experiments. In this study, we try
to simultaneously generate UHP (up to 80 GPa) andUHT (up to 3000 K) by combining BDD heater andSD anvils in MAP.
Experimental: High P-T experiments wereconducted using the multi-anvil apparatus, SPEEDMk.II, at BL04B1, SPring-8, Japan. First-stage
anvils are made of tungsten carbide with 27-mm

truncation. Second-stage anvils are made of SD andhave edge and truncation lengths of 14.0 and 1.5 mm,
respectively. The pressure medium is 5.7-mm MgOoctahedron. The tube heater of BDD powder with a
1.6-mm length and 0.5- and 0.7-mm inner and outer
diameters, respectively were placed normal to two
opposite faces of the anvil truncation. Temperatures
were measured using a 0.05-mm thick W-Re
thermocouple. A sintered block of MgO, mixed withdiamond for suppression of MgO grain growth, wasused as a pressure marker.
Results and Discussion: We succeeded togenerate temperature as high as 3000 K at 27 GPawith SD anvils. The pressure generation of current
cell assembly is similar with WC anvils due to thediamond support of BDD heater. Large thermalpressure (~2 GPa per 1000 K) can be generated in
the current cell assembly. The improvement ofhigher pressure generation efficiency is needed infuture work.
References:[1] Yamazaki. D., Ito, E., Yoshino, T., Tsujino, N.,
Yoneda, A., Guo, X., Xu, F., Higo, Y., Funakoshi,
K., Phys. Earth Planet. Inter., 228, 262-267 (2014).
[2] Xie, L., Yoneda, A., Yoshino, T., Yamazaki, D.,
Tsujino, N., Higo, Y., Tange, Y., Irifune, T., Shimei,
T., Ito, E., R. Sci. Instrum., 88, 093904 (2017).

High pressure generation in the Kawai-type multianvil apparatus
D. Yamazaki, Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan.
email:dy@misasa.okayama-u.ac.jp
High pressure and temperature generations are
the most essential importance in the experimental
study of the Earth’s interior. In this context, theKawai-type multianvil apparatus (KMA) has been
widely used as well as the diamond anvil cell (DAC)(cf. Ito et al., 2015). The conspicuous advantages of
the KMA over the DAC are the capability to compressa large volume sample, ~1000 times larger than thatof DAC, and create a quasi-hydrostatic environment
owing to squeezing an octahedral pressure medium byeight cubic anvils (Kawai and Endo, 1970). Moreover,
it is possible to keep the specimen in homogeneousand stable conditions at high temperature by adopting
an internal heating system. These advantages makes
it possible to measure physicochemical properties of
the Earth’s minerals precisely under high pressure andtemperature conditions (e.g., Nishiyama et al., 2004).
Generated pressure in the KMA with tungsten
carbide (WC) anvils had been limited to ~25 GPa (e.g.,
Keppler and Frost, 2005) for a long time. However,recent development of harder WC material, TJS01(Fuji Die Co., Ltd.) containing a small amount of Nibinder (<0.2 %), opened new era to attain the pressuremuch higher than 25 GPa. Kunimoto et al. (2016)
generated pressures up to 50 GPa at room temperatureusing 14 mm edge length TJS01 anvils. Later, Ishii etal., (2017) generated pressures up to 65 GPa at room
temperature and 48 GPa at 2000 K using the 26 mmedge length applying higher press load. On the other
hand, the attainable pressure with sintered diamond(SD) anvils has been gradually extended from 1998 topresent and the attainable pressure has been extended
to ~95 GPa by optimizing the pressure medium andgasket (Ito et al., 2005; Tange et al., 2008; Ito et al,2010). In the previous our study (Yamazaki et al.,2014), we used new type of SD anvils, "C2-grade"
and we could extend the generated pressure to 109
GPa. In this study, we report on the recent progress ofhigh pressure generation in the KMA with WC(TJS01) and SD (“C2-grade”) anvils.
In situ X-ray diffraction experiments at highpressure and temperature were conducted at beamline
BL04B1, SPring-8 synchrotron radiation facility
using the DIA type press (SPEED-Mk.II) (Katsura etal., 2004). Energy dispersive powder X-ray
diffraction technique was adopted with apolychromatic X-ray beam at a diffraction angle of~6º in conjunction with a germanium solid-state
detector. The sample was irradiated by the collimatedbeam with a size of 50 µm horizontally and 100 µm
vertically. A multi-channel analyzer was used toacquire diffracted photons in a range of 20-140 keV
through the sandwiched gaskets (anvil gaps). Theenergies of the photons were calibrated using
characteristic fluorescence X-ray lines of Cu, Mo, Ag,
Ta, Pt, Ag and Pb, or radiation sources of 55Fe, 57Co
and 133Ba. The precision in the energy measurements
was approximately 30-100 eV per channel. Duringacquisition of diffracted photons, sample was rotatedaround the vertical axis between 0º and 6º with respect
to the direction of the incident X-ray beam by
oscillating the press to average diffraction profile andto minimize the effect of grain growth (Katsura et al.,2004).
In the pressure generation tests with WC anvils,
we measured the generated pressure at 50-100 ton
intervals. After compression at room temperature, weheated the sample up to 1500 K. We conducted
several tests for the pressure generation with WC
anvils and pressure reached 71.3 GPa at press load of
7.5 MN at room temperature. Pressure generation
efficiency against press load in the present study ishigher than that in previous study by Ishii et al. (2017).
In SD experiments, we annealed the sample atevery 5-10 GPa interval up to 800-1000 K during
compression to relax stress and to reduce theprobability of explosion of the specimen (i.e. so called“blow out”). The pressure reached 112.7 GPa at 8.0
MN and 300 K before annealing. Although thepressure generation efficiency of this run is higher
than the previous study (Yamazaki et al., 2014) due tousage of smaller gaskets, the run was terminated byblow-out while increasing temperature up to ~550 K.
In the next run, we successfully increased the press
load up to 13.0 MN despite using 14 mm edge length
anvils because the harder first stage anvil with thetransverse rupture strength (TRS) of 4410 MPa (F09
grade, Fuji Die Co., Ltd.). In the previous study(Yamazaki et al., 2014), we used more brittle
materials for the first stage anvil (F10 grade, Fuji Die
Co., Ltd.) with TRS=3820 MPa and the maximum
press load was limited to ~10 MN. As a result, in thisstudy the pressure reached 120.3 GPa at room
temperature after annealing at 760 K, although thegeneration efficiency in this run was lower than thatin M1626 and was virtually identical (within ±5%) toprevious experiment (Yamazaki et al., 2014).

POSTERViscosity of Lower Mantle Estimated from the Common Diffusivity of Creep and Grain Growth
A Okamoto1* T Hiraga1* 1Earthquake Research Institute, University of Tokyo, Tokyo, Yayoi 113-0032, Japan.
*email:aokamoto@eri.u-tokyo.ac.jp
Introduction: Grain-size reduction caused by
the post-spinel transformation and subsequent grain
growth during the whole mantle convection should
control viscosity of the lower mantle, if it deforms
by diffusion creep which is a grain-size sensitive
mechanism [1]. Thus, to estimate viscosity of thelower mantle, grain growth has to be taken into
consideration.
Results and Discussion: Our group has recently
conducted high-temperature creep and grain growthexperiments on forsterite + enstatite aggregate(FoEn) [2] and forsterite + periclase aggregate(FoPer) [3] and found that grain boundary (GB)diffusivities extracted from both creep and grain
growth rates in both polymineralic systems are
essentially identical (Fig. 1). These results indicatethat the creep and grain growth are controlled by acommon diffusion mechanism in both systems where
the slowest diffusion species, which is silicon, is
contained or absent in the constituent elements of thesecondary phase.

Figure 1 Arrhenius plot of extracted grain boundary
diffusivities from the creep and grain growth rates.

Application to lower mantle: When creep andgrain growth rates are determined by the common
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 andviscosity at each depth and age of the mantle during
one cycle of the whole mantle convection. We usedlattice diffusivities of constituent elements inbridgmanite and post-perovskite estimated from ab
initiosimulations[4][5][6]anddiffusion
experiments [7][8][9]. Calculations show that grain
size and viscosity in downwelling mantle are ~0.2mm and 1018 ~ 1020 Pa·s while those in upwelling
mantle are ~0.5-10 mm and 1020 ~ 1024 Pa·s (Fig. 2).

Thus, we predict a large viscosity variation withinlower mantle. The viscosity profile estimated from ajoint inversion of convection and glacial rebounddata [10] is well within such variation (Fig. 2b).

Figure 2 Calculated depth profiles of grain size andviscosity in the lower mantle during whole mantle
convection. (a) Grain size, d. Grain growth ofpost-perovskite is calculated based on diffusion at different
crystallographic axes which are represented by different
colors. (b) Viscosity, η, of the lower mantle deforming bydiffusion creep. Colors correspond to that in (a). Viscosity
profile proposed by [10] is shown by a black solid line.

References: [1] Solomatov, V.S. and Reese, C.C. J.
Geophys. Res., 113, B07408 (2008). [2] Nakakoji, T.
and Hiraga, T. J. Geophys. Res., 123, 9513-9527(2018). [3] Okamoto, A. and Hiraga, T. in prep. [4]Ammann, M.W. et al. Phys. Chem. Miner., 36,
151-158 (2009). [5] Ammann, M.W. et al. Rev.
Mineral. Geochem., 71, 201-224 (2010a). [6]Ammann, M.W. et al. Nature., 465, 462-465 (2010b).
[7] Xu, J. et al. J. Geophys. Res., 116, B12205(2011). [8] Yamazaki, D. et al. Phys. Earth Planet.
Inter. 119, 299-309 (2000). [9] Dobson, D.P., Phys.
Earth Planet. Inter. 139, 55-64 (2003). [10]Mitrovica, J.X. and Forte, A.M. Earth Planet. Sci.
Lett. 225, 177-189 (2004).

Grain growth textures and kinetics in pyrolitic and basaltic materials under lower mantle
conditions
T Kubo1* and M. Imamura1 1Dep. Earth Planet Sci., Kyushu University, Fukuoka 819-0395, Japan.
*email: kubotomo@geo.kyushu-u.ac.jp

Peridotite and basaltic materials of deep
slabs cause significant grain-size reduction
across the upper and lower mantle boundary
through the post-spinel and post-garnet
transformations, respectively. The grain-size
sensitive creep possibly becomes dominant inboth materials, and therefore the grain-size
evolution controls viscosity variation andconvective mixing of chemical heterogeneities
in the lower mantle. Here we report on the
results of grain growth experiments inpyrolitic and MORB materials under lower
mantle conditions.
Each material consists of 3-4 phases in thelower mantle; those are bridgmanite,
Ca-perovskite, and ferropericlase (+majoritic
garnet at the top of the lower mantle) inpyrolite, and bridgmanite, Ca-perovskite,stishovite, and aluminous phase in MORB.
Grain
growthexperiments
inthese
assemblages were conducted using a
Kawai-type multi-anvil apparatus at ~25-27
GPa, 1873-2373K, and for 1-3000 min. XRD
and FE-SEM with EDS mapping were used to
examine phase identification, grain growth
texture and grain size of each phase.
Grain growth textures in pyrolite and
MORB materials at ~27 GPa are shown in Fig.
1. In the case of pyrolite material, the minor
phase of ferropericlase were solely located at
the grain boundary of the major phase ofbridgmanite. The dI/dII ratio was roughly
constant and estimated to be about 1.8 (! I:grain size of primary phase, ! II: grain size of
secondary phase). These observations suggestthat the grain growth of bridgmanite wascontrolled by Zener pinning and Ostwald
ripening of ferropericlase. Zener relationship(the dI/dII ratio with the volume fraction ofminor phase) in the pyrolitic lower-mantle
assemblages is almost consistent with thatobtained in the olivine-enstatite system(Tasaka and Hiraga, 2013). The grain size
evolution in peridotite materials will be
discussed based on the grain growth kineticsof the pining phase of ferropericlase and the
Zener relationship.
In MORB material, the volume fractions
are similar, however the grain sizes areslightly different among the 4 phases.
Stishovite and bridgmanite are larger thanothers, and stishovite exhibits columnar shape.
Because each phase is not connected, Ostwald
ripening likely controls the grain growth in allphases. The average grain size of 4 phases in
the MORB material is smaller than that in thepyrolitic material, which roughly corresponds
to the difference of ~300 K in temperature.
Quantitative analysis of grain growth kinetics
in each phase of MORB material will bepresented. We also discuss the difference ingrain size evolution and the possible contrast
in viscosity between pyrolitic and basaltic
materials in the lower mantle.

Figure 1 Grain growth textures in pyrolitic (top, 27GPa
1800°C 60min) and basaltic (bottom, 27GPa 2100°C
60min) materials under lower mantle conditions.

Technical development toward understanding the melting temperature of the materials at high pressureusing ultra-fast spectroradiometry
R Sinmyo1* 1Department of Earth and Planetary Science, University of Tokyo, Bunkyo, Tokyo 113-0033, Japan.
*email:sinmyo@eps.s.u-tokyo.ac.jp
Introduction: Melting is the most importantphenomena for understanding the co-evolution of
the Earth’s mantle and core. Researchers haveattempted to simulate melting of materials at highpressure and -temperature conditions forunderstanding the melting temperature, phaserelationships and element partitioning of thematerials at the core-mantle boundary. However, themelting temperature and phase relationships ofterrestrial materials are not yet understood well,partly because of the unstable/heterogeneous
heating in the laser-heated diamond anvil cell
(LHDAC) experiments. This project aims tounderstand the melting temperature and the phaserelationships under high-pressure conditions byusing newly developed ultra-fast spectroradiometry.
Experimental: High-pressure and -temperature
conditions were generated by using LHDAC andinternal-resistance-heated diamond anvil cell
(IHDAC) [1]. Metallic iron, boron-doped diamond,and silicate materials were used for the sample. DC
source was used for heating in IHDAC. A function
generator was used for controlling power source andspectrometer to synchronize heating andtemperature measurements. A bipolar source wasconnected to the function generator for theamplification of the square-wave pulse for heating
in some runs. The slew rate of the bipolar source wasseveral hundred volts/microsecond in theory.
Voltage and current were monitored by a high-speed
digital logging system.
A fast CCD camera was attached to an
astigmatism-reduced spectrometer for stationary 2D high-resolution fast spectroradiometry. For ultrafast 2-D spectroradiometry, galvanometer mirror
was combined with optical filters andphotomultiplier tubes. Streak camera was used for
one run to obtain time-resolved spectra.

Results and Discussion: In IHDAC
experiments, the temperature of the iron sample
started fluctuating at certain temperature uponincreasing voltage [1]. Such fluctuation is likely due
to a morphology change upon melting. Since theonsets of fluctuation coincide with the jump of theresistance and disappearance of XRD signals fromthe solid sample, the voltage-temperature
relationships can be used as a criterion for themelting. However, in the previous study,
temperatures were determined by a conventional
spectrometer and thus the spectra can be obtained <~ 2 frames/sec (~ 500 milliseconds/frame), whichmight be too slow to resolve dynamics of thetransition from solid to liquid. In this study, 2-D fast
spectroscopy was combined with LHDAC andIHDAC setup. The spectroscopic measurements
were successfully synchronized with the pulse or
short-time heating in IHDAC and LHDAC. Spectra
were obtained in ~50 frames/sec (~20
milliseconds/frame) by a newly developed system
for the full 2-D image using a fast CCD camera. In
contrast, several microseconds can be resolved byusing the streak camera. Although the streak camera
provides the fastest measurements, the signals wererelatively weak so that accumulations are necessary
for several ten seconds. Obtained spectra showedthat the increase or decrease of temperature ends
within several ten microseconds in square-wave
pulse heating experiments using IHDAC. Such ashort time can not be resolved by conventional
spectroscopy. By a combination of DAC
experiments and ultra-fast spectroscopy, it ispromising to determine the melting temperature ofterrestrial materials more precisely.
References: [1] Sinmyo, R., Hirose, K. and Ohishi,
Y. Earth Planet. Sci. Lett., 510, 45-52 (2019).

Pressure scales at multi-megabar pressure
T Sakai1* 1Geodynamics Research Center, Ehime University, Matsuyama, Ehime 790-8577, Japan.
*email:sakai@sci.ehime-u.ac.jp
Introduction: The pressure conditions of deep
interior of super-Earths much higher than that of thecenter of the Earth, and reach several hundreds ofgigapascal (GPa). Above 500 GPa, a lot of phasetransitions are predicted by theoretical studies foroxides, silicates [1]. Although diamond anvil cell(DAC) is widely used as an experimental tool togenerate very high pressure, its pressure is usuallylimited up to about 300 GPa. In order to beyond thelimit of conventional diamond anvils, the double
stage diamond anvil cell (ds-DAC) technique wasinvented by Dubrovinsky et al. [2], and it is thought
as a promising technique to generate ultra-high staticpressures. We have also developed a ds-DAC
technique by precisely fabricating 2nd stage anvils
using a focused ion beam system. Using ultra-fine (<10 nm) nano-polycrystalline diamond as 2nd stage
micro-anvils, we succeeded to generate a pressure
above 400 GPa [3] based on the equation of state ofrhenium (Re-EoS) proposed by Anzellini et al. [4],while it is about 630 GPa according to the Re-EoS
reported in Dubrovinsky et al. [2]. Although we
conclude that the most likely pressure achieved wasin a range of 430–460 GPa based on a calibration
experiments using the platinum pressure scale [5] to
280 GPa, it should be confirmed the consistency
between various pressure scales at multi-megabar
conditions. Here, the consistency between equationsof state (EoS) for rhenium (Re), Gold (Au), platinum(Pt) and periclase (MgO) at multi-megabar condition
will be discussed.
Experimental: We performed the compression
experiment of Pt and MgO using a conventional
DAC with a 40 μm double beveled culet. Pt andMgO were compressed up to about 308 GPa. The
samples were annealed at each pressure condition
using a laser heating system. For this run, MgO EoS
described by Keane equation was used as a pressure
standard [6]. In the second run, Au and Pt samples
were compressed up to about 350 GPa with a silicate
glass which was used as a pressure medium. Culet
size of diamond anvils was 20 μm. Second run was acold compression without a laser annealing. Powder
X-ray diffraction experiments were performed at
BL10XU, SPring-8.
Results and Discussion: First, we determined a
Pt-EoS based on MgO scale [6]. And then, Re-EoS’s
parameters were obtained based on the Pt-EoS using
a compression data of Re and Pt reported in Sakai etal. [3]. The new Re-EoS was shown in Figure 1 as
“Keane-MgO calibration”. As shown in Figure 1, we
could not reproduce the Re-EoS reported byDubrovinsky et al. [2] in any Pt scales calibrations[7,8] and by our new Re-EoS. Since Re-EoS by [2]was calibrated by Yokoo-Au scale [5], the difference
between Au and Pt scale is a key to discuss thisdiscrepancy. Simultaneous compression study of Au
and Pt (second run) yields the volume-volume
relation of these materials at high pressure condition.
Using this relation, we can check the pressure
difference between Au and Pt scale by [5]. As aresult, Yokoo-Au scale and Yokoo-Pt scale are“roughly” consistent, and the pressure difference
between these scales (10-20 GPa) cannot account forthe discrepancy (>100 GPa). The discrepancy
between Re-EoS by [2] and others should be
explained by the experimental problem caused by alarge/steep pressure gradient in the ds-DAC
experiments.

Figure 1 Compression curves of rhenium based on several
pressure standards.

References: [1] Tsuchiya, T., and Tsuchiya, J.,
Proc. Natl. Acad. Sci. 108, 1252-1255. (2011)[2] Dubrovinsky, L., et al., Nat. Commun. 3, D
OI:10.1038/ncomms2160 (2012). [3] Sakai, T., etal., High Press. Res. 38, 107-119. DOI:10.1080/08957959. 2018.1448082 (2018). [4] Anzellini,S., et al., J. Appl. Phys. 115, DOI:10.1063/1.486
3300 (2014). [5] Yokoo M., et al., Phys. Rev. B
80, 104114. (2009). [6] Sakai, T., et al., Sci. R
ep. 6, DOI:10.1038/srep22652 (2016). [7] Dorogo
kupets, P.I. and Oganov, A.R., Phys. Rev. B 75,
024115. (2007). [8] Sokolova, T.S., et al., Com
p. Geosci. 94, 162-169. (2016).

Polycrystalline diamond sintered from ultradispersed nanodiamonds
M Nishi1,2*, K Yamamoto1, Y Zhou1, T Irifune1,2
1
Geodynamics Research Center, Ehime University, Ehime 790-8577, Japan.
2
Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo 152-8550, Japan.
*email:nishi@sci.ehime-u.ac.jp
Introduction: NPD is a binder-lessnanodiamondaggregate(~50nm)
synthesized by direct conversion of graphite
under high pressure and temperature [1].
Although NPD has extremely high hardness
exceeding that of single-crystalline diamond,
it is difficult to obtain the large size of the
NPD above 1 cm3, because extreme highpressure conditions are required. Here weshow nanodiamond polyclystalline sinteredfrom ultradispersive nanodiamond underrelatively
moderatepressureandtemperature conditions.
Experimental: We used a multi-anvil
apparatus to sinter the nanodiamonds at 8-15
GPa and 1600-2300°C, where the diamondis thermodynamically stabilized. The
starting materials were enclosed in metal
capsules. The microstructures and chemicalcompositions of the recovered samples were
examined using a field-emission scanningelectron microscope with energy-dispersive
X-ray
spectroscopy.
Well-sinteredpolycrystalline were subjected to the Knoop
indentation test to evaluate its hardness.
Results and Discussion: We succeeded inrecovering the well-sintered polycrystalline
diamonds with grain size of ~10-30 nm insome runs (Figure 1). Full width at half
maximum of XRD peaks decreased withincreasing temperature due to the grain
growth of diamond particles. The color,hardness, and grain size of the sinteredpolycrystalline changed depending on thecapsule materials as well as the pressure andtemperature conditions. These features
might be affected by the porosity, the grainsize, and the impurities. Further studies are
required to synthesize the polycrystalline
with high hardness comparable to NPD.

Figure 1 SEM image of the recovered diamondpolycrystalline.
.

References: [1] T. Irifune, A. Kurio, S.
Sakamoto, T. Inoue, H. Sumiya., Nature,421, 599 (2003).

Development of ultrasonic measurement technique toward whole lower mantle conditions
Y Higo1*, T Irifune2
1JASRI, SPring-8, Kouto, Hyogo 679-5198, Japan.
2GRC, Ehime University, Matsuyama, Ehime 790-8577, Japan*email:higo@spring8.or.jp
Introduction: Elasticity data on mantle
minerals under high pressure and high temperatureare critical to interpret the seismic velocity anddensity profiles in the Earth’s deep interior.
However, ultrasonic measurements of elastic wave
velocities under high pressure and high temperature
have been limited to those corresponding to themantle transition region (<24GPa, <1673K),
because of the technical difficulties [1]. Since onlya small sample can be used in the experiment under
the lower mantle conditions, ultrasonic echoes arevery weak and cannot perform a precise elastic
measurement. In this study, to overcome thisproblem, the high-frequency arbitrary waveformgenerator, post amplifier and high-speed
semiconductor relay were installed in BL04B1 at
SPring-8 [2].
Experimental: For test measurement, purepolycrystalline alumina rod (General Electric (GE)brand LucaloxTM; f= 1.0mm, L= ~0.5mm) was used
as a test sample. Since alumina is very hard and there
is no phase transition under the condition of theupper part of the lower mantle, numbers of elastic
data, which can be compared is reported. An
assembly of eight cubic anvils of WC with edge
length of 26 mm and truncated corner of 3.0 mm has
been used in Kawai-type multi-anvil apparatus(SPEED-1500). Travel times for both P- and Swaves passing through the sample were measured
by the ultrasonic interferometry, and each sample
length under pressure was determined from the Xray image of the sample using a high-resolution
CCD camera. At the same time, X-ray diffraction
data from the sample were acquired, and thegenerated pressures were monitored throughout therun.
The travel time of ultrasonic waves through thesample was determined by a pulse echo overlap
method. The ultrasonic transducer was used togenerate and receive ultrasonic pulses. In this study,
a high-frequency waveform generator (Tektronix
AWG 710 B) was introduced to drive an ultrasonictransducer in high frequency and high voltage
signals, enabling the generation of a high-frequency
burst sinewave signal of 60–80MHz range, and a
low-noise post-amplifier (Thamway T142-4029A)
was also introduced to amplify the burst sine wave
signal (2 Vpp: voltage peak to peak) from the high-frequency generator to 30 Vpp for generating
powerful ultrasonic pulses (Fig. 1).

Figure 1 Images of the installed ultrasonic measurement
system. Waveform generator, post-amplifier, and digital
oscilloscope located outside of the experimental hutch.
High-speed semiconductor relay device located beside thehigh-pressure press inside the experimental hutch.

Results and Discussion: We have successfullymeasured elastic wave velocities of alumina up to~30GPa, which corresponds to the lower mantle PT condition. The waveforms observed very clear,and the echoes of P-wave and S-wave wereidentifiable at high pressure and high temperature(Fig. 2). Precise elastic wave velocity measurementof the lower mantle minerals will be attained using
this system. More recently, higher pressure
ultrasonic measurements of Mg-perovskite havebeen started, combined with the sintered diamondanvils. In this presentation, the recent experimental
results of Mg-perovskite and other mantle minerals
under high pressure will also be present.

Figure 2 Example of waveform data of Al2O3 for the Pwave signal measured at high pressure and temperature,~27 GPa and ~800℃.

References: [1] Higo, Y., Kono, Y., Inoue, T.,
Irifune, T., Funakoshi, K., J. Synchrotron. Rad. 16,
762 (2009) [2] Higo, Y., Irifune, T., Funakoshi, K.,
RSI, 89, 014501 (2018)

Importance of various Al substitutions in bridgmanite
T Inoue1,2,3*, M Noda3 , S Kakizawa3, T Kuribayashi4, A Sano5 and T Hattori5, 1 Department of Earth and Planetary
Systems Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526,
Japan, 2 Hiroshima Institute of Plate Convergence Region Research (HiPeR), Hiroshima University, HigashiHiroshima, Hiroshima 739-8526, Japan, 3 Geodynamics Research Center (GRC), Ehime University, Matsuyama,
Ehime 790-8577, Japan. 4 Department of Earth Science, Graduate School of Science, Tohoku University, Sendai
980-8578, Japan, 5 J-PARC Center, Japan Atomic Energy Agency, Tokai, Naka, Ibaraki 319-1195, Japan.
*email:toinoue@hiroshima-u.ac.jp
Introduction: Bridgmanite should be a major
constituent mineral in the Earth's lower mantle, and[1] reported that bridgmanite can incorporate almost
Al2O3 component in lower mantle. The Al
substitution mechanism is supposed to becomplicated, because there are two types of Al
substitution mechanisms in anhydrous bridgmanite,
Tschermak and oxygen vacancy substitutions (e.g.
[2]). However, the pure Tschermak and oxygen
vacancy substitutions bridgmanite has not beenreported so far in low Al content, when we checked
the previous studies carefully (e.g. [3, 4]). The
previous studies have used powder samples as thestarting materials, so we considered that theabsorbed water may affect the results, because wehave a knowledge of the possible existence ofhydrous bridgmanite which has a water content of~0.8 wt%. Therefore, we tried to investigate thepossible existence of the Al substitution mechanism
in bridgmanite as a function of Al content in
extremely anhydrous condition.
Experimental: The high pressure experiments
were conducted at 28 GPa and 1600-1700℃ for 1
hour using a Kawai type apparatus. Some different
Al content samples were prepared as the starting
materials along the ideal substitution line ofTschermak and oxygen vacancy substitutions,
respectively. Glass rods were used as the starting
materials to eliminate the absorbed water on thesample surface. Moreover, the glass rods wereenclosed in a rhenium capsule to prevent the water

incorporation from the surrounding cell assembly.
In addition, all parts of the cell assembly were dried
just before the synthesis experiments. The chemicalcompositions of the starting materials were
examined by SEM-EDS, and the recovered samples
were identified by X-ray and neutron (in J-PARC)
diffractions and SEM-EDS.
Results and Discussion: Our results show that
it is possible to exist both Tschermak and oxygen
vacancy substitution bridgmanites in low Al content
in anhydrous condition. The maximum Al content
for pure oxygen vacancy substitution bridgmanite
was less than ~0.025 pfu in total cation of 2, and theexistence of pure oxygen vacancy substitution
component is restricted to be less than Al=~0.1 pfu.
The present result combining with our previous
study in hydrous condition, shows that hydration in
Al-bearing bridgmanite should occur easily ifhydrogen exists in the system (lower mantle) inpyrolite (MgO-excess) composition. Thus the large
deviation from the Tschermak substitution in theprevious studies mainly should come from thehydration from the absorbed water.
References: [1] Irifune, T., Nature, 370, 131 (1994).
[2] Kojitani, H., Katsura, T. and Akaogi, M., Phys.
Chem. Mineral., 34, 257 (2007). [3] Irifune, T.
Koizumi, T. and Ando, J., Phys, Earth Planet. Inter.,
96, 147 (1996). [4] Kubo, A. and Akaogi, M., Phys,
Earth Planet. Inter., 121, 85 (2000).

Stability field of hydrous aluminosilicates from the mantle transition zone to the shallow part of the lower
mantleA Suzuki1* 1Department of Earth Science, Graduate School of Science, Tohoku University, Sendai, Miyagi 9808578, Japan.
*email:akio.suzuki.c5@tohoku.ac.jp
Introduction: Water is transported into the deep
Earth’s interior by hydrous minerals in thedescending slabs. Previous studies showed thathydrous aluminosilicates would be stable in thesedimentary layer of subducting slab. Discovery ofphase Egg in the diamond inclusion also supportsthat hydrous aluminosilicate could exist in the
Earth’s deep interior. Topaz-OH II was synthesized
by Kanzaki [1] at the pressure of 14 GPa and thetemperature of 1400 °C, but no experiment has beenreported under higher pressure conditions. In thehigh pressure and high temperature experimentusing starting materials of Al2SiO4(OH)2
composition have reported stable regions only at 26
GPa [2]. The phase relation of Al2SiO4(OH)2
aluminosilicates between 14 and 26 GPa isimportant for the discussion of water transport fromthe mantle transition layer to the shallow part of thelower mantle.
Experimental: In this study, quenchingexperiments and in situ X-ray diffraction studies on
the phase relation of Al2SiO4(OH)2 were conductedin the pressure range of 12.0–32.2 GPa and in thetemperature range of 800–1600 °C. Quenchingexperiments were carried out using a Kawai-typeapparatus at Tohoku University. The recovered
samples were analyzed by XRD and SEM. In situ Xray diffraction studies were carried out at thebeamline BL04B1 at SPring-8. Energy dispersive
method using a pure-Ge solid state detector was
adopted to collect X-ray diffraction data.
Results and Discussion: We observed thecoexistence of δ-AlOOH and stishovite at 31.0 GPa

and 1500 °C and the formation of phase Egg
together with corundum at 30.6 GPa and 1600 °C.
These results indicate that phase Egg is stable atleast up to 30.6 GPa and 1600 °C, which is higher
pressure and temperature condition than thatreported previously. Aluminous phase D, which wasreported by Pamato et al. [2], was not observed in
the present study. Phase Egg should be the importantwater carrier after the avalanche of the stagnant slab
up to the depth of approximately 900 km in thelower mantle.

Figure 1 Phase diagram of Al2SiO4(OH)2 composition
under high pressure and high temperature.

References: [1] Kanzaki, M., Amer. Mineral., 95,
1349 (2010). [2] Pamato, M.G., et al., Nature
Geosci., 8, 75 (2014).

Reaction between forsterite and nitrogen fluid at high pressure and high temperature
H Kagi1*, T. Kubo1, A. Shinozaki2, T. Okada1, H. Ohfuji3, A. Nakao4 1 Geochemical Research Center, Graduate
School of Science, The University of Tokyo, Hongo 7-3-1, Tokyo 113-0033, Japan. 2 Faculty of Science,
Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo 060-0810, Japan. 3 Geodynamics Research Center, Ehime
University, Bukyo-cho 2-5, Ehime 790-8577, Japan. 4 Institute for Physical and Chemical Research (RIKEN),
Hirosawa 2-1, Wako, 351-0012, Japan. *email:kagi@eqchem.s.u-tokyo.ac.jp
Introduction: Nitrogen is the essential elementin the biosphere and its geochemical behavior
dramatically changes with its chemical species. In
the crust, nitrogen exists as NH4+ substituting for K+
in silicate minerals. However, with increasing depth
in the Earth, uncertainties on geochemical behaviorof nitrogen remain unrevealed. Recently, Yoshioka
et al. (2018) investigated solubility of nitrogen in the
major minerals of the Earth’s transition zone and thelower mantle [1]. As mentioned, chemical
speciation of nitrogen strongly depends on oxygen
fugacity. Under the reduced condition in the deep
Earth, the nitrogen speciation could be as NH4+ orN3-. Interactions and reactions between mantle
minerals and nitrogen have to be investigated forunderstanding geochemical behavior of nitrogen. In
this study, we focused on a possibility of reaction
between a representative upper-mantle mineral,
forsterite (Mg2SiO4), and nitrogen and tried toconstrain the chemical states of nitrogen in the
mantle.
Experimental: For high pressure experiments,
diamond anvil cells (DACs) equipping a pair of typeIa diamond anvils were used. Starting samples werea single crystal synthetic forsterite (Mg2SiO4) or
powdered synthetic forsterite. After loading thestarting material, nitrogen was introduced to thesample hole by soaking the cell into liquid nitrogenand the pressure was applied after sealing the sample
and nitrogen. Before heating samples, N2 was loaded
to a gasket hole with a sample and pressure wasincreased to approximately 5 GPa, whichcorresponds to representative pressure in theshallow upper mantle where forsterite is the mostabundant mineral and stable phase. A carbon
dioxide laser and/or a fiber laser were used to heat
forsterite loaded in the DACs. Generated
temperature in the sample ranged from 1300 K to3500 K. Heated samples were quenched to room
temperature and characterized with various methods.
X-ray diffraction (XRD) patterns were obtained at
BL-18C of the Photon Factory, KEK. Sample
images were obtained with field-emission scanningelectron microscope (SEM, JSM-7000F; JEOL).
Chemical speciation of nitrogen was investigatedusing X-ray photoelectron spectroscopy (XPS, PHI
5000, VersaProbe II; ULVAC-PHI, Inc.) equippedwith a monochromatic Al Ka X-ray. forcompensating charge-up on the sample surface
Results and Discussion: Figure 1 shows a
representative X-ray diffraction pattern of powder
forsterite sample recovered from reaction with N2.
After the reaction, orthopyroxene (MgSiO3) was
detected. Moreover, a small peak assignable to themost intense reflection of Si3N4 was detected. The
present results indicate that the following
decomposition reaction occurs in N2 fluid at highpressure and high temperature.
Mg2SiO4 → MgSiO3 + MgOFigure 1 X-ray diffraction patterns of powder forsterite
sample before heating and after heating at high pressurein the DAC. After heating with the CO2 laser at 1400 K
and subsequently with the fiber laser at 1800 K, formationof orthopyroxene was observed. The inset shows enlarged
angle region corresponding to the most intense reflectionof Si3N4.

Dissolution of forsterite into nitrogen fluid was
also observed from the surface texture of a single
crystal of forsterite. The chemical composition of
forsterite surface suggested the preferential
dissolution of MgO component and incongruent
melting of forsterite which results in crystallizationof orthopyroxene and periclase. XPS spectra
revealed three nitrogen species, NH4+, N2, and N3-,
in forsterite. The present study was conducted undercoexisting with N2 fluid without controlling fO2. It
is worthwhile to note that the three nitrogen species
was found from forsterite heated with N2.
References: [1] Yoshioka, T. et al., Earth andPlanetary Science Letters 488, 134 (2018).

Behavior of light elements in the early stage of Earth’s evolution: In-situ high-pressure and temperatureneutron diffraction measurements on iron-silicate-water-sulfur system
R Iizuka-Oku1*, H Gotou2, K Fukuyama1 and H Kagi1, 1Geochemical Research Center, Graduate School of
Science, The University of Tokyo, Tokyo 113-0033, Japan, 2Institute for Solid State Physics, The University ofTokyo, Kashiwa, Chiba 277-8581, Japan.
*email: riizuka@eqchem.s.u-tokyo.ac.jp
the volume of fcc-Fe was significantly increased withtime at 700°C, whereas the sample without water
showed no change regardless of temperatures. The
cell volume of FeS-V did not increase for ~10 hours,suggesting that the formation of FeS was promoted in
the existence of water, but its hydrogenation was
negligible. Fe gradually incorporated D in theexistence of water and FeDx formed. The D content at
700°C even after >10 hours was x~0.10 at a maximum.
The value was small compared to that (x=0.23) by ourprevious study on Fe-silicate-D2O system without S.
From the SEM results, the inhibition of deuterization
might be due to the formation of FeS layer
surrounding Fe pellet, whereas such a thick FeS layer
was not observed when using the Fe+S pellet. The
sample without water did not include FeS layer nor
Fe-bearing silicates.
It is suggested that both S and Fe were not mobileand could not react with each other without theexistence of water. H and S can be preferentiallyincorporated into solid Fe at lower-T (~700°C) before
melting, i.e. in the very early stage of the Earth’s
formation. The other light elements (C, O, Si) could
have dissolved into molten iron hydride and/or FeS in
the later process of Earth’s core-mantle differentiation
at much higher-PT condition.
47.0

Unit cell volume (Å3)

46.8
46.6
46.4

Fe+S pellet_6.7 GPa, 700C
Fe pellet_6.7 GPa, 700C
Fe rod_6.6 GPa, 700C
Fe pellet_6.7 GPa, 700C
Fe rod_6.5 GPa, 700C

+water

Fe-fcc−water

46.2
46.0
45.8
0:00:00
57.3

2:24:00

4:48:00

7:12:00

9:36:00

12:00:00

Fe+S pellet

FeS-V

Fe pellet

57.2

Unit cell volume (Å3)

Introduction: The Earth’s core is considered toconsist of Fe alloy and some light elements (O, S, Si,
H, C). Hydrogen (H) is the most abundant element in
the universe and one of the promising candidates
existing in the Earth’s core. However, its amountdissolved in the core and its process are still unknown
because H cannot be detected by X-ray diffraction(XRD) and it easily escapes from iron by the releaseof pressure. Recently, H content in fcc-Fe at highpressure and temperature (high-PT) has been
determined using in-situ neutron diffraction
measurements at J-PARC [1], suggesting that H had
preferentially dissolved into iron before any otherlight elements have dissolved in the very early stageof Earth’s evolution. It is important to further study
the partitioning of the other light elements between
iron hydride (not pure iron) and silicates. To clarify
the effects of multi light elements on the core-mantle
segregation in the Earth’s formation, we have focusedon sulfur (S) and investigated its effect onhydrogenation of iron.
Experimental: As a starting material, Fe fine
powder was pelletized with/without S powder andplaced at the center of the graphite sample capsule.
Powder mixture of quartz (SiO2), brucite Mg(OD)2(or MgO for comparison of the water existence)surrounds the Fe pellet. Sample composition of
Fe:Mg(OD)2:SiO2=2:1:1 of molar ratio with 5wt.% ofS simulates an ideal condition of the primitive Earth.
In-situ high-PT neutron experiments were carriedout using a six-axis multi-anvil press “Atsuhime”
installed at PLANET (BL11), MLF, J-PARC. An
originally improved multi-anvil 6-6 type assembly
was applied. Three samples were pressurized up to 6–
7 GPa and then heated up to ~700 °C step by step. The
reaction processes (dehydration of Mg(OD)2, phasetransformations of Fe (bcc-fcc) and FeS, formation ofsilicates) were carefully checked in real time. The
diffraction patterns of fcc-Fe were measured at 550°C
and 700°C for several ~10 hours and analyzed using
the Rietveld refinement method to determine
structural and atomic parameters of fcc-Fe and subproducts. The recovered samples were examined by
XRD and a scanning electron microscope (SEM) Energy Dispersive X-ray Spectroscopy (EDS) to
more precisely identify the products, theircompositions, and the elements partition.
Results and Discussion: The cell volume changes
in fcc-Fe and subphase of FeS-V were investigated forevery hour during long-time measurements at 700°C
as shown in Fig. 1. For the sample including water,

Fe rod
57.1
57
56.9
56.8
56.7
0:00:00

2:24:00

4:48:00

7:12:00

9:36:00

12:00:00

Time (hh:mm:ss)

Figure 1 Time changes in unit cell volume of fcc-Fe (upper)
and FeS-V (lower) at 700°C. FeS-V was observed only inthe sample including water.

References: [1] Iizuka-Oku, R., et al., Nature
Commun., 8, 14096 (2017).

Structural study on new high-pressure forms of Al2SiO5
T Kuribayashi1*, Y Zhou2, T Irifune2, 3 and H Ohfuji2
1
Department of Earth Science, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
2
Geodynamics Research Center, Ehime University, Matsuyama 790-8577, Japan.
3
Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo 152-8550, Japan.
*email: t-kuri@m.tohoku.ac.jp
Introduction: Recently, two new high-PT formsof Al2SiO5 phases (kyanite-II and kyanite-III) havebeen synthesized at the conditions of 14-17 GPa and2300-2400 K for kyanite-II and 17-23 GPa and2400-2500 K, respectively (Zhou et al. 2018). They
reported that kyanite-II is a completely new phase,and kyanite-III corresponds to the phase with V3O5
type structure based on the similarity of the lattice
parameters and X-ray powder profile. Therefore, thecrystal structures of these two phases are needed to
be determined to discuss about their crystal
chemistry and physical properties.
Experimental: The samples of kyanite-II andkyanite-III synthesized by Zhou et al. (2018) wereused for present SC-XRD experiments. The
synthesized conditions are 2550K and 16.2 GPa forkyanite-II (OS2991) and 2750K and 19.3 GPa forkyanite-III (OS2992), respectively. Single crystal
pieces of Kyanite-II (0.06 ´ 0.04 ´ 0.04 mm3) andKyanite-III (0.06 ´ 0.07 ´ 0.02 mm3) used for X-ray
analysis were carefully selected because twinning
property were commonly revealed in polarized
microscope observation. SC-XRD experiments
were conducted using an automated four-circle Xray diffractometer (Rigaku, AFC-7S) withmonochromatized MoKa radiation (l = 0.71073 Å).
X-ray reflection intensity data were collected up to
2qmax = 60° (sinq / l ≈ 0.70). _Space groups of thephases were determined as P1 for kyanite-II andC2/c for kyanite-III based on the analyses of thesystematic absence rules in the distributions of Xray reflection intensity data.
Crystal structure determination and refinement
for two phases were succeed, yielding
R = 4.83% for_kyanite-II with space group P1 and R = 3.26 % forkyanite-III with space group C2/c. The X-ray
reflection intensity data with Fo > 4s(Fo) were used
for structure determinations and refinements of both
samples. No corrections for crystal absorption wereapplied because of the small absorption coefficientvalues and small size of crystals. Initial structuralparameters of both phases were obtained from thecharge flipping method with Superflip software(Palatinus and Chapuis, 2007). Extinction
corrections were applied for both analyses.
Anisotropic displacement parameters were used for
Al, Si and O atoms. Neutral atomic scattering factorof each atom specie (Al, Si and O) was taken fromInternational Tables for Crystallography Volume C(2004). All calculations for structural refinements
were performed by SHELXL97 with WinGX.
Results and Discussion: The crystallographic
information of each new phase obtained
through_refinements are as following: triclinic, P1, Z = 6, a =7.0560(7) Å, b = 9.4372(8) Å, c = 6.7755(7) Å, a =96.763(7)°, b = 99.177(8)°, g = 108.127(7)° and V =416.51(7) Å3 for kyanite-II, and monoclinic, C2/c, Z= 4, a = 9.2964(9) Å, b = 4.7084(7) Å, c =6.6289(10) Å, b = 111.300(9)° and V = 270.33(7) Å3
for kyanite-III. Calculated densities of these phaseare 3.877 and 3.982 (g·cm-3) for kyanite-II andkyanite-III, respectively.
The crystal structure of kyanite-II is shown in
Figure 1. The structure has two tetrahedral (T1 andT2), eight octahedral (Oct1 to Oct8) and fifteen
oxygen sites. T2 and M8 polyhedra arecharacteristic in kyanite-II structure. T2 tetrahedronshares a face with M8 octahedron and T2 and M8sites are too close each other, therefore they cannot
be occupied simultaneously. Also, T2 shares anedge with adjacent T2. T1 shares a corner with T2.
The mean T1 and T2 distances are 1.651 Å and1.743 Å. The mean octahedral Oct-O distances
implies that the distribution of Si and Al inoctahedral sites are disordered arrangement.
On the other hand, the crystal structure ofkyanite-III is shown in Figure 2. The structure has
two octahedral and three oxygen sites. Based on its
chemical formula, Si and Al should occupy Wycoff
4b site and Wycoff 8f site, respectively. The crystal
structure of kyanite-III is similar to that of V2TiO5.
The V2TiO5 structure is slightly different from V3O5
type structure in view of space group. The meanoctahedral Si-O and Al-O distances implies that the
distribution of Si and Al in octahedral sites are
disordered arrangement aswell as that of kyanite-II.

Figure 1. Crystal structure ofkyanite-II

Figure 2. Crystal
structure of kyanite-III

Static compression of B2 KCl to 230 GPa and its P-V-T equation of state
S Tateno1*, T Komabayashi2, K Hirose1,3 1Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo
152-8550, Japan, 2School of GeoSciences and Centre for Science at Extreme Conditions, University of Edinburgh,
Edinburgh EH9 3FE, U.K. 3Department of Earth and Planetary Science, The University of Tokyo, Tokyo 1130033, Japan.
*email: tateno@elsi.jp
Introduction: Potassium chloride is often used asa pressure gauge and pressure-transmitting medium inhigh-pressure experiments using a diamond-anvil cell
due to the chemically inert and soft natures. Coldcompression experiments on KCl in a helium pressure
medium performed up to 160 GPa reported its highly
compressible nature comparable to solid argon [1].
Walker et al. reported that B2 KCl exhibits lowthermal expansivity up to 8 GPa and 873 K [2], which
was supported by recent theoretical calculations [1].
Precise evaluation of its thermal EoS is of great
importance for high P-T experiments in the DAC.
Here we present a new EoS for B2-type KCl from ourhigh P-T experiments to 230 GPa/300 K and 60
GPa/2600 K in a laser-heated DAC.
Experimental: High P-T conditions weregenerated using laser-heated DAC techniques.
Diamond- anvils with a culet size of 300, 120, or 40
mm were used depending on the target pressure. The
starting material was powder of KCl that was mixed
with platinum black that served as an internal pressure
standard [3] and laser absorber. We used SiO2 glass(runs 1 and 2) or argon (runs 5 and 6) for thermal
insulation. Argon was cryogenically loaded into thesample chamber.
Angle-dispersive XRD measurements wereconducted at BL10XU, SPring-8. Heating was
performed from both sides of the sample byemploying a pair of 100 W Yb fiber lasers.
Results and Discussion: Four separate sets ofexperiments were performed to measure the unit-cellvolume of B2 KCl and Pt at 84.8–229 GPa at 300 K(runs 1 and 2) and 4.2–59.4 GPa at 300–2560 K (runs
3 and 4). We made efforts to minimize the effects ofthe deviatoric stress by employing thermal annealing
and choosing the diffraction lines for calculating theunit-cell volume, which was based on the gamma plot[4]. As a result, our P–V–T data represent much lesser
nonhydrostatic conditions than in the case of a He
pressure medium without thermal annealing.
To construct a thermal EoS for B2 KCl, all thedata were analyzed in the framework of a thermalpressure EoS based on the Mie-Grüneisen-Debye
model with a Vinet form at 300 K. Fitting all the hightemperature data simultaneously yielded K0 = 18.3(3),K0’ = 5.6(3), γ 0 = 2.3(2), and q = 0.8(2). Our
compression curve is in good agreement with therecent results by Dewaele et al. [1] to ~50 GPa, above
which the two curves, however, deviate from eachother slightly (Figure 1). The comparison between theprevious EoS reported by Dewaele et al. [1] and ourswith calibration against various Pt scales indicatesthat our EoS gives a lower pressure at a given volumeof KCl. In other words, our compression curve givesa smaller volume at a given pressure, which may arise
due to the different stress state developed in thesample chamber.
The calculated thermal pressure is almost pressure
insensitive due to the small Grüneisen parameter. This
is in good agreement with Dewaele et al. [1], in which
the thermal pressure is assumed to be independent ofvolume. The present study revealed that KCl shows asmall thermal pressure at any given pressure. For
instance, the thermal pressure of KCl is as small as~10 GPa at 3000 K, then increases to ~15 GPa at 4000
K regardless of the pressure, which are ~50% smaller
than the case for Pt, Au, or MgO. the determined low
thermal pressure of B2 KCl validates the use of a KCl
medium as a high-T pressure marker. This would add
another advantage of KCl over the other materials tothe soft and chemically inert natures.

Figure 1 (a) Volume data for B2 KCl and fit to
the Vinet EoS at room temperature. (b) Volume datafor 300 K and high-temperature and isothermal
compression curve based on the Mie-GrüneisenDebye model.
References: [1] Dewaele, A. et al., Phys. Rev. B,
85, 214105 (2012). [2] Walker, D. et al., Gephys. Res.
Lett. 87, 805 (2002). [3] Sokolova, T.S. et al., Comp.
Geosci., 94, 162 (2016). [4] Sing, A.K. and Takemura,K., J. App. Phys.,90, 3269 (2001).

Quantitative analysis from stigmatic isotope imaging of SIMS
S. Itoh1* 1Dept. Earth Planet.Sci., Kyoto University, oiwakecho sakyoku, Kyoto 606-8502, Japan.
*email:sitoh@kueps.kyoto-u.ac.jp

28Si
Area

A

Area

B

Area

C

Area

Area

D

50 pixels

Introduction:
Direct ion imaging with secondary ion mass
spectrometry (SIMS) has been developed in various
fields, such as Material sciences, Earth and planetarysciences, life sciences. Especially, quantitative
direct ion imaging techniques has recently
developed using stigmatic direct ion imaging
methods (e.g., Nittler, 1996; Yurimoto et al., 2003).
Experimental:
In this study, we try to develop the stigmatic
secondary ion imaging methods using Cameca ims4fE7 SIMS at Kyoto University. The imaging
detector system consists of micro-channel plate(MCP), florescent screen and Cooled 16bit chargedcoupled device (CCD) camera (BU-LN52 BitrunCo.). This conventional imaging system needs toestimate the calibration parameter with conversion
from ion to electron, and from electron to photon. In
Fig.1., the conversion between ADU/s/pixel andsecondary ion intensity are shown. The integrated
ADU is about 104/pixel. The CCD image is
512x512pixel. The magnification of secondary ion
image is about 0.4µm/pixel. The five area denotes
50x50pixel. The calculation of conversion equationshows the average value of five area.
Results and Discussion:
In principle, each micro-channel of MCP would be
different conversion parameter for electron
converted from secondary ions. Therefore, in orderto estimate the qualitative ion imaging using thissystem, we need to estimate the error of thisconversion parameter in different location of eachchannel.
In this talk, we introduce the estimation ofcalibration parameter between the light output countrate read by CCD camera and the count rate ofsecondary ions incident on MCP with different
experimental session. We will estimate the error ofeach nonlinear exponent parameter for five places(50 x 50 pixels) and these different parameters cause
the error of about 5%. We will discuss it in detailwith quantitative isotope imaging with applicationof high-pressure experiments.

50 pixelsE

y = 20.27 ± 1.01 x1.0111 ± 0.0089

Figure 1 Stigmatic 28Si- secondary ion image using CCD
camera. The plot diagram shows the relationship between
ADU/s/pixel and secondary ion count rate.

References: [1] Nittler, L.R. (1996) Quantitative
Isotopic Ratio Ion Imaging and its Application toStudies of Preserved Stardust in Meteorites. doctoral
dissertation Washington Univ. [2] Yurimoto, H.,
Nagashima, K., Kunihiro, T. (2003) High precisionisotope micro-imaging of materials. Appl. Surf. Sci.,
203-204, 793-797.

Controlling factor of whole-rock PGE concentrations in mantle peridotite
T. Kogiso1* and N. Akizawa2 1Graduate School of Human and Environmental Studies, Kyoto University, Kyoto,
Kyoto 606-8501, Japan. 2Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba
277-8564, Japan. *email: kogiso.tetsu.6s@kyoto-u.ac.jp
Platinum-group elements (PGE) are thought tobe concentrated strongly in the metallic core in the
Earth's interior, because they have strong affinity formetallic phases. This results in very low PGE
abundances in the silicate mantle, and it in turnenables PGE in the mantle to be used as a sensitive
indicator of the contribution of metallic phases tomantle chemistry. Thus, the abundances of PGE in
the mantle are an important key for understanding
the core-mantle differentiation process during
Earth's formation and the chemical interaction
between the mantle and core through Earth's history.
The PGE abundance in the mantle have been
estimated based on whole-rock PGE concentrationsof natural mantle peridotites. However, whole-rockPGE concentrations in peridotite samples areenormously scattered in general, and therefore it isdifficult to estimate the average abundances of PGE
in the mantle. This implies that even the best everestimation of the average PGE abundances in the
mantle [1,2] would contain large uncertainties.
Accurate knowledge about the behaviors of PGE in
mantle peridotite is thus necessary for the precise
estimation of the mantle PGE abundances, but it isstill to be quantitatively clarified how and by what
whole-rock PGE concentrations in mantle peridotite
are controlled and modified.
Recent micrometer-scale analytical studies haverevealed that the major host phases of PGE in mantle
peridotite are base-metal sulfides (BMS) andplatinum-group minerals (PGM) [e.g., 3-5]. It istherefore important to reveal the origin of the BMS
and PGM in peridotite for deciphering what controls
whole-rock PGE concentrations in peridotite. BMS
are commonly found in peridotite samples, andsome of BMS, such as those included in major
silicate minerals, potentially preserve pristine PGE
signatures of the mantle [3]. However, many BMS
are found in grain boundaries between silicate
minerals, and they are most likely to be formed inmetasomatic processes during transportation to the
Earth's surface [5]. The origin of PGM is muchdifficult to be investigated, because PGM have beenrarely discovered in peridotites due to their verysmall size (< several µm). Most of the PGM everfound in peridotite samples were associated with
BMS, and are likely to originate from subsolidus
exsolution from BMS [5-6]. These observations
suggest PGE hosts in peridotite are considerably
affected by secondary processes.
On the other hand, experimental studies revealed
that some of PGM can coexist with mantle minerals
at mantle temperatures, even at above solidus offertile peridotite, whereas BMS tend to be molten atsuch high temperatures [7 and references therein].
Model calculations on the basis of experimental data
showed that partial melting of fertile peridotite canjust roughly explain the correlations between PGE
and major element concentrations in naturalperidotite if PGM remain as solid phases in theresidue [8]. However, the modelling can't yet fully
reproduce the PGE variations in peridotite,
especially those in depleted harzburgite samples [8].
In addition, there have been so far no reports of theexistence of PGM that certainly originated fromresidue of peridotite partial melting.
Thus, it is still uncertain how PGE host minerals
in peridotite were formed, and therefore it's unclear
whether whole-rock PGE concentrations ofperidotite preserve pristine mantle signatures.
Further detailed petrological studies on theoccurrence of BMS and PGM in peridotite would benecessary for unraveling the origin of PGE hosts.
References: [1] Becker, H. et al., Geochim.
Cosmochim. Acta, 70, 4528 (2006). [2] FischerGödde, M. et al., Chem. Geol., 280, 365 (2006). [3]Alard, O. et al., Nature, 407, 891 (2000). [4] Kogiso,
T. et al., Geochem. Geophys. Geosyst., 9, Q03018(2008). [5] Lorand, J.-P. et al., Earth Planet. Sci.
Lett., 289, 298 (2010). [6] Akizawa, N., et al., Chem.
Geol., 475, 87 (2017). [7] Brenan, J. et al., Rev.
Mineral. Geochem., 81, 1 (2016). [8] Aulbach, S. etal., Rev. Mineral. Geochem., 81, 239 (2016).

Sulfur and carbon isotope fractionation under mantle conditions
F Maeda1, Y Horioka1, S Kamada1,2*, S Aoyama3, S Ozawa1, M Satish-Kumar3, A Suzuki1
1Department of Earth Science, Graduate school of Science, Tohoku Univ., Sendai, Miyagi 980-8578, Japan.
2Frontier Research Institute for Interdisciplinary Sciences, Tohoku Univ., Sendai, Miyagi 980-8578, Japan.
3Department of Geology, Faculty of Science, Niigata University, Nishi-ku, Niigata 950-2181, Japan.
*email:seijikmd@m.tohoku.ac.jp
Introduction: Isotopic compositions of sulfur andcarbon are important tracers for chemical evolutions
and ancient processes through the Earth history. A
recent study for isotope ratio of S reported that the
mantle was depleted in 34S based on analyses ofnatural mid-ocean ridge basalt (MORB) glasses [1].
As sulfur is a candidate of light elements in the core
because of the siderophile nature, this depletion in 34Smight be caused by a chemical reaction between the
mantle and the core during the magma ocean. Isotope
ratios of 12C and 13C (δ13C) have been examined forthe mantle samples such as carbonate, diamond, andvolcanic CO2. [e.g., 2] These analyses indicated acharacteristic δ13C value for the mantle as −5 ‰. In
contrast, some diamonds from the deep mantle
showed highly negative δ13C values such as δ13C of−20 ‰ [e.g., 3,4]. Origin of the mantle δ13C and thenegative δ13C of diamonds has been debated [3,5].
Since the isotope fractionations in the Earth interior
can play key roles to understand the isotopic
compositions of sulfur and carbon, pressure (P) andtemperature (T) effects on the isotope fractionations
were recently examined using high P−T experiments[5−7]. However, the experimental simulations are still
not sufficient in particular for pressures and systems
in the Earth. Present experiments investigated thesulfur isotope fractionation between the silicate melts
and metallic melts and carbon isotope fractionation
between carbonate and diamond or graphite at 3−10
GPa and 1500−1800 °C in order to reveal the P−T
effects on the sulfur and isotope fractionations in themagma ocean and the carbon isotope fractionations in
the modern mantle.
Experimental: High pressure and temperatureexperiments were conducted by using a Kawai-type
multi anvil press installed at Tohoku University.
Starting materials were mixtures of oxides for silicate
phases and mixtures of FeS and Fe for metallic phasesin the experiments for sulfur, and mixtures of natural
magnesite (Mg0.994Fe0.003Ca0.003CO3), reagent-glade
SiO2, and sp-2 graphite in the experiments for carbon.
Capsules made of hBN and Al2O3 were used andsurrounded by a graphite heater for the sulfur
experiments. An MgO capsule with a LaCrO3 heater
was used for the carbon experiments. Temperatures
were measured with W/Re thermocouples. The
compositions of recovered samples were analyzed by
SEM-EDS at Tohoku University and the sulfur andcarbon isotope ratios of that were analyzed by IRMS
at Niigata University.

Results and Discussion: Sulfur isotope ratios
only in metallic phases were analyzed becauseamounts of sulfur in silicate phases were not sufficientfor the analyses. Sulfur in the metal phases wereextracted using Cr(Ⅱ) reduction method [8]. The
pressure effects on δ34S were not observed. In contrast,
the temperature effects on δ34S were negative. The
present results indicate that S isotope fractionations
are difficult to occur in the present pressure range(3−5 GPa) under high-temperature conditions
corresponding to the magma ocean. On the other hand,an indirect-pressure effect on the sulfur isotope
fractionation is possible at higher pressurescorresponding to the bottom of the magma ocean(30−60 GPa): coordination numbers (CN) of cations
in silicate melts increase at such pressures [9]. Since
heavy isotopes prefer bonds of lower CN [e.g., 10, 11],
it is expected that the heavy isotope (i.e., 34S) is
depleted in silicate melts under high-pressure
conditions corresponding to the deep magma ocean.
The negative δ34S of mantle can hence be explainedby the indirect pressure effect on the sulfur isotope
fractionation. Carbon isotope ratios were be measured
for both of carbonates and diamond/graphite. The
differences of δ13C values between carbonates anddiamond/graphite were approximately 10−11 ‰.
These values were larger compared with previous
studies, showing the carbon isotope fractionation of
1−3 ‰ [5,7], but were consistent with a pervious
report for isotope fractionations between acarbonated-silicate and graphite [7]. The large
difference of δ13C between carbonate anddiamond/graphite can yield due to non-equilibrium
conditions for the carbon isotopes, or reduction ofcarbonates as shown by Mizutani et al. [7].
References: [1] Labidi J. et al., Nature, 501, 208-211.
(2013) [2] Denies P. Earth Sci, Rev., 58, 247−278. [3]Walter M.J. et al., Science, 334, 54−57. (2011) [4]Bulanova G.P. et al. Contrib. Miner. Petrol. 160,
489−510 (2010) [5] Satish-Kumar M. et al., Earth
Planet. Sci. Lett., 310, 340−348. (2011) [6] Labidi J.
et al., Geochim. Cosmochim Acta, 175, 181−194.
(2016) [7] Mizutani, S. et al. Earth Planet. Sci. Lett.,
392, 86−93. (2014) [8] Canfield D.E. et al., Chem.
Geol., 54, 149-155. (1986) [9] Bajgain S. et al., Nat.
Commun., 6, 8578. (2015) [10] Criss R.E. Oxford
University Press, Inc., New York, 254. (1999) [11]Schauble E.A. In Geochemistry of Non-Traditional
Stable Isotope, 55, 65-111. (2004)

The major element composition of the Hadean crusts: constraints from Sm-Nd isotope systematics andhigh-pressure melting experiments
N M Kondo1,2*, T Kogiso1
1Graduate School of Human and Environmental Studies, Kyoto University, Nihonmatsu-cho, Sakyo-ku, Kyoto,
Japan.
2Geodynamics Research Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime, Japan.
*email: kondo.nozomi.xg@ehime-u.ac.jp
Introduction: The mantle composition anddynamics have been evolved through formation andre-mixing of crust. Therefore, in order to understandthe history of the mantle chemical and dynamical
evolution, we have to know the initial condition of
the crustal formation and recycling. Previous studies
have investigated the crustal formation in the early
Earth from zircons <4.4 Ga, and from isotopic recordin 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, …) frommelting of pre-existing (primary, …) crust and remixing of these crusts. However, the rock record
before 4.0 Ga (the Hadean) has never or scarcely
found, and therefore, the major element compositionof the Hadean crusts have been unrevealed. The
major element composition controls physicalproperties such as density and viscosity of melt andcrust, and these physical properties in turns controls
the formation and recycling of the crust. Therefore,
in this study we constrained the major element
composition of the Hadean primary and secondary
crust and discussed about the formation and fate ofthese Hadean crusts.
Strategy: We combined the Sm-Nd isotope
systematics and high-pressure melting experiments
in order to constrain the major element compositionof the Hadean primary and secondary crust. For the
primary crust, we firstly estimated melting conditionof mantle at the Hadean silicate (mantle and crust)differentiation from the Sm-Nd systematics in theearly Archean rocks, that have higher and lower
142Nd/144Nd ratio than that of the present mantle. The
142Nd/144Nd anomalies are distinct in the earlyArchean rocks, and diminish from the late Archean
to the present. Due to the short half-life of the 146Sm(68 Myr), the parent nuclide of the 142Nd, the142Nd/144Nd anomalies and diminishing of them havebeen 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/Ndand 142Nd/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 these two variablesfrom 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 data of high-pressure melting experiments of aprimitive 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 ofsynthesized starting material with the hydrous
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 Hadeansilicate 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 compositionof the Hadean primary crust to be Ti-Fe-P-richkomatiitic by estimating the condition of the Hadeanmantle (mantle potential temperature, tectonics, andthickness of lithosphere). We also discussed theformation of the Hadean primary crust by estimating
the density and viscosity of the Ti-Fe-P-richkomatiitic melt. For the Hadean secondary crust, thesolidus 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 the hydrous
Hadean primary crust by comparing the solidus andsubduction P-T pass of the early Archean and thepresent subduction zones. We also discussed theformation 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 and secondary
crust by combining the Sm-Nd systematics and highpressure melting experiments. The Hadean primary
crust would have formed at extremely small melt
fraction and had Ti-Fe-P-rich komatiitic
composition. The Hadean secondary crust would
have formed subduction-related melting of thehydrous Hadean primary crust and had Ti-Fe-P-richmafic composition.

Completion of the seismic observation with Thai Seismic Array (TSAR)S Tanaka1* 1D-Earth, JAMSTEC, 2-15 Natsushima-cho, Yokosuka, 237-0061, Japan.
W. Siripunvaraporn2, S. Boonchaisuk2, S. Noisagool2 2Facuty of Science, Mahidol University, Bangkok, Thailand.
K. Kawai3, Y. Suzuki3 3Graduate School of Science, Univ. Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
T. Kim4, Y. Ishihara4 4CEAT, JAMSTEC, Showa-cho, Kanazawa-ku, Yokohama, 236-0001, Japan.
H. Kawakatsu5, N. Takeuchi5, K. Miyagawa5, R. Iritani5 5ERI, Univ. Tokyo, Yayoi, Bunkyo-ku, Tokyo, 113-0032,
Japan.
*email:stan@jamstec.go.jp
Introduction: Thailand occupies an importantarea to study the lowermost mantle below thewestern Pacific where is the western edge of the
Pacific Large Low Shear-Velocity Province(LLSVP) and the deep part of the inner core.
However, the density of seismic stations has notbeen so high compared with the neighboring regions,(e.g., China and India). Furthermore, tectonics inThailand is interesting to understand geology of the
Indochina peninsula and a moderate size earthquake
occurred in the northern Thailand in 2014. Thus,
Japanese and Thai seismologists have been keen forseismic observation in this area.
Under the project “Seismic and geoelectromagnetic observation for core and mantle”,
which is one of the KAKENHI grants for innovative
area “Core-mantle co-evolution and interaction”, wefinally got the opportunity for the broadband seismic
observation named Thai Seismic Array (TSAR)
from January, 2016 with deploying 2 pilot stations
and the array was completed with 40 stations in Feb.
2017. After about 2 years operation, thedismantlement of the TSAR stations has been
completed in January 2019. Here we briefly report
this observation.
Observation: Geographical distribution of the
TSAR stations is shown in Fig. 1. The typical stationinterval is about 100 km except for the western areaof the main Thailand. Originally, we had a plan to
deploy the stations in the Malay peninsula.
Unfortunately, due to heavy rain and severe flooding
in January and February 2017, we changed thedeployment area from the Malay peninsula to thecurrent area. As a result, we obtained a dense
network in the western area.
We could organize only 1 deployment team.
Thus, in order to complete the deployment of 40
stations except for 2 pilot stations, we tripped 4times during November 2016 to February 2017. The
maintenance and data collection trips are conductedby Thai members in summer, and by both Japaneseand Thai members in winter. Due to probably severe
flooding and activities of local creature, the sensors
and data logger at nearly half of the stations weredamaged. And lightning probably affected the GPS
clocks. The dismantlement trips were conducted in
December 2018 and January 2019.

Results and Discussion: In the period fromJanuary 2017 to December 2018 in which more thanabout half of stations works, there were 245
earthquakes with magnitude greater than or equal to
6.0 [1]. Among these, the nuclear explosion in North
Korea is included. And the focal depths of 48
earthquakes are greater than or equal to 100 km,
which are mainly distributed in the southwestern
Pacific and south America. Such deep earthquakes
are expected to provide the good data to obtain the
structure of the mantle and core. Additionally, we
had a moderate earthquake with magnitude of about
5 occurred in the western area of Thailand, of which
epicenter is 14.90°N, 99.14°E determined by Thai
Meteorological Department, on December 30, 2018
and 8 TSAR stations in the western area successfullyrecorded this event. Thus, the TSAR data willcontribute to hypocenter relocation and the further
understanding of the source mechanism.
Although we sent back the instruments
belonging to the ERI, Univ. Tokyo just after thedismantlement, 3 sets of the instruments belonging
to JAMSTEC are left in Bangkok. They will bereinstalled in the active fault area in the northern
Thailand for the continuing collaboration withMahidol Univ.

Figure 1 Distribution of the full TSAR stations (soldtriangles).

References:[1]
earthquakes/search/https://earthquake.usgs.gov/

S-to-P scattering in the lower mantle near subduction zones
S Kaneshima1* 1Department of Earth and Planetary Science, Kyushu University, Fukuoka, Nishi-ku, Motooka,
819-0395, Japan.
*email:kane@geo.kyushu-u.ac.jp
We investigate S-to-P scatterers in shallow to midlower mantle beneath subduction zones, where deep
seismicity extends down to the bottom of the upper
mantle. By array processing broadband and shortperiod wave form data obtained at seismic networks,
we seek anomalous later phases in the P coda. The
later phases usually arrive along off-great circle paths
and significantly later than S-to-P conversion at the"660 km" discontinuity. They are thus adequately
regarded as scattered waves, rather than conversion at
a global horizontal discontinuity, and indicate that aspatial change in elastic properties by several percent
occurs at the scatterers as abruptly as the post-spineltransformation, probably caused by compositional
heterogeneity. We locate prominent S-to-P scatterers
beneath Pacific subduction zones. Nearly half of 137
S-to-P scatterers located in this study and previous
studies by the authors are shallower than 1000 km,
and the number of scatterers decreases with depth. In
this presentation we focus on the S-to-P scatterers in
the mantle beneath Samoa hot spot north of the
Tonga-Fiji subduction zone, where seismic
tomography has revealed a large-scale upwellingfrom the Pacific LLSVP at the base of the mantle. In
the depth range from 900 to 1200 km we have founda few scatterers near the edge of a plume-like bodywith low shear velocity.

Core-mantle interaction inferred from a core surface flow model
M Matsushima1* 1Tokyo Institute of Technology, Tokyo 152-8551, Japan.
*email:masaki.matsushima@eps.sci.titech.ac.jp
Introduction: Fluid motions in the Earth’s
metallic liquid outer core are responsible for the
dynamo process by which the geomagnetic field isgenerated and maintained. Such core fluid flow canbe estimatee from geomagnetic field data, such as
spatial distribution of geomagnetic field and its
temporal change referred to as secular variation.
This implies that spatial and temporal variations of
fluid flow in the core provide information on any
interaction between the core and mantle. To
investigate possible core-mantle interaction, a coresurface flow model is obtained using a geomagnetic
field model.
Method: Following the method of [1], inside aviscous boundary layer at the core-mantle boundary(CMB), magnetic diffusion is assumed tosignificantly contribute to temporal change of
geomagnetic field, and the radial dependence of core
flow is expressed in terms of a spiral similar to the
Ekman spiral. Below the boundary layer, magnetic
diffusion is neglected as in the frozen-flux
approximation, and instead of the tangentiallygeostrophic constraint as used in [1], the tangentiallymagnetostrophic constraint is imposed on the flow;that is, the effect of magnetic field through theLorentz force is taken into account. Since it is betterto adopt a geomagnetic field model covering longer
duration, COV-OBS.x1 [2] which covers the range
between 1840 and 2015 is adopted.
Results and Discussion: Any heterogeneous
structure due to temperature or heat flux at the CMB
should have a strong effect on the core flow when athermal convection occurs in the outer core. The
heterogeneity successively influences the flow
pattern. Therefore, average of fluid flow is expected
to show possible core-mantle interaction. Hence,
fluid flows inside and below the boundary layer are
averaged over the time from 1840 to 2015 coveredby the COV-OBS.x1 model.
It turns out, however, that mean amplitudes of
upwelling and downwelling flows as well as mean
horizontal flows are smaller than those at respective
times, as shown in Fig. 1. This result suggests thatcompositional convection is dominant in the Earth’s
outer core, because possible thermal heterogeneity

due to the lowermost mantle structure has little
effect on the core surface flow. It should be notedthat there is a noticeable mean upwelling flowcorresponding to a counterclockwise vortex beneaththe south of Africa, and that the location is justoutside the tangent cylinder, an imaginary cylinderparallel to the rotational axis and attached to theequator of the inner core. This may indicate that thevortex corresponds to an edge of columnar
convective motion, although the other edge isunclear.

Figure 1 Core flows inside the boundary layer at the coremantle boundary (upper) averaged in the range from 1840
to 2015 and (lower) for the epoch of 2010. Arrows show
the horizontal velocity, and color contours denote
upwellings and downwellings.

References: [1] Matsushima, M., Geophys. J. Int.,
202, 1495 (2015). [2] Gillet, N., Barrios, O., andFinlay, C. C., Earth Planets Space, 67, 71 (2015).

Variation of the intensity of the paleomagnetic field during 38-50 Ma deduced from the marine sediments
recovered from the northwest Atlantic
Y Yamamoto1*, H Fukami1, W Taniguchi1, P.C. Lippert2
1
Center for Advanced Marine Core Research, Kochi University, Kochi 783-8502, Japan.
2
Department of Geology and Geophysics, University of Utah, Salt Lake City, UT 84112, USA.
*email:y.yamamoto@kochi-u.ac.jp
Introduction: Variations of the intensity of thepaleomagnetic field (paleointensity), which provide
clues about the evolution of the geodynamo, arerecorded in rocks and sediments. Marine sediments
give relative paleointensity (RPI) continuously intime. For the period of 0-2 Ma global RPI stacks[1][2] have been reported based on numerous
regional RPI records. For the period of 2-3 Ma there
have been increasing number of regional RPI
records [3][4]. However, published RPI records
older than ~3 Ma are very limited in time and space:14.5-18.5 Ma [5], 17.5-26.5 Ma [6], 23-41 Ma [7]from the equatorial Pacific; 23-34 Ma from theSouth Atlantic [8]. We have conducted apaleomagnetic study on the marine sediments
recovered in the northwest Atlantic to extend ourknowledge of the RPI variation in further geologic
past, and report on the preliminary RPI results forthe period of about 38-50 Ma.
Experimental: Integrated Ocean Drilling
Program (IODP) Expedition 342 recovered
hemipelagic sediment drifts from Sites U1403 andU1408 in the northwest Atlantic, off the coast of
Newfoundland [9]. Piston cores of the two sites were
subjected to a series of the paleomagnetic
measurements including analyses of natural,anhysteretic,andisothermal
remanent
magnetizations (NRM, ARM, and IRM). Excluding
the intervals showing signs of probable dissolutionof primary magnetic minerals (low ARM intensity
intervals) and inhomogeneous magnetic grain sizes(mainly for low ARM/IRM intervals), RPIs were
estimated based on ratios of NRM/ARM and
NRM/IRM.
Results and Discussion: Considering age
models of the studied cores [10][11], the resultant
RPI records cover the Chrons 18 (38.5-41.1 Ma), 19(41.1-42.9 Ma), 20 (42.9-46.4 Ma), 21r (47.8-48.6
Ma), and 22n (48.6-49.3 Ma). These records arecharacterized by RPI minima always at chronboundaries and large fluctuations between highs andlows during each chron. Such charactersistics arecommonly recognized in the published RPI records
back to 41 Ma [1-8]; this is first record to show thatthey persist at least since 49.3 Ma.

For the Chron 18 interval, we obtained RPI
results from both sites, which are approximately 380
km apart (Figure 1). Our results show common
features, including RPIs that are generally highduring C18n.2n (39.6-40.0 Ma) and low during C18r
(40.0-41.1 Ma). Prominent RPI lows, which appear
to be almost equivalent to the RPI minima at otherchron boundaries (i.e., during Chrons 19, 20, 21r,
and 22n), are also commonly recognized at ~40.5
Ma. We suggest that the RPI lows might be related
to a failed geomagnetic reversal.

Figure 1 Chron 18 RPI results from Site U1408 (upper
panel) and U1403 (lower panel).

References: [1] Channell, J.E.T. et al., Earth planet.
Sci. Lett., 283, 14–23 (2009). [2] Valet, J.-P. et al.,Nature, 435, 802–805 (2005). [3] Yamazaki, T. andOda, H., Geochem. Geophys. Geosyst., 6, Q11H20(2005). [4] Sakuramoto, Y. et al., J. Geophys. Res.
Solid Earth, 122, 7525–7543 (2017). [5] Ohneiser,
C. et al., Earth planet. Sci. Lett., 374, 227–238(2013). [6] Channell, J.E.T. and Lanci, L., Earthplanet. Sci. Lett., 387, 77–88 (2014). [7] Yamamoto,Y. et al., Geophys. J. Int., 196, 694–711 (2014). [8]Tauxe, L. and Hartl, P., Geophys. J. Int., 128, 217–
229 (1997). [9] Norris, R.D. et al., Proc. IODP, 342,
doi:10.2204/iodp.proc.342.101.2014 (2014). [10]Boulila, S. et al., Earth Planet. Sci. Lett., 486, 94–
107 (2018). [11] Yamamoto, Y. et al., Proc. IODP,
342, doi:10.2204/iodp.proc.342.207.2018 (2018).

Toward adjoint tomography of the large low seismic velocity provinces beneath the western PacificOcean
M Obayashi1*, T Miyoshi2, and J Yoshimitsu1
1Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima, Yokosuka 237-0061, Japan.
2
National Research Institute for Earth Science and Disaster Resilience, 3-1 Tennodai, Tsukuba 305-0006, Japan.
*email:obayashi@jamstec.go.jp
Introduction: It is well-known that there is alarge low seismic velocity provinces (LLSVP) where
the seismic velocity changes sharply above thecore-mantle boundary (CMB), however it is unclear
how it is distributed above the CMB. In recent years,
the detailed S-wave velocity structure around the
CMB was inferred from waveform inversion [1, 2].
In our previous study, we found an NE-SW running
low S-wave velocity structure within the LLSVP
lying beneath the western Pacific Ocean using
analyses of travel times and the finite frequency
inversion. To clarify the detail structure and its
relationship with old subduction, we determine athree-dimensional (3D) P and S-wave velocity
structure beneath the western Pacific Ocean based on
waveform tomography using the combination ofSpectral-element method (SEM) [3] and adjoint
method [4]. We show here some preliminary resultswith computational costs.
DATA and Method: We collected the seismic
waveforms of three components obtained at seismic
broadband stations from ~700 earthquakes occurredfrom 2008 to 2015. Distribution of seismic stations
used in this study is shown in Fig. 1. Removing the
response of each instrument from the originalrecords, we transferred into displacement waveforms
with a bandpass filter (10-150 sec) to use theinversion. We constructed global Earth model basedon S40RTS [5] as an initial 3D model in inversion to
calculate synthetic displacements and adjoint
waveforms using the SEM. Our SEM structuralmodel was parameterized using 1.6 billion grid
points to produce waveforms of a shortest period of
10 sec. The forward and adjoint simulation wereconducted using a flat 600 Message Passing
Interface (MPI) on Data Analyzer (DA) system inJapan Agency for Marine-Earth Science andTechnology (JAMSTEC). The model parameters Vp
and Vs were updated iteratively by gradient method
using the misfit kernels (Fig. 2) based on the adjoint
sources to minimize the misfit between observed
waveforms and synthetic waveforms. Here, we showsomepreliminary
results:
estimationofcomputational costs, forward modelling, and trial
inversion.
Results and Discussion: This study requires
large computational cost to calculate forward andbackward waveforms in the 3D whole Earth. We
estimated the calculation time on the DA system.
The time step of the solver was 0.1045 sec and 30
min waveforms were calculated. As a result, thecalculation time was required approximately 2 and 9hours for conducting forward and adjoint simulation,
respectively for each event. If the calculation isconducted as 4 independent parallel job, it takes 3
weeks to obtain one iterative results when ~200
events are used in inversion. We succeed
construction of the iterative model using the misfit
kernels of a few events as trial, synthetic waveforms
by iterative model were improved clearly. We areplanning to apply differential travel times of somecore phases. we are expected to revise the LLSVP
from initial 3D model more efficient.

Figure 1 Distribution of seismic stations used in this study.
Black, red and blue triangles indicate F-net, IRIS andChinese stations, respectively.

Figure 2 Example of beta kernel for the earthquake
occurred in Fiji on July, 2011. The kernel was calculatedusing S and ScS waves.

Acknowledgements: We used seismic waveforms
obtained by IRIS and NIED F-net stations and
SPECFEM3D Globe package used in this study.
References: [1] Konishi, K., Kawai, K., Geller, R.J.,
and Fuji, N., Geophy. J. Int., 199, 1245-1267 (2014).
[2] Yuan, K. and Romanowicz, B., Science, 357,
393-397 (2017). [3] Komatitsch, D. and Tromp, J.,
Geophy. J. Int., 149, 390-412 (2002). [4] Tromp, J.,
Tape, C., and Liu, Q., Geophy. J. Int., 160, 195-216(2005). [5] Ritsema, J., Deuss, A., van Heijst, H. J.,
and Woodhouse, J. H., Geophy. J. Int., 184,1223-1236 (2011).

Using S-P wave search the depth of mantle 660-discontinuity beneath Kuril Region
where subduction slab do not exist
G. Hao , Faculty of Science , Kyushu University , Fukuoka ,Japan

Introduction
The depth of the 660-km seismic
discontinuity is investigated at the Kuril
Region , by using the broadband
earthquake event data from provided by
IRIS. We processed about 50 eventsoccur at Kuril Region and Sea of
Okhotsk , depth range from 100 to 600
km. In these data , about 20 of themshow clear S660P phases , which S wave
propagate to the 660-km discontinuity
and convert to P wave then recorded byarrays at USA . These S660P wave
propagate away from the subducting
slab to America and Alaska. For
shallower and intermediate depth(100 ~
300km)
earthquake,theS-to-P
conversion occur at the 660-km
discontinuity that do not cross with thesubducting slab. For deeper events (400
~ 600km), the conversions occur withinor near the boundary of the slab (due tothe dip angle of the slab ). We estimate
the depth of 660-km discontinuity bycomputing the depth of conversion
points of S-to-P wave , the depth of
660-km discontinuity at Kuril andOkhotsk region that do not cross withthe subducting slab is about 660±5 km,
indicate that there is no comprehensive
depression at this region . Results ofdeeper events suggest that, at thevicinity of the slab, the 660-km
discontinuity have 10 to 15 km
depression, consistent with previous
research. In addition , for comparing
with the wave that propagate
within/near and away from thesubducting slab, we also process somedeep events data that recorded byarrays at Europe, suggest that
discontinuity has about 10km
depression (get results from only twoevents).

Figure 1 : the structure of subducting slab and ray path ofseismic waves processed in this research

Figure 2: the earthquake events and their depth(getting
deeper from green to red )Figure 3 : two examples (113km & 388km) that S660P canbe seen clearly, and the relatively arrival time of P & S660P

Sharpness of the hemispherical boundary in the inner core beneath the northern Pacific
R Iritani1*, H Kawakatsu1, N Takeuchi1 1Earthquake Research Institute, University of Tokyo, Bunkyo-ku, Tokyo
113-0032, Japan.
*email:ryohei9@eri.u-tokyo.ac.jp
Introduction: Hemispherical heterogeneity inthe topmost of the Earth’s inner core, fastervelocity and higher attenuation in the eastern
hemisphere and slower velocity and weakerattenuation in the western hemisphere, has been
revealedbyseismologicalstudies.
The
understanding of this feature is an important key togive constraint on the physical state and the growth
process of the inner core. However, it is notachieved consensus on the transition structure
between two hemispheres, because of the difficulty
to analyze complex core-sensitive data and thelimitation of earthquake and seismic array
distribution. We previously developed a waveform
inversion based on simulated annealing andanalyzed core phase data observed by globally
deployed seismic array. Using this approach, we
provided continuous depth profiles of velocity andattenuation structures and revealed the presence of
intricate heterogeneous structures in the top 300 kmof the inner core [1, 2]. In this study, we apply thiswaveform inversion approach to core phase data
sets that propagate beneath the northern Pacific toinvestigate the nature of the transition structure inthis region.
Data: Data set used in this study consists of
two directional event-station pairs, seismograms
observed by permanent European stations forevents at Fiji-Tonga region, and USArray forevents near Indonesia (Fig. 1). We analyze thebroadband vertical component of collected corephase data containing PKIKP and PKP phases (i.e.
the epicentral distance between 145 – 155 degree).
Each data is filtered by 0.5 – 1.5 Hz bandpass filter.
Resultant analyzed waveforms for EU stations andUSArray are 2,108 and 1,172 traces respectively.
Observations: Waveform inversion based on
simulated annealing is employed for each event
data to measure traveltime and attenuation in the
inner core. As a result, traveltime anomalies
observed by EU stations show obvious positive
anomaly suggesting mainly propagating the eastern
hemisphere, while traveltimes observed by USAray
show relatively smaller (or no) anomalies
suggesting effects by both of two hemispheres. On
the other hand, attenuation parameters for botharrays show similar trend that suggests highattenuation corresponding to the eastern
hemisphere.
To investigate a hemispherical transition
boundary in sampling region, we conduct a ray
theory based forward modeling of traveltime bychanging a shape of boundary from meridian
boundary to eyeball shaped boundary, and its
position. We compute root-mean-square (RMS) of
residual between observations and theoreticaltraveltimes computed with each boundary model.
Then, an eyeball shaped boundary, that is located atlongitude of 158°E on the equatorial line andlatitude of 80°N at the northernmost point, obtained
as the preferred hemispherical boundary, which
derives the minimum RMS value. Finally, weinvestigate a sharpness of the boundary by varying
a width of hemispherical transition. We assume
linear variation from the eastern and western
hemisphere in a given width and compute RMS. As
a result, the width of 600 km at the surface of theinner core shows smaller RMS than sharp boundary.
The obtained transition structure is shown in Fig. 2.

Figure 1 The distribution of events (star) and stations(triangle), and ray paths propagating in the inner core(solid line). Red and blue denotes the data for EU
stations and USArray respectively. Black line is
proposed hemispherical boundary in [3].

Figure 2 The preferred hemispherical transition
boundary projected on the Earth’s surface. The blackline is the hemispherical boundary and areas colored byblue and red denote the eastern and western hemisphere.

References:[1] Iritani, R., N. Takeuchi, and H. Kawakatsu,
Phys. Earth Planet. Inter., 230, (2014). [2] Iritani,R., N. Takeuchi, and H. Kawakatsu, Earth Planet.
Sci. Lett., 405, (2014). [3] Tanaka S., and H.
Hamaguchi, J. Geophys. Res., 102, (1997).

Sample-scale geochemical variation of the Inada granitic body, Ibaraki, Japan -toward the reduction ofgeoneutrino flux estimation errorsKazuki Minami1, Kenta Ueki2* Tsuyoshi Iizuka3, Sanshiro Enomoto4,5 and Hiroyuki K.M. Tanaka1
1
Earthquake Research Institute, University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan.
2
Department of Solid Earth Geochemistry, Japan Agency for Marine-Earth Science and Technology, Yokosuka
237-0061, Japan.
3
Department of Earth and Planetary Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
4
Kavli Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa 277-8583, Japan
5
Department of Physics, University of Washington, Seattle, WA 98195, United States*email: kenta_ueki@jamstec.go.jp
Introduction: Geoneutrio observation at antineutrino observatory "KamLAND" in Kamioka(Hida City, Gifu Prefecture), is expected to bringus direct information on the abundance ofradiogenic elements in the deep earth [1]. As
crustal rocks exhibit a higher concentration ofgeoneutrino producing radiogenic elements(Uranium and thorium) than mantle rocks, it isnecessary to subtract the contribution ofgeoneutrino from the Japanese crust from theobservation value in Kamioka to estimate
geoneutrino flux from core and mantle. For the
purpose, we are developing a 3D compositional
map of Japanese crust [2]. Geoneutrino flux
calculated using the compositional map exhibits alarge error (~ 80%) at present. We found that
information on the spatial correlation of the rockchemical composition on various spatial scales
such as a single rock suite scale (m to km scale),and outcrop or sample size scale (m-cm) is
fundamental to reduce the estimation error ofcrustal geoneutrino flux as small as the observation
error of the neutrino on KamLAND.
Geological background and Method: In thisstudy, we present a sample-scale (cm scale)geochemical heterogeneity of a granitic body ofInada, Ibaraki prefecture, Japan. Inada granite is a
Cretaceous granite in the Ryoke belt [3].
We collected rock samples from Inada granite,in order to evaluate the variance of chemicalcompositions in the single rock sample (~500g).
Grid sampling was conducted in two quarries in the
Inada area. The sample was subdivided into several
cubic samples with a weight of about 25g using a
diamond saw. Each cubic split was polished on agrinder, rinsed in an ultrasonic bath to avoid
surface contamination. Major and some traceelement concentrations of each cubic sample were
determined by X-ray fluorescence spectrometer(XRF) at the 1Earthquake Research Institute,
University of Tokyo. Also, we conducted analysis
by an ED-XRF at Japan Agency for Marine-Earth
Science and Technology to evaluate the mm scalespatial distribution of elements in each split.
Result: Wide compositional variations in a single
rock sample (~500g) such as 73〜77 SiO2 wt%
were observed. Based on the data, we evaluated therelationship between compositional variance andthe size of the sample. SiO2 concentration was
positively correlated with the modal concentrationof quartz, indicating the granite experienced mm tocm scale geochemical process to derive theheterogeneous distribution of quartz. Our result
indicates that, in addition to the kilometer or meterscale variations, cm-scale geochemical variation
should be considered to evaluate geochemicalvariation of granitic rocks. Also, this result will be
combined analysis with the geochemical databasefor the basement rocks of Japanese islands withgeographical coordinates [4] to evaluate multi-scalespatial correlations of rock compositions.
References: [1] The KamLAND Collaboration,
Nature Geosci. 4, 647-651 (2011). [2] Takeuchi,N., Ueki, K., Iizuka, T., Nagao, J., Tanaka, A.,
Enomoto, S., Shirahata, Y., Watanabe, H.,
Yamano, M. and Tanaka, H., Phys. Earth Planet.
Int (2019) in press. [3] Arakawa, Y. and Takahashi,
Y. Contrib. Mineral. Petrol., 101, 46-56 (1989). [4]Haraguchi, S., Ueki., K., Yoshida., K., Kuwatani,T., Mohamed, M., Horiuchi, S. and Iwamori, H.,
Jour. Geol. Soc. Japan, 124, 1049-1054.

Ab initio anharmonic lattice dynamics for Fe-bearing lower mantle minerals
Haruhiko Dekura1* and Taku Tsuchiya11
Geodynamics Research Center, Ehime University, Matsuyama, 790-8577, Japan.
*email:dekura.haruhiko.mf@ehime-u.ac.jp
Introduction: Determination of lattice
thermal conductivity (𝜅lat ) of lower 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 and MgSiO3
bridgmanite (Brg) are substantially reduced
by Fe incorporation [1-5]. In contrast,
Okuda et al. (2017) reported a very
different result on Brg with a marginal
effect of Fe particularly at high pressure [6].
Besides, the effect of Fe on MgSiO3 postperovskite (PPv) has never been reported.
Therefore, in this study, we investigate 𝜅latof Fe-bearing LM minerals (ferropericlase(FP), Brg, and PPv) in the LM pressure andtemperature conditions, based on the abinitio anharmonic lattice dynamics
techniques.
Computational
Methods:
We
performed density-functional theoretic
calculations combined with the internallyconsistent density-functional theory plus U
technique for more precisely describing the
Fe-O bond [7]. The harmonic (HFC) andanharmonic force constants (AFC) werethen extracted by numerical derivatives of
the adiabatic potential surface. The ferrous
iron was treated in the high spin state forBrg and PPv, and the low spin state for FP.
Using the HFC and AFC determined in thisstudy, we then calculated the 𝜅lat of thethree phases by fully solving the phonon
Boltzmann transport equation describing
phonon distribution function in theinteracting phonon systems [8].

Results and Discussion: Calculations
demonstrate strong negative solid solution
effects of Fe incorporation on 𝜅lat of thethree phases. Our detailed analysis
indicates that the strong Fe effect occurs
primarily due to the substantial change inharmonic properties. We found that thecalculated 𝜅lat of FP with ~13% iron at~100 GPa and 300 K is more than 2 times
higher than those reported by DAC
experiments with ~10–20% iron [3,4],
while the 𝜅lat of Brg (~6% iron) is foundto be lower than the experiment with ~7%iron [5]. The values of 𝜅lat of Brg and PPv
under the lowermost mantle condition isfound to be almost the same, and they are~10-20% of the value of 𝜅lat of FP. This
indicates both the FP and Brg/PPv almost
equally contributes to the thermal transport
properties of deep LM. The effective
conductivity for pyrolytic aggregate is also
discussed.
References:[1] Manthilake, GM. et al., Proc Natl Acad
Sci USA 108, 17901 (2012). [2] Goncharov,
AF. et al., Phys Earth Planet Inter 247, 11(2015). [3] Ohta, K. et al., Earth Planet Sci
Lett 465, 29 (2017). [4] Hsieh WP. et al.,Proc Natl Acad Sci USA 115, 4099 (2018).
[5] Hsieh WP. et al., J Geophys Res Solid
Earth 122, 4900 (2017). [6] Okuda, Y. etal., Earth Planet Sci Lett 465, 29 (2017).
[7] Tsuchiya, T. and Wang, X. J. Geophys.
Res. 118, 83 (2013). [8] Dekura, H. andTsuchiya, T. Phys. Rev. B 95, 184303(2017).

Melting phase equilibrium relations in MgSiO3-SiO2 system under high pressures
T. Moriguti1*, A. Yoneda1, and E. Ito1
1Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan.
*email:moriguti@misasa.okayama-u.ac.jp
Melting of silicates played important roles inchemical differentiation in a deep magma ocean in theearly Earth. Therefore, melting relations of the MgO–
SiO2 system have been extensively studied since a
pioneer work by Bowen and Anderson [1].
Furthermore, chemical differentiation in the deep
magma ocean has been simulated extensively basedon results of high pressure melting experiments (e.g.
[2] and [3]). However, almost all of these works havebeen carried out on the compositions ranging from
MgO to MgSiO3, assuming that the bulk mantle
composition is peridotitic or close to that derived fromCI chondrite. Recently, enstatite chondrite (Echondrite) has been attracted as the bulk earth source
material [4] because the isotope systematics of the
Earth and Moon are nearly identical to those of Echondrite over O, N, Mo, Re, Os, and Cr. In Echondrite, the silicate composition is characterized by
SiO2/(SiO2+MgO) = ~0.6, which is substantiallyhigher than that of the peridotitic mantle (~0.4).
In this context, understanding of the melting
relations over compositions between MgSiO3 andSiO2 is indispensable to clarify the mantle
fractionation. That also relates to investigations ofchemical compositions of the crust at early stage of
the Earth. Nevertheless, there have been very limited
works on the pressure effect on melting in the
MgSiO3–SiO2 system. Available information
regarding phase relations in the system has been so far
limited to 5 GPa [5]. In this study, we are determining
the melting relations in the MgSiO3–SiO2 system atpressures 5 to 20 GPa. Here we present the results
obtained at 10 GPa.
References: [1] Bowen and Anderson (1914) Am. J.
Sci. 4th ser. 37, 487-500. [2] Kato and Kumazawa(1985) Nature 316, 803-805. [3] Ito and Katsura(1992) Am. Geophys. Union Monogr. 67, 315-322.
[4] Javoy et al. (2010) Earth Planet. Sci. Lett. 293,259-268. [5] Dalton and Presnall (1997) Geochim.
Cosmochim. Acta 61, 2367-2373.

Pressure effect on IR spectra of anhydrous minerals
M Sakurai1*, N Tsujino1, 1Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan.
*email:msakurai@okayama-u.ac.jp
Introduction: Water incorporation mechanisms in
nominally anhydrous minerals in the Earth’s mantle areimportant to understand effect of water on some physicalproperties (e.g. rheological properties; [1]; electricalconductivity; [2, 3]). Olivine is the most consistent mineralin the upper mantle can contain small amount of water froma few wt.ppm to a few 1000 wt.ppm (e.g. [4]). Many water
incorporation mechanisms of olivine were suggested byexperimental studies (e.g. [5, 6]) and theoretical studies(e.g. [7]) and were controversial.
In order to study the role of water, the positions ofhydrogen ions in crystal sites should be investigated at first.
Experimental: In-situ observations at highpressure were conducted at room temperature up to ~7.1 GPa using a diamond-anvil cell (DAC). Diamondanvils (type IIA) with 600 µm culets were used in all
experiments. SUS304 stainless steel plates with 300
or 350 µm in thickness were used for gasket. A 400µm diameter hole was drilled in a gasket, and was preindented to ~280 µm in thickness, then the holes(sample chamber) in the gaskets were shrunk to ~300
µm in diameter. The starting material was placed inthis sample chamber with KBr pressure medium. The
semicircular shaped starting material was adopted inthis study because it is easy to identify the directionof crystal axis under microscope. Small ruby chips
were also inserted in the sample chamber as thepressure markers. After set of the sample assembly,
DAC was dried up in vacuum oven (~423 K) over 12hours to prevent the adsorption of water vapor. The
pressure was calculated from the ruby pressure scale
based on the shift of the fluorescent peak [8].
FT-IR spectra were obtained from a vacuum-type
FT-IR spectrometer (FT-IR-6100 and IRT-5000),
equipped with mid-IR light, a KBr beam splitter, anda mercury cadmium telluride (MCT) detector. The
degree of vacuum reached to 1Pa to reduce
interference by moisture. The samples were analysedwith a typically 75×75 µm polarized IR beam parallelto crystal axis. The back ground was measured atspace where signals from sample and ruby could be
avoided. The IR spectra were obtained by averaging
typically 256 scans with 4 cm-1 resolution.
Results and Discussion: In this study, we performed
in-situ IR observations at high pressures for forsterite (Fo)single crystals using DAC. At first, we developed in-situ IR
observation method at high pressure for low water content
of nominally anhydrous minerals in the upper mantle. Using
this technique, polarized IR spectra parallel to crystal axisof synthetic hydrous Fo were obtained under high pressure
for the first time. First principle calculation (DFT

(a)

(b)

Figure 1(a) The pressure effect of polarized absorption IR
spectra of synthetic forsterite parallel to a-axis. (b) The
enlarged figure of the range of 3650~3500 cm-1 in the (a).
Vertical positions of the spectra were shifted for acomparison.
calculation) for hydrogen position in Fo was carried out atvarious pressures. Hydrogen position in Fo was estimatedbased on the comparison of the vibrational frequencies
measured by the FT-IR methods and simulation by the firstprinciples methods. The band shift observed in experiments
under high pressure could be explained by the hydrogen
position change in Si Site with pressure calculated by DFT.

References: [1] Hirschmann, M., Kohlstedt, D.
(2012) Physics Today, 65 (3), 40-45. [2] Zang et al.
(2012) Earth Planet. Sci. Lett., 357-358, 11-20. [3]Schlechter et al. (2012) Phys. Chem. Minerals, 39,531-541. [4] Mosenfelder et al. (2006) Am. Min.,91(2-3), 285-294. [5] Bai, Q., Kohlstedt, D.L. (1993)
Phys. Chem. Minerals, 19, 460-471 [6] Berry et al.
(2005) Geology, 33(11), 869-872. [7] Umemoto et al.
(2011) Ame. Min., 96, 1475-1479. [8] Mao et al.
(1986) J. Geophys. Res., 91(B5), 4673-4676.

Deformation experiments on akimotoite
LL Guan1*, D Yamazaki1 & N Tsujino1
1
Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan.
*email: guanlongli@s.okayama-u.ac.jp
Introduction: The ilmenite structure of MgSiO3,
known as akimotoite, is inferred to occur in cold
subducting slabs in the bottom of Earth’s mantle
Al O pistontransition zone and the uppermost lower mantle along a
MgO
low-temperature geotherm [1]. Akimotoite is thought toTabe the most anisotropic mineral in the Earth’s mantle
Aki
693.750μm
transition zone [2-3]. The elastic anisotropy caused by
the lattice preferred orientation of akimotoite due to slabinduced deformation may be used plausibly to interpretthe significant seismic anisotropy observed in midAl O piston
mantle (depths 410-670km) [5-8]. However, previous
studies did not determine the slip plane or the dominantFigure 2 Scanning Electron Microscope images of theslip system precisely [9]. Therefore, precisely anddeformed akimotoite aggregates. Sample quenched at ~21 GPa
detailed lattice preferred orientation of akimotoite is
and 1200 ℃ (run D039).
needed. In this study, we conducted deformation
experiment to investigate the rheological properties of
akimotoite.
Experimental: For the preparation of starting
material of akimotoite aggregates for deformation
experiment, high pressure experiments using MgSiO3
glass as starting material, have been performed at
1400 ℃, 20-22GPa in the Kawai-type multi-anvil
apparatus. The starting material of synthesis experiments
was prepared using the following procedures. A mixtureof MgO and SiO2 with a 1:1 mol ratio was heated in a
furnace at 1683℃ for 15-45 minutes and quenched toform MgSiO3 glass. The glass was powdered in an agate
mortar with ethanol for half an hour. We conducted
Figure 3 The relationship between displacement of d-rams anddeformation experiment on akimotoite aggregates byload of d-rams.
using high pressure deformation apparatus. so called D111 type apparatus installed at Institute for Planetarychemical composition and observe microstructure,
Materials, Okayama University (Fig.1b). The
respectively. The recovered sample was well-sintereddeformation experiment was performed at 1200 ℃, ~21
and no-crack akimotoite aggregates with grain size of 2GPa. Schematic cross-section of cell assembly of pure
8 μm. These akimotoite aggregates were suitable as ashear experiments is shown as Fig1a. The original length
starting material for deformation experiments. Afterof akimotoite aggregates was 0.784 mm.
deformation, the length of recovered sample was 0.694ab
mm (Fig 3) with deformation time for 120 min. The
strain and average strain rate were estimated to be
ε~0.12and 𝜀̇ ≈ 1.67 × 10−4 𝑠 −1 , respectively. Figure 4
shows the relationship between displacement and load ofd-rams, suggesting the mechanism change from elastic toplastic deformation with increasing d-ram load (ordisplacement). Microstructural analysis by using EBSD
reveals the lattice preferred orientation pattern andindicates the dominant slip system.
2

3

2

Figure 1 Schematic cross-sections of cell assemblies of pure
shear deformation experiments(a) and photo of D-111 typeapparatus installed at Institute for Planetary Materials,
Okayama University(b).

Results and Discussion: The chemical compositionof synthetic glass was analyzed by an electron probe
micro-analyzer (EPMA). EPMA mapping showed that
Mg and Si were homogenously distributed in the glass.
After synthesis experiments, sample were investigatedby X-ray diffraction, electron probe microanalysis andscanning electron microscopy to identify phase, measure3

References: [1] Akaogi et al., Phys. Earth Planet.
Inter. 132, 303 (2002). [2] Zhang et al., Phys. Earth
Planet. Inter. 151, 309 (2005). [3] Weidner & Ito, Phys.
Earth Planet. Inter. 40, 65 (1985). [4] Wookey et al.,Nature 415, 777–780 (2002). [5] Nowacki et al.,Geochem. Geophys. Geosys. 16, 764 (2015). [6] Foley& Long, Geophys. Res. Lett. 38, L02303 (2011). [7]Lynner & Long, Geochem. Geophys. Geosys. 15, 2262
(2014). [8] Heintz, J. Geophys Res. 111, B09303 (2006).
[9] Shiraishi et al., Nature, 455, 657 (2008).

Latest remodeling of multi-axis DAC system for radial XRD experiments
H. Yusa1*, N. Hirao2, Y. Mori3, and Y. Ohishi2
1National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan.
2Japan Synchrotron Radiation Research Institute (JASRI), Sayo, Hyogo 679-5198, Japan
3Department of Applied Science, Okayama University of Science, Okayama 700-0005, Japan*email:yusa.hitoshi@nims.go.jp
Introduction: Under non-hydrostatic conditions,
uniaxial compression causes deviatoric stress inpressurized samples. A radial X-ray diffraction
method is one way to solve the deviatoric stress.
Several years ago, we have constructed a multi-axis
diamond anvil cell (DAC) oscillation system [1] for
powder X-ray diffraction experiments to overcome
a statistical problem on the analysis from a spotty
diffraction pattern taken with a low-emittancesynchrotron radiation X-ray. By recent remodeling,
the function as a radial X-ray diffraction was added
to the multi-axis DAC system [2].
Experimental: The multi-axis DAC oscillation
system has three axes: horizontal (θ), vertical swivel(ω), and rotating axes (ϕ) perpendicular to θ. The
DAC with a laterally large angular aperture (70°),
which is newly developed for the radial XRD
experiments, is inserted into the holder on ϕ axis
(Fig. 1). The sample position is adjusted to the centerby each axis. The position is remotely controlledwith a pulse motor system and the angle wasdetermined by high-precision encoders. The
incident X-ray focuses on the sample in a direction
perpendicular to compression axis of DAC. A
beryllium gasket is used to reduce the diffraction
from the gasket materials. The diffracted X-rays
are detected with an imaging plate. Since the DAC
also has a large aperture (70°) in an axis parallel tocompression, the oscillating mechanism still works
effectively in this system. This system is installedat SPring-8 (BL04B2).
Results and Discussion: We tested the system
for the radial XRD experiments under uniaxial
compression of MgO samples. The sample loaded
into the DAC without pressure medium wascompressed to 13.8 GPa and subsequently
decompressed to ambient pressure. Variation of
measured d-spacing (200) vs. azimuth was plotted in
Fig.2. Differential stress was calculated fromSingh’s method [3]. After the decompression toambient pressure, residual stress was observed in thesample. Further details will be presented in theposter session.

Figure 1 The multi-axis DAC oscillation system afterlatest remodeling for radial X-ray diffraction experiments.
Inset: The DAC for radial XRD experiments.

Figure 2 Variation of d-spacing (200) of MgO withazimuth under uniaxial compression (black) anddecompression (red).

References: [1] Yusa, H. Hirao, N. Ohishi, Y. andMori, Y., Rev. High Pressure Sci. Technol., 21, 76(2011). [2] Yusa, Mori, Y. H. Hirao, N. and Ohishi,Y., Rev. High Pressure Sci. Technol., 27, 220 (2017).
[3] Singh, A.K. Balashingh, C. Mao, H.K. Hemley,
R. J. and Shu, J., J. Appl. Phys., 83, 7567 (1998)

DREAM & Its applications: Software for Management of Samples and Data
Y Yachi1*, T Kunihiro1, and E Nakamura1 1Institute for Planetary Materials, Okayama University, Misasa, Tottori
682-0193, Japan.
*email:yyachi@misasa.okayama-u.ac.jp

Figure 1 Visualized sample with DREAM App. The
sample is a micrograin returned from the asteroid
Itokawa as a part of the Hayabusa mission [3]. DREAM
App displays a genetic hierarchy as navigation tree,
storage location on floor maps, and analysis spots on
surface maps.

It is important to archive samples with data
because well-managed samples can be traceable fora long time and reanalyzed with future state-of-art
technologies that we cannot even imagine. Institutefor Planetary Materials (IPM), Okayama University
is constructing DREAM, which is a depository that
stores research samples with data to support future
research [1], and “DREAM App”, which is a webbased software for sample curation that supports
personal and institutional sample and data
management [2].
DREAM App allows users to add custom fields
to meet the needs for their own sample collection,
establish the relationship between an original
sample and any sub-samples, track its storage
location and weight loss/gain history, correlate any
and all geochemical datasets (Figure 1), and show
datasets on interactive maps and diagrams (Figure 2).
In addition, DREAM App provides a RESTful API
to enhance interoperability. With the API, we havedeveloped several client applications. For example,
an Android application for sample management
registers a new sample at a field site, creates its subsamples at a laboratory, prints their QR code to label
printers, and tracks current locations by justscanning their QR codes. A smart scale for
automatic sample weighing updates current weightof a sample by just scanning its QR code withbarcode reader. With the application and the smart
scale, almost all sample management tasks can becompleted with an Android phone or tablet. We alsoplan to provide a cross platform application, which
supports iOS devices such as iPhone and iPad.
Furthermore, DREAM App supports seamlesssample registration to SESAR (System for Earth

Figure 2 Data visualization with DREAM App. The
visualized data are abundances of 52 elements in natural
waters determined by ICP-MS with FDC-ID-IS method[4]. DREAM App displays geochemical data as aformatted table and geochemical diagrams such as
spider plot. Sample localities are shown on aninteractive map created with Leaftet (javascript library)and OpenStreetMap (tile map service).

Sample Registration) [5], which provides access tothe sample catalog via the Global Sample Search,and operates the registry that distributes theInternational Geo Sample Number (IGSN).
Currently, DREAM stores 21,000 samples,
1,300 places, 4,900 analyses, 650 bibliographies,
and 22,000 images. With the seamless sample
registration to SESAR, we have obtained IGSNs for360 samples, which referred in 12 publications.
Datasets associated with the publications (500
samples, 260 places, 2,200 analyses, 12bibliographies, and 600 images) and DREAM App
are available at the following URL.
https://dream.misasa.okayama-u.ac.jp/
We focus on creating software manuals and user
guides to promote the use of our software in any
laboratory or institution. In addition, we plan toprovide cloud-based sample management softwarethat should help geochemists all over the world
manage samples by using the phone in their pocket
without IT expert knowledge.
References: [1] Kitagawa et al. Journal of Space
Science Informatics Japan, 3, 73-77 (2013).
[2] Yachi et al. Geostandards and Geoanalytical
Research, 38, 95-102, (2013). [3] Nakamura et al.
PNAS, 101, E624-E629 (2012). [4] Que et al.
Geostandards and Geoanalytical Research, 43,
147-161 (2018). [5] http://www.geosamples.org/

Measurement of thermal conductivity and thermal diffusivity for mantle minerals by the pulse heating
methodM Osako1*, A Yoneda2
1
National Musem of Nature and Science, Tsukuba, Ibaraki, 305-0005 Japan, 2Institute for Planetary Materials,
Okayama University, Misasa, Tottori 682-0193, Japan.
*email:sako@kahaku.go.jp
We have conducted simultaneous measurementsof thermal diffusivity and thermal conductivity ofmantle minerals under pressure by the plain
pulse–heating method in the Kawai-type apparatus at
the Institute for planetary materials, Misasa. We
adjust the method by Dzhavadov, who measured
thermal properties under pressure for a large (20 mm
in diameter) specimen, for mantle materials by
reducing the size of sample. This method is a
predominant one for deep Earth materials because it
has some advantages as follows: (1) comparatively
small amount of samples compared with othermethod such that uses cylindrical sample symmetry,(2) applicable to materials with anisotropy in thermal
conduction, (3) simple cell assembly. Moreover, thismethod has potential to obtain specific heat capacity
under pressure. We started measurement for upper
mantle minerals, olivine and garnet and hydrous
phases such as serpentine and talc using a sample of
4.3 mm in diameter and 1mm in length. The pressure
range was up to 10 GPa and temperature to 1100 K.
In order to extend pressure range, reduction of thesample cell assembly was needed. A new assembly
quite similar to our previous one was designed for asample of 2.6 mm in diameter and 0.6 mm inthickness (Fig. 1). The assembly was installed in an
octahedral pressure medium with edges of 14 mm
and compressed by anvils with truncated corner of 7
mm (14-7 cell). Test measurements were made using
garnet samples (Fig.2). This new cell enables toperform measurements at pressures exceeding 20
GPa, therefore applying to materials of the mantle
transition zone. The cell is also applicable to otherimportant minerals, for example, pyroxene, of which
specimen has necessarily limited size. A cell
assembly of more reduced in size is planned. The
coming cell will be used for measurements of
MgSiO3 perovskite (bridgemanite).
Thermal diffusivity or thermal conductivity
shows differences among literatures, even though incase of upper-mantle minerals. Measurement ofthese properties under pressure is indispensable to be
performed
underconsiderable
approximate
conditions due to limited size of the sample. Thismay cause discrepancies among experimental data.
Our measurement by a simple or clear method will
settle values of thermal conductivity of thermal
diffusivity for the major mantle minerals.

Fig. 1. 14-7 cell assembly for thermal conductivity andthermal diffusivity measurement in the Kawai apparatus (~20GPa). The numeral before the hyphen is edge size of anoctahedral pressure medium and after is truncated cornerof an anvil.

Fig. 2. Thermal conductivity (λ) and thermal diffusivity (κ)
measurement by various sizes of cell. Errors of λ (ca. 3%)
and κ (ca. 2%) come from the uncertainty of heating area,pulse heating power, sample thickness and fitting errors.
Systematic errors among runs may come from unexpected
deformation and/or displacement in the sample assembly,
in particular, at the initial pressurizing; more precise
machining of sample preparation is needed to avoid theseunfavorable effects.

References:[1] Dzhavadov,L.N.,1995, High Temp.-High
Pressures, 7, 49 (1995). [2] Osako,M., E.Ito,
A.Yoneda, Phys.Earth Planet. Inter., 143-144, 311(2004). [3] Wang,C., A.Yoneda, M.Osako, E.Ito,
T.Yoshino, Z.Jin, J. Geophys. Res., 119, 6277 (2014)

Low-frequency micro-Raman spectroscopy and its application to mineral sciences
Akira YONEDA1*, Shin-ichiro KOBAYASHI2, Seiji KAMADA3
1Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan.
2Department of Earth Science, Graduate school of Science, Tohoku Univ., 6-3, Aoba, Aramaki, Aoba-ku, Sendai,
980-8578
3Research Institute for Interdisciplinary Sciences, Tohoku Univ., 6-3, Aoba, Aramaki, Aoba-ku, Sendai, 980-8578*email: yoneda@okayama-u.ac.jp
GHz ultrasonic velocity measurements has beendeveloped up to ~15 GPa in diamond anvil cell(DAC). In order for GHz ultrasonic measurement,
both P and S wave buffer rods were manufactured
through sputtering ZnO piezoelectric film on single
crystal rods, such as sapphire, rutile (TiO2), andYAG. Several technical breakthroughs have beenachieved before observing stable signals from thespecimen squeezed in DAC: (1) Wiping by aqueous
ammonia on the contact surfaces enhancestransmissibility of GHz wave from buffer rod todiamond. (2) Cleaning by lathery detergent andwater jet is effective to remove sticky staff on rearsurface of diamond. (3) Steel ball supporter provides
easier adjustment of contact between buffer rod anddiamond. Consequently, we succeeded todemonstrate performance of GHz-DAC systemthrough measurements on KCl and natural olivine
samples.

(a)

(b)

(c)

(d)

Figure 2. Amplitude modulation along carrier
frequencies. (a) KCl at 1.4 GPa. (b) Natural olivine
at 4.5 GPa. (c) Smoothen plot of (a) through Fouriertransformation. (d) Fortier coefficients of the raw
data of (a). Upper plot is the raw coefficients on data
shown in (a). Middle plot shows truncation of longer
travel time components. Lower plot is horizontallymagnified plot of the middle plot. We can see thatcoefficients longer than ~50 ns were truncated to be
zero.

( )

(a)

(b)

Figure 1. (a) Schematic view of the present GHzDAC measurement assembly. A ruby tip is shown
schematically by black rectangle in the sample
cell. (b) Conceptual comparison between P and
S wave buffer rods; S wave buffer rod is available
by utilizing P-S conversion of ultrasonic wave.

(a)

(b)

( )

Figure 3. Resulted VP of sample. (a) Results on
KCl. Present data are shown by solid circle, while
those of Campbell and Heinz (1994) by crossshapes. Note that the highest data point in theparenthesis may correspond to measurement ofgasket material. (b) Natural olivine. Solid circles
and cross shapes indicate data measured underloading and unloading processes. Dotted line
shows reference data of Darling et al. (2004). Notethat the data point at 0 GPa in the parenthesis may
be deviated owing to voids inside specimen.

High-pressure synthesis of doped black phosphorous
N. Noguchi,1* Y. Fujii,1 T. Saitoh,1 and H. Okamura1
1Graduate School of technology, Industrial and Social Sciences, Tokushima University, Tokushima, Tokushima
770-8506, Japan.
*email:noguchi.naoki@tokushima-u.ac.jp

Results and Discussion: The single crystals
obtained have the maximum size of 500 μm. For
the experiments for S- and Pd-doping, theirelements were not detected by in BP crystals byenergy-dispersive spectroscopy. The shape of thegrains of S in the recovered samples shows that themelting occurred, while that of the grains of Pdshows that melting did not occur. For theexperiment of C-doping, 5-10 wt% of C element
was detected in BP crystals, and was scattereduniformly. The powdered XRD pattern of the
C-doped BP was very similar with that of pure BP.

CKa1000 008

PKa

900
800
700
600
500
400

SiKa

008

OKa

Experimental: The single crystals of doped BP
were grown by the gradual solidification method
reported in Endo et al. 1982 [2]. Starting materials
were molten at about 1000 ˚C and 1 GPa, andcooled to about 700 ˚C with a rate of 1 ˚C/min, andthen, were quenched. Powdered red phosphorous
mixed with 2-5 wt% the dopant reagent was usedas the starting material. Considering high chemical
reactivity of molten phosphorus, graphite was used
as a sample container. The recovered samples wereidentified and characterized using by XRD,
SEM-EDS, Raman and infrared spectroscopy.

The lattice parameters of C-doped BP matches withthat of pure BP within 0.01 Å order [2]. The
characteristic Raman bands due to the phononmodes of BP were appeared in the Raman spectra.
Their peaks are shifted to 3 ~ 5 cm-1 compared with
the Raman bands of pure BP. The polarized
infrared absorption spectra revealed the band gap(Fig.2). The dipole transition between the valenceband maximum and the conduction band minimum
is allowed for E//c polarization and is forbidden for
E//a [3]. The band gap of C-doped BP was 0.341
eV, which is almost same as that of pure-BP (0.335
eV). The situation of the C element in BP has notbeen revealed yet. There are three possible
situations; substitution, adatom, and intercalation.
The state analysis such as XPS and XAFS isneeded in order to reveal the situation.

CountsIntensity（CPS）

Introduction: Two-dimensional van der Waals
materials are promising fabricated materials forelectric components. The nano-sheets made fromthem by exfoliating are applicable to ultra-compact
electronic devises. In particular, phosphorene,
which is a single layer of black phosphorus (BP),has two excellent electrical properties derived fromthe band structure. First, it has a direct band gap of
0.8 eV along with a-axis. Second, the sloop of theband dispersion curve promises a high carrier
mobility along with the c-axis.
The doping technique to BP is required in orderto enhance its designability and stability. It will
enable us to control p-n type and the band gap, in
addition, increase the resistance to oxidation [1].
We tried to synthesize the single crystals of the
doped BP using the piston-cylinder high-pressure
apparatus. The high-pressure synthesis method hasan advantage which is not in the other methods.
The high homogeneity of the dopant elements arearchived by melting starting materials. In this study,
we selected three elements: carbon (C), sulfur (S),and palladium (Pd), as dopant.

300
200

10 μm

10
10 µm
µm

100
00.00

2.00

2.50

X-ray energy (keV)

0.50

1.00

1.50

keV

Figure 1 SEM image (left) and elemental spectrum(right) of C-doped BP crystal.

E//c
E//a

Figure 2 Polarized infrared absorption spectra of
C-doped BP crystal.

References: [1] Lv, W. et al., ACS Appl. Mater.
Interfaces, 10, 9663 (2018). [2] Endo, S. et al., J. J.
Appl. Phys., 21, L482 (1982). [3] Akahama, Y. and
Kawamura H., Phys. Stat. Sol. b, 223, 349 (2001).

3.00

3.50

4.00

4.50

5.00

Electrical conductivity of diaspore, δ-AlOOH and ε-FeOOH
Ran Wang1*, Takashi Yoshino 1
1
Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan.
*email: ranwang @s.okayama-u.ac.jp
Introduction: FeOOH and AlOOH are dominanthydrous phases in sedimentary rocks deposited in thesea or lake basins which were considered to bepossibly related to the deep water cycle by slab
subduction. Therefore, understanding of the electricalconductivity behaviors of these hydrous phases are
essential to explore the nature and dynamic process of
the Earth’s interior.

of these phases under the relevant pressures.
Examples of cell assembly for electrical conductivity
measurement and impedance spectroscopy wereshown as Fig 1 and Fig 2.

Figure 1 Cell assembly (25/15) for EC measurement
below 8GPa. 25 and 15 represent the lengths of edges ofoctahedron pressure medium and truncations of tungsten
carbide anvils, unit: mm.

Figure 3 Electrical conductivity of diaspore, δ-AlOOH
and ε-FeOOH as a function of reciprocal temperature.

Figure 2 Impedance spectrum of diaspore at 8GPa. Z’
and Z’’ are real and imaginary parts of the impedance,
respectively.[1]Experimental: In this study, the powders of anatural single crystal gem-level diaspore (αAlOOH)[2] and goethite (α-FeOOH) were used as thestarting material. Diaspore was pre-sintered at 8GPaand 700℃ to reduce the porosity before electricalconductivity measurements of diaspore and δ-AlOOH
was pre-synthesized at 19GPa and 1000℃. The
diaspore was kept in a Pt capsule of 2mm diameter.
Sintering and synthesis experiments were performedby the 1000ton and 5000ton Kawai-type multianvil
apparatus of the Institute for Planetary Materials,
Okayama University. Electrical conductivity of
diaspore (α-AlOOH), δ-AlOOH and ε-FeOOH was
measured by impedance spectroscopy with afrequency 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

Results and Discussion: Fig 3 showed theelectrical conductivity results of diaspore, δ-AlOOH
and ε-FeOOH. For diaspore at 8, 10, and 12 GPa, therelationship between electrical conductivity andreciprocal temperature could be well fitted by the
Arrhenius formula: σ = σ0 exp[-(ΔE+PΔV)/kT] andshows the pre-exponential factor (σ0), activationenergy (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 tothe remnant of free water in the sample caused byheating to insufficient temperature to proceed
dehydration of interstitial water. Thus, it is quitedifficult to measure the electrical conductivity of
diaspore at low pressures. The electrical conductivityof 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 and ε-FeOOH show one andtwo orders of magnitude higher electricalconductivity than diaspore. Due to isostructural
CaCl2-type hydroxide structure, δ-AlOOH and εFeOOH display the nearly identical activation
enthalpy (0.384 ±0.007 eV, 0.330 ±0.048 eV) whichis relatively lower than that of diaspore.
References:[1] Yoshino, T., Surv. Geophys., 31, 163(2010).
[2] Suzuki, A., Phys. Chem. Minerals., 27, 689(2000).

Intrinsic attenuation factor Q of partially molten Fe–S–O system
Chao Liu1*, Takashi Yoshino1, Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193,
Japan.
*Chaoliu@s.okayama-u.ac.jp

attenuation

system shows a positive correlation when melt
fraction reaches a certain value.
Partial melting could decrease Q-1, which could
explain the relative low attenuation on uppermost
30 km layer throughout the top of the inner core.
Combing with the positive correlation between
attenuation and velocity, a large amount of partial
melting could occur on the uppermost 30 km layerof the rest area except the Pacific hemisphere in the
inner core.

0.1

M2470
Fe-14 wt. %S

0.01
150

Young Modulus (GPa)Introduction: Heterogeneous seismic structures
have been found at the top of the Earth’s inner corein terms of attenuation and velocity 1. The outermost
part of the inner core with approximately 30 km
thickness shows low attenuation, then attenuation
increases beneath this layer 2. The positive andnegative correlations between velocity andattenuation were observed from the uppermost innercore in different areas: Pacific center in the innercore has negative correlation and the rest area has
positive correlation 3,4. In this study, experiments on
attenuation of partially molten Fe–S–O system were
performed to explain the possibility that could cause
seismic anomalies.
Experimental: We investigated Fe-S-O system.
Sulfur and oxygen are regarded as the representative
light element in the Earth’s core. Fe samples with
1, 3 and 14 wt. % S were synthesized in piston
cylinder apparatus at 900oC and 1 GPa. a small
amount of oxygen was included accidentally. In-situ
X-ray radiographic observations were performed at
the bending magnet beam line BL04B1 at SPring-8.
Deformation-DIA press with a facility of cyclicloading was used. This system could produce
sinusoidal displacement in a wide range ofoscillation periods from 0.2 to 100 s and generating
variable amplitudes 5. Q value characterizing
intrinsic attenuation was determined by phase lag ofsample strain against the reference material at 1 GPaand up to 1200oC.
Results and Discussion: The experimental results
show that frequency dependence of attenuation is
not remarkable except for a fine grained-sample,
whereas decrease of attenuation was found at 1100
and 920oC for Fe- 1 wt. %S and Fe- 14 wt. %S
samples, respectively. The attenuation drop would
occur with increasing melt fraction. Experiments of
Fe-14 wt. %S sample along heating and coolingpaths were done to check the influence of grain
growth during experiments. Data obtained fromboth heating and cooling paths show that abruptchange of the attenuation occurred at around
925oC. The Young’s modulus calculated from thestrain ratio of sample and reference shows strong
temperature dependence. An obvious drop occurred
between 900 and 980oC in association with theoccurrence of partial melting. Relationship between
velocity and attenuation anomalies of the Fe–S–O

100

50

700

750

800

850

900

950

1000

1050

temperature (oC)

Figure 1 The experimental results of attenuation andYoung Modulus from 14 wt. %S-bearing iron alloy sample
measurement.

References: 1. Tanaka, S. Depth extent ofhemispherical inner core from PKP(DF) andPKP(Cdiff) for equatorial paths. Phys. Earth Planet.
Inter. 210–211, 50–62 (2012). 2. Ibourichene, A. &Romanowicz, B. Detection of small scale
heterogeneities at the Inner Core Boundary. Phys.
Earth Planet. Inter. 281, 55–67 (2018). 3.
Attanayake, J., Cormier, V. F. & Silva, S. M. De.
Uppermost inner core seismic structure – newinsights from body waveform inversion. Earth
Planet. Sci. Lett. 385, 49–58 (2014). 4. Godwin, H.,
Waszek, L. & Deuss, A. Measuring the seismic
velocity in the top 15 km of Earth’ s inner core.
Phys. Earth Planet. Inter. 274, 158–169 (2018). 5.
Yoshino, T., Yamazaki, D., Tange, Y. & Higo, Y.
Short-period cyclic loading system for in situ X-ray
observation of anelastic properties at high pressure
Short-period cyclic loading system for in situ X-ray
observation of anelastic properties at high pressure.
105106, (2016).

Local Organizing Committee●Executive Committee Chairman
Xianyu Xue●Executive Committee Vice Chairman
Takashi Yoshino●Program committee
Takashi Yoshino, Xianyu Xue, Takuo Okuchi, Taku Tsuchiya●Public relations committee
Masami Kanzaki,

Shigeru Yamashita,

Matthew Izawa●Location committee
Akira Yoneda,

Daisuke Yamazaki,

Noriyoshi Tsujino,

Yusuke Yachi,

Takuya Moriguti,
Hitoshi Gomi,

Kaori Anji