O1
Frontiers of Technology, Exploring Earth's Seafloor and Beyond
Clive R. Neal1
1

Department of Civil & Env. Eng. & Earth Sciences, 156 Fitzpatrick Hall, University ofNotre Dame, Notre Dame, IN 46556, U.S.A. (cneal@nd.edu)

Planet Earth is unique in many ways compared to other planets in our Solar System. Not onlyis it the only one to date known to harbor life, plate tectonics only occurs on Earth. However,there are volcanic constructs that do not conform to plate tectonic theory, such as intraplate
volcanic chains, continental flood basalts (CFBs), and oceanic plateaus. At least some of these“large igneous provinces (LIPs)” appear to have originated at the core-mantle boundary(CMB) in regions of large low shear-velocity provinces (LLSVPs) that could represent plastic
lower mantle material heated by the core. Impetus to adiabatically rise may be given by the
subduction of old, cold, dense subducted oceanic crust to the CMB. The magma produced
when this buoyant plume reaches the base of the lithosphere is unprecedented in its volume,
flux, and potential for environmental impact. The thicknesses represent challenges forsampling LIPs to understand source regions as CFBs are invariably contaminated bycontinental crust and oceanic plateaus (uncontaminated by continental crust) are usually
below several kilometers of water and sediment. Generally, <<1 km of material from oceanic
LIPs has been recovered, except from the Ontong Java Plateau in the SW Pacific.
Plume volcanism is not common on Earth, but is the norm for other planetary bodies in our
Solar System. If plate tectonics indirectly promotes plume volcanism on Earth, how was it
initiated on Mercury, Venus, the Moon, and Mars? Using the Moon as an example, theProcellarum KREEP Terrane (PKT) could represent the surface expression of a hot spot thatwas uncovered by the Imbrium impactor. The PKT is enriched in heat-producing elements(e.g., Th) and the volcanism (which occurs mainly on the near side of the Moon because of thethinner crust) shows two peaks, at ~3.4 Ga and ~3.6 Ga, with a minor outpouring around 3 Ga,
after which volcanic activity dramatically declined. Therefore, the internal structure of theMoon remains essentially preserved since initial differentiation. An initiative is underway toestablish a globally distributed geophysical network on the Moon to use natural seismicity to
explore interior structure and bulk composition. The composition of mare basalts returned
by Apollo, Luna, and Chang’e missions indicate that the source regions still record evidence ofinitial lunar differentiation via a magma ocean. The Lunar Geophysical Network mission will
explore the initial stages of terrestrial planet evolution and potentially record fossil plume
structures in the lunar mantle.
This talk will examine how drilling at the Ontong Java Plateau and the Lunar Geophysical
Network mission could expand our knowledge of deep planetary processes.

O2
What can neutrinos do for geoscience?
Ingrida Semenec
Queen’s University

Due to their unique properties, neutrinos can be the ultimate messengers of the universe.
Specifically, geoneutrinos can provide insight into the radioactive composition of the planet, andprobe the depths of the Earth otherwise out of the reach of other current geological methods.
Geoneutrinos are electron antineutrinos coming from natural radioactive decays inside theearth (such as uranium and thorium). Measurements of the geoneutrino flux coming from the
Earth’s crust and the mantle can provide a constraint on the amount of heat-producing elements.
Such information would help determine the absolute concentration of the refractory elements, aswell as the radiogenic heat contribution to the total surface heat flux of the Earth. This talk will
give a brief introduction to geoneutrinos, and their detection methods, as well as provide a quick
overview of the latest measurements.

O3
Earth dynamics and its future
Craig O’Neill1
1

Origins Research Institute, Hungary (thecraigoneill@gmail.com)

With one exception, Earth is the most dynamic of the solar system’s terrestrial planets – afunction of its size and heat budget, and its rheology. Despite over 50 years of research on thefoundations of geodynamic motions, neither of these factors are satisfactorily understood.
Earth’s rheology is dominated by mechanisms of creep within dominant mineral phases, andmost historical work has focussed on the crust and upper mantle, which are most accessible todeformation apparatus. Even within this domain, variations in mineralogy, fluid interactions,strain and damage localisation, and grain size variations, lead to enormous deformational
complexity. Within the lower mantle, the situation is compounded by ambiguity in thedominant creep mechanisms, the modal abundances of lower mantle minerals, and theirindividual rheology, a complete dearth of knowledge on lower mantle – fluid interactions,
including with the core, and high-pressure phases within the D” layer.
Heat flow suffers from a similar malaise in that whilst the current terrestrial heat flux is tosome degree constrained, it is not in steady-state, and the relative contributions of core heat
flow, secular cooling and radioactive heating are unclear. This is of fundamental
cosmochemical importance.
In this presentation I summarise the state of the field and outline ways forward into thesefundamental issues. Enormous increases in computing power have led to the development ofever-more sophisticated numerical models of Earth’s interior, and, together with improved
numerical implementation of high-pressure rheologies, offers predictive hypotheses testing on
dynamic behaviour. Developments in ab-initio molecular dynamic simulations have offeredan alternative and promising route to constraining lower mantle rheologies. Lastly, improved
cosmochemical models, including those from upcoming geoneutrino results, can provide
constraints on modal abundances and thermal budgets. Together, these may allow thedevelopment of sophisticated whole-Earth models encapsulating the gamut of complexity
inherent in Earth processes, isolating dominant mechanisms, and allowing comparison withmacro-physical observations of planetary geoid, surface dynamics, heat flow, and evolution.

O4([SORULQJWKH/LPLWVRIWKH'HHS6XEVHDIORRU%LRVSKHUH)XPLR,QDJDNL-$067(& LQDJDNL#MDPVWHFJRMS
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O5Life in the deep biosphere
Shino Suzuki1
1

Japan Aerospace Exploration Agency (suzuki.shino2@jaxa.jp)

Studies of deep sea and deep subsurface environments have illustrated a picture of the
distinctive biosphere built on the complex chemical, physical, and biological interactions thatexist in the vast space.While varities of deep subsurface biospheres have been reported, I will
focus on the deep subsurface biosphere associated with water-rock reation. Almost all the
microbial ecosystems on present-day Earth are supported by photosynthesis including the
subsurface biosphere as organic carbons from the photosynthesis have been accumurated anddelivered into the deep subsurface ecosystem. Oxygen and oxidative compounds also have
distributed everywhere on the Earth through the water and contributed to creating chemical
gradients that can support microbial energy metabolisms. Therefore, opportunities are rare toaddress microbial ecosystems that are isolated from the effects of photosynthesis, but the effe
ct of photosynthesis has been minimized in several settings, one of which includes aserpentinized ecosystem. Here I will introduce the microial strategies to survive in the
deep-rock environments, and discuss the relations to the early evolution of life and also thepossibilities of life beyond Earth.

O6
A new journey to the Earth’s center with
global correlation wavefield
Hrvoje Tkalčić
Research School of Earth Sciences, The Australian National University, Canberra, ACT, Australia

Abstract

Understanding how Earth’s inner core forms and evolves, including fine details of its
structure and energy exchange across the boundary with the liquid outer core, helps us
constrain its age, relationship with the planetary differentiation, and other significant
global events throughout Earth’s history, as well as the changing magnetic field. Global
seismology has provided insights into the inner core’s internal structure and dynamics,
including 3D heterogeneity, attenuation, anisotropy, and differential rotation. Relatively
recently, global seismologists confirmed that its innermost part contains distinct seismic
anisotropy. Several new studies probed the inner core with probabilistic tomography,
which reveals further complexities. However, progress has been impeded by the lackof uniform geometric coverage of body waves from large earthquakes and the fact thatthe inner core is buried beneath multiple Earth shells that are still not fully mapped.
Furthermore, regarding material properties, it is still uncertain which type of iron crystal
is stabilized in the inner core, making seismological and other inferences challenging.
In seeking ways forward, we started experimenting with earthquake coda correlation.
This contributed to the rise of a new paradigm – the coda-correlation wavefield – a typeof seismological data based on waveform similarity. The new data probes the Earth withperiods ranging between 15 and 50 s, thus representing a new class of information that
falls between body-wave and normal-mode methods. The first application proved theinner core’s solidity by unambiguously detecting shear waves. As I hope to demonstratein this lecture, further advances in this field may hold the keys to refined measurementsof all inner core properties, informing dynamical models and strengthening mineral
physics interpretations of the inner core’s anisotropic structure and viscosity. The
correlation wavefield also serves as a powerful tool for probing the interiors of otherplanets. Apart from these novel probes of the deep interior, the proliferation ofseismographs and other geophysical instruments, especially in remote areas and theocean bottom, remains one of the priorities of 21st-century global geophysics.

O7
Frontiers of sampling the mantle by drilling to the Moho
Natsue Abe1,2 and Susumu Umino2
1

Mantle Drilling Promotion Office, MarE3, JAMSTEC (abenatsu@jamstec.go.jp)
2

Kanazawa University (sesumin@staff.kanazawa-u.ac.jp)

Drilling into the mantle from the ocean floor was initially launched in the late 1950s by US
scientists as the “Mohole Project” and consequently developed into ocean scientific drilling.
Since the start of the Integrated Ocean Drilling Program (IODP Phase I) in 2003, theinternational science community has been working toward the realization of drilling to themantle with the D/V Chikyu and submitted a proposal "Moho to Mantle (M2M*)” to IODP in
2012. Drilling entire sections of the oceanic crust and the upper mantle into the fast-spreading
lithosphere is expected to address primary scientific questions such as the structure andcomposition of the Earth's convective mantle, the geological nature of Moho, the contributionof the oceanic lithosphere to the global chemical cycle including carbon and water, theformation and evolution of the oceanic crust, and the limits and controlling factors of life.
This presentation will introduce the universal scientific objectives that led to the proposal for
mantle drilling, the technologies necessary for drilling and can be developed in the near future,
the three selected candidate sites for drilling, and a strategy** for drilling into Mantle.
*IODP active proposal #805-MDP (Umino and 66 proponents); **Umino et al. (2020) SD29,
69-82.

O8$JHRQHXWULQR³WHOHVFRSH´WRYLHZWKHLQDFFHVVLEO\GHHSLQWHULRURIWKH(DUWK
Ushering in a new era of multi-messenger geophysics
Matthew Jackson
University of California Santa Barbara
The deepest portions of the Earth remain a frontier to science. The deep oceans remain largely
unmapped, the deepest crust and upper mantle has never been sampled by drilling, and the
deepest mantle is so inaccessibly deep that its composition and thermal evolution remain
speculative. On the last point, the abundance and distribution of radioactive heat producing
elements (HEPs: U, Th, and K) in the deep Earth is fundamental to constraining the thermal
evolution and bulk composition of the planet. A mobile geoneutrino detector will enable key
advances on both fronts by constraining the abundance of HEPs in the Earth and evaluate
whether they are concentrated in regions of the deepest mantle that have the lowest seismic
velocities. Recent geochemical research suggests that subduction of continental crust, host to alarge fraction of the HPEs in the planet, may have been focused into the southern portion ofthese low seismic velocity regions. If so, seismic low-velocity regions will have higher
geochemically-constrained HPE abundances and, thus, higher geoneutrino luminosities.
Combining constraints from geophysics, geochemistry and geoneutrinos will revolutionize deep
Earth science in much the same way that the gravity wave-neutrino-optical astronomy trio has
ushered in a new era of multi-messenger astronomy.

O9
Big data analysis in geoscience
Karianne J. Bergen1
1 Data Science Initiative and Department of Earth, Environmental and Planetary Sciences,

Brown University (karianne_bergen@brown.edu)

Our ability to understand the complex, interacting physical processes governing the Earthsystem increasingly depends on the analysis of massive data sets. In this talk, I will outline thechallenges associated with Big Data Geoscience and the drivers creating new opportunities inthis domain. I will describe how new data mining and deep learning algorithms are playing a
key role in advancing research in the geosciences. I will describe recent examples of how thesetools have been used to extract new insights from seismic datasets at a scale that was notpreviously possible. I will conclude the talk with emerging research directions andrecommendations for broadening and accelerating progress in Big Data Geoscience.

O10
Planetary Hysteresis
John Hernlund1
1

Earth-Life Science Institute, Tokyo Institute of Technology

hernlund@elsi.jp

Abstract
What can be done to a planet, that cannot be undone? How do past events
influence future behaviors? Here I will discuss some of the many ways that deep
planetary memory can play a dominant role in dynamical evolution, the challenges
of capturing the fascinating range of complex planetary behaviors using traditionalmodeling approaches, and the need for new language and methodologies to study
planets as complex systems. I will touch on the concepts of passive and active memory, sub-critical dynamical states, and entanglement between dynamical states andsystems. Memory is passive when it only conveys information about past events,
and is active when the record influences future behaviors via modifications of physical and chemical properties. Sub-critical dynamical states are commonplace, andinclude important aspects such as habitability, plate tectonics, magnetic dynamos,
and more. Mutual catalysis between multiple dynamical states also occurs, andpresents enormous challenges for exoplanet characterization. These are all emerging thoughts, ideas, and directions. Feedback, ideas, and collaborations on tacklingthese grand challenges are welcome.

O11
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GHWHFWRUZLOOEHDEUHDNWKURXJKLQWKHLQWHUGLVFLSOLQDU\FRPPXQLW\O12
New technologies provide transformative insights into global geochemistry
Seema Kumari
Indian Institute of Science, Bangalore, India-560012 (seema091089@gmail.com)
Controversy remains regarding the composition of the silicate Earth (e.g., Mg/Si = sun;upper = lower mantle composition). Measuring Earth’s geoneutrino flux constraints its U andTh content and in turn that of Ca and Al, and tests compositional models of the upper and lower
mantle. However, geological understanding of the local lithosphere is essential to calculate the
U and Th content of the mantle. Results from Borexino (Agostini et al., 2020) and KamLAND(Abe et al, 2022) experiments are at odds. I will discuss how local lithology contributes to theobserved discrepancies.
Models of the chemical composition and structure of the Earth, e.g., pyrolite model(McDonough and Sun, 1995) versus bridgmanite-enriched ancient mantle structures (BEAMS)
model (Ballmer et al., 2017), do not converge to a unique composition. The BEAMS model
requires global differentiation. We evaluated and discussed the existing constraints of the Earthfrom geoneutrino studies.
Abe et al. (2022), Geophys. Res. Lett. in press; Agostini et al. (2020), Phys. Rev. D92, 031101; Ballmer et al.
(2017), Nat. Geosci. 10, 236-240; McDonough and Sun (1995), Chem. Geo. 120, 223-253.

O13
Looking for Dark Matter with Olivine
Sebastian Baum1
1

Stanford Insitute for Theoretical Physics, Stanford University(sbaum@stanford.edu)

Dark Matter makes up 85% of our Universe’s matter content, yet we do not knowwhat this mysterious substance is made out of. So-called direct detection experiments
search for Dark Matter via nuclear recoils that could be induced by Dark Matter particles
scattering of ordinary nuclei. Paleo-detectors are a proposed alternative to this approach— in lieu of using a large experiment to search for Dark Matter induced nuclear recoils ina real-time laboratory experiment, the idea behind paleo detectors is to use small detectors that could integrate signals from nuclear recoils over large timescales. Many naturalminerals found on Earth are excellent solid state track detectors, i.e., they record damage
tracks from nuclear recoils. Minerals commonly found on Earth are as old as a billion
years, and modern microscopy techniques may allow one to reconstruct damage tracks
with nanometer scale spatial resolution. Thus, paleo-detectors would constitute a technique to achieve keV recoil energy threshold with exposures comparable to a kiloton-scaleconventional ”real-time” detector. In order to suppress backgrounds from cosmic rays andradioactivity, radiopure mineral samples obtained from deep underground are best suited
as paleo detectors. Olivine and similar ultra-basic rocks obtained from deep boreholes
are promising candidates. I will also discuss the possible application of paleo-detectors
as tools to search for astrophysical neutrino sources such as supernovae or atmospheric
neutrinos produced by cosmic rays interacting with Earth’s atmosphere.

O14
The Earth’s thermal evolution
Kenji Ohta1
1

Department of Earth and Planetary Sciences, Tokyo Institute of Technology(k-ohta@geo.titech.ac.jp)

Heat in the Earth’s interior is transported dominantly by convection in the mantle and core,and by conduction at thermal boundary layers. The thermal conductivity of the bottom
thermal boundary layer of the solid mantle determines the magnitude of heat flux from thecore, and is intimately related to instability of the boundary layer and the formation of mantle
plumes, the long-term thermal evolution of both mantle and core, and the driving force forgeneration of the geomagnetic field. I review recent experimental and theoretical studies
examining the thermal conductivity of the Earth’s lower mantle. Existing results of thermal
conductivity measurements were combined to construct self-consistent models for the
lowermost mantle conductivity. These models were used to conduct simulations of thetemperature profiles at the base of the mantle and the CMB heat flux. The averaged global
CMB heat flow is estimated to be approximately 10 TW, which is in line with traditional
estimates. The total heat flow of approximately 10 TW with large regional flux variations
promotes interaction and coevolution of the core and mantle.

O15
Testing the Ontong Java Nui hypothesis
Sano T1, Tejada, MLG2, Neal, CR3, Coffin, MF4, Nakanishi, M5, Michael, PJ6, Geldmacher,J7, Hanyu, T2, Miura, S2, Timm, C8, Koppers, AAP9, Suetsugu, D2, Tonegawa, T2, Ishikawa,
A10, Shimizu, K11, Castillo, PR12, Erba, E13, Rychert, CA14, Delacour, A15,
1

National Museum of Nature and Science, Japan (sano@kahaku.go.jp)
IMG, Japan Agency for Marine-Earth Science and Technology, Japan(mtejada@jamstec.go.jp)
3
DCEGS, University of Notre Dame, USA (cneal@nd.edu)
4IMAS, University of Tasmania, Australia (mike.coffin@utas.edu.au)
5
GSS, Chiba University, Japan (nakanisi@earth.s.chiba-u.jp.ac)
6
DG, University of Tulsa, USA (pjm@utulsa.edu)
7
GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany (jgeldmacher@geomar.de)2

8Louisenlund School, Germany (C.Timm@gns.cri.nz)
COEAS, Oregon State University, USA (anthony.koppers@oregonstate.edu)
10
DEPS, Tokyo Institute of Technology (akr@eps.sci.titech.ac.jp)
11
KICSR, Japan Agency for Marine-Earth Science and Technology, Japan(shimmy@jamstec.go.jp)
12
SIO, University of California, San Diego, USA (pcastillo@ucsd.edu)
13
DES, University of Milan, Italy (elisabetta.erba@unimi.it)
14
NOCS, University of Southampton, UK (C.Rychert@soton.ac.uk)
15
LMV, Université Jean Monnet, Faculté des Sciences et Techniques, France(adelie.delacour@univ-st-etienne.fr)

9

The Ontong Java Nui is a super plateau inferred to comprise three of the largest volcanic
edifices in the Pacific Ocean, the Ontong Java (OJP), Manihiki and Hikurangi plateaus. If true,
the massive volcanism may have covered >1% of Earth’s surface. OJP, the largest of the three,has been drilled at seven sites, at Deep Sea Drilling Project (DSDP) Site 289 and Ocean
Drilling Program (ODP) Sites 289, 803, 807, 1183, 1185, 1186, and 1187. However, the size,
volume, and formation rate of the OJP are not yet well constrained. Various models for its
origin have been proposed, such as a surfacing mantle plume head, bolide impact, and fusible
mantle melting, but none satisfies all observational data. Volcanological studies also indicatethat long lava flows (or sills) from the OJP may have reached the adjacent Nauru, East
Mariana, and possibly Pigafetta basins, indicating that the maximum extent of OJP-related
volcanism may be even greater than currently estimated. To examine the true extent of the
OJP, i.e., the ~200 km long flows, and its inferred connection with the Manihiki and
Hikurangi plateaus to form the OJN, we propose drilling in the Eastern Salient and adjacentbasins to recover basement samples.

O16

Rheology and water cycle in the Earth and planetary interiors
Keishi Okazaki

1

1

Earth and Planetary Systems Science Program, Hiroshima University(keishiokazaki@hiroshima-u.ac.jp)

In the present Earth, outer-rise fault zones, which extend from the seafloor to theoceanic mantle, can be a major fluid pathway from the ocean to the deep of the Earth.
Rheology of olivine in the mantle peridotites controls the mechanism of the outer-riseseismicity and its depth limit as well as the overall dynamics of the plate tectonics. Whilevarious flow laws of olivine aggregates have been reported/proposed at various
conditions, deformation behavior of olivine aggregates at the brittle-plastic transition,
which could also control the outer-rise seismicity, is poorly understood. In thispresentation, I will talk on the deformation behavior of olivine aggregates at pressuretemperature conditions of the base of the seismogenic zone around outer-rise regions
around the Japan trench. Audible and violent stick-slips followed by acoustic emissions
were observed even at the temperature of 800˚C. However, the nominal friction
coefficient at this condition is ~0.35, which value is significantly lower than that expectedfrom the Byerlee’s friction law (i.e., 0.6–0.85). Comparison between mechanical data andmicrostructural observation indicates that the strain was localized along R1-shear
connected to Y- (or B-) shear with some contents of crystal-plastic deformation. These
weak but seismic deformation could be dominant in the oceanic lithosphere. Initial resultson high coffining and pore fluid pressures deformation experiments of olivine aggregates
under drained condition will also be talked.

O17
Mantle structures and their origins
Bernhard Steinberger
GFZ German Research Centre for Geosciences

The mantle contains both thermal and chemical structure. Convection creates thermal
structure, but erases chemical structure through mixing. Chemical structure is continuously recreated through melting processes. Subducted slabs of lithospheric plates sink towards the baseof the mantle, thinning the thermal boundary layer (TBL) beneath, and thickening it elsewhere.
The Large Low Shear Velocity Provinces (LLSVPs) at the base of the mantle are probably
chemically distinct, and have been rather stable in their position since at least 200 Ma, possibly
longer. They may be partly primordial, partly represent subducted slab material. Upwelling
plumes get generated at the base of the mantle, mostly above LLSVPs and primarily above their
margins and rise to the surface. Plume conduits become tilted and distorted in the mantle.
Although these basic ingredient of mantle structure and dynamics are largely agreed upon, there
are considerable uncertainties, to a large part because mantle viscosity is very poorly known. It
may depend on pressure (depth), temperature, strain rate and composition. Hence it remains
uncertain to what extent the lower mantle between slabs and plume and above the TBL isconvecting.

P1
Thermal Conductivity of Hydrous Stishovite and Phase A
Bill Sweidan1, Kenji Ohta1, Yoshiyuki Okuda2, Steeve Greaux3, Manabu Kodama1, Takashi
Yagi4, Hideharu Kuwahara3
1

Dept. of Earth and Planetary Sciences, Tokyo Institute of Technology(sweidan.n.aa@m.titech.ac.jp; k-ohta@geo.titech.ac.jp, tanaka.m.ay@m.titech.ac.jp)
2
The University of Tokyo (okuda.y@eps.s.u-tokyo.ac.jp)
3Geophysical Research Center, Ehime University (greaux@sci.ehime-u.ac.jp;
kuwahara.hideharu.vd@ehime-u.ac.jp)
4

National Institute of Advanced Industrial Science and Technology (t-yagi@aist.go.jp)

The buoyancy of subducting plates is controlled predominately by the forces of slab pull,which is due to the density-driven thermomechanical contrast between slab and mantle. As
this contrast increases, the seismicity of a subduction zone should generally exhibit a larger
b-value. This would result in more numerous and smaller magnitude earthquakes, which theJapanese Trench Subduction Zone does not exhibit. We hypothesize that the presence of large
abundances of hydrous minerals in a typical MORB lithology may cause tectonic plates atcold subduction zones to exhibit a younger thermal age due to thermal insulation or structural
instability within the slab. We conducted in-situ high-pressure thermoreflectance experiments
on dense hydrous magnesium silicate (DHMS) phase A and stishovite of varying levels of
H2O weight percentage up to 50 GPa (20 GPa for phase A) at 300 K. The presence of H2OZLWKLQ VWLVKRYLWH¶V FU\VWDO VWUXFWXUH ORZHUs its thermal conductivity by up to 40%. This
reduction constitutes a drop in average bulk thermal conductivity of subducting slabs by up to
13%, depending on distribution and stishovite hydration percentage within the slab. It isfurther hypothesized that future thermal and subduction modeling will determine if thisreduction is capable of generating positive up going buoyancy and stress accumulation at cold
subduction zones.

P2

The equations of state of B2 and bcc Fe1-xSix
Yoshihiro Nagaya , Hitoshi Gomi , Kenji Ohta , Kei Hirose
1

1

2

1

2

Tokyo Institute of Technology
2

The University of Tokyo

The Earth's inner core is thought to be an iron alloy containing nickel and a few percent
of light element(s) (Birch 1952). Si is one of the candidates for light elements. In Fe±Si
alloys that contain a large amount of Si, the cubic phase becomes stable at hightemperatures and pressures in a B2 or body-centered cubic (bcc) structure (Fischer et al.
2013, Ikuta et al. 2021). In the previous experiments, the phase identification was
performed by X-ray diffraction structure analysis and observation of diffraction lines in
the 001 and 111 planes, which are characteristic of the B2 structure. However, these
diffraction lines do not disappear unless the phase is completely bcc, and even the B2phase can have a finite degree of disorder. In this study, we combined the Korringa-KohnRostoker method with the coherent potential approximation to obtain the equations ofstate of Fe1-xSix with B2 and bcc structures. The pressures and bulk sound velocities
obtained in this study were compared with the Preliminary reference Earth model(Dziewonski and Anderson 1981). This leads to an understanding of the differences inphysical properties between the two structures and constraints on the composition of the
Earth's inner core.

P3
Large strain deformation experiments of FeO polycrystals under the thelower mantle pressures
Bunrin Natsui1, Shintaro Azuma 1, Keishi Okazaki2, Kentaro Uesugi3, Masahiro Yasutake3,
Ryuichi Nomura4
1

4

Department of Earth and Planetary Sciences, Tokyo Institute of Technology(natsui.b.aa@m.titech.ac.jp)
2
Earth and Planetary Systems Science Program, Hiroshima University
3
Japan Synchrotron Radiation Research InstituteHakubi Center / Graduate School of Human and Environmental Studies, Kyoto University

Seismic tomography has revealed the existence of Large Low Shear Velocity Provinces(LLSVP) with seismic anisotropy from the mid-lower to the lowermost mantle beneath the
African and South Pacific. Previous studies suggested that the development ofcrystallographic preferred orientation (CPO) of constitute minerals causes the seismic
anisotropy observed at the edges of LLSVP. In this study, we conducted high-pressure large
strain deformation experiments on FeO (wüstite) polycrystals to investigate the relationshipbetween the CPO development of minerals and the seismic anisotropy of the LLSVP. Ourdeformation experiments were performed using a newly developed rotational diamond anvil
cell under the high-pressure of 46-63 GPa, temperature of 300 K, and high-strain of more than
100%. The stress and CPO patterns of FeO during deformation experiments were observed byin-situ X-ray diffraction (XRD) measurements. The strain of deformed samples were
determined from the reconstructed cross-sectional images obtained using X-ray laminography
imaging techniques. We report the CPO development and slip system of FeO polycrystals
obtained from analysis of the XRD patterns.

P4
A Preliminary CMB Heat Flux map
Takumi Matsunaga1 , John Hernlund2
1

Earth-Life Science Institute, Tokyo Institute of Technology(matsunaga.t@elsi.jp)
2
Same as above(hernlund@gmail.com)

Estimating heat flux at Core-Mantle Boundary(CMB) is very important for understanding mantle thermal convection. Thanks to the discovery of perovskite post-perovskite
transition in the deep mantle, using Clapeyron slope has a possibility that can constrain
thermal gradient and geotherm above CMB. Seismic data is very useful in estimating
geotherm, but still have a lot of uncertainties, such as e↵ect of composition heterogeneity in the lower mantle, spin transition of iron, radioactive heat, partial melt e↵ect andthermal conductivity in high pressure condition. Using the maximum heat flux assumed
from the hypothesis ’Double-crossing’(Hernlund,2010) and P-wave velocity map which ishighly e↵ected in temperature, we can simply estimate the heat flux near the CMB. Thismethod is useful in its simpleness, but the problem is assuming linear correlation between
P-wave velocity and temperature.

P5
Non–thermal heterogeneity in the lowermost mantle andconstraints on convection parameters
Jun Su1 , Frédéric Deschamps2 , Christine Houser1 , John Hernlund1
1

Earth-Life Science Institute, Tokyo Institute of Technology, Japan
2
Institute of Earth Sciences, Academia Sinica, Taiwan(junsu@elsi.jp)

Seismic observation has suggested low-velocity anomalies near the core-mantle boundary beneath the Pacific and Africa, where shear wave velocity (VS ) is uncoupled withcompressional wave velocity (VP ). Previous studies associate the large low shear velocity
provinces (LLSVPs) with superplumes, accumulation of basaltic crust, and/or reservoirsof primordial materials. Su et al. (in revision) found that the uncorrelated VS and VP
cannot be explained as artifacts of relative resolution of the models and instead purposedlarge uncorrelated moduli provinces (LUMPs) to map the chemical heterogeneity. The
map reveals patchy and complicated structures in the lowermost mantle (D” layer), but
the dynamics remain unknown. In this study, we measure the length scale of LUMPs invarious geodynamical models and show that it is sensitive to a few convection parametersthat were poorly determined. Therefore, we can infer the convection parameters for Earthby comparing the outcome of mantle circulation models and non-thermal heterogeneity
in the observation.

P6
Lateral Chemical Reactions at the Core-Mantle Boundary
Austin Taylor1, John Hernlund2
1

Earth-Life Science Institute, Tokyo Institute of Technology (taylor.austin@elsi.jp)
2
Earth-Life Science Institute, Tokyo Institute of Technology (hernlund@elsi.jp)

Lateral variations in temperature and composition at the outer core near the core-mantle
boundary (CMB) are projected to be orders of magnitude smaller than their radial
counterparts, due to the viscous boundary between the core and mantle. However, regions of
FeO-poor ultra-low velocity zones (ULVZs) and FeO-rich subducted slabs have a chemical
potential gradient between them which is suspected to contribute to lateral flows near the
CMB. In future research, we will be modeling chemically-driven flows in a 3D rotating
spherical model in with hopes of understanding some possible transport mechanisms at the
CMB.

P7
Toward New Methods for modeling complex mantle dynamics
Laura Eberhard
Earth-Life Science InstituteTokyo Institute of Technology
Westfälische Wilhelms-Universität Münster
leberhar@wwu.de

How does the URFN\PDMRULW\RIWKH(DUWK¶VLQWHULRUPRYHDQGGHIRUPWRSURGXFHSODWH
tectonics, earthquakes, volcanic eruptions, circulate its inventory of elements in and out andcreate suitable conditions for the origin and evolution of life?
A century ago, geophysicists made a rough analogy between the movements of the thick,rocky mantle shell of the Earth and thermal convection in ordinary fluids, which came to be
NQRZQDV³PDQWOHFRQYHFWLRQ´
However, the description of solid rocks DV³DIOXLG´KDVOLPLWDWLRQVLQDFFRXQWLQJIRU
observations bearing on the physical and chemical state of the interior.
Mantle convection theory is presently based on experimental analogue study of fluids in thelaboratory and in numerical models. While such an approach is easy to implement,
deterministic, and reproducible, the critical weakness is that such a simplistic analogue isintrinsically incapable of capturing important behaviors of rock and explaining key
observations.
Today the field is due for a modeling approach that allows for degrees of complexity that is
up to the challenge of describing real rocks.

Classic conceptual sketch of fluid-like motions in the rocky mantle that would accompany tectonic
activities in the Earth crust (Holmes 1931).

P8

Current status of OBD development and prediction of observation
sensitivity for mantle geo-neutrino
A

Tohoku Univ. RCNS, BTohoku Univ., CUniv. of Maryland, DJAMSTEC

T.SakaiA(sakai@awa.tohoku.ac.jp), K.InoueA, H.WatanabeA, W.McDonoughA,B,C,
K.UekiD, N.AbeD, N.SakuraiD, M.KyoD, E.ArakiD, T.KasayaD, H.YoshidaD

Observation of geo-neutrinos originating from radioactive isotopes in the Earthcan be converted to the number of radioactive isotopes and the heatgenerated by their decays which governs the Earth dynamics.
To date, two experiments (KamLAND and Borexino) have measured geoneutrinos and constrained the range of acceptable models for the Earth’s
chemical composition but distinguishing the mantle flux by land-based
detectors is challenging as the crust signal is about 70% of the total antineutrino flux.
Given the oceanic crust is thinner and has lower concentration of radioactive
elements than continental crust, geo-neutrino detector in the ocean, Ocean
Bottom Detector (OBD), makes it sensitive to geo-neutrinos originating fromthe Earth’s mantle.
Our working group was jointly constructed from interdisciplinary communities
in Japan which include particle physics, geoscience, and ocean engineering. We
have started to work on technological developments of OBD.
In my presentation, current development status and performance evaluation
result.