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Invited researcher Eiji Ohtani
Contract number
14.B25.31.0032
Time span of the project
2013-2017
Head of the laboratory

As of 30.01.2020

30
Number of staff members
157
scientific publications
6
Objects of intellectual property
General information

Name of the project:

Experimental research of substances at ultra-high pressure and creation of thermodynamical model of deep structure of the Earth

Strategy for Scientific and Technological Development Priority Level: а


Goals and objectives

Research directions:

Phase diagrams and thermodynamics of minerals under high pressure, mantle petrology, high pressure minerals in meteorites, synthesis of carbon-based nanocrystalline materials

Project objective:

- Development of state equations and thermodynamical models for solid and liquid phases at high pressure for quantitative evaluation of processes of redistribution of matters in the depth of the Earth

- Solving the task of synthesizing sinters with unique abrasive characteristics by studying nano polycrystalline diamonds of the Poligai astrobleme.


The practical value of the study

  • We have developed an equation of state for solid and liquid phases of ferrum under pressure up to 400 GPa. Density and physical properties of ferrum in conditions similar to those in the core of the Earth have been calculated. Phase state equation for the MgSiO3-MgO system at 120 GPa. For the first time, phase transition lines have been calibrated, including transition from perovskite to post-perovskite at 110–120 GPa.
  • Thin structure of Popigai diamonds has been examined. We have gathered X-ray structure data on the nature of martensite transformations in nanocrystalline diamond aggregates. We have conducted testing ultra-hard aggregates of Popigai for usage as cutting instruments in drilling bits.
  • The Laboratory has studies isotope composition of ultra-deep diamonds of Brazil and come to a conclusion concerning the primary source of carbon in these diamonds. We have substantiated the discovery of merwinite in ultra-deep diamonds of Brazil – it serves as an indicator for high depth carbonatite melts
  • Our team has produced a model of formation of carbonatite diapirs in transition zones of the Earth's mantle. We have shown examples of subduction of continental rock that can be sources of fugitive components from the transition one. We have shown possible results of processes explained by those processes in the nature (through the example of studying basaltoid rock of the Central Asia).
  • As a result of analysis of phase diagrams in double and triple carbonate systems at pressures between 3 and 6 GPa, we have drawn fundamental conclusions concerning the nature of carbonate disintegration and carbon-silicate interactions in the Earth's mantle. We have calibrated compositions of molten masses in the peridotite-CO2 at 10-20 GPa. We have shown regions of temperature stability of carbonatite melts. It has been shown that primary melts of the Udachnaya pipe (Yakutia) were alkaline carbonatite melts.
  • Our team has produced an experimental phase diagram for methane under pressure of up to 80 GPa. We have substantiated of heavy carbohydrates from methane fluid under high pressure. We have studied stability and state equations for polycyclic aromatic hydrocarbons. Our research has demonstrated limited temperature stability and low thermal expansion rate at high pressure.
  • We have examined a sample of Lunar regolith and detected stishovite in the sample. This is the first exploration of a pressure mineral from an extra-terrestrial of non-meteorite nature. Coesite and stishovite have been found in the Béréba Eucrite on this asteroid. Asteroid 4 Vesta possibly belongs to this group. The research we have conducted allowed us to suggest impact events that preceded big explosions about 1 billion years ago reconstructed from the data gathered by the Dawn mission.
  • We have also studied big diamonds from fragments of the Almahata Sitta meteorite (asteroid 2008TC3). The studies have shown that the diamond's formation was caused by a sequence of fragmentation and re-accumulation. The most possible hypothesis is formation of diamonds at high PT parameters the way it happens on the Earth.

Implemented results of research:

  • We are manufacturing boring equipment from Poligai nanocrystalline diamonds that can be used in diamond mining industry

Education and career development:

  • One doctoral dissertation, 8 candidate dissertations, 5 masters dissertations and 4 bachelors dissertations have been defended
  • We have conducted 3 international symposiums: «Advances in High-Pressure Research: Breaking Scales and Horizons», «Advances in High-Pressure Research II: Deepest Understanding», «Advances in High-Pressure Research III: Towards Geodynamic Implications».
  • Our Laboratory has conducted two schools for young professionals: «GeoRAMAN School for students and young scientists», «High-pressure Techniques for Petrology and Geodynamics of Earth and Planetary Interiors».
  • We have developed lecture courses for the Faculty of Geology and Geophysics of the Novosibirsk State University and for the postgraduate school of the Institute of Geology and Mineralogy of the Siberian Department of the Russian Academy of Sciences «Petrology of the Earth's mantle and core»; «Crystallochemistry of minerals»; «Crystallography»; «Advanced Crystallography»; «Introduction to Geochmemistry»; «Technology of Experiments under High Pressures and in High Temperatures»; «Crystallochemisyty and Structure of Diamond»; «Design of Crystalls».

Organizational and structural changes:

  • In 2018 the Laboratory for Physics of the Earth and Planets has been launched that pursues the same areas of studies that have been started as a part of the mega-grant.

Collaborations:

  • Tohoku University (Japan), University of Tokyo (Japan), Ehime University (Japan): joint scientific projects and symposiums
  • Carnegie Institution of Washington (USA): internships of undergraduate and postgraduate students, joint projects
  • University of Bayreuth (Germany): internships of undergraduate and postgraduate students, joint projects

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Lobanov S.S., Chen P.N., Chen X.J., Zha C.S., Litasov K.D., Mao H.K., Goncharov A.F.
Carbon precipitation from heavy hydrocarbon fluid in deep planetary interiors. Nature Communications 4: 2446 (2013).
Litasov K.D., Shatski, A., Ohtani E.
Melting and subsolidus phase relations in peridotite and eclogite systems with reduced C-O-H fluid at 3-16 GPa. Earth and Planetary Science Letters 391: 87–99 (2014).
Miyahara M., Ohtani E., Yamaguchi A., Ozawa S., Sakai T., Hirao N.
Discovery of coesite and stishovite in eucrite. Proceedings of the National Academy of Sciences of the United States of America 111: 10939–10942 (2014).
Sharygin I.S., Litasov K.D., Shatskiy A.F., Golovin A.V., Ohtani E., Pokhilenko N.P.
Melting phase relations of the Udachnaya-East group-I kimberlite at 3.0-6.5 GPa: experimental evidence for alkali-carbonatite composition of primary kimberlite melt and implications for mantle plumes. Gondwana Research 28: 1391–1414 (2015).
Chanyshev A.D., Litasov K.D., Furukawa Y., Kokh K.A., Shatskiy A.F.
Temperature-induced oligomerization of polycyclic aromatic hydrocarbons at ambient and high pressures. Scientific Reports 7: 7889 (2017).
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