The Origin of Oceans

 

LECTURER
Prof. Fabrizio Nestola

University of Padova

DATE: 27th August 2019
TIME: 09:00 – 10:00 am
LOCATION: Rigoni Stern Institute, Asiago

The origin of water in our Planet remains one of the most intriguing and unanswered topics. When did the water that we today drink reach the Earth? There are two main theories that could answer to this crucial question: 1) the first theory would indicate comets, asteroids and meteorites as water taxi drivers to the Earth; 2) the second theory is simply based on the possibility that water was present from the first second of formation of our Planet. So, which one is correct? Which is the most plausible? Could be both the hypotheses correct and cooperate in combination?

A big help to this discussion could be provided if we combine geology and astronomy: indeed, one possible primitive signature of water, terrestrial and extra-terrestrial, could be the deuterium/hydrogen ratio (deuterium is one of the three isotopes of hydrogen and is generally indicated with the symbol “D”; the proper nomenclature for deuterium would be “2H”). Deuterium only represents 0.016% of all hydrogen but its presence could be crucial in providing a definitive answer to the origin of water in the Earth. Indeed, if water was transported to the Earth from the space, then our Planet and at least the solar system should share similar values of deuterium/hydrogen ratio (D/H).

The lecture “The origin of oceans” by Prof. Fabrizio Nestola will provide a wide perspective on this important topic using a “magic” terrestrial object, which is natural diamond. Natural diamonds are “magic” because not only they are among the oldest geological materials (they can be 3.6 billion years old) remained perfectly preserved in our hands but because they can be formed at extreme depths within the Earth (the deepest diamond never found formed at 780 km depth, Nestola et al. 2018). Accidentally, these old and deep materials can incorporate tiny mineral and fluid inclusions within them and therefore when inclusion-bearing diamonds reach the Earth’s surface, we are able to open real windows directly into the deep Earth. This allows to us to study “what there is” and “how it works” at really extreme depths and thanks to diamonds, we have discovered that our Planet contains much more water than what we thought before 2014 (at least three times more). In 2014, Pearson and coauthors found a tiny inclusion (called ringwoodite with chemistry Mg2SiO4) within a Brazilian diamond containing 1.4% H2O. Considering that this mineral can be stable only between 520 and 660 km depth in the Earth’s transition zone and represents about 35% of this shell, then this means that at those depths we have 4-5 times the water of the Pacific Ocean. In addition, in 2016, Smith and coauthors, studying diamonds from Lesotho (Africa) and formed at similar depths in the deep Earth, found methane (CH4) and molecular hydrogen (H2) around several inclusions, confirming the discovery that at extreme depths there is a significant amount of hydrogen. Very recently, Tschauner et al. (2018) found inclusions of ice (so-called “ICE VII”) still preserved within a diamond coming from 660 km depth. Finally, a further recent discovery (Smith et al. 2018) reported the presence of another important element, boron, B, contained in traces within the very famous blue diamonds (with provenance all over the world) and discovering that these diamonds are also very deep. The authors stated that the main source of boron in these super-deep diamonds must have been the old oceanic water.

All these diamonds could “tell” us if the hydrogen that they encapsulated billion years ago shares the same signature (i.e. same D/H ratio) with the extra-terrestrial bodies or has its own evolution. Combining the studies on the D/H measured on diamonds and on other very old terrestrial rocks, we could definitively be in the position to solve a crucial geological enigma. This goal could be achieved only if geologists and astronomers will be able to work in team and share their scientific backgrounds.

Main research interests

– Diamond mineralogy

Investigation on diamond and its mineral inclusions: determination of the pressure of formation of diamond; determination of syngenesis/protogenesis between diamond and its inclusions and implications for geochemical, geophysical, geodynamical Earth’s mantle models.

– Mineral Physics

Compressibility, thermal expansion, physical properties of minerals and crystalline compounds; crystal structure evolution under non-ambient conditions.

 

Main experimental techniques used

– single-crystal and powder X-ray diffraction

– neutron diffraction

– synchrotron X-ray diffraction

– micro-Raman and IR spectroscopy

– SEM-EDS and WDS techniques

– diamond-anvil cells and microfurnaces

– piston-cylinder

– multi-anvil press.

 

Academic record

– 1999: Master Degree in Geological Sciences at University of Torino (Italy).

– 2000-2003: Ph.D. position at University of Modena and Reggio Emilia (Italy) in Mineralogy, Petrology and Crystallography.

– 2002: Training Marie Curie at Bayerisches Geoinstitut for Ph.D. students.

– 2004: “Alexander von Humboldt Research Fellowship” at Bayerisches Geoinstitut for a total of 20 months (12 plus 8 months of renewal) of post-doc.

– 2005: “Associate post-doc position” at Virginia Polytechnic Institute and State University (USA).

– 2006 to 2010: Permanent position as “Researcher” in Mineralogy at University of Padua (Italy) (Department of Geosciences). Responsible for the single-crystal X-ray diffraction laboratory at Department of Geosciences. –

– 2010 to present: Associate Professor in Mineralogy at University of Padua (Department of Geosciences).

– 2012-2017: European Research Council Starting Grant 2012, IDEAS. Title: “Inclusions in Diamonds: messengers from the deep Earth”. Funds: 1,423,000 € (agreement number: 307322).

– 2013-2017: Secretary for the GMPV division of European Geoscience Union (subdivision “Mineral Physics”).

– 2014-2015: Member of the Executive Committee of Elements.

– 2015 to present: Associate Editor of Frontiers in Earth Sciences.

– 2015 to present: Associate Editor of European Journal of Mineralogy.

– 2015 to present: Head of the Ph.D. School in Earth Sciences at University of Padova.

– 2015 to present: Full Professor in Mineralogy at University of Padua (Department of Geosciences).

– 2016 to present: Associate Editor of American Mineralogist.

 

Key Figures

– H-index = 23 (year of first publication: 2001)

– Number of peer-review international publications: 222

– Number of total citations: 2282

– Average impact factor: 2.72

 

Organization of conference sessions and international schools; invited seminars

– Organization of more than 20 sessions at national and international conferences.

– Organization of four international schools on diamond research.

– More than 30 international invited seminars.

 

Teaching activity; supervision of bachelor and master students, Ph.D. students, post-docs; institutional responsibility

– Analytical Techniques in Earth Sciences (6 CFU)

– Crystallography and Mineral Physics (6 CFU).

– Supervised Bachelor and Master students: > 30

– Supervised Ph.D. students: 3

– Supervised post-docs: 7

 

2008 – 2106: member of the Earth Sciences Scientific Committee at University of Padova;

2009 – present: responsible for the single-crystal X-ray diffraction laboratory;

2016 – present: member of the executive board of “Scuola Galileiana di Studi Superiori dell’Universita’ di Padova”;

2016 – present: Vice-Head of Department of Geosciences of University of Padova.

 

National and International prizes

– 2003: Prize for “Ph.D. thesis” awarded by the Italian Society of Mineralogy and Petrology (SIMP).

– 2010: “Medal for excellence in research” awarded by European Mineralogical Union (EMU).

– 2011: “Mario Nardelli Prize” in crystallography awarded by the Italian Association of Crystallography (AIC).

– 2016: “Maria Teresa Messori Roncaglia e Eugenio Mari” prize awarded by Accademia Nazionale dei Lincei.

 

 

Reviewer for the following international journals:

 

  1. Earth and Planetary Science Letters
  2. American Mineralogist
  3. European Journal of Mineralogy
  4. Physics and Chemistry of Minerals
  5. Mineralogical Magazine
  6. Acta Crystallographica A
  7. Neues Jahrbuch für Mineralogie
  8. Canadian Mineralogist
  9. Journal of Physics and Chemistry of Solids
  10. Inorganic Chemistry
  11. Solid State Communications
  12. Zeitschrift für Kristallographie
  13. Journal of the American Ceramic Society
  14. Solid State Sciences
  15. Spectrochimica Acta Part A
  16. Nature Communications
  17. Physical Chemistry Chemical Physics
  18. Journal of Molecular Structure
  19. Biochimica et Biophysica Acta
  20. Lithos
  21. International Geology Review
  22. Surface Science
  23. Journal of Materials Research

References

– Nestola, F., Korolev, N., Kopylova, M., Rotiroti, N., Pearson, D.G., Pamato, M.G., Alvaro, M., Peruzzo, L., Gurney, J.J., Moore, A.E., Davidson, J. (2018) CaSiO3-perovskite in diamond confirms the recycling of oceanic crust into the lower mantle. Nature, 555, 237–241.

– Pearson, D.G., Brenker, F.E., Nestola, F., McNeill, J., Nasdala, L., Hutchison, M.T., Matveev, S., Mather, K., Silversmit, G., Schmitz, S., Vekemans, B., Vincze, L. (2014) Hydrous mantle transition zone indicated by ringwoodite included within diamond. Nature, 507, 221-224.

– Smith, E.M., Shirey, S.B., Nestola, F., Bullock, E.S., Wang, J., Richardson, S.H., Wang, W. (2016) Large gem diamonds from metallic liquid in Earth’s deep mantle. Science, 354, 1403-1405.

– Smith, E.M., Shirey, S.B, Richardson, S.H., Nestola, F., Bullock, E.S., Wang, J., Wang, W. (2018) Boron in blue diamonds from Earth’s lower mantle. Nature, doi: 10.1038/s41586-018-0334-5.

– Tschauner, O., Huang, S., Greenberg, E., Prakapenka, V.B., Ma, C., Rossman, G.R., Shen, A.H., Zhang, D., Newville, M., Lanzirotti, A., Tait, K. (2018) Ice-VII inclusions in diamonds: evidence for aqueous fluid in Earth’s deep mantle. Science, 359, 1136-1139.