Title: Origin of the Moon: An attempt to Solve the Isotopic Crisis

Presenter: Prof. Shun-ichiro Karato

Institution: Department of Geology & Geophysics, Yale University

Time: 20180511-15:00:00

Location: Room 2829, No. 2 Science Building.

Abstract: A giant impact model has been a standard model for the formation of the Moon. However, most of models showed that the Moon is mostly formed from the impactor and explaining the close similarity in the isotopic compositions is difficult. Many modified models have been proposed where different mechanical aspects of collision were considered. However, these models have difficulties in explaining the angular momentum, and successful models can be found only in a very small parameter space. Here we propose a new model where the giant impact by a solid impactor occurred to the proto-Earth that was covered with a magma ocean. Due to the large differences in the shock heating between silicate melts and solid silicates (rocks) shown by a new theory of equation of state of silicate melts, a substantial fraction of the ejected material is from the magma ocean even with a highly oblique collision. This model provides a natural explanation of the isotopic similarities between the Moon and Earth with the angular momentum constraint being satisfied

Homepage：https://people.earth.yale.edu/profile/shun-ichiro-karato/about

CV：SHUN-ICHIRO KARATO

(a) Professional preparation:

University of Tokyo, Tokyo (Japan), Geophysics, BSc., 1972

University of Tokyo, Tokyo (Japan), Geophysics, MSc., 1974

University of Tokyo, Tokyo (Japan), Geophysics, Ph.D., 1977

(b) Appointments:

2001-presentProfessor, Department of Geology & Geophysics, Yale University

1992- 2001Professor, Department of Geology & Geophysics, University of Minnesota

1989-1992Associate Professor, University of Minnesota

1981-1984Research Fellow, Australian National University

1977-1989Assistant Professor, Ocean Research Institute, University of Tokyo

(c) Awards/honors

Alexander von Humboldt Prize1995

Vening Meinesz lecture (Utrecht University)1998

Japan Academy Prize1999

Fellow of American Geophysical Union2000

Birch lecture (AGU)2004

Vening Meinesz medal (VMSG)2006

Fellow of Mineralogical Society of America2011

Augustus Love medal (EGU)2014

Fellow of Japan Geoscience Union2014

Inge Lehmann medal (AGU)2016

(d) Publications

Karato, S., Paterson, M.S. and Fitz Gerald, J.D., 1986. Rheology of synthetic olivine aggregates: influence of grain size and water, J. Geophys. Res., 91: 8151-8176.

Karato, S. 1990. The role of hydrogen in the electrical conductivity of the upper mantle, Nature, 347: 272-273.

Karato, S., 1992. On the Lehmann discontinuity, Geophys. Res Lett., 19: 2255-2258.

Karato, S. and P.Wu, 1993. Rheology of the upper mantle: A synthesis, Science. 260: 771-778.

Karato, S., 1993. Importance of anelasticity in the interpretation of seismic tomography, Geophys. Res. Lett., 20: 1623-1626

Zhang, S. and S. Karato, 1995. Lattice preferred orientation in olivine due to shear deformation, Nature, 375: 774-777.

Karato, S. and Jung, H., 1998. Water, partial melting and the origin of the seismic low velocity and high attenuation zone in the upper mantle, Earth Planet Sci. Lett., 157: 193-207.

Jung, H. and Karato, S., 2001. Water-induced fabric transitions in olivine, Science, 293: 1460-1463.

Bercovici, D. and Karato, S., 2003. Whole-mantle convection and the transition-zone water filter, Nature, 438: 39-44.

Huang, X., Xu, Y. and Karato, S., 2005. Water content in the transition zone from electrical conductivity of wadsleyite and ringwoodite, Nature, 434: 746-749.

Wang, D., Mookherjee, M., Xu, Y. and Karato, S., 2006. The effect of hydrogen on the electrical conductivity in olivine, Nature, 443: 977-980.

Karato, S., 2008. Deformation of Earth Materials: Introduction to the Rheology of Solid Earth, Cambridge University Press, Cambridge, pp. 463.

Karato, S., 2011. Water distribution across the mantle transition zone and its implications for the global material circulation, Earth Planet. Sci. Lett., 301: 413-423

Karato, S. 2012. On the origin of the asthenosphere, Earth, Planet. Sci. Lett., 321/322: 95-103.

Otsuka, K. and Karato, S., 2012. Deep penetration of molten iron into the mantle caused by the morphological instability, Nature, 492, 243-236.

Dai, L. and Karato, S., 2014. High and highly anisotropic electrical conductivity of the asthenosphere due to hydrogen diffusion in olivine, Earth Planet. Sci. Lett., 408: 79-86.

Karato, S., Olugboji, T., and Park, J., 2015. Mechanisms and geologic significance of the mid-lithosphere discontinuity in the continent, Nature Geoscience, 8: 509-514.

Girard, J., Amulele, G., Farla, R., Mohiuddin, A. and Karato, S., 2016. Shear deformation of bridgmanite + magnesiowüstite aggregates under the lower mantle conditions, Science, 251: 144-147.

(e) Synergetic activities

The PI was on the geophysics panel of NSF (2001-2004)

The PI was on the executive committee (vice chair) of COMPRES (2002-2005)

The PI is on the advisory board of IUGG (2011-2015)

The PI is on the advisory board of JpGU (2013-)

The PI is a member of Geodynamics section of EGU (2014-)