RheoMan: a five-year, ERC-funded (Advanced Grant), project to model the rheology of the Earth's mantle

Feb 5, 2013 Seminar from A.M. Goryaeva General

Alexandra M. Goryaeva  (Department of Crystallography and Crystal Chemistry, Moscow State University, Russie) will visit us from February 4th to February 7th, 2013

Alexandra will give us a seminar entitled:

" Theoretical study of the major rock-forming minerals anisotropy and its implication for the Siberian craton upper mantle seismic data"

February 5th, 2013 - 10:00 am

Building C6, Room 202



Siberian platform represents a remarkable region covered by a unique network of the long range profiles, where P waves from the nuclear explosions were recorded. According to the obtained seismic data, there are several low and high P velocity layers between 100 km and 250 km depth. The deviations within this zone could be caused by the lattice preferred orientation of olivine what is considered to be one of the main reasons inducing anisotropy in the upper mantle.

The coming presentation introduces the study of the essential rock forming minerals anisotropy and its implication for the Siberian craton upper mantle anisotropy exemplificative of the polycrystalline matter with the garnet harzburgite model compound containing 65% of olivine. The anisotropy percentage dependence on the depth was examined for the particular minerals, such as olivine Fo90, orthopiroxene En75.5 and clinopiroxene Di72, as well as for the polycrystalline harzburgite model in general. Olivine crystals with the maximal P-wave anisotropy of 24% ensure the 11-16% anisotropy of the polycrystalline matter with the investigated model compound. Comparing CRATON and METEORITE long range seismic profiles with the velocities evaluated for the garnet harzburgite compound, it can be inferred that the low P-velocity layers within the 100-250 km zone more likely correspond to the isotropic polycrystalline matter and the high velocity layers – to the polycrystalline matter with the partial olivine orientation along (100).