The aim is to give an overview on how geochemical and petrological data, obtained
from upper mantle xenoliths, could be utilized to provide information on the geophysical
properties of the upper mantle at their origin. First we demonstrate how a tentative
lithospheric column may be constructed based on the equilibrium temperature of upper
mantle xenoliths and the area specific depth-temperature curves. Then it is described
how the speed of seismic waves at the given pressure and temperature conditions could
be calculated from the modal composition and geochemistry of major rock forming minerals
of upper mantle xenoliths (e.g. olivine and orthopyroxene). It is also discussed how
the lattice preferred orientation of minerals in upper mantle xenoliths provides information
on the seismic anisotropy of the upper mantle, and how this information could be used
to calculate the orientation and thickness of the anisotropic layer in the upper mantle
if one anisotropic layer is assumed. Structural hydroxyl (or most commonly referred
to as 'water') incorporated in nominally anhydrous minerals plays a critical role
in determining the electrical conductivity and rheology of the upper mantle. Finally,
it is presented how electrical conductivity and effective viscosity of the upper mantle
could be approximated based on the structural hydroxyl content in olivine, the most
abundant mineral constituent of the upper mantle. Our study area, the Persani Mountains
is situated in the Carpathian Bend area (Romania) which is geologically one of the
most active areas in Europe. Abundant upper mantle xenoliths from the Persani Mountains
(Eastern Carpathians) will serve as examples how meaningful geophysical information
can be obtained for the upper mantle. Furthermore, it is shown how these pieces of
information may be utilized in interpreting geophysical and geodynamic challenges
of this area.
