  Antineutrinos born in the U and Th decay chains inside the Earth
(``Geoneutrinos'') carry out information on the amount and distribution of
radiogenic heat sources, which is of fundamental importance for geophysics.
Models of the Earth distribute U and Th masses mainly between the continental
crust and the lower mantle. It has been much discussed recently that a number
of detectors stationed at appropriate geographical sites can separate the crust
and mantle contributions. In present work we analyze directional separation of
antineutrino signals arriving from the crust and the lower mantle with only one
detector. We find that with a ~30-kton liquid scintillation antineutrino
spectrometer using $\bar{{\nu}_e}+p \to n + e^{+}$ detection reaction and
positron and neutron coordinates reconstruction techniques the U and Th
distribution model can roughly be tested. We also consider detector calibration
using ~1 MCi commercially available Sr90-Y90 beta source which emits
antineutrinos (Emax = 2.28 MeV) in the geoneutrino energy range.
