Their zoning makes, however, it rather difficult to find the exact amount of impact-influenced compositional effects. Garnets look rather fresh and intact in the impactite rocks studied. The original garnet composition reflects the high-T,P areal metamorphic environment. The FeO, MgO, MnO3 and CaO abundances in various garnets were analysed as point profiles from crystal edge to the centre. Abundance in the crystal centre was set to one unit.
Barbs indicate possible diffusion direction.
The exact numbers shown above represent only one sample but very similar analyses have also been obtained from samples from several other locations. The number of the samples is, however, still too low in order to provide a statistical importance high enough to get the actual diffusion rate. Longer cation migration paths through the whole crystal lattice are slower and more difficult in both cases. The the present erosion level and the impactite samples collected from it represent rather deep shock-metamorphic level of the original crater.