1. Geological Sciences/ CIRES; University of Colorado; Boulder CO 80309 USA
2. Samara Center for Theoretical Materials Science; Samara State Technical University; 244 Molodogvardeyskaya st. Samara 443100 Russia
3. FB 5 Geowissenschaften; Universität Bremen; Klagenfurter Str. 2 D-28359 Bremen Germany