1. Geographic Institute Univ. of Berne; Hallerstrasse 12 3012 Berne Switzerland
2. Johannes Gutenberg-Univ. Mainz; Earth System Science Research Center; Johann-Joachim-Becher-Weg 21 55128 Mainz Germany
3. Leibniz Univ. Hannover Institute of Mineralogy; Callinstraße 3 30167 Hannover Germany
4. Univ. of Frankfurt Institute of Geoscience; Altenhöferallee 1 60438 Frankfurt am Main Germany