[1] Univ Ferrara, Dept Earth Sci, I-44100 Ferrara, Italy
[2] ISTEC, CNR, I-48018 Faenza, Italy
[3] Univ Milan, Dept Earth Sci, I-20133 Milan, Italy
[4] Grenoble Inst Technol, Mat & Genie Phys Lab, CNRS, F-38043 Grenoble, France
[5] European Synchrotron Radiat Facil, F-38043 Grenoble, France