financially supported by Natural National Science Foundation of China (Nos.41272236 and 41202156);China Geological Survey (Nos.1212011121267, 1212020918036 and 12120114022901);Central Public-interest Scientific Institution Basal Research Fund (Nos.J1334 and J1126);European Marie Sklodowska-Curie Outgoing International Fellowship FP6 (No.040070)~~