Fenglin Lyu, ITP Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China, Chenglin Liu, Chinese Academy of Geological Sciences, Beijing, China, Hua Zhang, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing, China, Zhongping Lai, Shantou University, Shantou, China and Juzhi Hou, Chinese Academy of Sciences, Beijing, China