Kang Shichang, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, China, Qianggong Zhang, ITP Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing, China and Yulan Zhang, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, SKLCS, Lanzhou, China