基金The authors are indebted to Prof. Defan Xie from the School of Earth Sciences, China University of Geosciences, Wuhan for his guidance during field work, and thanks also go to Jianzhen Geng and Yongqing Zhang for the zircon U-Pb dating by LA-ICP-MS at the Tiunjin Center of China Geological Survey. This study was supported by the China Geological Survey （Nos. 1212010510507, 1212010811005, 1212011220448） and the Fundamental Research Funds for the Central Universities, China University of Geosciences, Wuhan （No. CUGL150816）. The final publication is available at Springer via https：//doi.org/ 10.1007/s12583-017-0942-2.
基金During the research work, we appreciated advice from Senior Engineer Yang Bin of the Gansu Province Geology and Mining Bureau and Zhang Xiang, Engineer, of Gansu Province Geological Survey. We thank the editors and anonymous reviewers for comments that greatly improved the presentation of the paper. Thanks to Shuangshuang Wang for the help during the laboratory work. This study was supported by the National Natural Science Foundation of China （Grant No. 41173014）, the Central Universities Fundamental Research Project （Lzu-Jbky-2012-128）, and Gansu Key Laboratory of Mineral Resources in Western China （Lanzhou University） funded project.