作者机构:[1]Institute of Geology, Chinese Aeademy of Geological Sciences, Beijing 100037, China
相关基金:This study was supported partly by National Natural Science Foundation of China (No.40674026), Commonweal Special Science Founda- tion of China (No. 200811037) and Geological Survey Foundation of Ministry of Land and Resource, China (No. 1212010916083). The authors express the thanks to the three reviewers for their valuable comments.