October 6, 2016
Dr. Yan Liu Institute of Geology Chinese Academy of Geological Sciences
The Himalayan Cenozoic Mianning–Dechang (MD) rare earth element (REE) belt in western Sichuan Province, southwest China, is about 270 km long and 15 km wide. All these deposits along MD are syenite-carboantite related REE deposits with total resources of >3 Mt of light rare earth oxides (REO). These fertile magmas were generated by the partial melting of sub-continental lithospheric mantle (SCLM), which was metasomatized by high-flux, REE- and CO2-rich fluids derived from subducted marine sediments. In the belt, Dalucao formed at 11 Ma and Maoniuping, Lizhuang and Muluozhai deposits formed at 22-27 Ma. Bastnäsite and other REE minerals formed below 300°C. The mineralization formed from magmatic and meteoric fluids containing CO2 derived from the decarbonation of carbonatite. It is found voluminous syenite–carbonatite complexes, extensive alteration, multiple REE mineralization stages, and frequent tectonism that guided ore formation are responsibe for the giant REE deposits.