REE-fluorocarbonates as major REE minerals in the Bayan Obo deposit, the largestREE deposit in the world, were analyzed for their stable isotopic compositions. The δ13C andδ18O values of huanghoite, cebaite and bast...REE-fluorocarbonates as major REE minerals in the Bayan Obo deposit, the largestREE deposit in the world, were analyzed for their stable isotopic compositions. The δ13C andδ18O values of huanghoite, cebaite and bastnaesite from late-stage veins vary in the ranges of -7. 8 - - 4. 0‰ and 6. 7 - 9. 4‰ respectively. These data are relatively similar tO those ofbastnaesites from banded ores: δ13C - 5. 6 - - 5. 2‰ and δ18O 3. 6 - 5. 5‰ The REEfluorocarbonates from both late-stage veins and banded ores are characterized by lower δ13C andδ18O values, especially the δ18O values of bastnaesites from banded ores. Compared with them,the disseminated bastnaesits the dolomite-type ores possess rather high δ13C and δ18O values, i.e., - 2. 1 - - O. 4‰ and 8. 6 - 12. 9‰ respectively. The high values are typical of thesedimentary host dolomite rocks as well as of the dolomite-type ores. The carbon and oxygenisotopic characteristics of REE fluorocarbonate minerals provide new evidence for the hypothesison the origin of Bayan Obo deposit-epigenetic hydrothermal metasomatism.展开更多
An almost complete skull, which was collected from the Upper Cretaceous of the Bayan Mandahu area in Inner Mongolia, China by the Sino-Canadian Dinosaur Project, is described and assigned to a new genus of protocerato...An almost complete skull, which was collected from the Upper Cretaceous of the Bayan Mandahu area in Inner Mongolia, China by the Sino-Canadian Dinosaur Project, is described and assigned to a new genus of protoceratopsid dinosaur, Magnirostris dodsoni gen. et sp. nov. This new taxon is distinguished from other protoceratopsids by the robust rostral bone and the existence of incipient orbital horn cores. The existence of an additional antorbital fenestra indicates a close relationship between Magnirostris and Bagaceratops.展开更多
文摘REE-fluorocarbonates as major REE minerals in the Bayan Obo deposit, the largestREE deposit in the world, were analyzed for their stable isotopic compositions. The δ13C andδ18O values of huanghoite, cebaite and bastnaesite from late-stage veins vary in the ranges of -7. 8 - - 4. 0‰ and 6. 7 - 9. 4‰ respectively. These data are relatively similar tO those ofbastnaesites from banded ores: δ13C - 5. 6 - - 5. 2‰ and δ18O 3. 6 - 5. 5‰ The REEfluorocarbonates from both late-stage veins and banded ores are characterized by lower δ13C andδ18O values, especially the δ18O values of bastnaesites from banded ores. Compared with them,the disseminated bastnaesits the dolomite-type ores possess rather high δ13C and δ18O values, i.e., - 2. 1 - - O. 4‰ and 8. 6 - 12. 9‰ respectively. The high values are typical of thesedimentary host dolomite rocks as well as of the dolomite-type ores. The carbon and oxygenisotopic characteristics of REE fluorocarbonate minerals provide new evidence for the hypothesison the origin of Bayan Obo deposit-epigenetic hydrothermal metasomatism.
文摘An almost complete skull, which was collected from the Upper Cretaceous of the Bayan Mandahu area in Inner Mongolia, China by the Sino-Canadian Dinosaur Project, is described and assigned to a new genus of protoceratopsid dinosaur, Magnirostris dodsoni gen. et sp. nov. This new taxon is distinguished from other protoceratopsids by the robust rostral bone and the existence of incipient orbital horn cores. The existence of an additional antorbital fenestra indicates a close relationship between Magnirostris and Bagaceratops.
