[Objective]The Bayan Obo deposit in Inner Mongolia is a rare superlarge REE-Nb-Fe polymetallic de-posit worldwide.There are still controversies on the timing of REE mineralization in the deposit due to the complex geological evolution in the region.[Methods]Based on previous isotopic dating results,in combination with geo-logical characteristics of the deposit,this paper re-evaluates potentially multiple episodes of REE mineralization.[Results]The Bayan Obo deposit has experienced the Precambrian tectonic evolution of the North China Craton between 2.5-1.8 Ga.The major REE mineralization was formed in the Bayan Obo rift at～1.3 Ga during the final stage of the breakup of the Columbia supercontinent,coeval with carbonate dike in the region.Hydrothermal meta-somatism or overprints occurred throughout the Bayan Obo area,which is related to the late Paleo-Asian Ocean sub-duction-collision orogeny in the northern margin of the North China Craton,producing the late REE veins and re-crystallization of original REE minerals.Such a hydrothermal modification event has variably disturbed the isotopic system of the H8 ore-bearing dolomite,resulting in multiple periods of isotopic ages(1.0-0.2 Ga)with peaks at 440 Ma and 270 Ma.[Conclusion]In summary,the Bayan Obo deposit primarily formed from the～1.3 Ga rift metallogenic event,superposed by Caledonian and Hercynian tectonothermal events.
关键词
白云鄂博矿床/同位素年龄/稀土成矿时代/华北克拉通
Key words
Bayan Obo deposit/isotopic age/rare earth metallogenic epoch/North China Craton
维普
万方数据