ZHANG ZongQing,TANG SuoHan,YUAN ZhongXin,BAI Ge and WANG JinHui,1. Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China2. Institute of Mineral and Resources,Chinese Academy of Geological Sciences,Beijing 100037,China. The Sm-Nd and Rb-Sr isotopic systems of the dolomites in the Bayan Obo deposit,Inner Mongolia, China[J]. Acta Petrologica Sinica, 2001, 17(4): 637-642. Citation: ZHANG ZongQing,TANG SuoHan,YUAN ZhongXin,BAI Ge and WANG JinHui,1. Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China2. Institute of Mineral and Resources,Chinese Academy of Geological Sciences,Beijing 100037,China. The Sm-Nd and Rb-Sr isotopic systems of the dolomites in the Bayan Obo deposit,Inner Mongolia, China[J]. Acta Petrologica Sinica , 2001, 17(4): 637-642. 白云鄂博矿床的年龄和成因长期争论.本文报道了白云鄂博矿床白云岩及其组成矿物的Sm-Nd、Rb-Sr同位素分析结果.采自该矿床主、东矿等地的15个白云岩样品的Sm-Nd同位素分析结果呈现一条等时线,等时年龄1273±100(2σ)Ma,INd=0.510919士36(2d),MSWD1.01.全岩Rb-Sr同位素分析结果分散,不构成等时线.87Rb/86Sr0～2.092×100-2,87Sr/86Sr0.70341～0.70541.白云岩矿物的Sm-Nd同位素分析结果给予了与全岩类似的Sm-Nd等时年龄,t=1250士210(2σ)Ma,1Nd=0.510914±77(2σ),MSWD0.56.白云鄂博矿床可能是中元古代末期大离子亲石微量元素略为富集地幔源区部分熔融岩浆活动产物. 同位素地质年代学 白云鄂博矿床 钐－钕同位素 铷－锶同位素