| 白云鄂博稀土超大型矿床的成矿时代及其主要地质热事件 |
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| 关键词:deposit Sm-Nd Th-Pb ￣(40)Ar/￣(39)Ar isochron age Bayan Obo |
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| STUDY ON HEAT EVENTS OF ORE-FORMING BAYAN OBO DEPOSIT |
| There are four ore-forming heat events in Bayan Obo deposit.(1)Proterozofic period;(2)LateProterozoic period;(3)Caledonian period;(4)Hercynian period;these events are determinated with radioisotope methods of whole-rock and minerals. The Middle Proterozoic age is based on the following data:the data of seven samples of early monazite and bastnaesite from main orebody form a Sm-Ndisochron line with isochron age of 1 312.5±41.24Ma and initial ￣(143)Nd/￣(144)Nd ratio(I_Nd)of 0.51092±13(2σ),corresponding to ε_Nd(t)=0.49±0.26.The heat plateau￣(40)Ar/￣(39)Ar age of one sample ofearly alkali amphibole from Dulahala carbonatite dyke is 1 288±11.94Ma,The late Proterozoic heatevent is determinated by Rb-Sr whole-rock isochron age and ￣(40)Ar/￣(39)A heat plateau age,The age ofRb-Sr whole-rock isochron of black slate is 749. 6±62.11 Ma and 685.9±24. 12Ma。The ￣(40)Ar/￣(39)Arheat plateau ages of three alkali amphiboles are 818±5Ma、720±20Ma and 719±2Ma. The Caledo-nian age is determinated by Th-Pb is ochron age of internal minerals and Sm-Nd isochron age of REEminerals.The Th-Pb internal isochron ages of monazites and bastnaesites are 550±4 00Ma and theSm-Nd isochron age of REE minerals are 402±18Ma、424±91Ma,with the initial ￣(143)Nd/￣(144)Nd ratioof 0. 51125、0.51128,corresponding to ε_Nd(t)=-16.9,ε_Nd(t)=-15.9.￣(40)Ar/￣(39)Ar plateau age oflate alkali amphibole is 380.4±2.1Ma,indicating also caledonian heat event.The Hercynian age is determinated by the K-Ar and Rb-Sr method of minerals and whole-rock. The REE mineralization of Bayan Obo ore deposite have two ore-forming stages. The first was Middle Proterozoic. The second was Caledonian period. |
| REN Ying-chen,ZHANG Ying-chen,ZHANG Zong-qing.1994.STUDY ON HEAT EVENTS OF ORE-FORMING BAYAN OBO DEPOSIT[J].Acta Geoscientica Sinica,15(1,2):95-101. |
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