三江中段Dupal同位素异常的识别及其意义  

RECOGNITION AND SIGNIFICANCE OF DUPAL ISOTOPE ANOMALY IN THE MIDDLE PART OF SANJIANG AREA

作　　者：魏启荣[1] 沈上越[2] 莫宣学[2] 路凤香[2] 

机构地区：[1]中国科学院广州地球化学研究所,广东广州510640 [2]中国地质大学,湖北武汉430074

出　　处：《地质地球化学》2003年第1期36-41,共6页Geology-Geochemistry

基　　金：中国博士后科学基金;国土资源部"九五"科技攻关项目 ( 95 0 2 0 0 1 0 2 ) ;国家科委"九五"科技攻关项目 ( 96 914 0 1 0 3)

摘　　要：玄武岩的Sr Pb同位素示踪表明 ,古特提斯时期 (D -T)三江中段普遍存在Dupal异常 ,其同位素指标为 :△2 0 7Pb/2 0 4 Pb>7,最高可达 3 4 ;△2 0 8Pb/2 0 4 Pb >5 2 ,最高可达 87;△Sr>3 9,最高可达 79。Nd Sr Pb同位素体系示踪表明 ,三江中段Dupal异常源于EM2地幔源区。Dupal异常的存在说明 ,自古特提斯时期以来 。Sr-Nd isotopic tracing shows that there widely exists Dupal anomaly in the middle part of Sanjiang, with the isotope ratios being △ 207Pb/ 204Pb>7,higher than 34,△ 208Pb/ 204Pb>52, higher than 87, and △Sr>39, higher than 79, in the paleo-Tethyan period (D-T). Meanwhile, Nd-Sr-Pb isotopic characteristics also suggest the Dupal anomaly resulted from EM2. The Dupal anomaly in the middle part of Sanjiang indicates, therefore, it has shifted northwards for several thousands of kilometers since the paleo-Tethyan period.

关 键 词：同位素 玄武岩 古特提斯 三江地区 火山作用 成矿作用 

分 类 号：P588.145[天文地球—岩石学]