扬子克拉通东北缘岩石圈地幔的Re-Os同位素地球化学:大陆岩石圈地幔的形成和演化的制约  

Re-Os Isotope Geochemistry of Lithospheric Mantle Beneath Northeastern Yangtze Craton: Constraint on the Origin and Evolution of Continental Lithospheric Mantle

作　　者：支霞臣[1] L.Reisberg 彭子成[1] 余春江[1] 

机构地区：[1]中国科学技术大学地球和空间科学系,安徽合肥230026 [2]法国国家科学研究中心(CNRS)南锡岩石学和地球化学研究中心(CRPG)

出　　处：《矿物岩石地球化学通报》2001年第4期248-250,共3页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金资助项目 ( 4 98730 0 5 )

摘　　要：苏皖地区新生代碱性玄武岩中有丰富的地幔橄榄岩捕虏体 ,测定了 2 0多个样品的Re Os元素丰度和锇同位素组成 ,结果 :Re =0 .0 2 7× 10 - 9～ 0 .375×10 - 9,Os=0 .112×10 - 9～ 3.35× 10 - 9,1 87Os 1 88Os=0 .117～ 0 .134。由代理等时线法1 87Os 1 88Os Yb获得该区岩石圈地幔早期熔体亏损事件的年龄为 1.7Ga(中元古代 )。苏皖地区岩石圈地幔的古老性表明它是元古代后岩石圈拆沉 减薄作用的残余地幔部分。岩石圈地幔经过了亏损 富集多阶段演化。The abundances of Re and Os and the isotopic compositions of Os are reported here, for more than 20 samples of mantle peridotite xenolith from Jiangsu-Anhui basaltic province. The concentration ranges of Re and Os are (0.027-0.375)×10 -9 and (0.112-3.35)×10 -9respectively and the Os isotopic composition range is 0.117-0.134. The early melt depletion age of the lithospheric mantle beneath the Northeastern Yangtze Craton is 1.7*!Ga, from the proxy isochron of 187Os/ 188Os vs. Yb. This evidence suggests that the present lithospheric mantle beneath the area is the relic part after the lithosphere thinning in the Post-Middle Proterozoic. The lithospheric mantle has multistage evolution of depletion and enrichment. It also suggests that there may occur a lithosphere mantle replacement in Eastern China during Pre-Middle Proterozoic.

关 键 词：RE-OS同位素体系 岩石圈地幔 橄榄岩捕虏体 扬子克拉通 

分 类 号：P597[天文地球—地球化学]