济南和邹平辉长岩的Pb-Sr-Nd同位素特征和岩浆源区中下地壳物质贡献

济南和邹平辉长岩的Pb-Sr-Nd同位素特征和岩浆源区中下地壳物质贡献

李全忠1，2，谢　智1，陈江峰1，高天山2，喻　钢1，钱　卉1

1. 中国科学技术大学地球和空间科学学院，中科院壳幔物质与环境重点实验室，合肥 230026 2. 南京地质矿产研究所，南京 210016

收稿日期:2007-06-20 修回日期:2007-06-20 出版日期:2007-06-20 发布日期:2007-06-20

Pb-Sr-Nd Isotopic Characteristics of the Gabbros from Jinan and Zouping and the Contribution of the Lower Crust to the Magma Source

LI Quan-zhong1,2，XIE Zhi1，CHEN Jiang-feng1，GAO Tian-shan2, YU Gang1，QIAN Hui1

1. CAS Key Laboratory of Crust-Mantle Materials and Environments，School of Earth and Space Sciences，University of Science and Technology of China, Hefei 230026, China; 2. Nanjing Institute of Geology and Mineral Resource, Nanjing 210016, China

Received:2007-06-20 Revised:2007-06-20 Online:2007-06-20 Published:2007-06-20

摘要/Abstract

摘要： 对鲁西晚中生代济南和邹平辉长岩的Pb-Sr-Nd同位素和元素组成的研究，给出(87Sr/86Sr)i=0.7041~0.7056，εNd(t )=-6.0~-13.0，( 206Pb/204Pb)i=16.545~16.998，(207Pb/204Pb)i=15.242~15.350，(208Pb/204Pb)i=36.488~36.944（除SD792表现出高放射成因Pb外）。由于辉长岩的堆晶性质，其微量元素组成不能用于指示其物质来源。与EMⅠ型大洋和大陆玄武岩对比，表明济南和邹平辉长岩的源区具有与EMⅠ地幔端元一致的同位素特征，但在Pb同位素图解上有明显的下地壳物质的贡献。下地壳物质的参与可能与拆沉有关。

Abstract: Pb-Sr-Nd isotopic ratios and element compositions of the gabbros from Jinan and Zouping have been studied. We obtain that (87Sr/86Sr)i＝0.7041~0.7056，εNd(t )＝-6.0~-13.0，( 206Pb/204Pb)i = 16.545~16.998，(207Pb/204Pb)i = 15.242~15.350，(208Pb/204Pb)i = 36.488~36.944 (except for SD792 possessing highly radiogenic Pb isotopic characteristics) . Trace element characters are not indicative of the source of the gabbros because of their cumulate nature. A comparison with typical EMⅠtype oceanic and continental basalts suggests that the mantle source of the Jinan and Zouping gabbros shows an isotopic characteristics similar to that of the EMⅠmantle，but with a significant contribution of the lower crust based on Pb isotopic diagrams. The addition of the lower crust into the mantle may be related to the subduction of the Pacific Ocean Plate, which resulted in the lower crust delamination.

李全忠,谢　智，陈江峰，高天山，喻　钢，钱　卉. 济南和邹平辉长岩的Pb-Sr-Nd同位素特征和岩浆源区中下地壳物质贡献[J]. J4.

LI Quan-zhong1,2，XIE Zhi1，CHEN Jiang-feng1，GAO Tian-shan2, YU Gang1，QIAN Hui1. Pb-Sr-Nd Isotopic Characteristics of the Gabbros from Jinan and Zouping and the Contribution of the Lower Crust to the Magma Source[J]. J4.