印度洋亚丁-欧文-卡尔斯伯格脊三联点邻近洋脊的玄武岩地球化学特征及其地幔源区性质

摘要

本文研究了亚丁-欧文-卡尔斯伯格脊(A O C)三联点邻近洋脊的玄武岩样品在主量、微量元素和Pb-Sr-Nd同位素特征上的差异和联系并分析其原因.结果表明,AOC附近卡尔斯伯格脊和希巴洋脊的玄武岩均为正常型洋脊玄武岩(N-MORB),起源自亏损地幔,其中卡尔斯伯格脊的样品较希巴洋脊样品更亏损;欧文洋脊玄武岩样品为洋岛玄武岩(OIB)特征,其地幔源区可能有残余陆块物质的混染;亚丁洋脊玄武岩样品类型包括N-MORB、E-MORB和可能的大陆玄武岩,与洋壳形成过程中大陆岩石圈物质的贡献程度有关.除了卡尔斯伯格脊外,阿法热点对各洋脊的岩浆均有一定程度的影响.%The major and trace elements as well as Sr-Nd-Pb isotope compositions of basalt samples were studied ,which were obtained from the ridges adjacent to Aden-Owen-Carlsberg(AOC) Triple Junction .The results show that samples from Carlsberg Ridge are typical N-M ORB derived from DM M-type mantle source;samples from Sheba also belong to N-M ORB ,but the mantle source contains some EM II component and hence is more enriched than that of Carlsberg Ridge ;samples from Owen Ridge are OIB ,probably reflecting the contamination of continental crust ;the types of samples from Aden Ridge vary from N-M ORB ,E-M ORB and perhaps continental basalt which derived from the different extent mixture of end-members from DMM ,EMII and HIMU .Except for Carlsberg Ridge ,all of the other ridges adjacent to AOC have been influenced by Afar Hot Spot .