作　　者： ; ; (周国庆）; (王冉）;

机构地区： 中国科学院广州地球化学研究所

出　　处： 《大地构造与成矿学》 2004年第3期270-278,共9页

摘　　要： 泽当蛇绿岩位于雅鲁藏布江蛇绿岩带东段 ,对其壳层火山熔岩的研究表明 ,该熔岩属亚碱性玄武岩 ,岩石化学上表现为低Si、Mg ,高Al、Na的特征 ;稀土分布型式表现为LREE微富集 ,HREE平缓 ,不具有Eu负异常 ;Nb、Ta、Zr、Hf等高场强元素较为富集 ,反映出泽当蛇绿岩的形成并未受到俯冲作用的影响。通过对其构造环境的判别 ,得出泽当蛇绿岩形成于边缘洋盆环境 ,由于印度板块向北推进 ,使边缘海盆俯冲消亡 ,而蛇绿岩被构造侵位到如今的位置上。 The Zedang ophiolite is located in the eastern segment of Yarluzangbu ophiolite belt. The research on Zedang ophiolite lava indicates that the lava belongs to the sub-alkaline basalts. It is characterized by low Si, Mg and high Al, Na; the REE pattern shows a faint LREE-enriched distribution without a Eu negative anomaly whereas the HREE distribution pattern is nearly flat, which demonstrates the characteristics of E-MORB; The enrichment of the HFS elements such as Nb,Ta,Zr,Hf suggests that the forming environment of Zedang ophiolite is not related to plate subduction. Through the discrimination of its constructive environment, we conclude that the Zedang ophiolite formed in a marginal ocean basin. With the northward advance of the Indian plate, the marginal ocean basin was eliminated and the ophiolite was emplaced into the region we see now.

关 键 词： 蛇绿岩 西藏 泽当 边缘洋盆

领　　域： [天文地球] [天文地球] [天文地球] [天文地球]