西藏东巧地区玄武岩地球化学特征及构造环境分析  

Geochemical signatures and tectonic setting of the basalts from the Dongqiao region,Xizang

作　　者：黄强太[1,2] 夏斌[1,3] 李强[3] 钟云[3] 胡西冲[3] 郑浩[3] 

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]中国科学院大学,北京100049 [3]中山大学海洋学院,广东广州510275

出　　处：《沉积与特提斯地质》2015年第2期97-103,共7页Sedimentary Geology and Tethyan Geology

摘　　要：东巧蛇绿岩出露于班公湖-怒江缝合带中段，是蛇绿岩组合单元出露较完整的地区。微量（稀土）元素分析结果表明，蛇绿岩中的玄武岩具有轻稀土元素（LREE）显著富集的右倾稀土元素配分模式。（La／Yb）。=7．05—12．02，Th、Nb、Ta、Zr和Hf略具有正异常的微量元素组成特征，属于典型的洋岛玄武岩（OIB），与洋中脊玄武岩（MORB）和板块汇聚环境下的岛弧玄武岩（IAB）存在明显差异。通过对其构造环境的判别，并结合蛇绿岩与相邻地质体的关系分析，认为东巧蛇绿岩中的玄武岩形成于大洋板内岩石圈上隆减压的洋岛环境，代表班公湖-怒江洋盆形成和发展阶段洋岛环境的大洋岩石圈残片。The Dongqiao ophiolites crop which the ophiolites are well preserved. out mostly in the central part of the The trace and rare earth element Bangong Lake-Nujiang suture zone, in analyses show that the basalts in the Dongqiao ophiolites display the noticeably LREE-enriched right-leaning REE distribution patterns. La/YbN = 7.05 -12.02. The elements Th, Nb, Ta, Zr and Hf exhibit slightly positive anomalies. The geochemical signatures cited above have disclosed that these basahs are assigned to the oceanic-island basalts（ OIB）, and remarkably vary from the mid-oceanic ridge basahs （MORB）and island-arc basahs （IAB）. The basahs in the Dongqiao ophiolites are interpreted to be formed in the oceanic-island environments where the lithospheric up oceanic plates, and represent the oceanic lithospheric remnants in the oceanic-island formation and development of the Bangong Lake-Nujiang oceanic basin. lifting took place in the enviroments during the

关 键 词：地球化学 构造环境 玄武岩 东巧 西藏 

分 类 号：P588.124[天文地球—岩石学]