| 西藏雅鲁藏布江缝合带西段东波蛇绿岩的构造背景特征 |
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| 关键词:OIB basalt mid-ocean ridge Dongbo ophiolite Yarlung Zangbo Suture |
| 基金项目:国家专项“深部探测技术与实验研究”(编号: SinoProbe-05-02);国家自然科学基金重点项目(编号: 40930313);国家自然科学基金创新群体项目(编号: 40921001);国家自然科学基金项目(编号: 41202036);中国地质调查局国土资源大调查项目(编号: 1212011121263; 12120114061801) |
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| Tectonic Setting of Dongbo Ophiolite in the Western Portion of the Yarlung Zangbo Suture Zone, Tibet |
| Located in the western part of the Yarlung Zangbo Suture Zone (YZSZ) of southern Tibet, the Dongbo ophiolite is composed of mantle peridotite, pyroxenite, gabbro and some other kinds of rocks, with harzburgite, dunite and a small amount of lherzolite constituting dominant lithologies. Basalts and siliceous rocks were found at the edge of the mantle tectonites. Occasionally, a small amount of pyroxenite and gabbro dikes with a width of about one meter crosscut the mantle tectonites in NW direction, which resembles the tectonic line of mantle tectonites. Geochemical characteristics of the different lithofacies in Dongbo ophiolite show remarkable differences, and geochemical characteristics of basalt are similar to features of ocean island basalt (OIB); however, pyroxenite and gabbro dikes in the peridotite are similar to MORB in geochemical characteristics, suggesting that they were derived from mid-ocean ridge (MOR) but affected by the subduction fluids at the second stage. The lherzolite in Dongbo ophiolite is consistent with the abyssal peridotite in the feature of LREE depletion; however, geochemical characteristics of harzburgite and dunite show that they were formed at the mid-ocean ridge (MOR) and reformed in a subduction zone setting. The lithogeochemical characteristics of Dongbo ophiolite indicate a tectonic setting of ocean island overlaid with ocean ridge. |
| XIONG Fa-hui,YANG Jing-sui,LI Yuan,LIU Zhao,GUO Guo-lin,ZHOU Wen-da,CHEN Song-yong,LI Yi-bing,XU Xiang-zhen,NIU Xiao-lu.2015.Tectonic Setting of Dongbo Ophiolite in the Western Portion of the Yarlung Zangbo Suture Zone, Tibet[J].Acta Geoscientica Sinica,36(1):31-40. |
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