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| Geochemistry and Sr-Nd isotope characteristics of tonalites in Zêtang,Tibet:New evidence for intra-Tethyan subduction | |
| 作者姓名： | WEI DongLiang XIA Bin ZHOU GuoQing YAN Jun WANG Ran & ZHONG LiFeng Key Laboratory of Marginal Sea Geology Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China Graduate University of Chinese Academy of Sciences Beijing China |
| 作者单位： | WEI DongLiang1，2，XIA Bin1，ZHOU GuoQing1，3，YAN Jun1，WANG Ran1，2 & ZHONG LiFeng1，2 1 Key Laboratory of Marginal Sea Geology，Guangzhou Institute of Geochemistry，Chinese Academy of Sciences，Guangzhou 510640，China; 2 Graduate University of Chinese Academy of Sciences，Beijing 100049，China; 3 Department of Earth Sciences，Nanjing University，Nanjing 210093，China |
| 基金项目： | the National Natural Science Key Foundation of China (Grant No. 40534019)，Open Research Fund Program of Key Laboratory of Marginal Sea Ge-ology of the Chinese Academy of Sciences (Grant No. MSGL-04-13)，the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KZCXZ-SW-117) |
| 摘 要： | Tonalites from the island arc rock assemblage in the Zêtang segment of the Yarlung Zangbo suture zone were analyzed for major,trace elements (including REE) and Sr-Nd isotope. The experimental data demonstrate that the tonalites have the adakite-like characteristics,including high SiO2 (58%―63%),Al2O3 (18.4%―22.4%),Sr (810×10 6―940×10 6),Sr/Y (77―106),low HREE (Y=9×10 6―11×10 6,Yb= 1×10 6―1.3×10 6),with LREE enrichment and faint Eu positive anomaly. ISr (0.70421―0.70487) is rela-tively low whereas 143Nd/144Nd (0.512896―0.512929) and εNd(t) values ( 6.7― 7.3) are high. These fea-tures suggest that Zêtang tonalites were formed by the partial melting of subducted oceanic crust,with involvement of a small amount of oceanic sediments. The identification of Zêtang adakites,derived from slab melting,presents new evidence for the intra-Tethyan subduction and the previous sugges-tion about the existence of intra-oceanic island arc within Tethys. |
| 关 键 词： | adakite Zêtang tonalites subduction Yarlung Zangbo suture zone Tibet |
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