| Geochemistry and Sr-Nd isotope characteristics of tonalites in Zêtang, Tibet: New evidence for intra-Tethyan subduction |
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| 作者单位： | WEI DongLiang（Key Laboratory of Marginal Sea Geology, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China;Graduate University of Chinese Academy of Sciences, Beijing 100049, China） ;
XIA Bin（Key Laboratory of Marginal Sea Geology, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China） ;
ZHOU GuoQing（Key Laboratory of Marginal Sea Geology, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China;Department of Earth Sciences, Nanjing University, Nanjing 210093, China） ;
YAN Jun（Key Laboratory of Marginal Sea Geology, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China） ;
WANG Ran（Key Laboratory of Marginal Sea Geology, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China;Graduate University of Chinese Academy of Sciences, Beijing 100049, China） ;
ZHONG LiFeng（Key Laboratory of Marginal Sea Geology, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China;Graduate University of Chinese Academy of Sciences, Beijing 100049, China） ; |
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| 基金项目： | Supported by the National Natural Science Key Foundation of China (Grant No.40534019), Open Research Fund Program of Key Laboratory of Marginal Sea Geology of the Chinese Academy of Sciences (Grant No. MSGL-04-13) and the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No.KZCXZ-SW- 117) |
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| 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 datademonstrate 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 relatively low whereas 143Nd/144Nd (0.512896-0.512929) and εNd(t) values ( 6.7- 7.3) are high. These feainvolvement of a small amount of oceanic sediments. The identification of Z(e)tang adakites, derived from slab melting, presents new evidence for the intra-Tethyan subduction and the previous suggestion about the existence of intra-oceanic island arc within Tethys.
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| 关 键 词： | adakite Zêtang tonalites subduction Yarlung Zangbo suture zone Tibet |
| 收稿时间： | 8 May 2006 |
| 修稿时间： | 17 July 2006 |
Geochemistry and Sr-Nd isotope characteristics of tonalites in Zêtang,Tibet: New evidence for intra-Tethyan subduction |
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| Authors: | Wei DongLiang Xia Bin Zhou GuoQing Yan Jun Wang Ran Zhong LiFeng |
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| Institution: | (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 |
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| Abstract: | 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. I
Sr (0.70421−0.70487) is relatively low whereas 143Nd/144Nd (0.512896−0.512929) and ɛ
Nd(t) values (+6.7–+7.3) are high. These features 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 suggestion about the existence of intra-oceanic
island arc within Tethys.
Supported by the National Natural Science Key Foundation of China (Grant No. 40534019), Open Research Fund Program of Key
Laboratory of Marginal Sea Geology of the Chinese Academy of Sciences (Grant No. MSGL-04-13) and the Knowledge Innovation
Program of the Chinese Academy of Sciences (Grant No. KZCXZ-SW-117) |
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| Keywords: | adakite Zêtang tonalites subduction Yarlung Zangbo suture zone Tibet |
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