Adakite-type sodium-rich rocks in Awulale Mountain of west Tianshan:Significance for the vertical growth of continental crust

作     者：XIONG Xiaolin ZHAO Zhenhua BAI Zhenghua MEI Houjun WANG Yixian WANG Qiang XU Jifeng Niu Hecai BAO Zhiwei 

作者机构：Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China State Key Laboratory of Mineral Deposit Research of Nanjing UniversityNanjing 210093China 

出 版 物：《Chinese Science Bulletin》 (中国科学通报)

年 卷 期：2001年第46卷第10期

页      面：811-817页

核心收录：

学科分类：070902[理学-地球化学] 0709[理学-地质学] 07[理学] 

基　　金：This workwas co-supported by the State Major Basic Research Program of China (Grant No. G1999043200) the State "305" Program of China (Grant No. 96-915-03-02) the Chinese Academy of Sciences (Grant No. KZCX2-102) the State Climbing Program of Chi 

主　　题：Awulale adakite-type rocks underplating vertical growth of continental crust. 

摘      要：The sodium-rich dacites and albite porphyries of Permian in the Awulale Mountain of west Tianshan have unique chemical and trace element signatures identical to adakite. These intermediate-acidic igneous rocks are characterized by high Na2O, Al2O3 and Sr contents and high Sr/Y and La/Y ratios (40 and 20, respectively), and low Y and Yb contents, and strong depletion in HREE, and positive Eu anomaly. The (143Nd/144Nd)i is in the range from0.51236 to 0.51248 and the εNd(t) is positive value (+0.79-+3.11); the (87Sr/86Sr)i is in the range from 0.7052 to 0.7054. These Nd and Sr isotopic composition features indicate that the source rocks of these adakite-type rocks are from a weakly depleted mantle, or a depleted mantle, but was contaminated by the crustal materials. These adakite-type rocks were most likely derived from the partial melting of new underplated basaltic rocks under the conditions of amphibo-lite to eclogite transition in the postcollisional environment of North Xinjiang during the Permian