| 1 | Adakite-type sodium-rich rocks in Awulale Mountain of west Tianshan:Significance for the vertical growth of continental crust显示文摘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 | XIONG Xiaolin ZHAO Zhenhua BAI Zhenghua MEI Houjun WANG Yixian WANG Qiang XU Jifeng Niu Hecai BAO Zhiwei | 2001 | Chinese Science Bulletin2001，46，10： | 25 |
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