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对东天山沿康古尔塔格缝合带分布的企鹅山群和梧桐窝子组火山岩的地球化学特征及Rb-Sr和Sm-Nd同位素进行了系统研究。结果显示:企鹅山群火山岩富集LREE,Eu异常变化较大(从明显负异常到微弱正异常),富集Sr、Ba和U等大离子亲石元素,相对亏损Nb、Zr、Ti等高场强元素,Sr-Nd同位素特征是ISr=0.703 97～0.704 26,εNd(t)=5.61～6.99,具有亏损地幔性质,表明其岩浆源区可能来自古生代期间被古亚洲洋俯冲板片释放的流体/熔体交代过的岩石圈地幔楔;梧桐窝子组玄武岩富集轻稀土元素(LREE)和大离子亲石元素,而高场强元素没有明显负异常,样品的εNd值都在9以上,ISr(330 Ma)为0.704 71～0.705 33,表明梧桐窝子组玄武岩可能来自亏损的软流圈地幔的部分熔融。企鹅山群和梧桐窝子组火山岩在Zr-Zr/Y判别图解中分别落在岛弧拉斑玄武岩(IAB)和板内玄武岩(WPB)范围内,表明企鹅山群可能为准噶尔洋盆向南俯冲形成的石炭纪岛弧火山岩,而梧桐窝子组火山岩可能形成于在弧后盆地的基础上拉张为裂陷槽的伸展环境。
The geochemical characteristics and Rb-Sr and Sm-Nd isotopes of volcanic rocks of Penguashan Group and Wutongwozi Group distributed along Kangkurtag suture zone in eastern Tianshan Mountains are systematically studied. The results show that the enrichment of LREE and Eu in volcanic rocks of Penguin Group is large (from obvious negative anomalies to weak positive anomalies), enrichment of large ion lithophile elements such as Sr, Ba and U, relative depletion of Nb, Zr and Ti The Sr-Nd isotopes are characterized by ISr = 0.703 97 ~ 0.704 26 and εNd (t) = 5.61 ~ 6.99, indicating a depleted mantle property, indicating that the magmatic source may be derived from the subducted slab of the Paleozoic during the Paleozoic. Fluid / melt metamorphic lithospheric mantle wedge. The Wutongwozi basalt is enriched in both LREE and LILE, while the high field strength elements have no obvious negative anomalies. The εNd values of samples are above 9 , And ISr (330 Ma) is 0.704 71 ~ 0.705 33, suggesting that the basalt of the Wutongwozi Formation may come from a partial melting of the depleted asthenosphere mantle. The penguins and Indus group volcanic rocks fall within the range of IAB and WPB in the Zr-Zr / Y discriminant scheme, respectively, indicating that the Penguin group may be southward of the Junggar basin The Carboniferous island arc volcanic rocks formed by the subduction are formed in the volcanic rocks of Wutongwozi Formation, which may be formed on the basis of the back-arc basins.