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研究了东天山企鹅山群火山岩的主量元素、微量元素和Sr-Nd同位素特征。结果显示:火山岩Si O2含量介于47.75%~57.78%,Al2O3含量为17.92%~19.88%,Mg O含量为3.96%~6.46%,Mg#值介于52.16~58.20,属于亚碱性系列;微量元素分析表明,火山岩轻稀土元素(LREE)富集、重稀土元素(HREE)相对亏损、轻重稀土元素分馏较强,富集大离子亲石元素(LILE),而亏损高场强元素。Sr-Nd同位素组成表明,火山岩ISr(t)变化范围为0.702 386~0.704 264,εNd(t)变化范围为5.61~8.66。地球化学研究表明,企鹅山群火山岩可能源于长期亏损的地幔,而且含有洋中脊和火山弧的物质成分,是软流圈地幔熔体和被俯冲板片流体/熔体交代过的岩石圈地幔楔熔体的混合物。企鹅山群火山岩的母体可能形成于不同的时期和不同的大地构造位置,是板块碰撞后洋脊和火山弧物质在一狭长地带上的混杂堆积。结合前人研究成果,认为企鹅山群火山岩属于古亚洲洋南缘洋壳向北俯冲消减作用的产物,这为古亚洲洋南缘古生代构造演化研究提供了约束。
The main elements, trace elements and Sr-Nd isotopic characteristics of volcanic rocks in Pengushan Group of East Tianshan Mountains were studied. The results show that the content of Si O2 in volcanic rocks ranges from 47.75% to 57.78%, the content of Al2O3 is 17.92% ~ 19.88%, the content of MgO is 3.96% ~ 6.46%, and the value of Mg # is 52.16 ~ 58.20, Elemental analysis shows that LREE is enriched in volcanic rocks, and relatively depleted in heavy rare earth elements (HREEs). The fraction of light and heavy rare earth elements is enriched, enriched in LILE and depleted in high field strength elements. The Sr-Nd isotopic composition shows that ISr (t) of volcanic rocks varies from 0.702 386 to 0.704 264, and εNd (t) ranges from 5.61 to 8.66. Geochemical studies indicate that Penguishan group volcanic rocks may be derived from long-term depleted mantle, and the material composition of mid-ocean ridges and volcanic arcs is composed of asthenospheric mantle melt and lithosphere that has been replaced by subducted slab fluid / melt Mantle wedge melt mixture. The parent body of Penguin mountain group volcanic rocks may form at different times and in different tectonic positions, which is the mixed accumulation of ocean ridge and volcanic arc material in a long strip after plate collision. Based on the results of previous studies, it is considered that Penguashan group volcanic rocks belong to the product of northward subduction of the oceanic crust in the southern margin of the ancient Asian continent, which provides a constraint for the study of the Paleozoic tectonic evolution in the southern margin of the Paleo-Asian Ocean.