东天山雅满苏火山弧石炭纪火山岩地球化学特征及其构造环境探讨

发布时间：2018-05-04 20:36

本文选题：雅满苏火山弧 + 地球化学特征　；参考：《新疆大学》2015年硕士论文

【摘要】：觉罗塔格造山带内出露了大量不同构造环境的石炭纪火山岩,其地球化学特征对于探讨觉罗塔格的构造环境演化具有重要意义。本文对雅满苏火山弧带早石炭世雅满苏组和晚石炭世土古土布拉克组的火山岩进行了主量元素、微量元素和Sr-Nd同位素特征研究。研究显示雅满苏火山弧带火山岩富集轻稀土元素和Ba、Th、U、Sr等大离子亲石元素,亏损重稀土元素和Ta、Nb、P、Ti等高场强元素,结合主量元素高Al2O3、低MgO、TiO2和微量元素La/Sm、Ba/La比值的指示意义,说明其具有俯冲带岛弧火山岩的地球化学特征。Sr-Nd同位素表明其母岩浆来源于受交代的富集岩石圈地幔楔,同时显示类似亏损的MORB特征,这是中亚造山带许多岩浆岩的共同特性。结合区域地质背景研究成果,认为雅满苏火山弧为石炭纪初期逐渐成型的海相不成熟岛弧,在晚石炭世逐渐演化为陆相较成熟的岛弧,揭示其海陆演化的构造环境,并根据火山岩时空分布特征,说明雅满苏岛弧带是形成于晚古生代吐哈大洋俯冲阶段和岛弧体系碰撞拼接阶段的产物。同时,这种时空展布与岩浆活动特征揭示出石炭纪南带地壳从老到新、自北向南逐渐增厚的特征,为吐哈古大洋在石炭纪时期向南俯冲的极性提供了极其重要的证据。
[Abstract]:A large number of Carboniferous volcanic rocks with different tectonic environments have been exposed in the jagrotg orogenic belt. The geochemical characteristics of the volcanic rocks are of great significance to the evolution of the tectonic environment of jagrotagg. In this paper, the main elements and trace elements of the volcanic rocks of the Early Carboniferous and Late Carboniferous soil Braque group in the jagunsu volcanic arc zone were carried out. The study shows that the volcanic rocks of the volcanic arc zone of the Joman Suo volcanic arc zone are enriched with light rare earth elements, such as Ba, Th, U, Sr and other large ionic stone elements, and the heavy rare earth elements and Ta, Nb, P, Ti and other high field elements are depleted, and the directive significance of the ratio of major elements, Al2O3, low MgO, TiO2 and trace elements, is combined with the subduction zone. The geochemical characteristics of.Sr-Nd isotopes of the island arc volcanic rocks indicate that their parent magma originated from the metasomatic enriched lithospheric mantle wedge and also showed a similar loss of MORB characteristics. This is the common characteristic of many magmatic rocks in the Central Asian orogenic belt. The marine immature island arc gradually evolved into a more mature island arc in the Late Carboniferous, revealing the tectonic environment of the evolution of sea and land, and according to the characteristics of the space-time distribution of volcanic rocks, that the jacousu island arc zone is the product of the collision stage of the late Paleozoic Tuha oceanic subduction stage and the island arc system. The characteristics of the pulp activity revealed that the crustal crust of the Carboniferous southern zone from the old to the new and gradually thickened from north to South provided a very important evidence for the polarity of the puthago ocean to subduction to the South during the Carboniferous period.

【学位授予单位】：新疆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P588.14

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