阿尔泰地区霍热木德克花岗岩体年代学、地球化学特征及构造意义

发布时间：2018-10-12 15:21

【摘要】：中阿尔泰构造带出露大面积晚三叠世花岗岩,对其进行详细研究是了解阿尔泰造山带构造演化和陆壳增生过程的重要途径。本文对霍热木德克岩体进行详细的岩石学、锆石U-Pb年代学、岩石地球化学及Sr-Nd同位素研究。霍热木德克花岗岩体主要有粗粒二长花岗岩、细粒二长花岗岩和正长花岗岩。LA-ICP-MS锆石U-Pb年代学研究结果表明,其结晶年龄为(222.3±1.8)Ma(MSWD=1.6),为晚三叠世岩浆活动产物。地球化学研究表明,岩石具有高SiO_2、Al_2O_3、ALK,低TiO_2、MnO、MgO、P_2O_5的特征,轻稀土富集、轻重稀土分馏明显,具有Eu的负异常(δEu=0.37~0.50),富集大离子亲石元素、相对亏损高场强元素,显示出强过铝质S型花岗岩的特征,花岗岩具有负的εNd(t)(-3.7~-2.7)和较老的二阶段模式(T2DM)年龄(1.2~1.3Ga)。综合分析认为,霍热木德克花岗岩由富含白云母和黑云母的变泥质岩经历部分熔融形成,其源区有富钙斜长石、钛铁矿的残留,为同碰撞造山阶段挤压环境下地壳加厚而发生部分熔融的产物,形成于同碰撞构造环境。
[Abstract]:It is an important way to understand the tectonic evolution and continental crust accretion process of the Altay orogenic belt in which a large area of late Triassic granites emerged from the Middle Altay tectonic belt. In this paper, detailed petrology, zircon U-Pb chronology, geochemistry and Sr-Nd isotopic studies were carried out on the Horemudek rock body. The LA-ICP-MS zircon U-Pb chronological study shows that its crystallization age is (222.3 卤1. 8) Ma (MSWD=1.6), which is the product of late Triassic magmatic activity. Geochemical studies show that the rocks have the characteristics of high SiO_2,Al_2O_3,ALK, and low TiO_2,MnO,MgO,P_2O_5, light rare earth enrichment, obvious fractionation of light and light rare earths, negative Eu anomaly (未 Eu=0.37~0.50), enrichment of large ion lithophile elements, and relative depletion of high field strength elements. The strong peraluminous S-type granite is characterized by a negative 蔚 Nd (t) (-3.7 ~ (-2.7) and an older two-stage model (T2DM) age (1.2~1.3Ga). The comprehensive analysis shows that the Huo Ximudek granite is formed by partial melting of the metamorphic argillite rich in Muscovite and biotite, and its source area is rich in calcareous plagioclase and remains of ilmenite. The product of partial melting of crust thickening in the squeezing environment during the same collision orogenic stage was formed in the same collision tectonic environment.
【作者单位】：中国地质大学地球科学与资源学院;中国人民武装警察部队黄金第八支队;长安大学地球科学与资源学院;
【基金】：中国地质调查局地质调查项目(12120113071900) 中央高校基本科研业务费资助项目(310827161002)
【分类号】：P588.121

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