新疆阿尔泰地区辉腾花岗岩体年代学、地球化学特征及构造意义

发布时间：2018-06-21 13:12

本文选题：阿尔泰造山带 + 辉腾花岗岩体　；参考：《岩石学报》2017年10期

【摘要】：中阿尔泰构造带出露大面积晚三叠世花岗岩,对其进行详细的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。本研究对侵入于中元古界苏普特岩群的辉腾花岗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。研究结果显示,辉腾花岗岩体主要岩石类型有似斑状碱长花岗岩、似斑状正长花岗岩和似斑状二长花岗岩。LA-ICP-MS锆石U-Pb年代学研究结果表明,其形成时代为202.3±2.2Ma(MSWD=0.81),为晚三叠世。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,富集Cs、Rb、Th、La、Ce、Nd等元素,亏损Ba、Sr、P、Ti等元素,显示出I-A型花岗岩的特征,具有负的εNd(t)(-1.2~-0.3)特征和较老的两阶段模式(t2DM)年龄(1.04~1.08Ga)。综合分析认为,该岩体为富含黑云母的变泥质岩和少量变杂砂岩在低压、高温条件下脱水熔融形成,源区有富钙斜长石、钛铁矿和磷灰石的残留,同时幔源物质有少量混入,是阿尔泰造山带板内构造演化阶段的产物。
[Abstract]:A large area of late Triassic granites emerged from the Middle Altay tectonic belt and a detailed study of them is an important way to understand the tectonic evolution and continental crust accretion process of the Altai orogenic belt. In this study, detailed petrology, zircon U-Pb geochronology, geochemistry and Sr-Nd isotopic studies of the pyroxenite intruded into the Supute group of the Middle Proterozoic have been carried out. The results show that the main rock types of the feldsphalite are porphyry feldspar granite, porphyry syenite granite and porphyry monzomorphic granite. LA-ICP-MS zircon U-Pb chronology shows that the age of its formation is 202.3 卤2.2 Mai MSWDN 0.81, which is the late Triassic. The rocks have the characteristics of high SiO2Al2O3ALK, low TiO2MnOOMgOP2O5, light rare earth enrichment, obvious fractionation of heavy and heavy rare earths, negative EU anomalies, enrichment of elements such as Cslr RbTH, LaTiCe ND, and depletion of BaSrPTi, etc., which show the characteristics of I-A type granites. It has the characteristics of negative 蔚 Ndndndndltchus (-1.2) -0.3) and the older two-stage model (t _ 2DM) with a 1.04 ~ 1.08Ga ~ (2 +) age. The comprehensive analysis shows that the rock mass is rich in biotite, argillaceous rock and a small amount of mixed sandstone are dehydrated and melted under low pressure and high temperature, and the source area is rich in calcium plagioclase, the residue of ilmenite and apatite, at the same time, there is a small amount of mantle source material mixed in. It is the product of the intraplate tectonic evolution stage of the Altai orogenic belt.
【作者单位】：长安大学地球科学与资源学院;西部矿产资源与地质工程教育部重点实验室;中国人民武装警察部队黄金第八支队;
【基金】：国家自然科学基金项目(41502191、41472191、41602229) 中央高校基本科研业务费专项资金项目(310827161002、310827161010) 中国地质调查局地质调查项目(12120113071900、12120115041301)联合资助
【分类号】：P588.121

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