阿尔泰地区变质带中淡色花岗岩脉体研究

发布时间：2018-01-26 16:09

本文关键词： 淡色花岗岩脉体岩相学地球化学 U-Pb年代学阿尔泰造山带　出处：《中国地质大学(北京)》2016年硕士论文　论文类型：学位论文

【摘要】：中国阿尔泰地区位于中亚造山带的西南缘,广泛发育花岗岩与花岗片麻岩。在变质带中常可见淡色花岗岩脉体分布。淡色花岗岩的化学成分以及时代对讨论淡色花岗岩的成因以及区域地质演化具有重要意义。本文通过对区内高级变质带中的淡色花岗岩脉体的岩石学、地球化学以及锆石年代学等进行分析,取得的主要认识为:(1)淡色花岗岩脉体主要发育于变质程度较高的夕线石带中,脉体岩石类型主要包括无片理化的石榴石白云母英云闪长岩、石榴石二云母英云闪长岩、二云母二长花岗岩、石榴石二云母二长花岗岩、石榴石白云母二长花岗岩、二云母正长花岗岩、石榴石二云母碱性长石花岗岩;片理化石榴石白云母英云闪长岩、石榴石二云母英云闪长岩、夕线石石榴石二云母英云闪长岩、电气石石榴石二云母二长花岗岩、石榴石白云母正长花岗岩。(2)岩相学特征与地球化学特征均表明阿尔泰高级变质带中的淡色花岗岩脉体主要为过铝质S型花岗岩。主量元素显示富硅,富铝,贫铁、镁,A/CNK=1.00~2.16。微量元素显示无片理淡色花岗岩脉体富集Cs、Rb、K、Zr、Sn,亏损Ba、Nb、Eu、Ti,P元素在石榴石白云母英云闪长岩中富集,石榴石二云母二长花岗岩中亏损。片理化淡色花岗岩脉体均富集Cs、Rb、W、U、K、P、Zr,亏损Ba、Nb、Eu、Sr、Ti。总体上稀土含量较低,样品轻重稀土分馏多不明显;多数样品可见明显的Eu(δEu=0.09~0.59)的负异常,少数的样品可见明显的Eu(δEu=1.64~4.90)的正异常。(3)阿尔泰高级变质带中的淡色花岗岩脉体主要形成于三叠纪(197±12~254.9±5.6Ma),可能分多期次形成,(1)~254 Ma,(2)230~233 Ma,(3)216~223 Ma,(4)197~204 Ma。其中二长花岗岩与正长花岗岩的形成年代早于英云闪长岩与碱性长石花岗岩。
[Abstract]:The Altai area of China is located in the southwest margin of the Central Asian orogenic belt. Granite and granitic gneiss are widely developed. The distribution of pale granite veins is often seen in metamorphic zones. The chemical composition and age of pale granite are of great significance to discuss the genesis and regional geological evolution of pale granite. This paper deals with the petrology of the pinkish granite vein in the high grade metamorphic belt in this area. Geochemistry and zircon chronology are analyzed. The main understanding is that the pallor granite vein is mainly developed in the higher metamorphic sillimanite belt. The main types of vein rocks include garnet phlogopite diorite, garnet diorite, monomorphite monzogranite and garnet monomorphite monzogranite. Garnet Muscovite monzogranite, monomorphite syenite granite, garnet dimica alkaline feldspar granite; Schistatic garnet Muscovite diorite, garnet diorite, siliite garnet, tourmaline garnet diorite, tourmaline garnet diorite. The petrographic and geochemical characteristics of garnet Muscovite syenite granite show that the pinkish granite vein in the Altai high grade metamorphic belt is mainly peraluminous S-type granite. Aluminum-rich, iron-poor, mg ~ (2 +) A / CNK _ (1.00) ~ (2.16). Trace elements show that the grain-free pinkish granite veins are rich in Csln RbCK ~ (2 +) Zr ~ (2 +) Sn, and depleted in Ba-Nb ~ (2 +) EU ~ (+) Ti. P element is enriched in garnet Muscovite quartz diorite and depleted in garnet dimica monzodiorite. Generally speaking, the content of rare earth is low, and the fractionation of light and heavy rare earth is not obvious. Negative anomalies of EU (未 Eu0.09 ~ 0.59) can be seen in most of the samples. A few samples show obvious positive anomalies of EU (未 EU ~ (1.64) ~ (4.90)). The pinkish granite veins in the Altai high grade metamorphic belt are mainly formed in the Triassic. (197 卤12) 254.9 卤5.6 Ma). It may be formed in several stages at 230U 233Ma / 216U 223Ma. The formation date of the monzogranite and syenite is earlier than that of Yingyun diorite and alkaline feldspar granite.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P588.121

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