青海窑洞山地区晚奥陶世花岗岩岩石地球化学特征及地质意义

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英文篇名：Geochemical characteristics and geological significance of Late Ordovician granite in Yadongshan Area of Qinghai Province 作者：杨雪松 ; 王国良 ; 余福承 ; 孟红 ; 赵景 英文作者：YANG Xue-song;WANG Guo-liang;YU Fu-cheng;MENG Hong;ZHANG Xing;Key Laboratory of Geological Processes and Mineral Resources in the Northern part of the Qinghai-Tibet Plateau in Qinghai Province;Qinghai Institute of Geological Survey; 关键词：钙碱性系列 ; 壳源花岗岩 ; 碰撞花岗岩 ; 岛弧 ; U-Pb年龄 英文关键词：calcium alkalescence siries;;crusta source granite;;collision granite;;island arc;;U-Pb age 中文刊名：YSJS 英文刊名：Mineral Exploration 机构：青海省青藏高原北部地质过程与矿产资源重点实验室;青海省地质调查院; 出版日期：2019-03-28 出版单位：矿产勘查 年：2019 期：v.10;No.63 基金：中国地质调查局大调查项目(编号:12120113033014)资助 语种：中文; 页：YSJS201903005 页数：10 CN：03 ISSN：11-5875/TD 分类号：25-34

摘要

对青海省格尔木窑洞山地区四道沟侵入岩进行岩石学、岩石化学、微量元素的分析及研究,主要岩石类型有二长花岗岩、二云母二长花岗岩和白云母花岗岩等,SiO_2含量为65. 65%～77. 32%,K_2O、Na_2O分别含量为2.78%～7.73%和1.26%～5.78%,显示钙碱性系列特征,σ=0.61～2.07,Al_2O_3>CaO+K_2O+Na_2O,A,CNK=1. 09～2.48,为中高钾过铝质岩石。LREE/REE=3. 30～6.24,δEu=0.37～0. 56,均小于1,具明显的负铕异常。K、Rb、Ba、Th、Ce富集,其中Ba具负异常特征,Ta、Zr亏损,具碰撞花岗岩特征。由上述特征表明,窑洞山地区的晚奥陶世花岗岩具壳源花岗岩(S型)特征,是非典型碰撞型花岗岩,形成于岛弧或陆缘弧部位。同时在四道沟西侧的二云母二长花岗岩中获得(471±2)Ma LA-ICP-MS锆石U-Pb年龄,为东昆仑地区古生代多级构造—岩浆演化提供了精确的地质时代证据。
        The analysis and study of petrology, petrochemistry and trace elements of the Sidao gou in Yaodongshan area of Golmud City, Qinghai Province, the main rock types are monzonite granites, Biotite-Mus monzonite granites and muscovite granites, the rocks have the following chemical composition:siO_2= 65. 65%～77. 32%,K_2O and Na_2O are different between 2. 78% ～7. 73 %and 1. 26% ～5. 78 %, This indicates the granite rocks with the character of calcium alkalescence siries. σ = 0. 61 ～2.07,Al_2O_3>CaO+ K_2O+Na_2O,A/CNK = 1. 09 ～ 2. 48, They are medium-high potassium aluminum rocks. LREE/REE = 3. 30 ～ 6. 24,△Eu = 0. 37～ 0. 56, all less than 1, indicate Eu pronounced Obviously negative abnormalty. K, Rb, Ba, Th, Ce are abundant, of which Ba has negative abnormalty, Ta, Zr are loss-making, with collision granite characteristics. From the above characteristics, it is shown that the late Ordovician granites in the Yaodongshan area are Crustal granite(S-type granite), Atypical Syn-Collision granite,formed in island arcs or continental margin arcs. At the same time, We took a sample of the Biotite-Mus monzonite granites in the Yaodongshan area to analys U-Pb age. The LA-ICP-MS U-Pb age analyses show that the granite ages of late Ordovician are(471±2)Ma, the zircon trace elements age provide accurately Geological Age on the Paleozoic multi-stage tectonic-magmatic events of the Eastern Kunlun area.

引文

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