| 东昆仑东段香加南山花岗岩基中加鲁河中基性岩体形成时代、成因及其地质意义 |
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| 引用本文： | 陈国超,裴先治,李瑞保,李佐臣,刘成军,陈有炘,裴磊,张永明,王盟,李小兵,张玉.东昆仑东段香加南山花岗岩基中加鲁河中基性岩体形成时代、成因及其地质意义[J].大地构造与成矿学,2017,41(6):1097-1115. |
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| 作者姓名： | 陈国超 裴先治 李瑞保 李佐臣 刘成军 陈有炘 裴磊 张永明 王盟 李小兵 张玉 |
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| 作者单位： | 1. 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, 国土资源部岩浆作用与找矿重点实验室,陕西西安 710054;南阳理工学院土木工程学院,河南南阳 473000;2. 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, 国土资源部岩浆作用与找矿重点实验室,陕西西安 710054;3. 中国地质大学 (北京)地球科学与资源学院,北京,100083;4. 山西师范大学地理科学学院,山西临汾,041000 |
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| 基金项目： | 国家自然科学基金，中央高校基本科研业务费专项资金，青海省国土资源厅?中国铝业公司公益性区域地质矿产调查基金 |
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| 摘 要： | 东昆仑东段香加南山花岗岩基中加鲁河中基性岩体主要岩石类型包括角闪辉长岩和石英闪长岩。LA-ICP-MS锆石U-Pb同位素定年结果显示加鲁河中基性岩体的结晶年龄为220 Ma。岩体SiO_2含量较低,为47.91%~58.92%,Al_2O_3含量为15.54%~18.35%,Na2O为1.70%~3.34%,K_2O为0.58%~1.92%,Na_2O/K_2O比值为1.34~2.93,平均1.92,MgO含量为3.69%~8.24%,Mg~#为46~61,铝饱和指数A/CNK介于0.70~0.90之间,主体属于准铝质中钾钙碱性系列。岩体富集轻稀土元素,亏损重稀土元素,具明显的Eu负异常(δEu=0.40~0.59);微量元素富集Rb、Th、Ba等大离子亲石元素(LILE),亏损Nb、Ta、Ti等高场强元素(HFSE)。岩石学和地球化学研究显示岩体在地壳深部和浅部经历了两次岩浆混合作用。在深部,幔源岩浆底侵作用使下地壳部分熔融形成长英质岩浆,两种岩浆不同比例混合,经过化学扩散均一化,从而具有相似的同位素特征和岩石地球化学特征。在地壳浅部,经深部混合的岩浆注入花岗质岩浆,岩浆边部同花岗岩完全混合形成加鲁河岩体中石英闪长岩,不完全混合则形成暗色微粒包体。对加鲁河中基性岩体研究表明,东昆仑东段在晚三叠世处于古特提斯演化的后碰撞阶段,在这一时期存在岩浆底侵事件。
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| 关 键 词： | 东昆仑造山带 布青山?阿尼玛卿洋 加鲁河中基性岩体 地球化学 锆石U-Pb年龄 晚三叠世 |
Age and Petrogenesis of Jialuhe Basic-Intermediate Pluton in Xiangjia'nanshan Granite Batholith in the Eastern Part of East Kunlun Orogenic Belt,and its Geological Significance |
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| CHEN Guochao,PEI Xianzhi,LI Ruibao,LI Zuochen,LIU Chengjun,CHEN Youxin,PEI Lei,ZHANG Yongming,WANG Meng,LI Xiaobing,ZHANG Yu.Age and Petrogenesis of Jialuhe Basic-Intermediate Pluton in Xiangjia'nanshan Granite Batholith in the Eastern Part of East Kunlun Orogenic Belt,and its Geological Significance[J].Geotectonica et Metallogenia,2017,41(6):1097-1115. |
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| Authors: | CHEN Guochao PEI Xianzhi LI Ruibao LI Zuochen LIU Chengjun CHEN Youxin PEI Lei ZHANG Yongming WANG Meng LI Xiaobing ZHANG Yu |
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| Abstract: | The Jialuhe basic-intermediate intrusion is situated inside of the Xiangjia'nanshan granitic batholith at the eastern end of the East Kunlun orogenic belt. It is mainly composed of hornblende gabbro and quartz diorite. LA-ICP-MS zircon U-Pb dating showed that the Jialuhe intrusion was emplaced at 220 Ma. The rocks have low SiO2 (47.91%–58.92%) and Al2O3(15.54%–18.35%) contents, low A/CNK (0.70–0.90) ratios, high Mg#(46–61), and display . metaluminous middle-K calc-alkaline affinities. The rocks are enriched in the large lithophile elements such as Rb、Th、Ba、Cs and LREE, depleted in the high field strength elements like Nb、Ta、Ti and HREE, and displaying obvious negative Eu anomalies (δEu=0.40–0.59). Petrological and geochemical analyses showed that the rocks underwent two stages of magmatic mixing in the deep and shallow crust respectively. The mixing of the underplating mantle magma with felsic melt of the lower crust as a result of mantle upwelling at depth and the mixed magma experienced chemical and isotopic homogenization. In the shallow part of the crust, the formerly mixed magma intruded the crystallizing granitic magma, and mixed with the latter to form the quartz diorite in the outer zone of the pluton, or mingled with the granitic magma to produce the mafic microgranular enclaves. This study indicated that the east part of the East Kunlun orogenic belt was in the post-collision stage during the Late Triassic. |
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| Keywords: | East Kunlun Orogenic Belt Buqingshan-A'nemaqen Ocean Jialuhe basic-intermediate pluton geochemistry zircon U-Pb chronology the Late Triassic |
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