| 青海三江北段拉地贡玛地区印支期花岗岩地球化学特征及地质意义 |
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| 作者姓名： | 李善平 李延京 任 华 林 浩 金婷婷 窦永斌 |
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| 作者单位： | 1.青海省地质调查院 青海省青藏高原北部地质过程与矿产资源重点实验室，西宁 810012； ;2.青海省海东市地震局，海东 810600； ;3.青海大学，西宁 810016 |
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| 基金项目： | 中国地质调查局“青海三稀资源调查(编号: 2012000100630144)”和“青海省科技计划项目(编号: 2014-Z-Y06,Y19,2015-ZJ-763,2014-ZJ-701)”联合资助。 |
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| 摘 要： | 拉地贡玛地区花岗岩处于金沙江缝合带内,区域上隶属西金乌兰—金沙江缝合带的物质组成部分,在研究区属通天河构造岩浆岩带。据出露岩石类型,将其划分为3个单元:拉地贡玛花岗闪长岩(T_3γδ)、日阿日曲石英闪长岩(T_3δο)、缅切英云闪长岩(T_3δi)。岩浆侵位时代为晚三叠世;侵入岩体是以高硅富铝、多碱质和挥发组分为特征的兼具I型和S型花岗岩,属过铝质花岗岩;轻重稀土分馏程度明显,轻稀土富集,Eu、Ce呈弱负异常,Rb、Th、Ba等元素富集,Y、Yb、Cr等元素亏损,具I型和S型花岗岩的特点,与火山弧钙碱性花岗岩特征相似。研究区花岗岩形成构造环境与晚三叠世多彩—当江构造混杂带的俯冲作用有关,是与俯冲汇聚构造环境有关的大陆碰撞弧型花岗岩。
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| 关 键 词： | 青海三江北段 金沙江缝合带 花岗岩 地球化学 构造环境 |
| 收稿时间： | 2015-06-12 |
Geochemistry and geological significance of Indosinian granites in the Ladigongma area of northern segment of the Sanjiang belt,Qinghai |
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| Authors: | LI Shanping LI Yanjing REN Hua LIN Hao JIN Tingting DOU Yongbin |
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| Institution: | 1.Qinghai Province Key Laboratory of Geological Processes and Mineral Resources of Northern Qinghai-Tibetan Plateau,Qinghai Institute of Geological Survey, Xining 810012, China; 2.Seismological Bureau of Qinghai Haidong,Haidong 810600, China; 3.Qinghai University, Xining 810016, China |
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| Abstract: | The Ladigongma granite is located in the Tongtian river tectono-magmatic belt of the Xijin Ulan - Jinsha river suture zone. According to the outcrop research, the rock types could be subdivided into 3 units: the Ladigongma granodiorite (T3γδ), the Riariqu quartz diorite (T3δo) and the Mianqie tonalite (T3δi). All of the granites are formed in the Late Triassic. The major elements results show that the granites are rich in silicon, aluminum, alkalis and volatile components; the rare earth elements results show intense fractionation between LREE and HREE with significant LREE enrichment and weak negative of Eu and Ce; and the trace elements are characterized by Rb, Th and Ba enrichment, and Y, Yb and Cr depletion. All of these are the characteristics of I- and S-type peraluminous granite. They have the same geochemical characteristics as the calc-alkaline granite in volcanic arc. It is inferred that the subduction of Duocai—Dangjiang tectonic melange zone in Late Triassic may be responsible for the granites in the study area. The granites are the continental collision type granite and the tectonic setting is subduction-convergent environment. |
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| Keywords: | northern segment of the Sanjiang belt Qinghai Jinsha river suture zone granite geochemistry tectonic environment |
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