文章摘要
魏小林,甘承萍,保善斌,王维,康波,于小亮.东昆仑马尼特地区中奥陶世侵入岩地球化学特征及地质意义[J].矿产勘查,2018,9(10):1852-1861
东昆仑马尼特地区中奥陶世侵入岩地球化学特征及地质意义
Geochemical Characteristics and Geological Significance of Middle Ordovician Intrusive Rocks in Manite Area of East Kunlun
投稿时间:2018-05-07  
DOI:
中文关键词: 英云闪长岩  中奥陶世  地球化学  马尼特地区  东昆仑
英文关键词: tonalite,middle Ordovician,geochemistry,manite area,east Kunlun
基金项目:中国地质调查局资源调查项目(编号:121201011000150005-05)资助。
作者单位
魏小林 青海省地质调查局,西宁 810001 
甘承萍 青海省第三地质矿产勘查院,西宁 810029 
保善斌 青海省地质调查局,西宁 810001 
王维 青海省地质调查局,西宁 810001 
康波 青海省地质调查局,西宁 810001 
于小亮 青海省地质调查局,西宁 810001 
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中文摘要:
      马尼特地区位于东昆仑阿尼玛卿成矿带,为确定该区英云闪长岩的形成时代、源区性质和构造背景,对其进行了LA-ICP-MS锆石U-Pb年代学和同位素及地球化学研究。结果显示岩体侵位时间为(463.9±8.1)Ma(MSWK=0.19),属于中奥陶世。岩石SiO2含量为54.89%~67.62%,Na2O、K2O含量分别为3.06%~5.01%和0.79%~1.40%,全碱ALK=3.69%~6.41%,铝饱和指数A/CNK=0.84~1.33,属准铝质-过铝质系列岩石。稀土元素分布模式为轻稀土富集,具弱负Eu异常。岩石富集有大离子亲石元素(Rb、Ba、Th),Zr、Hf、Ta等高场强元素相对亏损,Nb、Y、Ti、P等元素显著亏损。以上特征表明,岩石为钙碱性-高钾钙碱性的I型花岗岩,结合岩石成岩年龄、地球化学特征以及区域构造演化,岩石具有活动陆缘俯冲消减带中岩浆弧的特征。推测其形成于早古生代早期与洋壳俯冲有关的早期陆缘弧或洋盆俯冲起始构造环境,该事件可能是原特提斯洋扩张演化在东昆仑地区的响应。
英文摘要:
      Manite area is located on the Animaqing metallogenic belt in East Kunlun. In roder to determine the formation time, magma sources and tectonic setting of the tonalite, the papper analyzed the zircon LA-ICP-MS U-Pb age, isotope data and geochemistry of tonalite. The results showe that the pluton emplacement time is 463.9±8.1 Ma(MSWK=0.19, which is era of Middle Ordovician. The contents of SiO2 (54.89%~67.62%),Na2O(3.06%~5.01%), K2O ( 0.79%~1.40%),ALK (3.69%~6.41%) and A/CNK( 0.84~1.33) in tonalite indicate that the tonalite belongs to a series of quasi-aluminous or -superaluminous rocks .The distribution modes of REE is that there is a deficit in LREE and a weak negative Eu anomaly. The tonalite is characterized by the enrichment of LILEs (Rb, Ba and Th), relative depleting in HFSEs (Zr, Hf andTa) and other elements (Nb, Y, Ti and P). Above features show that the rocks are I-type granites of calc-alkaline or high-K calc-alkaline. Combined the geochronological data, geochemical characteristics and the regional tectonic evolution, with the magmatic arc characteristics of rocks, it can be concluded that the tonalite formed in early stage of Early Paleozoic in the setting of initial continental margin arc-zone or the primary subduction stage of oceanic basin, and the event may be a material response to expansion of proto-Tethys ocean in the East Kunlun.
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