小兴安岭西北部霍龙门地区花岗质杂岩锆石U--Pb年龄、岩石地球化学特征及地质意义  

Zircon U--Pb ages,geochemical characteristics and their geological implication of granitic complex in Huolongmen area,northwestern Xiao Hinggan mountains

作　　者：曲晖 李成禄 杨福深 

机构地区：[1]黑龙江省地质调查研究总院,哈尔滨150036

出　　处：《世界地质》2015年第1期34-43,共10页World Geology

基　　金：中国地质调查局项目(1212010781024;1212011120690)资助

摘　　要：小兴安岭西北部的霍龙门地区位于兴蒙造山带东段,该区出露的大面积花岗质杂岩为新开岭—科洛杂岩的重要组成部分。该花岗质杂岩主要由花岗质和花岗闪长质糜棱岩等组成,其中花岗质糜棱岩的SHRIMP锆石U--Pb定年结果为310.7±6.5 Ma,表明其原岩形成于晚石炭世。该杂岩的主量元素总体显示中、高钾钙碱性准铝质--过铝质系列岩石的特点;微量元素表现出Th、Zr、Hf、Nd、Rb、K明显富集,而Ba、Sr、Nb、P、Ti明显亏损;稀土元素具有明显的轻稀土元素富集、重稀土元素相对亏损的特征,有较明显的负Eu异常,轻、重稀土元素分馏程度较强。结合区域构造演化特点及花岗质杂岩的形成环境等,综合显示该杂岩的原岩应形成于晚古生代,于三叠纪时期发生明显的变质变形作用。The Huolongmen area in Xiao Hinggan mountains is tectonically located in the eastern Xingmeng oregenic belt. A large area of exposed granitic complex is an important part of the Xinkailing--Kele complex. The granitic complex is mainly composed of granite and granodioritic mylonite. Dating of the zircon U-Pb SHRIMP,concordant age of the granitic mylonite is 310. 7 ± 6. 5 Ma,implying that their protolith formed in the Late Carboniferous. Major elements of the granitic complex indicate medium to high potassium calc-alkaline and metaluminous to peraluminous in composition. Trace elements demonstrate the enrichment of Th,Zr,Hf,Nd,Rb,K and depletion of Ba,Sr,Nb,P,Ti. The samples are enriched in LREE（ light rare earth elements） and depleted in HREE（ heavy rare earth elements） with pronounced negative Eu anomalies,suggesting a high degree fractionation of LREE and HREE. Based on the regional tectonic evolution characteristics and forming environment of granitic complex,we interpreted that their protolith formed in Late Paleozoic,but significant deformation and metamorphism occurred in Trassic.

关 键 词：花岗质杂岩 锆石U-PB年龄 地球化学特征 霍龙门地区 小兴安岭 

分 类 号：P595[天文地球—地球化学] P597[天文地球—地质学]