大兴安岭北段洛古河地区晚寒武世花岗岩的岩石成因及其对兴蒙造山带构造演化的约束  

Petrogenesis of Late Cambrian granite in Luoguhe district of the northern Great Xing'an Range and its constrain on the tectonic evolution of the Xing-Meng Orogenic Belt

作　　者：周传芳 杨华本[1,3] 段明新 陈卓 于俊博 杜海双 李少文 张起鹏 胡宸 ZHOU Chuanfang;YANG Huaben;DUAN Mingxin;CHEN Zhuo;YU Junbo;DU Haishuang;LI Shaowen;ZHANG Qipeng;HU Chen(Harbin Center for Integrated Natural Resources Survey,China Geological Survey,Harbin 150086,Heilongjiang,China;School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China;Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;China University of Geosciences,Wuhan 430074,Hubei,China)

机构地区：[1]中国地质调查局哈尔滨自然资源综合调查中心,黑龙江哈尔滨150086 [2]中国地质大学(北京)地球科学与资源学院,北京100083 [3]中国地质科学院地质研究所,北京100037 [4]中国地质大学,湖北武汉430074

出　　处：《地质通报》2023年第11期1924-1937,共14页Geological Bulletin of China

基　　金：中国地质调查局项目《黑龙江大兴安岭地区洛古河、兴华沟林场、阿凌河、1072.3高地幅15万区域地质矿产调查》(编号:DD2016007803);《大兴安岭山区生态地质调查》(编号:DD20191014);《小兴安岭黑河地区自然资源综合调查》(编号:DD20230504)。

摘　　要：大兴安岭北段早古生代花岗岩主要分布于漠河—塔河一线。对漠河北部洛古河二长花岗岩开展岩石年代学与岩石地球化学研究。二长花岗岩中锆石为岩浆成因,LA-ICP-MS U-Pb测年表明,其形成时代为晚寒武世(486±3 Ma)。岩石具高硅(SiO 2=62.75%~73.32%)、富碱(ALK=8.30%~9.45%)、高铝(Al_(2)O_(3)=13.97%~16.53%)、低镁、低钙和低钛的特点,铝饱和指数A/CNK为0.91~1.10,属偏铝质高钾钙碱性岩石系列。SiO 2与Al_(2)O_(3)和P 2 O 5具有较好的负相关性;富集Rb、Th、U、K、Zr、Hf等元素,而强烈亏损Ba、Nb、Ta、Sr、P、Ti等元素,球粒陨石标准化的稀土元素配分曲线图中呈轻稀土元素富集、重稀土元素亏损的右倾型配分模式,显示了I型花岗岩特征。综合分析认为,洛古河岩体形成于西伯利亚板块南缘与额尔古纳等微陆块碰撞造山晚期由挤压体制向拉张体制转换的后碰撞构造环境。The Early Paleozoic granites in the northern part of the Great Xing’an Range are mainly distributed along the Mohe-Tahe.In this paper,geochronological and geochemical characteristics of the Luoguhe monzonite in the north of Mohe are studied.Zircons in the monzogranite is of magmatic origin,and LA-ICP-MS U-Pb dating indicates that it was formed in the Late Cambrian(486±3 Ma).The monzonite are characterized by high silicon(SiO 2=62.75%~73.32%),rich alkali(AlK=8.30%~9.45%),high aluminum(Al_(2)O_(3)=13.97%~16.53%),low magnesium,low calcium and low titanium,with A/CNK value ranging from 0.91 to 1.10,indicating that monzonite belongs to aluminous and high potassium calc-alkaline rock series.The SiO 2 content has a negative correlation with Al_(2)O_(3)and P 2 O 5.Rb,Th,U,K,Zr,Hf elements are enriched,while Ba,Nb,Ta,Sr,P and Ti are strongly depleted.In the chondrite normalized REE partition curves,LREE is enriched and HREE is depleted,which shows the characteristics of I-type granites.Comprehensive analysis shows that the Luoguhe pluton was formed in a post-collisional tectonic setting during the late period of the orogeny between the southern margin of the Siberian plate and the Erguna micro landmass,which was transformed from compression system to extension system.

关 键 词：晚寒武世 二长花岗岩 岩石地球化学 锆石U-PB年龄 大兴安岭 地质调查工程 洛古河地区 

分 类 号：P534.4[天文地球—古生物学与地层学] P588.12[天文地球—地质学]