安哥拉地盾Quibala斑状花岗岩的年代学、地球化学特征:对Columbia超大陆演化的制约  

Geochronology and geochemistry of Quibala porphyritic granites in the Angolan shield:Implications for the evolution of the Columbia supercontinent

作　　者：靳立杰 张洪瑞 罗迪柯 贾鹏飞 刘伟 王子圣 李金镇 周永刚 江振国 JIN Lijie;ZHANG Hongrui;LUO Dike;JIA Pengfei;LIU Wei;WANG Zisheng;LI Jinzhen;ZHOU Yonggang;JIANG Zhenguo(No.1 Institute of Geology and Mineral Resource Exploration of Shandong Province,Ji'nan,Shandong 250014,China;Shandong Engineering Research Center of High-grade Iron Deposits Exploration and Exploitation,Ji'nan,Shandong 250014,China;Citic Construction Co.,Ltd.,Beijing 100027,China)

机构地区：[1]山东省第一地质矿产勘查院,山东济南250014 [2]富铁矿勘查开发技术山东省工程研究中心,山东济南250014 [3]中信建设有限责任公司,北京100027

出　　处：《地质学报》2025年第4期1209-1222,共14页Acta Geologica Sinica

基　　金：安哥拉国家地质调查计划项目(PLANAGEO)资助的成果。

摘　　要：2.1~1.8 Ga发生了全球范围的Columbia超大陆汇聚事件,导致Congo克拉通与S2o Francisco克拉通沿Eburnean造山带发生汇聚。作为Congo克拉通的重要组成部分,安哥拉地盾记录了这一时期的构造-岩浆事件。本文对安哥拉地盾Quibala地区的斑状花岗岩进行了岩石学、锆石U-Pb年代学和地球化学研究。Quibala斑状花岗岩LA-ICP-MS锆石U-Pb年龄为1987±20 Ma、1967±6 Ma和1956±12 Ma,限定斑状花岗岩其形成于1987~1956 Ma期间,为古元古代Eburnean期岩浆作用产物。岩石地球化学特征表明,Quibala斑状花岗岩具有典型的A型花岗岩地球化学特征,形成于后碰撞伸展环境,可能是受到壳幔相互作用影响的下地壳物质发生部分熔融而形成。综合年代学与地球化学研究结果,本文认为Congo克拉通与S2o Francisco克拉通的汇聚发生在Columbia超大陆开始形成阶段(2.1 Ga左右),在1987~1956 Ma已转为碰撞后伸展环境。Global Columbia supercontinent assemblage occurred between 2.1 Ga and 1.8 Ga.The collision between the Congo and S2o Francisco cratons formed the Eburnean orogenic belt.As an important part of the Congo craton,the Angolan shield has recorded tectono-magmatic events during this period.This study investigates the petrology,zircon U-Pb chronology,and geochemistry of porphyritic granites in the Quibala area of the Angolan shield.LA-ICP-MS zircon U-Pb dating yielded ages of 1987±20 Ma,1967±6 Ma,and 1956±12 Ma,indicating that the porphyritic granite crystallized between 1987 Ma and 1956 Ma,coinciding with Paleoproterozoic Eburnean magmatism.Geochemical data classifies the Quibala porphyritic granite as A-type granite,suggesting formation in a post-collision extension setting.This granite may be formed by partial melting of lower crustal material influenced by crust-mantle interaction.Combining chronological and geochemical data,we propose that the Congo and S2o Francisco cratons,integral parts of the Columbia supercontinent,transitioned from a collisional to a post-collision extensional stage between 1987 Ma and 1956 Ma.

关 键 词：安哥拉地盾 Congo克拉通 Quibala斑状花岗岩 A型花岗岩 Columbia超大陆 

分 类 号：P597[天文地球—地球化学]