新太古代-古元古代熊耳山地区的岩浆作用与大地构造意义  

Magmatic Activity and Tectonic Significance in the Xiong'ershan Area during the Neoarchean to Early Paleoproterozoic

作　　者：刘恒[1,2] 刘磊 张德贤[1,2] 康诗胜 胡天杨[1,2] Liu Heng;Liu Lei;Zhang Dexian;Kang Shisheng;Hu Tianyang(Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring,Ministry of Education in Central South University,Changsha 410083,China;School of Geosciences and Info-Physics,Central South University,Changsha 410083,China)

机构地区：[1]中南大学有色金属成矿预测与地质环境监测教育部重点实验室,湖南长沙410083 [2]中南大学地球科学与信息物理学院,湖南长沙410083

出　　处：《地球科学》2025年第2期667-686,共20页Earth Science

基　　金：国家自然科学基金资助项目(No.41972198);湖南省自然科学基金资助项目(No.2022JJ30702);中南大学研究生自主探索创新项目(No.2023ZZTS0439);国家留学基金资助(No.CSC202306370128).

摘　　要：华北克拉通南缘出露的古老岩石主要为TTG和钾质花岗岩的岩石组合,该组合是研究花岗岩成因和大陆地壳生长演化的一个重要对象.聚焦于熊耳山地区,利用锆石微区Hf-O同位素和微量元素分析来示踪岩浆的演化过程,探讨不同阶段花岗岩的地球化学特征、源区性质及其成因机理,厘定了2.5~2.4 Ga,~2.3 Ga两期重要岩浆−构造事件.研究发现,小南沟地区2.51~2.43 Ga奥长花岗岩含有富钛氧化物,εHf(t)值为−6.9至+5.0,锆石δ^(18)O值平均值分别为6.03‰和5.18‰,可能跟地壳物质的部分熔融和沉积物质的加入有关.黄沟和穆册地区2.3 Ga钾质花岗岩显示锆石δ^(18)O值平均值分别为3.98‰和3.10‰,εHf(t)值较低,为−5.8至−3.5.锆石δ^(18)O值的明显降低,可能跟地幔物质上涌引起的高温水岩反应过程有关.不同时代花岗岩的不同类型锆石微量元素呈现出大陆弧环境的特征,结合较低的εHf(t)和降低的δ^(18)O同位素组分变化,熊耳山地区在岩浆静寂期前夕可能形成于活动大陆边缘弧环境.The ancient rocks exposed along the southern margin of the North China Craton primarily comprise a suite of rocks known as TTG(Tonalite-Trondhjemite-Granodiorite)and K-rich granites.This suite represents a critical target for the study of granite genesis and the evolution of continental crust.This paper focuses on the Xiong′ershan region and employs zircon microanalysis of Hf-O isotopes and trace elements to trace the evolution of magma.It explores the geochemical characteristics of granites at different stages,the nature of their source regions,and the mechanisms behind their formation.This study identifies two significant magmatic-tectonic events around 2.5 to 2.4 Ga and~2.3 Ga.The research reveals that in the Xiaonangou region,trondhjemite from 2.51 to 2.43 Ga contain rich titanium oxides,with lowεHf(t)values ranging from−6.9 to+5.0.The zircon oxygen isotope values average 6.03‰and 5.18‰,suggesting potential associations with partial crustal melting and the incorporation of sedimentary material.In the Huanggou and Muce regions,~2.3 Ga potassic granites exhibit zircon oxygen isotope values averaging 3.98‰and 3.10‰,with enrichedεHf(t)values ranging from−5.8 to−3.5,respectively.The significant decrease in zirconδ^(18)O values may be linked to high-temperature hydrothermal-magmatic interactions caused by upwelling mantle material.Zircon trace element compositions of different types in granites from different eras exhibit characteristics of continental arc environments.Combined with continuously lowεHf(t)and reducingδ^(18)O isotopic composition,the Xiong′ershan region likely formed in an active continental margin arc environment on the eve of the magmatic quiet period.

关 键 词：锆石Hf-O同位素 氧逸度 华北克拉通南缘 2.5~2.3 Ga 活动大陆边缘 构造地质学. 

分 类 号：P595[天文地球—地球化学]