豫西栾川矿集区南泥湖和石宝沟岩体锆石U-Pb-Hf-O同位素特征及地质意义  

Zircon U-Pb-Hf-O Isotopic Characteristics and Geological Significance of Nannihu and Shibaogou Rock Mass in Luanchuan Ore Concentration Area,Western Henan Province

作　　者：陈雅鹏 唐利[1] 胡昕凯 盛渊明 曾涛 陈龙龙 赵江林 CHEN Yapeng;TANG Li;HU Xinkai;SHENG Yuanming;ZENG Tao;CHEN Longlong;ZHAO Jianglin(School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China;Second Institute of Oceanography,MNR,Hangzhou 310012,Zhejiang,China)

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]自然资源部第二海洋研究所,浙江杭州310012

出　　处：《西北地质》2024年第6期278-289,共12页Northwestern Geology

基　　金：科技部重点研发计划项目“大陆碰撞带岩浆演化过程成矿物质的富集机理”(YBC018004);中国地质大学(北京)求真学人项目“秦岭造山带碳酸岩型矿床Mo-REE富集成矿机理”(590223001)联合资助。

摘　　要：栾川矿集区位于华北克拉通南缘,区内矿产资源丰富,产出多个大型–超大型斑岩–矽卡岩型钼钨矿床。矿集区内晚中生代岩浆活动频繁,形成多个含矿花岗岩体和斑岩岩株,其成矿差异和成矿潜力的控制因素仍不清楚。笔者以栾川矿集区南泥湖富Mo花岗岩体和石宝沟贫矿岩体为研究对象,基于锆石U-Pb定年和Hf-O同位素研究,揭示其成岩成矿年龄、岩浆源区及成矿指示意义。石宝沟花岗岩和南泥湖岩体的锆石U-Pb年龄分别为(147.5±2.2)Ma和(139.5±1.8)Ma,二者均为燕山期岩浆活动的产物。石宝沟岩体的锆石ε_(Hf)(t)值为-27.4~-14.51,二阶段模式年龄TDM2值为2.15~2.93 Ga,δ^(18)O值为5.42‰~6.77‰。南泥湖岩体的锆石ε_(Hf)(t)值为-16.84~-8.04,二阶段模式年龄TDM2值为1.70~2.26 Ga,δ^(18)O值为5.88‰~8.27‰。锆石U-Pb年龄和Hf-O同位素结果表明,在碰撞后造山的局部伸展背景下,石宝沟贫矿岩体岩浆源区源于秦岭造山带加厚下地壳部分熔融,南泥湖富Mo斑岩岩浆具有壳幔混源特征。The Luanchuan mining area is located at the southern edge of the North China Craton,which is rich in mineral resources and has produced a number of large-sized and super-large porphyry-silica type molybdenum and tungsten deposits.There are frequent magmatic activities in Late Mesozoic,forming several ore-bearing granite bodies and porphyry rock strains,and the controlling factors of their mineralization differences and potentials are still unclear.In this paper,we take the Mo-rich granite body of Nannihu and the ore-poor granite body of Shibaogou in the Luanchuan mining concentration area as the research objects,and based on zircon UPb dating and Hf-O isotope study,we reveal the age of their diagenesis and metallogeny,magma source area,and metallogeny indication significance.The zircon U-Pb ages of the Shibaogou rock and the Nannihu rock are(147.5±2.2)Ma and(139.5±1.8)Ma,respectively,and both are the products of Yanshan-age magmatism.The zirconε_(Hf)(t)values of the Shibaogou body range from−27.40~−14.51,and the two-stage mode age TDM2 values range from 2.15~2.93 Ga,withδ^(18)O values of 5.42‰to 6.77‰.The zirconε_(Hf)(t)values of the Nannihu body range from−16.84~−8.04,with second-stage mode age TDM2 values ranging from 1.70~2.26 Ga andδ^(18)O values of 5.88‰~8.27‰.The zircon U-Pb ages and Hf-O isotope results indicate that the source area of the Shibaogou ore-poor magma originated from partial melting of the thickened lower crust of the Qinling orogenic belt in the context of localized extensional downstretching of post-collisional orogeny;and that the Mo-rich porphyry magma of the Nannihu is characterized by crust-mantle mixing.

关 键 词：花岗斑岩 锆石U-Pb-Hf-O同位素 岩浆源区 栾川矿集区 

分 类 号：P581[天文地球—岩石学] P597[天文地球—地质学]