赣西北麦斜黑云母花岗闪长岩中黑云母矿物化学特征及其对岩石成因的指示意义  

Mineral Chemistry Characteristics and Petrogenesis Implication of Biotite in Maixie Biotite Granodiorite,Northwest Jiangxi Province,South China

作　　者：陶继华[1,2,3] 苏献源 张泽凤 王帅 李明阳[1] 冷成彪 许德如 TAO Jihua;SU Xianyuan;ZHANG Zefeng;WANG Shuai;LI Mingyang;LENG Chengbiao;XU Deru(School of Earth Sciences,East China University of Technology,Nanchang 330013,Jiangxi,China;State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,Jiangxi,China;Jiangxi Province Key Laboratory of the Causes and Control of Atmospheric Pollution,East China University of Technology,Nanchang 330013,Jiangxi,China;Nuclear Industry Jinhua Engineering Investigation Institute,Jinhua 321000,Zhejiang,China)

机构地区：[1]东华理工大学地球科学学院,江西南昌330013 [2]东华理工大学,核资源与环境国家重点实验室,江西南昌330013 [3]东华理工大学江西省大气污染成因与控制重点实验室,江西南昌330013 [4]核工业金华工程勘察院,浙江金华321000

出　　处：《大地构造与成矿学》2024年第6期1385-1393,I0011-I0016,共15页Geotectonica et Metallogenia

基　　金：国家自然科学基金项目(41963002、42063001);东华理工大学-中国铀业有限公司联合基金项目(2022NRE-LH-19);江西省大气污染成因与控制重点实验室开放基金项目(AE2104)联合资助。

摘　　要：黑云母是花岗岩中常见的暗色矿物之一,其化学成分可以有效反演寄主岩岩浆演化和成岩过程的物理化学条件、岩石成因类型及岩浆源区性质。本文利用电子探针对麦斜岩体黑云母花岗闪长岩中的黑云母进行了化学成分分析。结果显示,麦斜黑云母花岗闪长岩中黑云母以镁质黑云母和铁质黑云母为主,MgO含量为8.81%~10.69%,FeO^(T)含量为18.94%~21.27%,黑云母矿物化学成分特征指示麦斜黑云母花岗闪长岩属于I型花岗岩,并具有壳幔混合特征。黑云母结晶温度为492~645℃,平均595℃,岩浆氧逸度log(ƒ_(O_(2)))为-15.8~-13.7(≈ΔFMQ+0.1~ΔFMQ+0.2)。综合地质特征、矿物化学特征及前人岩石地球化学研究成果,认为幔源基性岩浆底侵作用提供热能,导致下地壳以岩浆岩为主的源区物质发生部分熔融,同时伴有少量幔源基性岩浆混入并直接参与了岩浆作用,进而形成麦斜黑云母花岗闪长岩。The Early Paleozoic intracontinental orogeny resulted in extensive magmatism in South China.Identifying the nature of the related magmatism is essential for understanding the orogeny.Biotite is a minor rock-forming mineral in granites,and its mineral chemistry can reveal the physical-chemical conditions,petrogenesis,and source of the granitic magmas.In this study,the mineral compositions of biotite in the Maixie biotite granodiorite were studied using electron microprobe.The results show that the biotite from the Maixie biotite granodiorite belongs to Mg-biotite and Fe-biotite with MgO=8.81%-10.69% and FeO^(T)=18.94%-21.27%.Biotite geochemistry indicates that the Maixie biotite granodiorite belongs to I-type granite and exhibits characteristics of crust-mantle affinity.The crystallization temperature of the biotite is 492-645℃,with an average of 595℃,and the log(ƒ_(O_(2)))of the magma is-15.8 to-13.7(≈ΔFMQ+0.1-ΔFMQ+0.2).Combined with the geological,mineralogical,and previous geochemical data,we suggest that the underplating of mantle-derived magma provides heat flow for the partial melting of magmatic rocks in the lower crust with some mantle-derived materials involved,resulting in the formation of the Maixie biotite granodiorite.

关 键 词：黑云母 花岗岩 麦斜岩体 岩石成因 矿物化学 

分 类 号：P581[天文地球—岩石学]