赣南水头岩体岩石地球化学特征及地质意义  

Geochemical characteristics and geological significance of Shuitou Pluton in southern Jiangxi Province

作　　者：龚良信 张德富 孙言[1] 曹明轩 王先广 GONG Liangxin;ZHANG Defu;SUN Yan;CAO Mingxuan;WANG Xianguang(Jiangxi Nonferrous Geology and Mineral Exploration and Development Institute,Nanchang 330013,Jiangxi,China;Key Laboratory of Ionic Rare Earth Resources and Environment,Ministry of Natural Resources,Jiangxi College of Applied Technology,Ganzhou 341000,Jiangxi,China;School of Earth Science,East China University of Technology,Nanchang 330013,Jiangxi,China;Hefei University of Technology,School of Resources and Environmental Engineering,Hefei 230000,Anhui,China;Jiangxi Mineral Resources Guarantee Service Center,Nanchang 330013,Jiangxi,China)

机构地区：[1]江西省地质调查勘查院基础地质调查所,江西南昌330013 [2]江西应用技术职业学院自然资源部离子型稀土资源与环境重点实验室,江西赣州341000 [3]东华理工大学地球科学学院,江西南昌330013 [4]合肥工业大学资源与环境工程学院,安徽合肥230000 [5]江西省矿产资源保障服务中心,江西南昌330013

出　　处：《矿产勘查》2024年第10期1765-1780,共16页Mineral Exploration

基　　金：江西省安远县石头坪离子型中重稀土成矿作用及绿色采选技术试验(20220014);江西省自然资源厅科技创新项目(ZRKJ20232526,ZRKJ20232411);自然资源部离子型稀土资源与环境重点实验室开放基金课题(2022IRERE103,2023IRERE106)联合资助。

摘　　要：赣南水头岩体传统上认为是加里东期花岗岩,其成因尚不明确。以水头岩体黑云母花岗岩为研究对象,进行岩石学、锆石U-Pb年代学、独居石U-Pb年代学和锆石Hf同位素研究。研究结果显示,水头岩体黑云母花岗岩LA-ICP-MS锆石、独居石U-Pb加权平均年龄分别为(151.6±1.80)Ma和(145.3±1.20)Ma;地球化学显示,水头岩体高硅和富碱,SiO_(2)含量为72.85%~76.14%,全碱(K_(2)O+Na_(2)O)含量为7.98%~8.39%,富集Rb、Th、U、Nd等元素,亏损Ba、Nb、Sr、P、Ti等元素轻稀土相对富集((La/Yb)_(N)=2.20~9.38),明显负Eu异常(δEu=0.11~0.40);锆石ε_(Hf)(t)值为-6.78~10.04,二阶段模式年龄(T_(DM2))为1832~1633。综合分析,水头岩体为高分异I型花岗岩,属晚侏罗世岩浆作用产物,起源于古元古代下地壳部分熔融,形成于弧后伸展构造环境,与岩浆沿政和—大埔深大断裂底侵有关。Shuitou Pluton in southern Jiangxi is traditionally considered to be Caledonian granite,and its genesis is still unclear.The biotite granite of Shuitou pluton is taken as the research object,and petrology,zircon U-Pb chronology,monazite U-Pb chronology and zircon Hf isotope are studied.The results show that the LA-ICP-MS zircon and monazite U-Pb weighted average ages are(151.6±1.80)Ma and(145.3±1.20)Ma.Geochemistry shows that Shuitou pluton is rich in silicon and alkali,with SiO2 content of 72.85%-76.14% and total alkali(K_(2)O+Na_(2)O)content of 7.98%-8.39%.It is enriched in elements such as Rb,Th,U,and Nd,and depleted in elements such as Ba,Nb,Sr,P,and Ti.LREE is relatively enriched((La/Yb)N=2.20-9.38),with obvious negative Eu anomaly(δEu=0.11-0.40).The zircon εHf(t)values range from-6.78 to 10.04,and the two-stage model age(TDM2)ranges from 1832 Ma to 1633 Ma.which is the product of partial melting of the lower crust in Mesoproterozoic.In conclusion,the Shuitou pluton is a highly differentiated type I granite,formed during Late Jurassic magmatic activity,originating from partial melting of the lower crust in the mid-Proterozoic era.It formed in a post-arc extensional tectonic environment and is related to magma intrusion along the Zhenhe-Dapu deep fault.

关 键 词：水头岩体 成岩年代 Lu–Hf同位素 高分异I型花岗岩 中生代 

分 类 号：P581[天文地球—岩石学]