赣南河源锂矿床伟晶岩岩石成因及其锂超常富集机制:来自锆石、磷灰石U-Pb定年和全岩地球化学的约束  

Petrogenesis of pegmatite and supernormal enrichment mechanism of lithium in Heyuan lithium deposit,southern Jiangxi Province:Constraints from zircon and apatite U-Pb dating and whole-rock geochemistry

作　　者：冯莲花 田世洪 李海立[4] 孙建东[4] 龚迎莉[5] 杨世文 黄昌祺 刘文斌 FENG LianHua;TIAN ShiHong;LI HaiLi;SUN JianDong;GONG YingLi;YANG ShiWen;HUANG ChangQi;LIU WenBin(School of Earth Sciences,East China University of Technology,Nanchang 330013,China;National Key Laboratory of Uranium Resource Exploration-Mining and Nuclear Remote Sensing,Nanchang 330013,China;State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;Nanjing Center,China Geological Survey,Nanjing 210016,China;Department of Energy and Power Engineering,Tsinghua University,Beijing 100084,China)

机构地区：[1]东华理工大学地球科学学院,南昌330013 [2]铀资源探采与核遥感全国重点实验室,南昌330013 [3]东华理工大学,核资源与环境国家重点实验室,南昌330013 [4]中国地质调查局南京地质调查中心,南京210016 [5]清华大学能源与动力工程系,北京100084

出　　处：《岩石学报》2025年第4期1217-1251,共35页Acta Petrologica Sinica

基　　金：中国地质调查项目(DD20240066);国家重点研发计划项目(2021YFC2901903);自然资源部开放课题(Sino Probe Lab 202217、2022IRERE102);江西省“双千计划”创新领军人才长期项目(2020101003);江西省自然科学基金重点项目(20224ACB203011);东华理工大学高层次人才引进配套经费(1410000874)联合资助.

摘　　要：锂在国民经济建设和国防科技领域具有重要地位,被誉为“推动世界前进的金属”。华南是我国花岗岩型铌、钽、锂等稀有稀土金属矿产重要产地,其中江西省伟晶岩型锂矿床主要集中分布在赣南地区,被认为与会同岩体密切相关。然而,伟晶岩岩石成因及其锂超常富集机制尚未得到很好理解和揭示。本文以江西省伟晶岩型锂矿床的典型代表——河源锂矿床为研究对象,系统开展了成岩成矿年代学、地球化学及Hf-Nd同位素研究,查明伟晶岩岩石成因,揭示锂超常富集机制,建立伟晶岩型锂矿床成矿模型,解开江西省伟晶岩型锂矿床成因难题。研究获得会同复式岩体细粒碱长花岗岩和粗粒黑云母花岗岩锆石U-Pb年龄分别为408.7±2.8Ma和401.2±2.7Ma,获得含锂辉石伟晶岩中磷灰石U-Pb年龄387±10Ma,在误差范围内与会同复式岩体锆石U-Pb年龄基本一致,表明锂辉石成矿作用与会同岩体具有成因联系。粗粒黑云母花岗岩表现出A型花岗岩特征:稀土元素含量高(∑REE平均值为276.57×10^(-6)),高硅(69.81%~75.31%),适度富碱(K 2O:3.96%~6.16%,Na_(2)O:2.22%~3.25%),具有较为明显的Eu负异常(δEu平均值0.34),10000Ga/Al比值范围为2.98~3.76(>2.6),高场强元素Zr+Nb+Ce+Y含量范围为408.3×10^(-6)~544.1×10^(-6)(>350×10^(-6))。细粒碱长花岗岩则表现出过铝质高分异S型花岗岩特征:低的TiO_(2)、Fe_(2)O_(3)、CaO、MgO、∑REE、Nb/Ta、Zr/Hf比值,更高的Li、Rb、Cs和分馏效应(La/Yb)N;白云母矿物的存在;且其所有样品均出现标准刚玉分子,质量分数范围为2.87%~3.56%,均大于1%;铝饱和指数(A/CNK)均大于1.1;Th和Y含量低,且Th、Y与Rb呈现负相关关系。前后两者εNd(t)同位素比值分别为-9.43~-9.10、-13.49~-13.35,Nd同位素组成非常均一,能较好地反映源区的特征,粗粒黑云母花岗岩(A型)应源自下地壳部分熔融,细粒碱长花岗岩(S型)可能为中下地壳部分熔融的产物。Lithium plays an important role in national economic construction and national defense science and technolog,and is known as“the metal that moves the world forward”.South China is an important producing area for granite-type niobium,tantalum,lithium and other rare earth minerals,among which pegmatite-type lithium deposits in Jiangxi Province are mainly distributed in the southern Jiangxi Province and are believed to be closely related to Huitong pluton.However,petrogenesis of pegmatite and supernormal enrichment mechanism of lithium have not been well understood and revealed.In this paper,Heyuan lithium deposit,a typical representative of pegmatite-type lithium deposit in Jiangxi Province,is taken as the research object.The diagenetic and metallogenic chronology,geochemistry and Hf-Nd isotopes are systematically carried out to clarify the petrogenesis of pegmatite,reveal the supernormal enrichment mechanism of lithium,establish the metallogenic model of pegmatite-type lithium deposit,and finally uncover the genetic problems of pegmatite-type lithium deposit in Jiangxi Province.The zircon U-Pb ages of fine-grained alkali feldspar granite and coarse-grained biotite granite obtained from the Huitong complex rock are 408.7±2.8Ma and 401.2±2.7Ma.The U-Pb age of apatite in the spodumene pegmatite is 387±10Ma,which is basically consistent with the zircon U-Pb age of the Huitong complex rock within the error range,showing that the mineralization of spodumene is genetically related to the Huitong complex rock.Coarse-grained biotite granite shows A-type granite characteristics:high content of rare earth elements(average∑REE is 276.57×10^(-6)),high silicon(69.81%~75.31%),moderately rich alkali(K 2O:3.96%~6.16%,Na_(2)O:2.22%~3.25%),relatively obvious negative Eu anomaly(δEu mean 0.34);10000Ga/Al ratio and high field strength elements Zr+Nb+Ce+Y content range from 2.98 to 3.76(>2.6)and 408.3×10^(-6) to 544.1×10^(-6)(>350×10^(-6)),respectively.Fine-grained alkali feldspar granite shows aluminous highly differenti

关 键 词：伟晶岩岩石成因 锂超常富集机制 U-PB定年 全岩地球化学 赣南河源锂矿床 

分 类 号：P588.131[天文地球—岩石学] P597.3[天文地球—地质学] P618.71