北秦岭伟晶岩型高纯石英矿床铌钽铁矿和白云母同位素年代学及其地质意义
Isotopic dating of columbite—tantalite and muscovite from pegmatite-type high-purity quartz deposit in North Qinling Mountains and geological implications
摘要
Abstract
Objectives:High-purity quartz ore,as a new mineral species,serves as an important raw material for the development of modern high-tech industries.The discovery of the Longquanping high-purity quartz deposit in the North Qinling belt represents a significant breakthrough in China's exploration of pegmatite-type high-purity quartz deposits,but its genetic mechanism remains unclear. Methods:Based on detailed studies of ore deposit geological characteristics and petrography,columbite—tantalite and muscovite from the No.10 high-purity quartz pegmatite in the Longquanping deposit were selected to carry out in-situ U—Pb,Rb—Sr,and 40Ar—39Ar isotope geochronological research,aiming to constrain the formation age,metallogenic geological setting,and post-ore metamorphic modification history of the high-purity quartz deposit. Results:The results show that the U—Pb age of columbite—tantalite from the No.10 pegmatite vein at the Longquanping deposit is 422.1±2.8 Ma,which is essentially consistent with the peak mineralization period(430～410 Ma)of rare-metal pegmatites in the region.These pegmatites were likely formed in a post-collisional extensional setting.The 40Ar—39Ar and in-situ Rb—Sr ages of muscovite are 330.5±3.2 Ma and 306.0±15.0 Ma,respectively,which are significantly later than the columbite—tantalite U—Pb age(422.1 Ma)but consistent with the previously reported metamorphic thermal event of 320～300 Ma in the North Qinling region.This indicates that the 40Ar—39Ar and Rb—Sr isotopic systems in the pegmatite were reset during a later metamorphic event,thereby recording the metamorphic modification history experienced by the high-purity quartz pegmatite after its formation. Conclusions:Combined with petrographic characteristics of quartz,it is demonstrated that the Longquanping high-purity quartz pegmatite vein is similar to the pegmatite-type high-purity quartz deposits in the world,such as the Spruce Pine deposit in the United States and the Tysfjord deposit in Norway.After the formation of pegmatites,these deposits underwent multiple stages of metamorphic modification,leading to deformation and dynamic recrystallization of quartz,which facilitated the formation of high-purity quartz.Therefore,post-formation metamorphic modification may be a critical factor for the formation of pegmatite-type high-purity quartz deposits.关键词
铌钽铁矿U—Pb年龄/白云母原位Rb—Sr年龄/白云母原位40Ar—39Ar年龄/高纯石英/伟晶岩/龙泉坪矿床/北秦岭Key words
columbite—tantalite U—Pb age/muscovite Rb—Sr age/muscovite 40Ar—39Ar age/high-purity quartz/pegmatite/Longquanping deposit/North Qinling Mountains引用本文复制引用
贾龙,樊献科,张海啟,朱黎宽,王红杰,田明君,于得水,王守敬..北秦岭伟晶岩型高纯石英矿床铌钽铁矿和白云母同位素年代学及其地质意义[J].地质论评,2026,72(5):1411-1430,20.基金项目
本文为科技部国家重点研发计划项目(编号:2024YFC2910101)、国家自然科学基金委地质联合基金资助项目(编号:U2344206)、中国地质调查局地质调查项目(编号:DD20250208807)和矿冶科技集团有限公司"揭榜挂帅"科研基金资助项目(编号:JTKY202427822)的成果. This study was supported by:the National Key Research and Development Program of China:"Metallogenic Mechanism and Key Purification Technologies of High-Purity Quartz Raw Material Deposits"(No.2024YFC2910101) （编号:2024YFC2910101）
the National Natural Science Foundation of China—Geological Survey Joint Fund:"Study on the Formation Mechanism and Impurity Occurrence of Pegmatite-Hosted High-Purity Quartz in the Eastern North Qinling"(No.U2344206) （No.U2344206）
the Geological Survey Project of China Geological Survey:"Investigation on Metallogenic Geological Setting of Pegmatite-Type High-Purity Quartz Deposits in the North Qinling and Altai Regions"(No.DD20250208807) （No.DD20250208807）
and the"Unveiling and Leading"Research Fund Project of Beijing General Research Institute of Mining and Metallurgy Technology Group(No.JTKY202427822) （No.JTKY202427822）
