Petrogenesis of rodingites along the northern margin of the North China Craton: Constraints from zirconology and whole-rock geochemistry  

作　　者：Jing RAN Hao WANG Jinhui YANG Yaoqi YAN Yusheng ZHU Baoquan ZHOU 

机构地区：[1]State Key Laboratory of Lithospheric and Environmental Coevolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [2]College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Science China Earth Sciences》2025年第3期750-767,共18页中国科学(地球科学英文版)

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 42322203 & 42288201);the Chinese Academy of Sciences (Grant Nos. 2020068 & XDB0710000)。

摘　　要：Rodingite is a metasomatic product formed from various rock types by aqueous fluids, providing a direct record of lithosphere-hydrosphere interactions and serving as a key carrier of surface water into Earth's deep interior(water content >1.5wt.%). Determining the properties of metasomatic fluids is crucial for understanding the petrogenesis of rodingites. In this study,we conducted a detailed study of mineral inclusions, U-Pb ages, trace elements, and Hf-O isotopes of zircon, as well as wholerock geochemical and Sr-Nd-Hf isotopic data on rodingites and associated felsic alkaline veins/dikes along the northern margin of the North China Craton(NMNCC), with aims to elucidate their formation ages, petrogenesis, and geodynamic settings. The results show that zircons from syenite and albite syenite veins/dikes exhibit clear oscillatory zoning, a wide range of Th/U ratios(0.0001–4.073), low concentrations of rare-earth elements(REEs), and low crystallization temperatures(<600℃). These characteristics suggest that the zircons crystallized from fluids separated from late-stage melts during magma evolution. Consequently, the zircon U-Pb ages obtained through Secondary Ion Mass Spectrometry(SIMS) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry(LA-ICPMS) analyses(389.1±3.5 to 390.2±1.6 Ma) record the timing of hydrothermal fluid activity. Zircons within the rodingites contain grandite, hematite, and aqueous fluid inclusions, indicating their formation during rodingitization, with an oxidizing, water-rich fluid acting as the metasomatic agent. SIMS and LA-ICPMS analyses of these zircons yielded U-Pb ages of 388.1±3.9 and 388.6±4.6 Ma, which register the formation ages of the rodingites. Both the syenite and albite syenite samples display high total alkali contents(9.9–13.9 wt.%), consistent initial Sr isotopic ratios(0.7047–0.7051),negative εNd(t)(-10.1 to-8.5) and εHf(t)(-13.9 to-13.7) values, and slightly elevated zircon δ^(18)O values(6.20‰±0.18‰)compared to mantle zircon. These charact

关 键 词：North China Craton RODINGITE SYENITE INCLUSIONS Zircon U-Pb age Sr-Nd-Hf-O isotopes 

分 类 号：P58[天文地球—岩石学]