Geochemical Characteristics of Magnetite from Washan Iron Deposit in Ningwu Ore District and Its Constraints on Ore-Forming

详细信息   

• 责任者：Duan Chao (State Key Laboratory of Geological Processes and Mineral Resources ; School of the Earth Sciences and Resources ; China University of Geosciences ; Beijing 100083 ; China) ; Li Yanhe
• 刊名：Acta Petrologica Sinica
• 出版年：2012
• 卷期：28(1)
• 关键词：玢岩铁矿床 ; porphyrite iron deposit ; 磁铁矿 ; magnetite ; 元素地球化学 ; elements geochemistry ; 长江中下游成矿带 ; Metallogenic Belt of Middle and Lower Reaches of Yangtze River
• 页码：p.243-257
• 图表：10 illus., 2 tables, 64 refs.
• 分类号：1001
• issnNo：ISSN1000-0569
• isbnNo：CN11-1922/P

摘要

 Washan iron deposit is a typical porphyry-type iron deposit,with a multi-stage ore-forming process.It displays the iron mineralization evolution of the Washan ore field.Based on the detailed field geological investigation,mineralogy and petrology study, the magnetite formation is divided into four stages,namely,disseminated magnetite,magnetite in breccia,coarse-grained vein magnetite and pegmatitic vein magnetite.In situ electron microprobe and LA-ICP-MS analysis of the magnetite from Washan iron deposit show that with the evolution of mineralization,the contents of Ti,Mn,V in magnetite are consistent;the Al and Mg contents increased;the contents of Ga,Sn and high field strength elements(Zr,Hf,Nd,Ta)change in a small range;from magnetite in breccia to pegmatitic vein magnetite,Co content gradually increased and Sc decreased gradually.The compositions of magnetite in various stages indicate that the process of magnetite mineralization has a continuous evolution with a similar source.Combined with previous studies,the mineralization formed from the iron-rich melt in the later of magmatic evolution.The large-scale iron precipitation triggered by cryptoexplosion and the corresponding breccia pipes provide available space for the mineralization.The disseminated ores and brecciated ores formed in the early stage.With the magmatic-hydrothermal evolution,magnetite showed more hydrothermal likely signature in the later stage.