辽宁弓长岭铁矿床磁铁富矿成因的年代学及单矿物微量元素地球化学约束

弓长岭铁矿床是辽宁鞍本地区大型BIFs型铁矿，其中弓长岭铁矿床二矿区以产出磁铁富矿而闻名，但关于该区磁铁富矿的形成时代及成因机制目前还存在较大争议。本项目拟采用单矿物逐级酸淋滤Pb-Pb等时线法，分别对条带状铁建造（贫矿）、磁铁富矿、富矿围岩进行年代学研究，以期获得条带状铁建造、磁铁富矿的形成时代，以及围岩的变质作用时代；同时借助LA-ICP-MS技术对条带状铁建造和富铁矿石中的磁铁矿，及富矿围岩中的石榴石进行分析，对比两类磁铁矿微量元素组成异同，并进一步查明石榴石的微量元素分布特征；最后，通过对比条带状铁建造、磁铁富矿的形成时代，以及围岩的变质作用时代，结合单矿物的元素地球化学研究，为弓长岭铁矿床二矿区磁铁富矿成因提供约束。本项目的研究不仅可以深化对弓长岭铁矿床二矿区磁铁富矿成因的认识，而且对我国其它与BIFs相关的富铁矿的研究具有重要借鉴意义。

The Gongchangling iron deposit located in the Anshan-Benxi area of Liaoning Province is a large-scale BIFs-type iron deposit, and the No.2 mining area of the Gongchangling iron deposit is famous for the production of high-grade iron ore. However, as to the formation age and genesis of the high-grade iron ore, they are still unsolved problems which have been hotly debated. In this project, the Pb-stepwise leaching experiment will be carried out to obtain the formation age of BIFs (low-grade iron ore) and high-grade iron ore, as well as the metamorphic age of the wall-rock of high-grade iron ore. And the chemical composition of magnetite from BIFs and high-grade iron ore, and garnet from wall-rock of high-grade iron ore will be measured by in-situ LA-ICP-MS analysis, the geochemical characteristics of magnetite from BIFs will be compared to that from high-grade iron ore, and the minor element distribution of garnet will be ascertained. These results will provide new evidences to the genesis of high-grade iron ore by comparing the formation age of BIFs and high-grade iron ore with the metamorphic age of the wall-rock of high-grade iron ore, and the geochemical characteristics of single minerals. This research will not only deepen the understanding of the genesis of high-grade iron ore in the Gongchangling No.2 mining area, but also have valuable reference to the research on BIFs-related high-grade iron ore in other area of China.