山西省袁家村铁矿成矿时代及成矿环境  

Metallogenic Age and Metallogenic Environment of Yuanjiacun Iron Deposit in Shanxi Province

作　　者：李家掀 胡天杨 刘磊[1,2] Li Jiaxian;Hu Tianyang;Liu Lei(Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring,Ministry of Education,Central South University,Changsha,410083,China;School of Geosciences and Info-Physics,Central South University,Changsha 410083,China)

机构地区：[1]中南大学有色金属成矿预测与地质环境监测教育部重点实验室,湖南长沙410083 [2]中南大学地球科学与信息物理学院,湖南长沙410083

出　　处：《地球科学》2023年第12期4404-4426,共23页Earth Science

基　　金：国家自然科学基金面上项目(No.41972198)。

摘　　要：为了进一步约束袁家村铁矿成矿年龄和成矿作用,揭示其对古海洋环境的指示,对采集自袁家村铁矿的BIFs样品进行碎屑锆石U-Pb年龄测定、全岩主微量元素分析及赤铁矿原位微量元素分析.其碎屑锆石U-Pb年龄可将袁家村铁矿沉积时代约束在2200~2235 Ma.主微量元素特征表明其受陆源碎屑干扰较小,成矿物质主要来源于海水与热液的混合,并且沉积过程中存在河流输入铁源的可能性.袁家村铁矿沉积在大氧化事件末期,其稀土配分模式特征存在明显的分组,同时存在负Ce异常和微弱的正Ce异常指示一个还原和氧化并存的环境,表明当时的古海洋环境特征为氧化还原分层的状态.说明大氧化事件后古海洋环境发生巨变,海水发生了一定程度的氧化,从原先单一的还原环境转变成了氧化还原分层的状态.In order to restrict the age and mineralization of the Yuanjiacun iron deposit and reveal its implications for the paleomarine environment,it determined the detrital zircon U-Pb chronology,major and trace elements of whole rock and trace elements of hematite for BIFs samples which collected from the Yuanjiacun iron deposit.Its detrital zircon U-Pb age constrains the sedimentary age of Yuanjiacun iron ore between 2200 and 2235 Ma.The characteristics of major and trace elements indicate that it is a relatively pure sediment and formed by the mixing of seawater and high temperature hydrothermal fluid.And the river input may be one of iron sources during the deposition process.Yuanjiacun iron deposit was formed at the end of the GOE.There are obvious grouping of REE distribution pattern characteristics in Yuanjiacun iron deposit,as well as negative Ce anomaly and slight positive Ce anomaly.This agrees with a reductive and oxidative environment,indicating that the paleomarine environment at that time was characterized by redox stratification.These features suggest a dramatic change in the paleo-marine environment after the GOE,with some degree of oxidation occurring in seawater and shifting from the original single reducing environment to a redox stratified state.

关 键 词：大氧化事件 古海洋环境演化 袁家村铁矿 赤铁矿微量元素 碎屑锆石 矿床 

分 类 号：P618.31[天文地球—矿床学]