河南舞阳经山寺铁矿床地球化学特征及其地质意义  

Geochemical characteristics of Jingshansi iron deposit in Wuyang, Henan Province, and their geological significance

作　　者：刘清泉[1,2,3,4] 李永峰 罗正传 谢克家 黄自力 

机构地区：[1]中南大学有色金属成矿预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 [3]河南省有色金属矿产探测工程技术研究中心,河南郑州450016 [4]河南省有色金属地质勘查总院,河南郑州450052

出　　处：《矿床地质》2014年第4期697-712,共16页Mineral Deposits

基　　金：中国地质调查局河南省舞阳新蔡铁矿整装勘查区关键基础地质研究(编号:12120114035101);河南省国土资源地质矿产科技攻关项目(编号:2010_61_4)联合资助

摘　　要：河南经山寺铁矿床位于华北板块南缘,矿体形态为似层状和透镜状,铁建造以条带状铁矿石为主,含有少量的块状矿石,其顶、底板围岩及矿体夹层主要为太华群铁山庙组大理岩.矿床地球化学分析结果表明,本区条带状铁建造是与海相火山沉积有关的前寒武纪火山沉积变质型铁矿.Sr/Ba平均值20.55,Ti/V平均值104.24,Ni/Co平均值2.31,Y/Ho平均值62.67,具La的正异常（La/La＊=0.807～1.564）,Eu的正异常（Eu/Eu＊=1.246～2.821）,Y的正异常（Y/Y＊=2.426～3.310）,反映出经山寺条带状铁矿床形成于火山热液和海水混合的环境.极低的Zr、Hf、Th含量,表明陆源碎屑物质对BIF的贡献极少.无明显Ce负异常（Ce/Ce＊ =0.809～0.955）,揭示条带状铁建造沉积于海水缺氧环境.流体包裹体均一温度主要集中在150～320℃,成矿流体具有低盐度[w（NaCleq）=2.07％ ～18.80％]、低密度（0.846～0.979 g/cm3）特征,流体包裹体成分显示成矿热液是一种低盐度的Na＋、C1-型水,并含有较高的CO2.经山寺铁矿床经历了海底火山喷流沉积和区域变质作用2个成矿期,成矿流体具多源性,且发生过强烈的不混溶作用,影响铁质发生进一步的迁移和富集.The Jingshansi iron deposit in Henan Province is located in the southeastern part of the North China craton. The orebodies occur in nearly bedded and lenticular forms, and iron ores are predominantly banded in shape, with a small amount of massive ore. Marbles of Tieshanmiao Formation in Taihua Group constitute main wall rocks and intercalations among the orebodies. Geochemical analysis indicates that the Jingshansi banded iron formation belongs to the Precambrian volcanic-sedimentary metamorphic iron deposit, and chemical analvses show that the iron ores are characterized by the data Sr/Ba = 20.55, Ti/V = 104.24, Ni/Co = 2.31, Y/Ho = 62.67, positive anomaly of La （La/La＊ = 0. 807 -- 1. 564）, positive anomaly of Eu （ Eu/Eu＊ = 1.246 - 2.821 ） and positive anomaly of Y （Y/Y＊ = 2.426--3.310） with generally low concentrations of Zr, Hf, Th, suggesting that the ore-forming materials ware derived from the intermixture of volcanic kiydrothermal solution and seawa- ter, whereas crustal materials contributed very little to the volcanic-sedimentary process. The negative anomaly of Ce indicates anoxic condition in the local seawater. The homogenization temperatures of fluid inclusions vary in the range of 150- 320~, implying that the ore-forming fluid was of low salinity （ w （NaC~） = 2.07 % 18.80%） and low density （0.846--0.979 g/cm3）. Components of fluid inclusions show that mineralized hy- drothermal fluid was low salinity water with Na＋, （21- and some CO2. The Jingshansi iron deposit underwent the ferrosilicon sedimentary deposition stage followed by further enrichment during the late regional metamorphic process. The ore-forming fluids were characterized by multi-sources and exhibited immiscibility phenomena which influenced the migration and enrichment of iron.

关 键 词：地球化学 条带状铁建造 流体包裹体 经山寺铁矿 河南 

分 类 号：P618.31[天文地球—矿床学]