河南省经山寺铁矿床成矿物质来源探讨

Discussion on Ore-forming Material Source of Jingshansi Iron Deposit in Henan Province

对经山寺铁矿主量、微量和稀土元素地球化学特征进行了分析,并与国内该类型铁矿进行了对比,探讨了其成矿物质来源.经山寺铁矿的化学成分主要由Fe2O3、FeO、SiO2组成,Al2O3和TiO2含量非常低,微量元素Sc、V、Cr等含量也比较低,指示其形成时极少受到陆源碎屑物质的混染;矿石的w（Sr）/w（Ba）值为3.37 ～ 52.20,均大于1,与海相-热液沉积物w（Sr）/w（Ba）值一致;w（SiO2）/w（Al2O3）值为48.35 ～ 75.49,指示经山寺铁矿与火山沉积作用有关;经PAAS标准化后,稀土元素的配分模式表现为重稀土元素富集,轻稀土元素亏损,La、Eu、Y正异常,较高的δY/δHo值（55.96 ～75.29）及δLa/δYb＜1,指示矿石稀土元素可能来自海水和高温海底热液的混合溶液.综合研究认为经山寺铁矿的成矿物质来源于海底火山热液和海水的混合.

The geochemical characteristics of the main elements,trace elements and rare earth elements of Jingshansi iron deposit are analyzed. Through comparing with the same kind of iron deposits at domestic, the ore-forming material source of this deposit is discussed. Jingshansi iron deposit mainly consists of Fe2 O3, FeO and SiO2 with rather low contents of Al2O3, TiO2, and trace elements Sc, V, Cr, which indicates that terrigenous clast materials contributed little to the ore-forming process. The w （Sr）/w （Ba） value among the mineral is from 3.37 to 52.20, all over 1, which is in accordance with that of marine-hydrother- mal sediments. The value of w（ SiO2 ）/w（ Al2 O3 ） is from 48.35 to 75.49, indicating that Jingshansi iron deposit is related to the volcanic sedimentation. After PAAS standardization, the distribution patterns of rare earth elements show up as enrichment of heavy rare earth elements, deficit of light rare elements and positive anomaly of La, Eu, Y, high value of 8Y/$Ho from 55.96 to 75.29 and the value of 8La/SYb less than 1 ,which reflect that rare earth elements maybe come from the mixed solution of seawater and high temperature submarine hydrothermal solution. Therefore,it is considered that the ore-forming material source of Jingshansi iron deposit derives from the intermixture of submarine volcanic hvdrothermal solution and seawater.