辽西八家子铅锌矿元素地球化学及矿床成因探讨

由接触带向远离接触带元素组合由高温向低温演化,矿石及矿物中微量元素地球化学特征与接触交代矿床一致,微量元素对黄铁矿的聚类分析表明成矿热液主要来自黑云石英闪长岩,黄铁矿中微量元素主成分分析也表明成矿物质主要来自岩体,有部分是围岩提供,成矿过程是多阶段的,可分为氧化物阶段、硫化物阶段和硫酸盐—碳酸盐阶段。

A STUDY ON THE GEOCHEMISTRY AND ORE GENESIS IN BAJIAZI LEAD-ZINC DEPOSIT

The Bajiazi lead-zinc deposit, located in northwest Liaoning province, occurs at the contact between the Yanshanian biotitequartz diorite and dolomite of Sinian Gaoyuzhuang formation as well as in the NW-trending fault zone. And the biotite-quartz diorite must have played an important role in mineralization.After studying the variation of contents and assemblages for metallogenic and trace elements, It is noted that the contents of Cu, Fe, decreased and Pb, Zn,Ag,Mn increased in ores, the assemblages of metallogenic elements changed from Fe-Mo to Fe-Cu-Pb-Zn and Pb-Zn-Ag, from the contact toward the country rock far from the contact. Along with the increasing of Pb-Zn content in ores the content of MnO increased. The cluster analysis and major elements analysis show that the ore materials come mainly from biotite-quartz diorite, but some of them from Sinian Gaoyuzhuang dolomite. The metallogenic process may be devided into magnetite, quartz-sulfide and carbonatesuff ate stages.The metallogenic liquor came from biotite-quartz diorite and had moved from contact to far from contact along NW trending fault zone. Except physicochemical conditions such as temperature, pressure ,etc., which controlled the zoning of elements, the geochemical characteristics of elements themselves is also an important factor. The Fe among ore elements has both oxyphile and sulfophile properties, the oxide occured at the contact at the condition of high fo2 in early stage, and the sulfide took the place of oxide when fo2 decreased and fs2 increased as the ore liquor evolved and so formed the oxide (magnetite)and the sulfide(pyrite) zoning.In addition because of the difference of the sulfophile character and the stability of Fe, Zn, Pb in liquor, a further zoning of sulfide, i.e.the pyrite zone, Pb-Zn zone were formed.