甘肃毕家山铅锌矿床成矿地球化学特征

本文系统地研究了甘肃西成铅锌矿田毕家山矿床的成矿地球化学条件、矿床成因和成矿物质来源。研究结果表明:(1)该区成矿金属物质主要取自基底地层,而不是含矿层。地层地球化学和铅同位素研究都证实了这一论点;(2)该矿床矿石硫主要取自海水硫酸盐的还原硫;(3)矿床成矿流体的水主要来源于渗流加热的大气降水和部分回灌的海水;(4)该矿床应属于同生热液沉积-动力分异热液强改造型层控铅锌矿床。本文并建立了该矿床的成矿模式,以便直观地了解该矿床的成矿地球化学条件。

GEOCHEMICAL CHARACTERISTICS OF METALLIZATION OF BIJIASHAN LEAD-ZINC DEPOSIT, GANSU PROVINCE

This paper deals systematically with the geochemical condition of metallization, gene- sis and the ore-forming material source of Bijiashan Pb-Zn deposit in the Xicheng orefield of Gansu province, through which the following conclusions have been reached: (1) the ore-forming metals in this area are mainly derived from the basement strata and not from the ore-bearing strata (the Middle Devonian ). this view has been proved by the systematic studies of the stratigraphic and lead isotopic geochemistries; (2) the ore sulfur of this de posit is mainly derived from marine sulphate through blogenic reduction; (3) the water of the mineralizing fluid of the deposit is derived from the heated infiltrating meteoric water and partially from the recharged sea water; (4) Bijiashan deposit should belong to the syn- genetic hydrothermal deposition and the dynamic differential hydrothermal strong re worked metallizing stratabound Pb-Zn deposit. Finally, the model of metallogenic process of this deposit has been found to show di rectly the geochemical condition of metallization of this deposit.