长江中下游某些火山岩铁矿微量元素的地球化学 |
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ON GEOCHEMISTRY OF TRACE ELEMENTS OF SEVERAL PORPHYRITE IRON DEPOSITS ALONG THE MIDDLE LOWRE CHANGJIANG VALLEY |
This paper deals with trace elements in iron deposits and their altered country rocks inthe volcanic area: statistical analysis is applied to discover the rules governing the migrationsof trace elements and trace element groups. Detailed study shows that the trace element groupsdistribute in the following succession (from outside toward the ore body):1. First chalcophile element group-Cu. Zn and Mn;2. (Ti. V) and Sr;3. Second chalcophile element group-Pb. and (Ag, Cu);4. Co. Ni and Mo, near the iron ore body. The cause of trace element zoning is that: as trace elements migrate in solution its zoning depends upon the volatility of compounds of trace elements. The sequence of volatility which ranks from high to low, lgH2O=+3, lgHCl=+1, lg∑S=1 and 427℃, is given as follow: Sn-Zn-Pb-Mn-Fe-Cu-Mo-Ag As trace elements are precipitaled from solution their zoning depends upon the solubility product of the sulfides of these trace elements in aqueous solution. This is a sequence of solubility product constants, starting with the most soluble (at 0℃-400℃) ZnS>PbS>CuS>CuS2>AgS In addition, analyzing the rules governing the migrations of trace elements indicates that the metals in the iron ore body are concentrated by metasomatism, which causes the withdraw of iron and trace elements from host rocks and forms ore body. |
ZHANG Rong-hua,LIU Long-long,LU Cheng-qing.1979.ON GEOCHEMISTRY OF TRACE ELEMENTS OF SEVERAL PORPHYRITE IRON DEPOSITS ALONG THE MIDDLE LOWRE CHANGJIANG VALLEY[J].Acta Geoscientica Sinica,1(1):83-103. |
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