铅、锌流-熔分配实验结果及其在矿床成因研究中的应用

本文用铅、锌在花岗质硅酸盐熔体与流体间的分配实验确立了铅、锌的流-熔分配系数(D^V/L)与氯化钠摩尔浓度^mNaCl]（0-6mol/L）间的3个线性关系式以及D^V/L与F/Cl、K/Na摩尔比值间的变化关系。

THE EXPERIMENTAL RESULTS OF Pb AND Zn PARTITIONING BETWEEN FLUID AND MELT, AND THEIR APPLICATION TO THE RESEARCH ON MINERALIZATION

Three linear equations between D_Me^V/L and ^mNacl],i. e. In D_ph^V/L=1.15 In ^mNaCl]+0.85(0.1M≤^mNacl] ≤0.7M), In D_ph^V/L=0.7153 In ^mNaCl]+0.68(0.7M < ^mNacl]≤6M) and In D_Zn^V/L=0.46^mNaCl]-0.675(0.1M≤^mNaCl]≤6M, and the relationship of DMcVIL versus F/C1 or K/Na mole ratios have been established by the experiments of the partitioning of Pb and Zn between granitic silicate melt and aqueous fluid. These results have been used to quantitatively study some essential problems, such as tbe Pb-Zn mineralization possibility and scale in the system of granitic magma and hydrothe-rmal fluid, and the influence of the relative contents of alkali and volatiles on the Pb-Zn mineralization in the same system.The calculation and analysis show that in the system of granitic melt and hydrothermal fluid, the relative contents of Cl, F, H₂O, K and Na may all affect the partitioning of Pb and Zn between the melt and fluid. The increase of Cl (Na) fractions in the fluid is favourable for the fluid extraction of Pb and Zn from the granitic melt, but the increase of F (K) may more or less hinder this extraction. An appropriate content of water in the melt may contribute to the increase of concentrations and contents of Pb and Zn in the fluid.Fluids released during granitic magmatic crystallization or magma-boiling due to pressure reduction possess a mineralization potentiality, and those released during the early-middle stage have a greater potentiality. 4 km³ of granitic magma can provide the fluid with such an amount of metal material as capable of forming a medium-sized Pb-Zn deposit. If a larger volume of magma exists or the participation of metal material from other sources (such as strata) occurs, a larger Pb-Zn deposit may be formed.The most potential region for searching for large Pb-Zn deposits in Hunan is the area containing small hypabyssal, relatively Cl(Na)-rich calc-alkaline rock bodies of Diwa (geo-depression) stage and late Pelaeozoic platform carbonate strata.