Na-F solutions with different pH were allowed to react under flow conditions with limestone, dolomite and siderite at 300 and 400℃ at 500 bars, in order to understand the geochemical characteristics of the interaction between rock and F-bearing hydrothermal solutions. The mineralogical and chemical composition of these carbonate rocks was studied by chemical analysis, XRD and SEM/EDAX before and after reaction with Na-F solutions. Based on an approximate thermodynamic calculation the formation of alteration phases is discussed. The pH value at room conditions and the contents of K, Na, Ca, Mg, Fe, F, SiO2 and total dissolved CO2 in solution after interaction with carbonate rocks were determined. From solution chemistry data, it is found that the amount of Na and F in the reacted solutions seemed to have roughly similar fluctuations with time, and hence, carbonate might be an effective precipitating agent for Fe in hydrothermal solutions. The present experimental study demonstrates that hydrothermal metasomatism played a very important role in the formation of the Baiyun Ebo iron deposit.

The carboxylate (formate, acetate, propionate and oxalate) and common inorganic anions (F-, Cl- and SO2-4) compositions for aqueous fluid inclusion leachates from 17 mineral samples collected from various deposits have been determined using ion chromatography in conjunction with microthermometric measurements on the fluid inclusions of their host minerals. The minerals, quartz, fluorite, barite, beryl and a fewore' minerals (wolframite, pyrite and galena), came from hydrothermal vein-type deposits in felsic igneous rocks or Archean metamorphic rocks. The results indicate that short-chain carboxylates are common components in hydrothermal fluids and can be present in considerable amounts. Formic acid (as formate) is the dominant species over other carboxylic acids. The present study raises new questions about the origin and geochemical significance of carboxylates in hydrothermal ore-forming processes.

本文于300℃，500bar时，用金袋式热液设备测定了MH（磁铁矿+赤铁矿）缓冲组合在HCl水溶液中的溶解度.计算了热水溶液中离子的活度，并用岭回归和叠代的方法处理实验数据，与多种可能的Fe存在形式模型拟合。结果表明，实验溶液中的 Fe 主要成 FeOH+存在。求得MH组合溶解反应的平衡常数K=57.161。计算了ΔG0f，FeOH+＝260.3kJ/mol。300℃时，在地质上可能的pH和氯化物浓度条件下，热液中的Fe主要成羟络合物存在。